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Kimberly WT, Sorby-Adams AJ, Webb AG, Wu EX, Beekman R, Bowry R, Schiff SJ, de Havenon A, Shen FX, Sze G, Schaefer P, Iglesias JE, Rosen MS, Sheth KN. Brain imaging with portable low-field MRI. NATURE REVIEWS BIOENGINEERING 2023; 1:617-630. [PMID: 37705717 PMCID: PMC10497072 DOI: 10.1038/s44222-023-00086-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/06/2023] [Indexed: 09/15/2023]
Abstract
The advent of portable, low-field MRI (LF-MRI) heralds new opportunities in neuroimaging. Low power requirements and transportability have enabled scanning outside the controlled environment of a conventional MRI suite, enhancing access to neuroimaging for indications that are not well suited to existing technologies. Maximizing the information extracted from the reduced signal-to-noise ratio of LF-MRI is crucial to developing clinically useful diagnostic images. Progress in electromagnetic noise cancellation and machine learning reconstruction algorithms from sparse k-space data as well as new approaches to image enhancement have now enabled these advancements. Coupling technological innovation with bedside imaging creates new prospects in visualizing the healthy brain and detecting acute and chronic pathological changes. Ongoing development of hardware, improvements in pulse sequences and image reconstruction, and validation of clinical utility will continue to accelerate this field. As further innovation occurs, portable LF-MRI will facilitate the democratization of MRI and create new applications not previously feasible with conventional systems.
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Affiliation(s)
- W Taylor Kimberly
- Department of Neurology and the Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Annabel J Sorby-Adams
- Department of Neurology and the Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Andrew G Webb
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Rachel Beekman
- Division of Neurocritical Care and Emergency Neurology, Department of Neurology, Yale New Haven Hospital and Yale School of Medicine, Yale Center for Brain & Mind Health, New Haven, CT, USA
| | - Ritvij Bowry
- Departments of Neurosurgery and Neurology, McGovern Medical School, University of Texas Health Neurosciences, Houston, TX, USA
| | - Steven J Schiff
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA
| | - Adam de Havenon
- Division of Vascular Neurology, Department of Neurology, Yale New Haven Hospital and Yale School of Medicine, New Haven, CT, USA
| | - Francis X Shen
- Harvard Medical School Center for Bioethics, Harvard law School, Boston, MA, USA
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
| | - Gordon Sze
- Department of Radiology, Yale New Haven Hospital and Yale School of Medicine, New Haven, CT, USA
| | - Pamela Schaefer
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Juan Eugenio Iglesias
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Centre for Medical Image Computing, University College London, London, UK
- Computer Science and AI Laboratory, Massachusetts Institute of Technology, Boston, MA, USA
| | - Matthew S Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Kevin N Sheth
- Division of Neurocritical Care and Emergency Neurology, Department of Neurology, Yale New Haven Hospital and Yale School of Medicine, Yale Center for Brain & Mind Health, New Haven, CT, USA
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Thakkar RN, Kioutchoukova IP, Griffin I, Foster DT, Sharma P, Valero EM, Lucke-Wold B. Mapping the Glymphatic Pathway Using Imaging Advances. J 2023; 6:477-491. [PMID: 37601813 PMCID: PMC10439810 DOI: 10.3390/j6030031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2023] Open
Abstract
The glymphatic system is a newly discovered waste-clearing system that is analogous to the lymphatic system in our central nervous system. Furthermore, disruption in the glymphatic system has also been associated with many neurodegenerative disorders (e.g., Alzheimer's disease), traumatic brain injury, and subarachnoid hemorrhage. Thus, understanding the function and structure of this system can play a key role in researching the progression and prognoses of these diseases. In this review article, we discuss the current ways to map the glymphatic system and address the advances being made in preclinical mapping. As mentioned, the concept of the glymphatic system is relatively new, and thus, more research needs to be conducted in order to therapeutically intervene via this system.
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Affiliation(s)
- Rajvi N. Thakkar
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | | | - Ian Griffin
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Devon T. Foster
- College of Medicine, Florida International University, Miami, FL 33199, USA
| | | | | | - Brandon Lucke-Wold
- Department of Neurosurgery, University of Florida, 1600 SW Archer Rd., Gainesville, FL 32610, USA
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Wu D, Turnbill V, Lee HH, Wang X, Ba R, Walczak P, Martin LJ, Fieremans E, Novikov DS, Northington FJ, Zhang J. In vivo Mapping of Cellular Resolution Neuropathology in Brain Ischemia by Diffusion MRI. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.08.552374. [PMID: 37609182 PMCID: PMC10441332 DOI: 10.1101/2023.08.08.552374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Non-invasive mapping of cellular pathology can provide critical diagnostic and prognostic information. Recent developments in diffusion MRI have produced new tools for examining tissue microstructure at a level well below the imaging resolution. Here, we report the use of diffusion time ( t )-dependent diffusion kurtosis imaging ( t DKI) to simultaneously assess the morphology and transmembrane permeability of cells and their processes in the context of pathological changes in hypoxic-ischemic brain (HI) injury. Through Monte Carlo simulations and cell culture organoid imaging, we demonstrate feasibility in measuring effective size and permeability changes based on the peak and tail of t DKI curves. In a mouse model of HI, in vivo imaging at 11.7T detects a marked shift of the t DKI peak to longer t in brain edema, suggesting swelling and beading associated with the astrocytic processes and neuronal neurites. Furthermore, we observed a faster decrease of the t DKI tail in injured brain regions, reflecting increased membrane permeability that was associated with upregulated water exchange upon astrocyte activation at acute stage as well as necrosis with disrupted membrane integrity at subacute stage. Such information, unavailable with conventional diffusion MRI at a single t, can predict salvageable tissues. For a proof-of-concept, t DKI at 3T on an ischemic stroke patient suggested increased membrane permeability in the stroke region. This work therefore demonstrates the potential of t DKI for in vivo detection of the pathological changes in microstructural morphology and transmembrane permeability after ischemic injury using a clinically translatable protocol.
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Zhong Z, Ryu K, Mao J, Sun K, Dan G, Vasanawala SS, Zhou XJ. Accelerating High b-Value Diffusion-Weighted MRI Using a Convolutional Recurrent Neural Network (CRNN-DWI). Bioengineering (Basel) 2023; 10:864. [PMID: 37508891 PMCID: PMC10376839 DOI: 10.3390/bioengineering10070864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/05/2023] [Accepted: 07/11/2023] [Indexed: 07/30/2023] Open
Abstract
PURPOSE To develop a novel convolutional recurrent neural network (CRNN-DWI) and apply it to reconstruct a highly undersampled (up to six-fold) multi-b-value, multi-direction diffusion-weighted imaging (DWI) dataset. METHODS A deep neural network that combines a convolutional neural network (CNN) and recurrent neural network (RNN) was first developed by using a set of diffusion images as input. The network was then used to reconstruct a DWI dataset consisting of 14 b-values, each with three diffusion directions. For comparison, the dataset was also reconstructed with zero-padding and 3D-CNN. The experiments were performed with undersampling rates (R) of 4 and 6. Standard image quality metrics (SSIM and PSNR) were employed to provide quantitative assessments of the reconstructed image quality. Additionally, an advanced non-Gaussian diffusion model was employed to fit the reconstructed images from the different approaches, thereby generating a set of diffusion parameter maps. These diffusion parameter maps from the different approaches were then compared using SSIM as a metric. RESULTS Both the reconstructed diffusion images and diffusion parameter maps from CRNN-DWI were better than those from zero-padding or 3D-CNN. Specifically, the average SSIM and PSNR of CRNN-DWI were 0.750 ± 0.016 and 28.32 ± 0.69 (R = 4), and 0.675 ± 0.023 and 24.16 ± 0.77 (R = 6), respectively, both of which were substantially higher than those of zero-padding or 3D-CNN reconstructions. The diffusion parameter maps from CRNN-DWI also yielded higher SSIM values for R = 4 (>0.8) and for R = 6 (>0.7) than the other two approaches (for R = 4, <0.7, and for R = 6, <0.65). CONCLUSIONS CRNN-DWI is a viable approach for reconstructing highly undersampled DWI data, providing opportunities to reduce the data acquisition burden.
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Affiliation(s)
- Zheng Zhong
- Departments of Radiology, Stanford University, Stanford, CA 94305, USA
- Center for Magnetic Resonance Research, Chicago, IL 60612, USA
| | - Kanghyun Ryu
- Departments of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Jonathan Mao
- Henry M. Gunn High School, Palo Alto, CA 94306, USA
| | - Kaibao Sun
- Center for Magnetic Resonance Research, Chicago, IL 60612, USA
| | - Guangyu Dan
- Center for Magnetic Resonance Research, Chicago, IL 60612, USA
| | | | - Xiaohong Joe Zhou
- Center for Magnetic Resonance Research, Chicago, IL 60612, USA
- Department of Radiology, Neurosurgery and Biomedical Engineering, University of Illinois Chicago, Chicago, IL 60607, USA
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Wong A, Bhuiyan MIH, Rothman J, Drew K, Pourrezaei K, Sun D, Barati Z. Near infrared spectroscopy detection of hemispheric cerebral ischemia following middle cerebral artery occlusion in rats. Neurochem Int 2023; 162:105460. [PMID: 36455748 PMCID: PMC10263189 DOI: 10.1016/j.neuint.2022.105460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/22/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
Timely and sensitive in vivo estimation of ischemic stroke-induced brain infarction are necessary to guide diagnosis and evaluation of treatments' efficacy. The gold standard for estimation of the cerebral infarction volume is magnetic resonance imaging (MRI), which is expensive and not readily accessible. Measuring regional cerebral blood flow (rCBF) with Laser Doppler flowmetry (LDF) is the status quo for confirming reduced blood flow in experimental ischemic stroke models. However, rCBF reduction following cerebral artery occlusion often does not correlate with subsequent infarct volume. In the present study, we employed the continuous-wave near infrared spectroscopy (NIRS) technique to monitor cerebral oxygenation during 90 min of the intraluminal middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats (n = 8, male). The NIRS device consisted of a controller module and an optical sensor with two LED light sources and two photodiodes making up two parallel channels for monitoring left and right cerebral hemispheres. Optical intensity measurements were converted to deoxyhemoglobin (Hb) and oxyhemoglobin (HbO2) changes relative to a 2-min window prior to MCAO. Area under the curve (auc) for Hb and HbO2 was calculated for the 90-min occlusion period for each hemisphere (ipsilateral and contralateral). To obtain a measure of total ischemia, auc of the contralateral side was subtracted from the ipsilateral side resulting in ΔHb and ΔHbO2 parameters. Infarct volume (IV) was calculated by triphenyl tetrazolium chloride (TTC) staining at 24h reperfusion. Results showed a significant negative correlation (r = -0.81, p = 0.03) between ΔHb and infarct volume. In conclusion, our results show feasibility of using a noninvasive optical imaging instrument, namely NIRS, in monitoring cerebral ischemia in a rodent stroke model. This cost-effective, non-invasive technique may improve the rigor of experimental models of ischemic stroke by enabling in vivo longitudinal assessment of cerebral oxygenation and ischemic injury.
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Affiliation(s)
- Ardy Wong
- Drexel University School of Biomedical Engineering, Science and Health Systems, Philadelphia, PA, USA
| | - Mohammad Iqbal Hossain Bhuiyan
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, PA, 15260, USA; Veterans Affairs Pittsburgh Health Care System, Geriatric Research, Education and Clinical Center, Pennsylvania, PA, 15260, USA; Department of Pharmaceutical Sciences, School of Pharmacy, University of Texas at El Paso, El Paso, TX, 79968, USA
| | | | - Kelly Drew
- Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, USA
| | - Kambiz Pourrezaei
- Drexel University School of Biomedical Engineering, Science and Health Systems, Philadelphia, PA, USA
| | - Dandan Sun
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, PA, 15260, USA; Veterans Affairs Pittsburgh Health Care System, Geriatric Research, Education and Clinical Center, Pennsylvania, PA, 15260, USA
| | - Zeinab Barati
- Barati Medical LLC, Fairbanks, AK, USA; Center for Transformative Research in Metabolism, Institute of Arctic Biology, University of Alaska Fairbanks, USA.
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Velikina JV, Jung Y, Field AS, Samsonov AA. High-resolution dynamic susceptibility contrast perfusion imaging using higher-order temporal smoothness regularization. Magn Reson Med 2023; 89:112-127. [PMID: 36198002 PMCID: PMC9617779 DOI: 10.1002/mrm.29425] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 08/03/2022] [Accepted: 08/05/2022] [Indexed: 01/12/2023]
Abstract
PURPOSE To improve image quality and resolution of dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI) by developing acquisition and reconstruction methods exploiting the temporal regularity property of DSC-PWI signal. THEORY AND METHODS A novel regularized reconstruction is proposed that recovers DSC-PWI series from interleaved segmented spiral k-space acquisition using higher order temporal smoothness (HOTS) properties of the DSC-PWI signal. The HOTS regularization is designed to tackle representational insufficiency of the standard first-order temporal regularizations for supporting higher accelerations. The higher accelerations allow for k-space coverage with shorter spiral interleaves resulting in improved acquisition point spread function, and acquisition of images at multiple TEs for more accurate DSC-PWI analysis. RESULTS The methods were evaluated in simulated and in-vivo studies. HOTS regularization provided increasingly more accurate models for DSC-PWI than the standard first-order methods with either quadratic or robust norms at the expense of increased noise. HOTS DSC-PWI optimized for noise and accuracy demonstrated significant advantages over both spiral DSC-PWI without temporal regularization and traditional echo-planar DSC-PWI, improving resolution and mitigating image artifacts associated with long readout, including blurring and geometric distortions. In context of multi-echo DSC-PWI, the novel methods allowed ∼4.3× decrease of voxel volume, providing 2× number of TEs compared to the previously published results. CONCLUSIONS Proposed HOTS reconstruction combined with dynamic spiral sampling represents a valid mechanism for improving image quality and resolution of DSC-PWI significantly beyond those available with established fast imaging techniques.
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Affiliation(s)
- Julia V. Velikina
- Department of RadiologyUniversity of Wisconsin‐Madison
MadisonWisconsinUSA
| | - Youngkyoo Jung
- Department of RadiologyUniversity of California‐DavisDavisCaliforniaUSA
| | - Aaron S. Field
- Department of RadiologyUniversity of Wisconsin‐Madison
MadisonWisconsinUSA
| | - Alexey A. Samsonov
- Department of RadiologyUniversity of Wisconsin‐Madison
MadisonWisconsinUSA
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Usuda K, Ishikawa M, Iwai S, Yamagata A, Iijima Y, Motono N, Matoba M, Doai M, Hirata K, Uramoto H. Pulmonary Nodule and Mass: Superiority of MRI of Diffusion-Weighted Imaging and T2-Weighted Imaging to FDG-PET/CT. Cancers (Basel) 2021; 13:cancers13205166. [PMID: 34680313 PMCID: PMC8533899 DOI: 10.3390/cancers13205166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 09/25/2021] [Accepted: 10/12/2021] [Indexed: 12/01/2022] Open
Abstract
Simple Summary Although diffusion-weighted imaging (DWI) can be valuable for differential diagnosis of lung cancer from benign pulmonary nodules and masses (PNMs), the diagnostic capability may not be perfect. This study’s purpose was to compare the diagnostic efficacy of 18-fluoro-2-deoxy-glucose positron emission tomography–computed tomography (FDG-PET/CT) and magnetic resonance imaging (MRI) of DWI and T2-weighted imaging (T2WI) in PNMs. There were 278 lung cancers and 50 benign PNMs that were examined by FDG-PET/CT and MRI. The sensitivity of the maximum standardized uptake value (SUVmax) was significantly lower than that of the apparent diffusion coefficient (ADC) and the T2 contrast ratio (T2 CR). The accuracy of SUVmax was significantly lower than that of ADC and that of T2 CR. The sensitivity and accuracy of MRI were significantly higher than those of FDG-PET/CT. MRI can replace FDG-PET/CT for differential diagnosis of PNMs. Abstract The purpose of this retrospective study was to compare the diagnostic efficacy of FDG-PET/CT and MRI in discriminating malignant from benign pulmonary nodules and masses (PNMs). There were 278 lung cancers and 50 benign PNMs that were examined by FDG-PET/CT and MRI. The T2 contrast ratio (T2 CR) was designated as the ratio of T2 signal intensity of PNM divided by T2 signal intensity of the rhomboid muscle. The optimal cut-off values (OCVs) for differential diagnosis were 3.605 for maximum standardized uptake value (SUVmax), 1.459 × 10−3 mm2/s for apparent diffusion coefficient (ADC), and 2.46 for T2 CR. Areas under the receiver operating characteristics curves were 67.5% for SUVmax, 74.3% for ADC, and 72.4% for T2 CR, respectively. The sensitivity (0.658) of SUVmax was significantly lower than that (0.838) of ADC (p < 0.001) and that (0.871) of T2 CR (p < 0.001). The specificity (0.620) of SUVmax was that the same as (0.640) ADC and (0.640) of T2 CR. The accuracy (0.652) of SUVmax was significantly lower than that (0.808) of ADC (p < 0.001) and that (0.835) of T2 CR (p < 0.001). The sensitivity and accuracy of DWI and T2WI in MRI were significantly higher than those of FDG-PET/CT. Ultimately, MRI can replace FDG PET/CT for differential diagnosis of PNMs saving healthcare systems money while not sacrificing the quality of care.
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Affiliation(s)
- Katsuo Usuda
- Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.I.); (S.I.); (A.Y.); (Y.I.); (N.M.); (H.U.)
- Shimada Hospital, Fukui 910-0855, Japan
- Correspondence: ; Tel.: +81-76-286-2211; Fax: +81-76-286-1207
| | - Masahito Ishikawa
- Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.I.); (S.I.); (A.Y.); (Y.I.); (N.M.); (H.U.)
| | - Shun Iwai
- Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.I.); (S.I.); (A.Y.); (Y.I.); (N.M.); (H.U.)
| | - Aika Yamagata
- Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.I.); (S.I.); (A.Y.); (Y.I.); (N.M.); (H.U.)
| | - Yoshihito Iijima
- Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.I.); (S.I.); (A.Y.); (Y.I.); (N.M.); (H.U.)
| | - Nozomu Motono
- Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.I.); (S.I.); (A.Y.); (Y.I.); (N.M.); (H.U.)
| | - Munetaka Matoba
- Department of Radiology, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.M.); (M.D.)
| | - Mariko Doai
- Department of Radiology, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.M.); (M.D.)
| | - Keiya Hirata
- MRI Center, Kanazawa Medical University Hospital, Ishikawa 920-0293, Japan;
| | - Hidetaka Uramoto
- Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa 920-0293, Japan; (M.I.); (S.I.); (A.Y.); (Y.I.); (N.M.); (H.U.)
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Meier EL, Sheppard SM, Goldberg EB, Kelly CR, Walker A, Ubellacker DM, Vitti E, Ruch K, Hillis AE. Dysfunctional Tissue Correlates of Unrelated Naming Errors in Acute Left Hemisphere Stroke. LANGUAGE, COGNITION AND NEUROSCIENCE 2021; 37:330-347. [PMID: 35665076 PMCID: PMC9159539 DOI: 10.1080/23273798.2021.1980593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 08/31/2021] [Indexed: 06/15/2023]
Abstract
Most naming error lesion-symptom mapping (LSM) studies have focused on semantic and/or phonological errors. Anomic individuals also produce unrelated word errors, which may be linked to semantic or modality-independent lexical deficits. To investigate the neural underpinnings of rarely-studied unrelated errors, we conducted LSM analyses in 100 individuals hospitalized with a left hemisphere stroke who completed imaging protocols and language assessments. We used least absolute shrinkage and selection operator regression to capture relationships between naming errors and dysfunctional brain tissue metrics (regional damage or hypoperfusion in vascular territories) in two groups: participants with and without impaired single-word auditory comprehension. Hypoperfusion-particularly within the parietal lobe-was an important error predictor, especially for the unimpaired group. In both groups, higher unrelated error proportions were associated with primarily ventral stream damage, the language route critical for processing meaning. Nonetheless, brain metrics implicated in unrelated errors were distinct from semantic error correlates.
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Affiliation(s)
- Erin L. Meier
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Shannon M. Sheppard
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Communication Sciences and Disorders, Chapman University, Irvine, CA
| | - Emily B. Goldberg
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Catherine R. Kelly
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Alexandra Walker
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
| | | | - Emilia Vitti
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Kristina Ruch
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Argye E. Hillis
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Cognitive Science, Johns Hopkins University, Baltimore, MD
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Portable, bedside, low-field magnetic resonance imaging for evaluation of intracerebral hemorrhage. Nat Commun 2021; 12:5119. [PMID: 34433813 PMCID: PMC8387402 DOI: 10.1038/s41467-021-25441-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
Radiological examination of the brain is a critical determinant of stroke care pathways. Accessible neuroimaging is essential to detect the presence of intracerebral hemorrhage (ICH). Conventional magnetic resonance imaging (MRI) operates at high magnetic field strength (1.5-3 T), which requires an access-controlled environment, rendering MRI often inaccessible. We demonstrate the use of a low-field MRI (0.064 T) for ICH evaluation. Patients were imaged using conventional neuroimaging (non-contrast computerized tomography (CT) or 1.5/3 T MRI) and portable MRI (pMRI) at Yale New Haven Hospital from July 2018 to November 2020. Two board-certified neuroradiologists evaluated a total of 144 pMRI examinations (56 ICH, 48 acute ischemic stroke, 40 healthy controls) and one ICH imaging core lab researcher reviewed the cases of disagreement. Raters correctly detected ICH in 45 of 56 cases (80.4% sensitivity, 95%CI: [0.68-0.90]). Blood-negative cases were correctly identified in 85 of 88 cases (96.6% specificity, 95%CI: [0.90-0.99]). Manually segmented hematoma volumes and ABC/2 estimated volumes on pMRI correlate with conventional imaging volumes (ICC = 0.955, p = 1.69e-30 and ICC = 0.875, p = 1.66e-8, respectively). Hematoma volumes measured on pMRI correlate with NIH stroke scale (NIHSS) and clinical outcome (mRS) at discharge for manual and ABC/2 volumes. Low-field pMRI may be useful in bringing advanced MRI technology to resource-limited settings.
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Liu G, Lu Y, Dai Y, Xue K, Yi Y, Xu J, Wu D, Wu G. Comparison of mono-exponential, bi-exponential, kurtosis, and fractional-order calculus models of diffusion-weighted imaging in characterizing prostate lesions in transition zone. Abdom Radiol (NY) 2021; 46:2740-2750. [PMID: 33388809 DOI: 10.1007/s00261-020-02903-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 12/01/2020] [Accepted: 12/06/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE To compare various models of diffusion-weighted imaging including mono-exponential, bi-exponential, diffusion kurtosis (DK) and fractional-order calculus (FROC) models in diagnosing prostate cancer (PCa) in transition zone (TZ) and distinguish the high-grade PCa [Gleason score (GS) ≥ 7] lesions from the total of low-grade PCa (GS ≤ 6) lesions and benign prostatic hyperplasia (BPH) in TZ. METHODS 80 Patients with 103 lesions were included in this study. Nine metrics [including apparent diffusion coefficient (ADC) derived from mono-exponential model, slow diffusion coefficient (Ds), fast diffusion coefficient (Df),, and f (the fraction of fast diffusion) from bi-exponential model; mean diffusivity (MD) and mean kurtosis (MK) from DK model; diffusion coefficient (D), fractional-order derivative in space (β), and spatial metric (μ) from FROC model] were calculated. Comparisons between BPH and PCa lesions as well as between clinically significant PCa (CsPCa) (GS ≥ 7, n = 31) and clinically insignificant lesions (Cins) (GS ≤ 6 and BPH, n = 72) of these metrics were conducted. Mann-Whitney U-test and receiver operating characteristic (ROC) analysis were used for statistical evaluations. RESULTS The areas under the ROC curve (AUC) values of β derived from FROC model were 0.778 and 0.853 in differentiating PCa from BPH and in differentiating CS (GS ≥ 7) from Cins (GS ≤ 6 and BPH), both were the highest compared to other metrics. The AUC value of β was significantly higher than that of ADC (P = 0.009) in differentiating CS from Cins, while the differentiation between BPH and PCa did not reach the statistical significance when comparing with ADC (P = 0.089). CONCLUSION Although no significant difference was found in distinguishing PCa from BPH, the metric β derived from FROC model was superior to other diffusion metrics in differentiation between CS and Cins in TZ.
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Affiliation(s)
- Guiqin Liu
- Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, 160 Pujian Road, Shanghai, 200127, China
| | - Yang Lu
- Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, 160 Pujian Road, Shanghai, 200127, China
| | | | - Ke Xue
- United Imaging Healthcare, Shanghai, China
| | | | - Jianrong Xu
- Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, 160 Pujian Road, Shanghai, 200127, China
| | - Dongmei Wu
- Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronics Science, East China Normal University, 3663 N. Zhongshan Road, Shanghai, 200062, China.
| | - Guangyu Wu
- Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, 160 Pujian Road, Shanghai, 200127, China.
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Karaman MM, Zhang J, Xie KL, Zhu W, Zhou XJ. Quartile histogram assessment of glioma malignancy using high b-value diffusion MRI with a continuous-time random-walk model. NMR IN BIOMEDICINE 2021; 34:e4485. [PMID: 33543512 DOI: 10.1002/nbm.4485] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/15/2021] [Indexed: 06/12/2023]
Abstract
The purpose of this study is to investigate the feasibility of using a continuous-time random-walk (CTRW) diffusion model, together with a quartile histogram analysis, for assessing glioma malignancy by probing tissue heterogeneity as well as cellularity. In this prospective study, 91 patients (40 females, 51 males) with histopathologically proven gliomas underwent MRI at 3 T. The cohort included 42 grade II (GrII), 19 grade III (GrIII) and 29 grade IV (GrIV) gliomas. Echo-planar diffusion-weighted imaging was conducted using 17 b-values (0-4000 s/mm2 ). Three CTRW model parameters, including an anomalous diffusion coefficient Dm , and two parameters related to temporal and spatial diffusion heterogeneity α and β, respectively, were obtained. The mean parameter values within the tumor regions of interest (ROIs) were computed by utilizing the first quartile of the histograms as well as the full ROI for comparison. A Bonferroni-Holm-corrected Mann-Whitney U-test was used for the group comparisons. Individual and combinations of the CTRW parameters were evaluated for the characterization of gliomas with a receiver operating characteristic analysis. All first-quartile mean CTRW parameters yielded significant differences (p-values < 0.05) between pair-wise comparisons of GrII (Dm : 1.14 ± 0.37 μm2 /ms; α: 0.904 ± 0.03, β: 0.913 ± 0.06), GrIII (Dm : 0.88 ± 0.21 μm2 /ms; α: 0.888 ± 0.01, β: 0.857 ± 0.06) and GrIV gliomas (Dm : 0.73 ± 0.22 μm2 /ms; α: 0.878 ± 0.01; β: 0.791 ± 0.07). The highest sensitivity, specificity, accuracy and area-under-the-curve of using the combinations of the first-quartile parameters were 84.2%, 78.5%, 75.4% and 0.76 for GrII and GrIII classification; 86.2%, 89.4%, 75% and 0.76 for GrIII and GrIV classification; and 86.2%, 85.7%, 84.5% and 0.90 for GrII and GrIV classification, respectively. Quartile-based analysis produced higher accuracy and area-under-the-curve than the full ROI-based analysis in all classifications. The CTRW diffusion model, together with a quartile-based histogram analysis, offers a new way for probing tumor structural heterogeneity at a subvoxel level, and has potential for in vivo assessment of glioma malignancy to complement histopathology.
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Affiliation(s)
- M Muge Karaman
- Center for MR Research, University of Illinois at Chicago, Chicago, Illinois, USA
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Jiaxuan Zhang
- Department of Radiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Karen L Xie
- Department of Radiology, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Wenzhen Zhu
- Department of Radiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaohong Joe Zhou
- Center for MR Research, University of Illinois at Chicago, Chicago, Illinois, USA
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
- Department of Radiology, University of Illinois at Chicago, Chicago, Illinois, USA
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois, USA
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Brugnara G, Herweh C, Neuberger U, Bo Hansen M, Ulfert C, Mahmutoglu MA, Foltyn M, Nagel S, Schönenberger S, Heiland S, Ringleb PA, Bendszus M, Möhlenbruch M, Pfaff JAR, Vollmuth P. Dynamics of cerebral perfusion and oxygenation parameters following endovascular treatment of acute ischemic stroke. J Neurointerv Surg 2021; 14:neurintsurg-2020-017163. [PMID: 33762405 PMCID: PMC8785045 DOI: 10.1136/neurintsurg-2020-017163] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/06/2021] [Accepted: 02/10/2021] [Indexed: 11/03/2022]
Abstract
BACKGROUND We studied the effects of endovascular treatment (EVT) and the impact of the extent of recanalization on cerebral perfusion and oxygenation parameters in patients with acute ischemic stroke (AIS) and large vessel occlusion (LVO). METHODS Forty-seven patients with anterior LVO underwent computed tomography perfusion (CTP) before and immediately after EVT. The entire ischemic region (Tmax >6 s) was segmented before intervention, and tissue perfusion (time-to-maximum (Tmax), time-to-peak (TTP), mean transit time (MTT), cerebral blood volume (CBV), cerebral blood flow (CBF)) and oxygenation (coefficient of variation (COV), capillary transit time heterogeneity (CTH), metabolic rate of oxygen (CMRO2), oxygen extraction fraction (OEF)) parameters were quantified from the segmented area at baseline and the corresponding area immediately after intervention, as well as within the ischemic core and penumbra. The impact of the extent of recanalization (modified Treatment in Cerebral Infarction (mTICI)) on CTP parameters was assessed with the Wilcoxon test and Pearson's correlation coefficients. RESULTS The Tmax, MTT, OEF and CTH values immediately after EVT were lower in patients with complete (as compared with incomplete) recanalization, whereas CBF and COV values were higher (P<0.05) and no differences were found in other parameters. The ischemic penumbra immediately after EVT was lower in patients with complete recanalization as compared with those with incomplete recanalization (P=0.002), whereas no difference was found for the ischemic core (P=0.12). Specifically, higher mTICI scores were associated with a greater reduction of ischemic penumbra volumes (R²=-0.48 (95% CI -0.67 to -0.22), P=0.001) but not of ischemic core volumes (P=0.098). CONCLUSIONS Our study demonstrates that the ischemic penumbra is the key target of successful EVT in patients with AIS and largely determines its efficacy on a tissue level. Furthermore, we confirm the validity of the mTICI score as a surrogate parameter of interventional success on a tissue perfusion level.
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Affiliation(s)
- Gianluca Brugnara
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Christian Herweh
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Ulf Neuberger
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Mikkel Bo Hansen
- Center of Functionally Integrative Neuroscience and MINDLab, Aarhus Universitet, Aarhus, Midtjylland, Denmark
| | - Christian Ulfert
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Mustafa Ahmed Mahmutoglu
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Martha Foltyn
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Simon Nagel
- Department of Neurology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Silvia Schönenberger
- Department of Neurology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Sabine Heiland
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Peter Arthur Ringleb
- Department of Neurology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Martin Bendszus
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Markus Möhlenbruch
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Johannes Alex Rolf Pfaff
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
| | - Philipp Vollmuth
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Baden-Württemberg, Germany
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13
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Magill ST, Nguyen MP, Aghi MK, Theodosopoulos PV, Villanueva-Meyer JE, McDermott MW. Postoperative diffusion-weighted imaging and neurological outcome after convexity meningioma resection. J Neurosurg 2021; 135:1008-1015. [PMID: 33513570 DOI: 10.3171/2020.8.jns193537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 08/10/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Convexity meningiomas are commonly managed with resection. Motor outcomes and predictors of new deficits after surgery are poorly studied. The objective of this study was to determine whether postoperative diffusion-weighted imaging (DWI) was associated with neurological deficits after convexity meningioma resection and to identify the risk factors for postoperative DWI restriction. METHODS A retrospective review of patients who had undergone convexity meningioma resection from 2014 to 2018 was performed. Univariate and multivariate logistic regressions were performed to identify variables associated with postoperative neurological deficits and a DWI signal. The amount of postoperative DWI signal was measured and was correlated with low apparent diffusion coefficient maps to confirm ischemic injury. RESULTS The authors identified 122 patients who had undergone a total of 125 operations for convexity meningiomas. The median age at surgery was 57 years, and 70% of the patients were female. The median follow-up was 26 months. The WHO grade was I in 62% of cases, II in 36%, and III in 2%. The most common preoperative deficits were seizures (24%), extremity weakness/paralysis (16%), cognitive/language/memory impairment (16%), and focal neurological deficit (16%). Following resection, 89% of cases had no residual deficit. Postoperative DWI showed punctate or no diffusion restriction in 78% of cases and restriction > 1 cm in 22% of cases. An immediate postoperative neurological deficit was present in 14 patients (11%), but only 8 patients (7%) had a deficit at 3 months postoperatively. Univariate analysis identified DWI signal > 1 cm (p < 0.0001), tumor diameter (p < 0.0001), preoperative motor deficit (p = 0.0043), older age (p = 0.0113), and preoperative embolization (p = 0.0171) as risk factors for an immediate postoperative deficit, whereas DWI signal > 1 cm (p < 0.0001), tumor size (p < 0.0001), and older age (p = 0.0181) were risk factors for deficits lasting more than 3 months postoperatively. Multivariate analysis revealed a DWI signal > 1 cm to be the only significant risk factor for deficits at 3 months postoperatively (OR 32.42, 95% CI 3.3-320.1, p = 0.0002). Further, estimated blood loss (OR 1.4 per 100 ml increase, 95% CI 1.1-1.7, p < 0.0001), older age (OR 1.1 per year older, 95% CI 1.0-1.1, p = 0.0009), middle third location in the sagittal plane (OR 16.9, 95% CI 1.3-216.9, p = 0.0026), and preoperative peritumoral edema (OR 4.6, 95% CI 1.2-17.7, p = 0.0249) were significantly associated with a postoperative DWI signal > 1 cm. CONCLUSIONS A DWI signal > 1 cm is significantly associated with postoperative neurological deficits, both immediate and long-lasting. Greater estimated blood loss, older age, tumor location over the motor strip, and preoperative peritumoral edema increase the risk of having a postoperative DWI signal > 1 cm, reflective of perilesional ischemia. Most immediate postoperative deficits will improve over time. These data are valuable when preoperatively communicating with patients about the risks of surgery and when postoperatively discussing prognosis after a deficit occurs.
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Jiang Z, Alamuri TT, Muir ER, Choi DW, Duong TQ. Longitudinal multiparametric MRI study of hydrogen-enriched water with minocycline combination therapy in experimental ischemic stroke in rats. Brain Res 2020; 1748:147122. [DOI: 10.1016/j.brainres.2020.147122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 09/06/2020] [Accepted: 09/07/2020] [Indexed: 12/11/2022]
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15
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Meier EL, Sheppard SM, Goldberg EB, Head CR, Ubellacker DM, Walker A, Hillis AE. Naming errors and dysfunctional tissue metrics predict language recovery after acute left hemisphere stroke. Neuropsychologia 2020; 148:107651. [PMID: 33045231 PMCID: PMC7546715 DOI: 10.1016/j.neuropsychologia.2020.107651] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/29/2020] [Accepted: 10/02/2020] [Indexed: 12/11/2022]
Abstract
Language recovery following acute left hemisphere (LH) stroke is notoriously difficult to predict. Global language measures (e.g., overall aphasia severity) and gross lesion metrics (e.g., size) provide incomplete recovery predictions. In this study, we test the hypothesis that the types of naming errors patients produce, combined with dysfunctional brain tissue metrics, can provide additional insight into recovery following acute LH stroke. One hundred forty-eight individuals who were hospitalized with a new LH stroke completed clinical neuroimaging and assessments of naming and global language skills. A subset of participants again completed language testing at subacute, early (5-7 months post-stroke), and late (≥11 months post-stroke) chronic phases. At each time point, we coded naming errors into four types (semantic, phonological, mixed and unrelated) and determined error type totals and proportions. Dysfunctional tissue measures included the percentage of damage to language network regions and hypoperfusion in vascular territories. A higher proportion of semantic errors was associated with better acute naming, but higher proportions of other error types was related to poorer accuracy. Naming and global language skills significantly improved over time , but naming error profiles did not change. Fewer acute unrelated errors and less damage to left angular gyrus resulted in optimal naming and language recovery by the final testing time point, yet patients with more acute errors and damage to left middle temporal gyrus demonstrated the greatest increases in language over time. These results illustrate that naming error profiles, particularly unrelated errors, add power to predictions of language recovery after stroke.
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Affiliation(s)
- Erin L Meier
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Shannon M Sheppard
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Communication Sciences and Disorders, Chapman University, Irvine, CA, USA
| | - Emily B Goldberg
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Catherine R Head
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Delaney M Ubellacker
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alexandra Walker
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Argye E Hillis
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Cognitive Science, Johns Hopkins University, Baltimore, MD, USA
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16
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Mai W. Reduced field-of-view diffusion-weighted MRI can identify restricted diffusion in the spinal cord of dogs and cats with presumptive clinical and high-field MRI diagnosis of acute ischemic myelopathy. Vet Radiol Ultrasound 2020; 61:688-695. [PMID: 32931630 DOI: 10.1111/vru.12907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 11/29/2022] Open
Abstract
Diffusion-weighted imaging MRI is the gold standard imaging technique for diagnosis of suspected acute brain ischemia in dogs and cats; however, it is technically challenging to apply to spinal cord imaging, due to its very small size, the inherent low spatial resolution of diffusion-weighted imaging, and the marked distortion resulting from magnetic field inhomogeneities caused by the osseous components of the vertebral column surrounding the spinal cord. Ischemic myelopathy is a common cause of acute non-compressive myelopathy in dogs and cats. Technological improvement in diffusion-weighted imaging pulse sequences allow imaging at smaller field of view with better spatial resolution and less image distortion. We sought to evaluate reduced field-of-view diffusion-weighted imaging MRI using a dedicated proprietary pulse sequence (FOCUS, General Electric) in a small sample of dogs and cats with a presumptive clinical and MRI diagnosis of acute ischemic myelopathy that were imaged with this pulse sequence. Five dogs and two cats fitted these inclusion criteria. In all of them, hyperintense spinal cord parenchyma signal was seen on diffusion-weighted imaging images corresponding to decreased signal on apparent diffusion coefficient map indicative of restricted diffusion, consistent with ischemia and cytotoxic edema. These areas matched the areas of abnormal T2-weighted signal and cord swelling observed on conventional spinal MRI. This small exploratory descriptive study indicates feasibility and possible usefulness of reduced field-of-view diffusion-weighted imaging MRI in dogs and cats with suspected acute ischemic myelopathy and that it may be added to the imaging protocol of the spine in such patients in an appropriate clinical setting.
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Affiliation(s)
- Wilfried Mai
- Department of Clinical Sciences and Advanced Medicine, Section of Radiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, USA
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17
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Etherton MR, Gadhia RR, Schwamm LH. Thrombolysis beyond 4.5 h in Acute Ischemic Stroke. Curr Neurol Neurosci Rep 2020; 20:35. [PMID: 32607627 DOI: 10.1007/s11910-020-01055-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE OF REVIEW The purpose of this article is to review the current approaches using neuroimaging techniques to expand eligibility for intravenous thrombolytic therapy in acute ischemic stroke patients with stroke of unknown symptom onset. RECENT FINDINGS In recent years, several randomized, placebo-controlled trials have shown neuroimaging-guided approaches to be feasible in determining eligibility for alteplase beyond 4.5 h from last known well, and efficacious for reducing disability. DWI-FLAIR mismatch on MRI is an effective tool to identify stroke lesions less than 4.5 h in onset in patients with stroke of unknown symptom onset. Additionally, an automated perfusion-based approach, assessing for a disproportionate amount of salvageable tissue, is effective in identifying patients likely to benefit from late window alteplase treatment. In patients with stroke of unknown symptom onset, an individualized approach using neuroimaging to determine time of stroke onset or presence of salvageable brain tissue is feasible in the acute setting and associated with improved long-term outcomes.
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Affiliation(s)
- Mark R Etherton
- JPK Stroke Research Center, Department of Neurology, Massachusetts General Hospital (MGH) and Harvard Medical School, Boston, MA, USA.
| | - Rajan R Gadhia
- Department of Neurology, Eddy Scurlock Stroke Center, Houston Methodist, Houston, TX, USA
| | - Lee H Schwamm
- JPK Stroke Research Center, Department of Neurology, Massachusetts General Hospital (MGH) and Harvard Medical School, Boston, MA, USA
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18
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Cerebral hemodynamics associated with fluid-attenuated inversion recovery hyperintense vessels in patients with extracranial carotid artery stenosis. Neuroradiology 2020; 62:677-684. [PMID: 32152648 DOI: 10.1007/s00234-020-02385-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/21/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE Fluid-attenuated inversion recovery hyperintense vessels (FHVs) are linked to sluggish or disordered blood flow. The purpose of this study is to compare FHVs with digital subtraction angiography (DSA) findings and cerebral hemodynamic changes on acetazolamide challenge SPECT and to determine the clinical and imaging metrics associated with FHVs in patients with extracranial carotid artery stenosis (ECAS). METHODS The subjects were patients with chronic ECAS who underwent carotid artery stenting in our department between March 2011 and October 2018. Relationships of FHVs with age, sex, medical history, cerebral angiographic findings using DSA, and quantitative values of cerebral blood flow (CBF) were examined. The resting CBF (rCBF) and cerebrovascular reactivity (CVR) in the middle cerebral artery territory were measured quantitatively using SPECT with acetazolamide challenge. We used multivariate logistic regression analysis to identify independent predictors of FHVs. RESULTS Of 173 patients included, 92 (53.2%) had FHVs. Patients with FHVs had more severe stenosis (P < 0.01) and more leptomeningeal collateral vessels (P < 0.01). FHV-positive cases had significantly reduced CVR compared with FHV-negative cases (P < 0.01), although there was no significant difference in rCBF between FHV-positive and FHV-negative cases. Logistic regression analysis showed that ipsilateral rCBF and ipsilateral CVR were significant predictors for FHVs (P < 0.01). CONCLUSION In patients with ECAS, cerebral hemodynamic metrics, especially ipsilateral rCBF and ipsilateral CVR, are associated with the presence of FHVs.
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Huang Y, Zhang X, Guo H, Chen H, Guo D, Huang F, Xu Q, Qu X. Phase-constrained reconstruction of high-resolution multi-shot diffusion weighted image. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 312:106690. [PMID: 32066067 DOI: 10.1016/j.jmr.2020.106690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/18/2020] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
Diffusion weighted imaging (DWI) is a unique examining method in tumor diagnosis, acute stroke evaluation. Single-shot echo planar imaging is currently conventional method for DWI. However, single-shot DWI suffers from image distortion, blurring and low spatial resolution. Although multi-shot DWI improves image resolution, it brings phase variations among different shots at the same time. In this paper, we introduce a smooth phase constraint of each shot image into multi-shot navigator-free DWI reconstruction by imposing the low-rankness of Hankel matrix constructed from the k-space data. Furthermore, we exploit the partial sum minimization of singular values to constrain the low-rankness of Hankel matrix. Results on brain imaging data show that the proposed method outperforms the state-of-the-art methods in terms of artifacts removal and our method potentially has the ability to reconstruct high number of shot of DWI.
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Affiliation(s)
- Yiman Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Electronic Science and Engineering, Xiamen University, Xiamen 361005, China
| | - Xinlin Zhang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Electronic Science and Engineering, Xiamen University, Xiamen 361005, China
| | - Hua Guo
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing 100084, China
| | - Huijun Chen
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing 100084, China
| | - Di Guo
- School of Computer and Information Engineering, Fujian Provincial University Key Laboratory of Internet of Things Application Technology, Xiamen University of Technology, Xiamen 361024, China
| | - Feng Huang
- Neusoft Medical System, Shanghai 200241, China
| | - Qin Xu
- Neusoft Medical System, Shanghai 200241, China
| | - Xiaobo Qu
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Electronic Science and Engineering, Xiamen University, Xiamen 361005, China.
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20
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Kerkelä L, Henriques RN, Hall MG, Clark CA, Shemesh N. Validation and noise robustness assessment of microscopic anisotropy estimation with clinically feasible double diffusion encoding MRI. Magn Reson Med 2019; 83:1698-1710. [DOI: 10.1002/mrm.28048] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/03/2019] [Accepted: 10/02/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Leevi Kerkelä
- UCL Great Ormond Street Institute of Child Health University College London London United Kingdom
| | - Rafael Neto Henriques
- Champalimaud Neuroscience Programme Champalimaud Research Champalimaud Centre for the Unknown Lisbon Portugal
| | - Matt G. Hall
- UCL Great Ormond Street Institute of Child Health University College London London United Kingdom
- National Physical Laboratory Teddington United Kingdom
| | - Chris A. Clark
- UCL Great Ormond Street Institute of Child Health University College London London United Kingdom
| | - Noam Shemesh
- Champalimaud Neuroscience Programme Champalimaud Research Champalimaud Centre for the Unknown Lisbon Portugal
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22
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Thamm T, Zweynert S, Piper SK, Madai VI, Livne M, Martin SZ, Herzig CX, Mutke MA, Siebert E, Liebig T, Sobesky J. Diagnostic and prognostic benefit of arterial spin labeling in subacute stroke. Brain Behav 2019; 9:e01271. [PMID: 30912272 PMCID: PMC6520295 DOI: 10.1002/brb3.1271] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/31/2019] [Accepted: 02/25/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND AND PURPOSE Brain perfusion measurement in the subacute phase of stroke may support therapeutic decisions. We evaluated whether arterial spin labeling (ASL), a noninvasive perfusion imaging technique based on magnetic resonance imaging (MRI), adds diagnostic and prognostic benefit to diffusion-weighted imaging (DWI) in subacute stroke. METHODS In a single-center imaging study, patients with DWI lesion(s) in the middle cerebral artery (MCA) territory were included. Onset to imaging time was ≤7 days and imaging included ASL and DWI sequences. Qualitative (standardized visual analysis) and quantitative perfusion analyses (region of interest analysis) were performed. Dichotomized early outcome (modified Rankin Scale [mRS] 0-2 vs. 3-6) was analyzed in two logistic regression models. Model 1 included DWI lesion volume, age, vascular pathology, admission NIHSS, and acute stroke treatment as covariates. Model 2 added the ASL-based perfusion pattern to Model 1. Receiver-operating-characteristic (ROC) and area-under-the-curve (AUC) were calculated for both models to assess their predictive power. The likelihood-ratio-test compared both models. RESULTS Thirty-eight patients were included (median age 70 years, admission NIHSS 4, onset to imaging time 67 hr, discharge mRS 2). Qualitative perfusion analysis yielded additional diagnostic information in 84% of the patients. In the quantitative analysis, AUC for outcome prediction was 0.88 (95% CI 0.77-0.99) for Model 1 and 0.97 (95% CI 0.91-1.00) for Model 2. Inclusion of perfusion data significantly improved performance and outcome prediction (p = 0.002) of stroke imaging. CONCLUSIONS In patients with subacute stroke, our study showed that adding perfusion imaging to structural imaging and clinical data significantly improved outcome prediction. This highlights the usefulness of ASL and noninvasive perfusion biomarkers in stroke diagnosis and management.
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Affiliation(s)
- Thoralf Thamm
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sarah Zweynert
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sophie K Piper
- Institute of Biometry and Clinical Epidemiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Vince I Madai
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurosurgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Michelle Livne
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Steve Z Martin
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Cornelius X Herzig
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Matthias A Mutke
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Eberhard Siebert
- Department of Neuroradiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Thomas Liebig
- Department of Neuroradiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neuroradiology, Ludwig-Maximilian-University, Munich, Germany
| | - Jan Sobesky
- Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurology, Johanna-Etienne-Hospital, Neuss, Germany
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23
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Zaro-Weber O, Fleischer H, Reiblich L, Schuster A, Moeller-Hartmann W, Heiss WD. Penumbra detection in acute stroke with perfusion magnetic resonance imaging: Validation with 15 O-positron emission tomography. Ann Neurol 2019; 85:875-886. [PMID: 30937950 PMCID: PMC6593670 DOI: 10.1002/ana.25479] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 03/20/2019] [Accepted: 03/31/2019] [Indexed: 12/17/2022]
Abstract
Objective Accurate identification of the ischemic penumbra, the therapeutic target in acute clinical stroke, is of critical importance to identify patients who might benefit from reperfusion therapies beyond the established time windows. Therefore, we aimed to validate magnetic resonance imaging (MRI) mismatch–based penumbra detection against full quantitative positron emission tomography (15O‐PET), the gold standard for penumbra detection in acute ischemic stroke. Methods Ten patients (group A) with acute and subacute ischemic stroke underwent perfusion‐weighted (PW)/diffusion‐weighted MRI and consecutive full quantitative 15O‐PET within 48 hours of stroke onset. Penumbra as defined by 15O‐PET cerebral blood flow (CBF), oxygen extraction fraction, and oxygen metabolism was used to validate a wide range of established PW measures (eg, time‐to‐maximum [Tmax]) to optimize penumbral tissue detection. Validation was carried out using a voxel‐based receiver‐operating‐characteristic curve analysis. The same validation based on penumbra as defined by quantitative 15O‐PET CBF was performed for comparative reasons in 23 patients measured within 48 hours of stroke onset (group B). Results The PW map Tmax (area‐under‐the‐curve = 0.88) performed best in detecting penumbral tissue up to 48 hours after stroke onset. The optimal threshold to discriminate penumbra from oligemia was Tmax >5.6 seconds with a sensitivity and specificity of >80%. Interpretation The performance of the best PW measure Tmax to detect the upper penumbral flow threshold in ischemic stroke is excellent. Tmax >5.6 seconds–based penumbra detection is reliable to guide treatment decisions up to 48 hours after stroke onset and might help to expand reperfusion treatment beyond the current time windows. ANN NEUROL 2019;85:875–886.
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Affiliation(s)
- Olivier Zaro-Weber
- Max Planck Institute for Neurological Research, Cologne, Germany.,Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Hermann Fleischer
- Max Planck Institute for Neurological Research, Cologne, Germany.,Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Lucas Reiblich
- Max Planck Institute for Neurological Research, Cologne, Germany.,Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany
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24
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Holdsworth SJ, O'Halloran R, Setsompop K. The quest for high spatial resolution diffusion-weighted imaging of the human brain in vivo. NMR IN BIOMEDICINE 2019; 32:e4056. [PMID: 30730591 DOI: 10.1002/nbm.4056] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 09/11/2018] [Accepted: 11/08/2018] [Indexed: 06/09/2023]
Abstract
Diffusion-weighted imaging, a contrast unique to MRI, is used for assessment of tissue microstructure in vivo. However, this exquisite sensitivity to finer scales far above imaging resolution comes at the cost of vulnerability to errors caused by sources of motion other than diffusion motion. Addressing the issue of motion has traditionally limited diffusion-weighted imaging to a few acquisition techniques and, as a consequence, to poorer spatial resolution than other MRI applications. Advances in MRI imaging methodology have allowed diffusion-weighted MRI to push to ever higher spatial resolution. In this review we focus on the pulse sequences and associated techniques under development that have pushed the limits of image quality and spatial resolution in diffusion-weighted MRI.
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Affiliation(s)
- Samantha J Holdsworth
- Department of Anatomy Medical Imaging & Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | | | - Kawin Setsompop
- Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA
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25
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Alahmari AF. Medical treatment of brain aspergilloma followed by MRI: A case report. Radiol Case Rep 2019; 14:103-111. [PMID: 30386448 PMCID: PMC6205868 DOI: 10.1016/j.radcr.2018.09.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 08/29/2018] [Accepted: 09/28/2018] [Indexed: 11/27/2022] Open
Abstract
This is a brain aspergilloma case in an immunocompetent patient who suffered from a rare fungal infection transmitted from the mediastinum to the brain and eventually caused pancreatitis. This fungal infection affected the thalamus, hypothalamus, and extended to the midbrain. This case showed a good prognosis for the brain aspergilloma without need for any surgical intervention. The radiological documentation for the brain aspergilloma shows a positive response to a combination of voriconazole and Keppra.
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26
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Tang L, Zhou XJ. Diffusion MRI of cancer: From low to high b-values. J Magn Reson Imaging 2018; 49:23-40. [PMID: 30311988 DOI: 10.1002/jmri.26293] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/20/2018] [Accepted: 07/23/2018] [Indexed: 12/14/2022] Open
Abstract
Following its success in early detection of cerebral ischemia, diffusion-weighted imaging (DWI) has been increasingly used in cancer diagnosis and treatment evaluation. These applications are propelled by the rapid development of novel diffusion models to extract biologically valuable information from diffusion-weighted MR signals, and significant advances in MR hardware that has enabled image acquisition with high b-values. This article reviews recent technical developments and clinical applications in cancer imaging using DWI, with a special emphasis on high b-value diffusion models. The article is organized in four sections. First, we provide an overview of diffusion models that are relevant to cancer imaging. The model parameters are discussed in relation to three tissue properties-cellularity, vascularity, and microstructures. An emphasis is placed on characterization of microstructural heterogeneity, given its novelty and close relevance to cancer. Second, we illustrate diffusion MR clinical applications in each of the following three categories: 1) cancer detection and diagnosis; 2) cancer grading, staging, and classification; and 3) cancer treatment response prediction and evaluation. Third, we discuss several practical issues, including selection of image acquisition parameters, reproducibility and reliability, motion management, image distortion, etc., that are commonly encountered when applying DWI to cancer in clinical settings. Lastly, we highlight a few ongoing challenges and provide some possible future directions, particularly in the area of establishing standards via well-organized multicenter clinical trials to accelerate clinical translation of advanced DWI techniques to improving cancer care on a large scale. Level of Evidence: 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:23-40.
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Affiliation(s)
- Lei Tang
- Department of Radiology, Peking University Cancer Hospital & Institute, Key laboratory of Carcinogenesis and Translational Research, Beijing, China
| | - Xiaohong Joe Zhou
- Center for MR Research and Departments of Radiology, Neurosurgery, and Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
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27
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Etherton MR, Barreto AD, Schwamm LH, Wu O. Neuroimaging Paradigms to Identify Patients for Reperfusion Therapy in Stroke of Unknown Onset. Front Neurol 2018; 9:327. [PMID: 29867736 PMCID: PMC5962731 DOI: 10.3389/fneur.2018.00327] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 04/25/2018] [Indexed: 12/17/2022] Open
Abstract
Despite the proven efficacy of intravenous alteplase or endovascular thrombectomy for the treatment of patients with acute ischemic stroke, only a minority receive these treatments. This low treatment rate is due in large part to delay in hospital arrival or uncertainty as to the exact time of onset of ischemic stroke, which renders patients outside the current guideline-recommended window of eligibility for receiving these therapeutics. However, recent pivotal clinical trials of late-window thrombectomy now force us to rethink the value of a simplistic chronological formulation that “time is brain.” We must recognize a more nuanced concept that the rate of tissue death as a function of time is not invariant, that still salvageable tissue at risk of infarction may be present up to 24 h after last-known well, and that those patients may strongly benefit from reperfusion. Multiple studies have sought to address this clinical dilemma using neuroimaging methods to identify a radiographic time-stamp of stroke onset or evidence of salvageable ischemic tissue and thereby increase the number of patients eligible for reperfusion therapies. In this review, we provide a critical analysis of the current state of neuroimaging techniques to select patients with unwitnessed stroke for revascularization therapies and speculate on the future direction of this clinically relevant area of stroke research.
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Affiliation(s)
- Mark R Etherton
- Department of Neurology, JPK Stroke Research Center, Massachusetts General Hospital (MGH), Harvard Medical School, Boston, MA, United States
| | - Andrew D Barreto
- Stroke Division, Department of Neurology, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Lee H Schwamm
- Department of Neurology, JPK Stroke Research Center, Massachusetts General Hospital (MGH), Harvard Medical School, Boston, MA, United States
| | - Ona Wu
- Department of Neurology, JPK Stroke Research Center, Massachusetts General Hospital (MGH), Harvard Medical School, Boston, MA, United States.,Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital (MGH), Charlestown, MA, United States
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28
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Sharma P, Bhaisora KS, Pandey S, Srivastava AK, Pani KC, Sardhara J, Das KK, Mehrotra A, Sahu RN, Jaiswal AK, Behari S. Aspergilloma Mimicking Olfactory Groove Meningioma. Asian J Neurosurg 2018; 13:436-439. [PMID: 29682054 PMCID: PMC5898125 DOI: 10.4103/1793-5482.228571] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Central nervous system aspergillosis is rare with reported mortality rate of 13–50% involving foci in paranasal sinuses and even higher mortality rates (80–100%) in patients of immune-compromised status. Modern day imaging offers an opportunity for early diagnosis, but findings are minimal. A typical finding is that of a space occupying mass lesion with iso-hypointense signal on T1-weighted sequences and extreme hypointense appearance on T2-weighted. This results from the concentration of ferromagnetic substances (iron/zinc/magnesium/manganese) within the lesion. Gadolinium enhancement pattern varies from homogeneous to peripheral ring enhancement. The immune-competent hosts present with homogeneous enhancement while those with immune compromise bear more variable radiological appearance. Due to such radiological appearance, meningioma or tuberculoma is considered in differential earlier than fungal granuloma, if not for the hypointense appearance on T2-weighted sequences which strongly points to fungal granuloma. Through this case report, we attempt to highlight the unusual radiological presentation of the entity.
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Affiliation(s)
- Pradeep Sharma
- Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India
| | | | - Satyadeo Pandey
- Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India
| | | | - Krushna C Pani
- Department of Pathology, SGPGIMS, Lucknow, Uttar Pradesh, India
| | - Jayesh Sardhara
- Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India
| | - Kuntal K Das
- Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India
| | - Anant Mehrotra
- Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India
| | | | | | - Sanjay Behari
- Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India
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Ohta T, Morimoto M, Okada K, Fukuda M, Onishi H, Masahira N, Matsuoka T, Tsuno T, Takemura M. Mechanical Thrombectomy in Anterior Circulation Occlusion Could Be More Effective than Medical Management Even in Low DWI-ASPECTS Patients. Neurol Med Chir (Tokyo) 2018; 58:156-163. [PMID: 29479041 PMCID: PMC5929913 DOI: 10.2176/nmc.oa.2017-0203] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The purpose of this study was to investigate whether patients with low preoperative Diffusion-weighted Imaging Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS) could benefit from mechanical thrombectomy for acute anterior circulation occlusion. This was a retrospective, non-blinded, cohort study. From September 2012 to August 2016, 83 consecutive patients of acute anterior circulation occlusion were treated with thrombectomy using second-generation devices or medical management. The DWI-ASPECTS was scored after the first MRI. Patient characteristics and clinical outcomes were compared between the treatment groups. Significant dependence was defined as a modified Rankin scale score ≥3 at 90 days. As a result, 33 patients underwent mechanical thrombectomy and 50 received medical management. In the mechanical thrombectomy group, the variable of lower DWI-ASPECTS (5, 4–6 vs. 8, 7–8, P < 0.001), especially ≤6, was significantly associated with poor prognosis. However, compared with patients of DWI-ASPECTS ≤ 6 who received medical management, there were significantly fewer patients with poor outcomes in thrombectomy (dependent in 11 of 15 vs. 23 of 23, respectively; P = 0.019). Although patients with lower pretreatment DWI-ASPECTS could benefit less from thrombectomy, their outcomes were still better than medical management. Therefore, mechanical thrombectomy could be considered in some patients with low pretreatment DWI-ASPECTS.
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Affiliation(s)
- Tsuyoshi Ohta
- Department of Neurosurgery, Kochi Health Sciences Center
| | | | - Kenji Okada
- Department of Neurosurgery, Kochi Health Sciences Center
| | - Maki Fukuda
- Department of Neurosurgery, Kochi Health Sciences Center
| | - Hirokazu Onishi
- Department of Emergency Medicine, Kochi Health Sciences Center
| | | | | | - Takaya Tsuno
- Department of Neurosurgery, Kochi Health Sciences Center
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JOURNAL CLUB: Evaluation of Diffusion Kurtosis Imaging of Stroke Lesion With Hemodynamic and Metabolic MRI in a Rodent Model of Acute Stroke. AJR Am J Roentgenol 2018; 210:720-727. [PMID: 29470156 DOI: 10.2214/ajr.17.19134] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Diffusion kurtosis imaging (DKI) has emerged as a new acute stroke imaging approach, augmenting routine DWI. Although it has been shown that a diffusion lesion without kurtosis abnormality is more likely to recover after reperfusion, whereas a kurtosis lesion shows poor response, little is known about the underlying pathophysiologic profile of the kurtosis lesion versus the kurtosis lesion-diffusion lesion mismatch. MATERIALS AND METHODS We performed multiparametric MRI, including arterial spin labeling, pH-sensitive amide proton transfer, and DKI, in a rodent model of acute stroke caused by embolic middle cerebral artery occlusion. Diffusion and kurtosis lesions were semiautomatically segmented, and multiparametric MRI indexes were compared among the kurtosis lesion, diffusion lesion, kurtosis lesion-diffusion lesion mismatch, and the contralateral normal tissue area. RESULTS We confirmed a significant difference between diffusion lesion and kurtosis lesion volumes (mean [± SD] volume, 151 ± 65 vs 125 ± 47 mm3; p < 0.05). Although ischemic lesions have significantly reduced cerebral blood flow compared with contralateral normal tissue, we did not find a significant difference in cerebral blood flow between the kurtosis lesion and the kurtosis lesion-diffusion lesion mismatch (mean cerebral blood flow, 0.53 ± 0.10 vs 0.47 ± 0.14 mL/g of tissue per minute; p > 0.05). Of importance, the pH of the kurtosis lesion was significantly lower than that of the lesion mismatch (mean pH, 6.81 ± 0.08 vs 6.89 ± 0.09; p < 0.01). CONCLUSION The present study confirms that DKI provides an expedient approach for refining the heterogeneous DWI lesion that is associated with graded metabolic derangement, which is promising for improving the infarction core definition and ultimately helping to guide stroke treatment.
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31
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Edlow BL, Hurwitz S, Edlow JA. Diagnosis of DWI-negative acute ischemic stroke: A meta-analysis. Neurology 2017; 89:256-262. [PMID: 28615423 DOI: 10.1212/wnl.0000000000004120] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 04/20/2017] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To determine the prevalence of diffusion-weighted imaging (DWI)-negative acute ischemic stroke (AIS) and to identify clinical characteristics of patients with DWI-negative AIS. METHODS We systematically searched PubMed and Ovid/MEDLINE for relevant studies between 1992, the year that the DWI sequence entered clinical practice, and 2016. Studies were included based upon enrollment of consecutive patients presenting with a clinical diagnosis of AIS prior to imaging. Meta-analysis was performed to synthesize study-level data, estimate DWI-negative stroke prevalence, and estimate the odds ratios (ORs) for clinical characteristics associated with DWI-negative stroke. RESULTS Twelve articles including 3,236 AIS patients were included. The meta-analytic synthesis yielded a pooled prevalence of DWI-negative AIS of 6.8%, 95% confidence interval (CI) 4.9-9.3. In the 5 studies that reported proportion data for DWI-negative and DWI-positive AIS based on the ischemic vascular territory (n = 1,023 AIS patients), DWI-negative stroke was strongly associated with posterior circulation ischemia, as determined by clinical diagnosis at hospital discharge or repeat imaging (OR 5.1, 95% CI 2.3-11.6, p < 0.001). CONCLUSIONS A small but significant percentage of patients with AIS have a negative DWI scan. Patients with neurologic deficits consistent with posterior circulation ischemia have 5 times the odds of having a negative DWI scan compared to patients with anterior circulation ischemia. AIS remains a clinical diagnosis and urgent reperfusion therapy should be considered even when an initial DWI scan is negative.
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Affiliation(s)
- Brian L Edlow
- From the Department of Neurology (B.L.E.) and Athinoula A. Martinos Center for Biomedical Imaging (B.L.E.), Massachusetts General Hospital, Department of Medicine (S.H.), Brigham and Women's Hospital, and Department of Emergency Medicine (J.A.E.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
| | - Shelley Hurwitz
- From the Department of Neurology (B.L.E.) and Athinoula A. Martinos Center for Biomedical Imaging (B.L.E.), Massachusetts General Hospital, Department of Medicine (S.H.), Brigham and Women's Hospital, and Department of Emergency Medicine (J.A.E.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Jonathan A Edlow
- From the Department of Neurology (B.L.E.) and Athinoula A. Martinos Center for Biomedical Imaging (B.L.E.), Massachusetts General Hospital, Department of Medicine (S.H.), Brigham and Women's Hospital, and Department of Emergency Medicine (J.A.E.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
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Abstract
In this chapter we review the optimal imaging modalities for subacute and chronic stroke. We discuss the utility of computed tomography (CT) and multimodal CT imaging. Further, we analyze the importance of specific magnetic resonance imaging sequences, such as diffusion-weighted imaging for acute ischemic stroke, T2/fluid-attenuated inversion recovery for subacute and chronic stroke, and susceptibility imaging for detection of intracranial hemorrhages. Different ischemic stroke mechanisms are reviewed, and how these imaging modalities may aid in the determination of such. Further, we analyze how topographic patterns in ischemic stroke may provide important clues to the diagnosis, in addition to the temporal evolution of the stroke. Lastly, specific cerebrovascular occlusive diseases are reviewed, with emphasis on the optimal imaging modalities and their findings in each condition.
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Pirimoglu B, Sade R, Ogul H, Kantarci M, Eren S, Levent A. How Can New Imaging Modalities Help in the Practice of Radiology? Eurasian J Med 2017; 48:213-221. [PMID: 28149149 DOI: 10.5152/eajm.2016.0260] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The purpose of this article was to provide an up-to-date review on the spectrum of new imaging applications in the practice of radiology. New imaging techniques have been developed with the objective of obtaining structural and functional analyses of different body systems. Recently, new imaging modalities have aroused the interest of many researchers who are studying the applicability of these modalities in the evaluation of different organs and diseases. In this review article, we present the efficiency and utilization of current imaging modalities in daily radiological practice.
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Affiliation(s)
- Berhan Pirimoglu
- Department of Radiology, Ataturk University School of Medicine, Erzurum, Turkey
| | - Recep Sade
- Department of Radiology, Ataturk University School of Medicine, Erzurum, Turkey
| | - Hayri Ogul
- Department of Radiology, Ataturk University School of Medicine, Erzurum, Turkey
| | - Mecit Kantarci
- Department of Radiology, Ataturk University School of Medicine, Erzurum, Turkey
| | - Suat Eren
- Department of Radiology, Ataturk University School of Medicine, Erzurum, Turkey
| | - Akın Levent
- Department of Radiology, Ataturk University School of Medicine, Erzurum, Turkey
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Revisiting Current Golden Rules in Managing Acute Ischemic Stroke: Evaluation of New Strategies to Further Improve Treatment Selection and Outcome. AJR Am J Roentgenol 2017; 208:32-41. [DOI: 10.2214/ajr.16.16557] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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35
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Weavers PT, Shu Y, Tao S, Huston J, Lee SK, Graziani D, Mathieu JB, Trzasko JD, Foo TKF, Bernstein MA. Technical Note: Compact three-tesla magnetic resonance imager with high-performance gradients passes ACR image quality and acoustic noise tests. Med Phys 2016; 43:1259-64. [PMID: 26936710 DOI: 10.1118/1.4941362] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE A compact, three-tesla magnetic resonance imaging (MRI) system has been developed. It features a 37 cm patient aperture, allowing the use of commercial receiver coils. Its design allows simultaneously for gradient amplitudes of 85 millitesla per meter (mT/m) sustained and 700 tesla per meter per second (T/m/s) slew rates. The size of the gradient system allows for these simultaneous performance targets to be achieved with little or no peripheral nerve stimulation, but also raises a concern about the geometric distortion as much of the imaging will be done near the system's maximum 26 cm field-of-view. Additionally, the fast switching capability raises acoustic noise concerns. This work evaluates the system for both the American College of Radiology's (ACR) MRI image quality protocol and the Food and Drug Administration's (FDA) nonsignificant risk (NSR) acoustic noise limits for MR. Passing these two tests is critical for clinical acceptance. METHODS In this work, the gradient system was operated at the maximum amplitude and slew rate of 80 mT/m and 500 T/m/s, respectively. The geometric distortion correction was accomplished by iteratively determining up to the tenth order spherical harmonic coefficients using a fiducial phantom and position-tracking software, with seventh order correction utilized in the ACR test. Acoustic noise was measured with several standard clinical pulse sequences. RESULTS The system passes all the ACR image quality tests. The acoustic noise as measured when the gradient coil was inserted into a whole-body MRI system conforms to the FDA NSR limits. CONCLUSIONS The compact system simultaneously allows for high gradient amplitude and high slew rate. Geometric distortion concerns have been mitigated by extending the spherical harmonic correction to higher orders. Acoustic noise is within the FDA limits.
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Affiliation(s)
| | | | | | | | - Seung-Kyun Lee
- GE Global Research, Niskayuna, NY 12309, USA and CNIR, Department of Biomedical Engineering, Sungkyunkwan University, Suwon 440-746, South Korea
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Tievsky A, Wu O, Gonzalez R, Rosen B, Sorensen A. ADC and Diffusion Anisotropy Indices in Wallerian Degeneration. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/19714009980110s238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- A.L. Tievsky
- Current Affiliation: Georgetown University Medical Center; Washington, D.C
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Lövblad KO, Kiefer C, Oswald H, Arnold M, Nedeltchev K, Mattle H, Schroth G. Imaging the Ischemic Penumbra. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/197140090301600534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | | | | | - M. Arnold
- Department of Neurology, Inselspital, Bern; Switzerland
| | - K. Nedeltchev
- Department of Neurology, Inselspital, Bern; Switzerland
| | - H. Mattle
- Department of Neurology, Inselspital, Bern; Switzerland
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Yang H, Li Y, Jiang Y. Insufficient platelet inhibition and thromboembolic complications in patients with intracranial aneurysms after stent placement. J Neurosurg 2016; 125:247-53. [DOI: 10.3171/2015.6.jns1511] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECT
Insufficient platelet inhibition has been associated with an increased incidence of thromboembolic complications in cardiology patients undergoing percutaneous coronary intervention. Data regarding the relationship between insufficient platelet inhibition and thromboembolic complications in patients undergoing neurovascular procedures remain controversial. The purpose of this study was to assess the relationship of insufficient platelet inhibition and thromboembolic complications in patients with intracranial aneurysm undergoing stent treatment.
METHODS
The authors prospectively recruited patients with intracranial aneurysms undergoing stent treatment and maintained the data in a database. MRI with diffusion-weighted sequences was performed within 24 hours of stent insertion to identify acute ischemic lesions. The authors used thromboelastography to assess the degree of platelet inhibition in response to clopidogrel and aspirin. Univariate and multivariate logistic regression analysis was used to identify potential risk factors of thromboembolic complications.
RESULTS
One hundred sixty-eight patients with 193 aneurysms were enrolled in this study. Ninety-one of 168 (54.2%) patients with acute cerebral ischemic lesions were identified by diffusion-weighted MRI. In 9 (5.4%) patients with ischemic lesions, transient ischemic attack or stroke was found at discharge, and these complications were found in 11 (6.5%) patients during the follow-up period. The incidence of periprocedural thromboembolic complications increased with resistance to antiplatelet agents, hypertension, hyperlipidemia, complete occlusion, and aneurysm of the anterior circulation. The multivariate regression analysis demonstrated that the anterior circulation and adenosine diphosphate (ADP) inhibition percentage were independent risk factors of perioperative thromboembolic complications. The maximum amplitude and ADP inhibition percentage were independent risk factors for thromboembolic complications during the follow-up period.
CONCLUSIONS
The ADP inhibition percentage is related to thromboembolic complications after stent placement for intracranial aneurysms. The increase of the ADP inhibition may decrease the risk of thromboembolic complications.
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Usuda K, Maeda S, Motono N, Ueno M, Tanaka M, Machida Y, Matoba M, Watanabe N, Tonami H, Ueda Y, Sagawa M. Diffusion Weighted Imaging Can Distinguish Benign from Malignant Mediastinal Tumors and Mass Lesions: Comparison with Positron Emission Tomography. Asian Pac J Cancer Prev 2016; 16:6469-75. [PMID: 26434861 DOI: 10.7314/apjcp.2015.16.15.6469] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Diffusion-weighted magnetic resonance imaging (DWI) makes it possible to detect malignant tumors based on the diffusion of water molecules. It is uncertain whether DWI is more useful than positron emission tomography-computed tomography (PET-CT) for distinguishing benign from malignant mediastinal tumors and mass lesions. MATERIALS AND METHODS Sixteen malignant mediastinal tumors (thymomas 7, thymic cancers 3, malignant lymphomas 3, malignant germ cell tumors 2, and thymic carcinoid 1) and 12 benign mediastinal tumors or mass lesions were assessed in this study. DWI and PET-CT were performed before biopsy or surgery. RESULTS The apparent diffusion coefficient (ADC) value (1.51±0.46x10(-3) mm2/sec) of malignant mediastinal tumors was significantly lower than that (2.96±0.86x10(-3) mm2/sec) of benign mediastinal tumors and mass lesions (P<0.0001). Maximum standardized uptake value (SUVmax) (11.30±11.22) of malignant mediastinal tumors was significantly higher than that (2.53±3.92) of benign mediastinal tumors and mass lesions (P=0.0159). Using the optimal cutoff value (OCV) 2.21x10(-3) mm2/sec for ADC and 2.93 for SUVmax, the sensitivity (100%) by DWI was not significantly higher than that (93.8%) by PET-CT for malignant mediastinal tumors. The specificity (83.3%) by DWI was not significantly higher than that (66.7%) for benign mediastinal tumors and mass lesions. The accuracy (92.9%) by DWI was not significantly higher than that (82.1%) by PET-CT for mediastinal tumors and mass lesions. CONCLUSIONS There was no significant difference between diagnostic capability of DWI and that of PET-CT for distinguishing mediastinal tumors and mass lesions. DWI is useful in distinguishing benign from malignant mediastinal tumors and mass lesions.
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Affiliation(s)
- Katsuo Usuda
- Department of Thoracic Surgery, Kanazawa Medical University, Daigaku, Uchinada, Ishikawa, Japan E-mail :
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Kamalian S, Lev MH, Gupta R. Computed tomography imaging and angiography - principles. HANDBOOK OF CLINICAL NEUROLOGY 2016; 135:3-20. [PMID: 27432657 DOI: 10.1016/b978-0-444-53485-9.00001-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The evaluation of patients with diverse neurologic disorders was forever changed in the summer of 1973, when the first commercial computed tomography (CT) scanners were introduced. Until then, the detection and characterization of intracranial or spinal lesions could only be inferred by limited spatial resolution radioisotope scans, or by the patterns of tissue and vascular displacement on invasive pneumoencaphalography and direct carotid puncture catheter arteriography. Even the earliest-generation CT scanners - which required tens of minutes for the acquisition and reconstruction of low-resolution images (128×128 matrix) - could, based on density, noninvasively distinguish infarct, hemorrhage, and other mass lesions with unprecedented accuracy. Iodinated, intravenous contrast added further sensitivity and specificity in regions of blood-brain barrier breakdown. The advent of rapid multidetector row CT scanning in the early 1990s created renewed enthusiasm for CT, with CT angiography largely replacing direct catheter angiography. More recently, iterative reconstruction postprocessing techniques have made possible high spatial resolution, reduced noise, very low radiation dose CT scanning. The speed, spatial resolution, contrast resolution, and low radiation dose capability of present-day scanners have also facilitated dual-energy imaging which, like magnetic resonance imaging, for the first time, has allowed tissue-specific CT imaging characterization of intracranial pathology.
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Affiliation(s)
- Shervin Kamalian
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Michael H Lev
- Division of Emergency Radiology and Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Rajiv Gupta
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Krieger DA, Dehkharghani S. Magnetic Resonance Imaging in Ischemic Stroke and Cerebral Venous Thrombosis. Top Magn Reson Imaging 2015; 24:331-352. [PMID: 26636639 DOI: 10.1097/rmr.0000000000000067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Imaging is indispensable in the evaluation of patients presenting with central nervous system emergencies. Although computed tomography (CT) is the mainstay of initial assessment and triage, magnetic resonance imaging (MRI) has become vital in expanding diagnostic capabilities, refining management strategies, and developing our understanding of disease processes. Ischemic stroke and cerebral venous thrombosis are 2 areas wherein MRI is actively revolutionizing patient care. Familiarity with the imaging manifestations of these 2 disease processes is crucial for any radiologist reading brain MR studies. In this review, the fundamentals of image interpretation will be addressed in-depth. Furthermore, advanced imaging techniques which are redefining the role of emergency MRI will be outlined, with a focus on the pathophysiological mechanisms that underlie image interpretation. In particular, emerging data surrounding the use of MR perfusion imaging in acute stroke management portend dramatic shifts in neurointerventional management. To this end, a review of the recent stroke literature will hopefully enhance the radiologist's role in both meaningful reporting and multidisciplinary teamwork.
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Affiliation(s)
- Daniel A Krieger
- Emory University School of Medicine, Department of Radiology and Imaging Sciences, Division of Neuroradiology, Atlanta, Georgia
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Karaman MM, Sui Y, Wang H, Magin RL, Li Y, Zhou XJ. Differentiating low- and high-grade pediatric brain tumors using a continuous-time random-walk diffusion model at high b-values. Magn Reson Med 2015; 76:1149-57. [PMID: 26519663 DOI: 10.1002/mrm.26012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/08/2015] [Accepted: 09/15/2015] [Indexed: 12/15/2022]
Abstract
PURPOSE To demonstrate that a continuous-time random-walk (CTRW) diffusion model can improve diagnostic accuracy of differentiating low- and high-grade pediatric brain tumors. METHODS Fifty-four children with histopathologically confirmed brain tumors underwent diffusion MRI scans at 3Twith 12 b-values (0-4000 s/mm(2) ). The diffusion imageswere fit to a simplified CTRW model to extract anomalous diffusion coefficient, Dm , and temporal and spatial heterogeneity parameters, α and β, respectively. Using histopathology results as reference, a k-means clustering algorithm and a receiver operating characteristic (ROC) analysis were employed to determine the sensitivity, specificity, and diagnostic accuracy of the CTRW parameters in differentiating tumor grades. RESULTS Significant differences between the low- and high-grade tumors were observed in the CTRW parameters (p-values<0.001). The k-means analysis showed that the combination of three CTRW parameters produced higher diagnostic accuracy (85% vs. 75%) and specificity (83% vs. 54%) than the apparent diffusion coefficient (ADC) from a mono-exponential model. The ROC analysis revealed that any combination of the CTRW parameters gave a larger area under the curve (0.90-0.96) than using ADC (0.80). CONCLUSION With its sensitivity to intravoxel heterogeneity, the simplified CTRW model is useful for non-invasive grading of pediatric brain tumors, particularly when surgical biopsy is not feasible. Magn Reson Med 76:1149-1157, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- M Muge Karaman
- Center for MR Research, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Yi Sui
- Center for MR Research, University of Illinois at Chicago, Chicago, Illinois, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - He Wang
- Philips Research China, Shanghai, China
| | - Richard L Magin
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Yuhua Li
- Xinhua Hospital, Shanghai, China
| | - Xiaohong Joe Zhou
- Center for MR Research, University of Illinois at Chicago, Chicago, Illinois, USA. .,Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, USA. .,Department of Radiology, University of Illinois at Chicago, Chicago, Illinois, USA. .,Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois, USA.
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Malyarenko DI, Ross BD, Chenevert TL. Analysis and correction of gradient nonlinearity bias in apparent diffusion coefficient measurements. Magn Reson Med 2015; 71:1312-23. [PMID: 23794533 DOI: 10.1002/mrm.24773] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
PURPOSE Gradient nonlinearity of MRI systems leads to spatially dependent b-values and consequently high non-uniformity errors (10-20%) in apparent diffusion coefficient (ADC) measurements over clinically relevant field-of-views. This work seeks practical correction procedure that effectively reduces observed ADC bias for media of arbitrary anisotropy in the fewest measurements. METHODS All-inclusive bias analysis considers spatial and time-domain cross-terms for diffusion and imaging gradients. The proposed correction is based on rotation of the gradient nonlinearity tensor into the diffusion gradient frame where spatial bias of b-matrix can be approximated by its Euclidean norm. Correction efficiency of the proposed procedure is numerically evaluated for a range of model diffusion tensor anisotropies and orientations. RESULTS Spatial dependence of nonlinearity correction terms accounts for the bulk (75-95%) of ADC bias for FA = 0.3-0.9. Residual ADC non-uniformity errors are amplified for anisotropic diffusion. This approximation obviates need for full diffusion tensor measurement and diagonalization to derive a corrected ADC. Practical scenarios are outlined for implementation of the correction on clinical MRI systems. CONCLUSIONS The proposed simplified correction algorithm appears sufficient to control ADC non-uniformity errors in clinical studies using three orthogonal diffusion measurements. The most efficient reduction of ADC bias for anisotropic medium is achieved with non-lab-based diffusion gradients.
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Usuda K, Maeda S, Motono N, Ueno M, Tanaka M, Machida Y, Matoba M, Watanabe N, Tonami H, Ueda Y, Sagawa M. Diagnostic Performance of Diffusion - Weighted Imaging for Multiple Hilar and Mediastinal Lymph Nodes with FDG Accumulation. Asian Pac J Cancer Prev 2015; 16:6401-6. [DOI: 10.7314/apjcp.2015.16.15.6401] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Malkyarenko DI, Chenevert TL. Practical estimate of gradient nonlinearity for implementation of apparent diffusion coefficient bias correction. J Magn Reson Imaging 2015; 40:1487-95. [PMID: 25667948 DOI: 10.1002/jmri.24486] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
PURPOSE To describe an efficient procedure to empirically characterize gradient nonlinearity and correct for the corresponding apparent diffusion coefficient (ADC) bias on a clinical magnetic resonance imaging (MRI) scanner. MATERIALS AND METHODS Spatial nonlinearity scalars for individual gradient coils along superior and right directions were estimated via diffusion measurements of an isotropicic e-water phantom. Digital nonlinearity model from an independent scanner, described in the literature, was rescaled by system-specific scalars to approximate 3D bias correction maps. Correction efficacy was assessed by comparison to unbiased ADC values measured at isocenter. RESULTS Empirically estimated nonlinearity scalars were confirmed by geometric distortion measurements of a regular grid phantom. The applied nonlinearity correction for arbitrarily oriented diffusion gradients reduced ADC bias from 20% down to 2% at clinically relevant offsets both for isotropic and anisotropic media. Identical performance was achieved using either corrected diffusion-weighted imaging (DWI) intensities or corrected b-values for each direction in brain and ice-water. Direction-average trace image correction was adequate only for isotropic medium. CONCLUSION Empiric scalar adjustment of an independent gradient nonlinearity model adequately described DWI bias for a clinical scanner. Observed efficiency of implemented ADC bias correction quantitatively agreed with previous theoretical predictions and numerical simulations. The described procedure provides an independent benchmark for nonlinearity bias correction of clinical MRI scanners.
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Affiliation(s)
- Dariya I Malkyarenko
- University of Michigan Hospitals, 1500 E. Medical Center Dr., UHB2, Ann Arbor, MI, USA.
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Usuda K, Sagawa M, Motomo N, Ueno M, Tanaka M, Machida Y, Maeda S, Matoba M, Tonami H, Ueda Y, Sakuma T. Recurrence and metastasis of lung cancer demonstrate decreased diffusion on diffusion-weighted magnetic resonance imaging. Asian Pac J Cancer Prev 2015; 15:6843-8. [PMID: 25169535 DOI: 10.7314/apjcp.2014.15.16.6843] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Diffusion-weighted magnetic resonance imaging (DWI) is reported to be useful for detecting malignant lesions. The purpose of this study is to clarify characteristics of imaging, detection rate and sensitivity of DWI for recurrence or metastasis of lung cancer. METHODS A total of 36 lung cancer patients with recurrence or metastasis were enrolled in this study. While 16 patients underwent magnetic resonance imaging (MRI), computed tomography (CT) and positron emission tomography-computed tomography (PET-CT), 17 underwent MRI and CT, and 3 underwent MRI and PET-CT. RESULTS Each recurrence or metastasis showed decreased diffusion, which was easily recognized in DWI. The detection rate for recurrence or metastasis was 100% (36/36) in DWI, 89% (17/19) in PET-CT and 82% (27/33) in CT. Detection rate of DWI was significantly higher than that of CT (p=0.0244) but not significantly higher than that of PET-CT (p=0.22). When the optimal cutoff value of the apparent diffusion coefficient value was set as 1.70?10-3 mm2/sec, the sensitivity of DWI for diagnosing recurrence or metastasis of lung cancer was 95.6%. CONCLUSIONS DWI is useful for detection of recurrence and metastasis of lung cancer.
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Affiliation(s)
- Katsuo Usuda
- Department of Thoracic Surgery, Kanazawa Medical University,Uchinada, Ishikawa, Japan E-mail :
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Cremers CHP, Vos PC, van der Schaaf IC, Velthuis BK, Vergouwen MDI, Rinkel GJE, Dankbaar JW. CT perfusion during delayed cerebral ischemia after subarachnoid hemorrhage: distinction between reversible ischemia and ischemia progressing to infarction. Neuroradiology 2015; 57:897-902. [PMID: 26032925 PMCID: PMC4572064 DOI: 10.1007/s00234-015-1543-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 05/14/2015] [Indexed: 12/05/2022]
Abstract
Introduction Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) can be reversible or progress to cerebral infarction. In patients with a deterioration clinically diagnosed as DCI, we investigated whether CT perfusion (CTP) can distinguish between reversible ischemia and ischemia progressing to cerebral infarction. Methods From a prospectively collected series of aSAH patients, we included those with DCI, CTP on the day of clinical deterioration, and follow-up imaging. In qualitative CTP analyses (visual assessment), we calculated positive and negative predictive value (PPV and NPV) with 95 % confidence intervals (95%CI) of a perfusion deficit for infarction on follow-up imaging. In quantitative analyses, we compared perfusion values of the least perfused brain tissue between patients with and without infarction by using receiver-operator characteristic curves and calculated a threshold value with PPV and NPV for the perfusion parameter with the highest area under the curve. Results In qualitative analyses of 33 included patients, 15 of 17 patients (88 %) with and 6 of 16 patients (38 %) without infarction on follow-up imaging had a perfusion deficit during clinical deterioration (p = 0.002). Presence of a perfusion deficit had a PPV of 71 % (95%CI: 48–89 %) and NPV of 83 % (95%CI: 52–98 %) for infarction on follow-up. Quantitative analyses showed that an absolute minimal cerebral blood flow (CBF) threshold of 17.7 mL/100 g/min had a PPV of 63 % (95%CI: 41–81 %) and a NPV of 78 % (95%CI: 40–97 %) for infarction. Conclusions CTP may differ between patients with DCI who develop infarction and those who do not. For this purpose, qualitative evaluation may perform marginally better than quantitative evaluation.
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Affiliation(s)
- Charlotte H P Cremers
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, Utrecht, The Netherlands. .,Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Pieter C Vos
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Birgitta K Velthuis
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mervyn D I Vergouwen
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, Utrecht, The Netherlands
| | - Gabriel J E Rinkel
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, Utrecht, The Netherlands
| | - Jan Willem Dankbaar
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
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Hansen MB, Nagenthiraja K, Ribe LR, Dupont KH, Østergaard L, Mouridsen K. Automated estimation of salvageable tissue: Comparison with expert readers. J Magn Reson Imaging 2015; 43:220-8. [DOI: 10.1002/jmri.24963] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/15/2015] [Indexed: 11/07/2022] Open
Affiliation(s)
- Mikkel B. Hansen
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University; Aarhus Denmark
| | - Kartheeban Nagenthiraja
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University; Aarhus Denmark
| | - Lars R. Ribe
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University; Aarhus Denmark
| | - Kristina H. Dupont
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University; Aarhus Denmark
- Department of Neuroradiology; Aarhus University Hospital; Aarhus Denmark
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University; Aarhus Denmark
- Department of Neuroradiology; Aarhus University Hospital; Aarhus Denmark
| | - Kim Mouridsen
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University; Aarhus Denmark
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Low SW, Teo K, Lwin S, Yeo LLL, Paliwal PR, Ahmad A, Sinha AK, Teoh HL, Wong LYH, Chong VF, Seet RCS, Chan BPL, Yeo TT, Chou N, Sharma VK. Improvement in cerebral hemodynamic parameters and outcomes after superficial temporal artery-middle cerebral artery bypass in patients with severe stenoocclusive disease of the intracranial internal carotid or middle cerebral arteries. J Neurosurg 2015; 123:662-9. [PMID: 26023999 DOI: 10.3171/2014.11.jns141553] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Both the older and the recent extracranial-intracranial (EC-IC) bypass trials for symptomatic carotid occlusion failed to demonstrate a reduction in stroke recurrence. However, the role of superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in patients with symptomatic intracranial stenoocclusive disease has been rarely evaluated. The authors evaluated serial changes in various cerebral hemodynamic parameters in patients with severe stenoocclusive disease of the intracranial internal carotid artery (ICA) or middle cerebral artery (MCA) and impaired cerebral vasodilatory reserve (CVR), treated by STA-MCA bypass surgery or medical treatment. METHODS Patients with severe stenoocclusive disease of the intracranial ICA or MCA underwent transcranial Doppler (TCD) ultrasonography and CVR assessment using the breath-holding index (BHI). Patients with impaired BHI (< 0.69) were further evaluated with acetazolamide-challenge technitium-99m hexamethylpropyleneamine oxime ((99m)Tc HMPAO) SPECT. STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. All patients underwent TCD and SPECT at 4 ± 1 months and were followed up for cerebral ischemic events. RESULTS A total of 112 patients were included. This total included 73 men, and the mean age of the entire study population was 56 years (range 23-78 years). (99m)Tc HMPAO SPECT demonstrated impaired CVR in 77 patients (69%). Of these 77 patients, 46 underwent STA-MCA bypass while 31 received best medical treatment. TCD and acetazolamide-challenge (99m)Tc HMPAO SPECT repeated at 4 ± 1 months showed significant improvement in the STA-MCA bypass group. During a mean follow-up of 34 months (range 18-39 months), only 6 (13%) of 46 patients in the bypass group developed cerebral ischemic events, as compared with 14 (45%) of 31 patients receiving medical therapy (absolute risk reduction 32%, p = 0.008). CONCLUSIONS STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial stenoocclusive disease of the intracranial ICA or MCA results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.
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Affiliation(s)
| | | | | | | | | | | | - Arvind K Sinha
- Department of Diagnostic Imaging, National University Hospital System, Singapore; and
| | | | | | - Vincent F Chong
- Department of Diagnostic Imaging, National University Hospital System, Singapore; and
| | | | | | | | | | - Vijay K Sharma
- Division of Neurology, and.,YLL School of Medicine, National University of Singapore, Singapore
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