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Jensen-Kondering U, Manavaki R, Ejaz S, Sawiak SJ, Carpenter TA, Fryer TD, Aigbirhio FI, Williamson DJ, Baron JC. Brain hypoxia mapping in acute stroke: Back-to-back T2' MR versus 18F-fluoromisonidazole PET in rodents. Int J Stroke 2017; 12:752-760. [PMID: 28523963 DOI: 10.1177/1747493017706221] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background Mapping the hypoxic brain in acute ischemic stroke has considerable potential for both diagnosis and treatment monitoring. PET using 18F-fluoro-misonidazole (FMISO) is the reference method; however, it lacks clinical accessibility and involves radiation exposure. MR-based T2' mapping may identify tissue hypoxia and holds clinical potential. However, its validation against FMISO imaging is lacking. Here we implemented back-to-back FMISO-PET and T2' MR in rodents subjected to acute middle cerebral artery occlusion. For direct clinical relevance, regions of interest delineating reduced T2' signal areas were manually drawn. Methods Wistar rats were subjected to filament middle cerebral artery occlusion, immediately followed by intravenous FMISO injection. Multi-echo T2 and T2* sequences were acquired twice during FMISO brain uptake, interleaved with diffusion-weighted imaging. Perfusion-weighted MR was also acquired whenever feasible. Immediately following MR, PET data reflecting the history of FMISO brain uptake during MR acquisition were acquired. T2' maps were generated voxel-wise from T2 and T2*. Two raters independently drew T2' lesion regions of interest. FMISO uptake and perfusion data were obtained within T2' consensus regions of interest, and their overlap with the automatically generated FMISO lesion and apparent diffusion coefficient lesion regions of interest was computed. Results As predicted, consensus T2' lesion regions of interest exhibited high FMISO uptake as well as substantial overlap with the FMISO lesion and significant hypoperfusion, but only small overlap with the apparent diffusion coefficient lesion. Overlap of the T2' lesion regions of interest between the two raters was ∼50%. Conclusions This study provides formal validation of T2' to map non-core hypoxic tissue in acute stroke. T2' lesion delineation reproducibility was suboptimal, reflecting unclear lesion borders.
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Affiliation(s)
- Ulf Jensen-Kondering
- 1 Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,3 Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Roido Manavaki
- 4 Department of Radiology, University of Cambridge, Cambridge, UK
| | - Sohail Ejaz
- 1 Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Stephen J Sawiak
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - T Adrian Carpenter
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Tim D Fryer
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Franklin I Aigbirhio
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - David J Williamson
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Jean-Claude Baron
- 1 Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,5 INSERM U894, Université Paris Descartes, Hôpital Sainte-Anne, Paris, France
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Jin N, Guo Y, Zhang Z, Zhang L, Lu G, Larson AC. GESFIDE-PROPELLER approach for simultaneous R2 and R2* measurements in the abdomen. Magn Reson Imaging 2013; 31:1760-5. [PMID: 24041478 DOI: 10.1016/j.mri.2013.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 07/22/2013] [Accepted: 08/13/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE To investigate the feasibility of combining GESFIDE with PROPELLER sampling approaches for simultaneous abdominal R2 and R2* mapping. MATERIALS AND METHODS R2 and R2* measurements were performed in 9 healthy volunteers and phantoms using the GESFIDE-PROPELLER and the conventional Cartesian-sampling GESFIDE approaches. RESULTS Images acquired with the GESFIDE-PROPELLER sequence effectively mitigated the respiratory motion artifacts, which were clearly evident in the images acquired using the conventional GESFIDE approach. There was no significant difference between GESFIDE-PROPELLER and reference MGRE R2* measurements (p=0.162) whereas the Cartesian-sampling based GESFIDE methods significantly overestimated R2* values compared to MGRE measurements (p<0.001). CONCLUSION The GESFIDE-PROPELLER sequence provided high quality images and accurate abdominal R2 and R2* maps while avoiding the motion artifacts common to the conventional Cartesian-sampling GESFIDE approaches.
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Affiliation(s)
- Ning Jin
- Department of Biomedical Engineering, Northwestern University Chicago, IL, USA; Department of Radiology, Northwestern University Chicago, IL, USA; Siemens Medical Solutions USA, Inc., Chicago, IL, USA.
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Boehm-Sturm P, Farr TD, Adamczak J, Jikeli JF, Mengler L, Wiedermann D, Kallur T, Kiselev V, Hoehn M. Vascular changes after stroke in the rat: a longitudinal study using optimized magnetic resonance imaging. CONTRAST MEDIA & MOLECULAR IMAGING 2013; 8:383-92. [DOI: 10.1002/cmmi.1534] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 11/30/2012] [Accepted: 01/15/2013] [Indexed: 01/13/2023]
Affiliation(s)
- Philipp Boehm-Sturm
- In-Vivo-NMR Laboratory; Max Planck Institute for Neurological Research; Cologne; Germany
| | - Tracy D. Farr
- In-Vivo-NMR Laboratory; Max Planck Institute for Neurological Research; Cologne; Germany
| | - Joanna Adamczak
- In-Vivo-NMR Laboratory; Max Planck Institute for Neurological Research; Cologne; Germany
| | | | - Luam Mengler
- In-Vivo-NMR Laboratory; Max Planck Institute for Neurological Research; Cologne; Germany
| | - Dirk Wiedermann
- In-Vivo-NMR Laboratory; Max Planck Institute for Neurological Research; Cologne; Germany
| | - Therése Kallur
- In-Vivo-NMR Laboratory; Max Planck Institute for Neurological Research; Cologne; Germany
| | - Valerij Kiselev
- Medical Physics, Department of Diagnostic Radiology; University Hospital Freiburg; Freiburg; Germany
| | - Mathias Hoehn
- In-Vivo-NMR Laboratory; Max Planck Institute for Neurological Research; Cologne; Germany
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Jensen-Kondering U, Baron JC. Oxygen imaging by MRI: can blood oxygen level-dependent imaging depict the ischemic penumbra? Stroke 2012; 43:2264-9. [PMID: 22588263 DOI: 10.1161/strokeaha.111.632455] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Ulf Jensen-Kondering
- Stroke Research Group, University of Cambridge, Department of Clinical Neurosciences, Addenbrooke's Hospital, Cambridge, UK
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Kavec M, Gröhn OHJ, Kettunen MI, Silvennoinen MJ, Garwood M, Kauppinen RA. Acute cerebral ischemia in rats studied by Carr-Purcell spin-echo magnetic resonance imaging: assessment of blood oxygenation level-dependent and tissue effects on the transverse relaxation. Magn Reson Med 2004; 51:1138-46. [PMID: 15170833 DOI: 10.1002/mrm.20089] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Acute cerebral ischemia has been shown to be associated with an enhanced transverse relaxation rate in rat brain parenchyma, chiefly due to the blood oxygenation level-dependent (BOLD) effect. In this study, Carr-Purcell R(2) (CP R(2)), acquired both with short and long time intervals between centers of adiabatic pi-pulses (tau(CP)), was used to assess the contributions of BOLD and tissue effects to the transverse relaxation in two brain ischemia models of rat at 4.7 T. R(1rho) and diffusion MR images were also acquired in the same animals. During the first minutes of global ischemia, the long tau(CP) R(2) in brain parenchyma increased, whereas the short tau(CP) R(2) was unchanged. Based on the simulations, and using constraints of intravascular BOLD effect on parenchymal R(2), the former observation was ascribed to be due to susceptibility changes arising in the extravascular compartment. R(1rho) declined almost immediately after the onset of focal cerebral ischemia, and further declined during the evolution of ischemic damage. Interestingly, short tau(CP) CP R(2) started to decline after some 20 min of focal ischemia and declined over a time course similar to that of R(1rho), indicating that it may be an MRI marker for irreversible tissue changes in cerebral ischemia. The present results show that CP R(2) MRI can reveal both tissue- and blood-derived contrast changes in acute cerebral ischemia.
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Affiliation(s)
- Martin Kavec
- Department of Biomedical NMR and National Bio-NMR Facility, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland
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Klarhöfer M, Barth M, Moser E. Comparison of multi-echo spiral and echo planar imaging in functional MRI. Magn Reson Imaging 2002; 20:359-64. [PMID: 12165355 DOI: 10.1016/s0730-725x(02)00505-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Multi-echo spiral and echo-planar (EPI) imaging sequences were compared in functional imaging experiments at 3 Tesla. Both sequence types allow calculation of the effective transversal relaxation time T(2)* and the initial signal intensity I(0). These parameters can be used in evaluation of the functional signal with respect to inflow effects and other vascular sources. Prior to functional magnetic resonance imaging (fMRI) experiments T(2)* measurements in the human brain were performed with single- and multi-echo FLASH (fast low angle shot) and compared with EPI und spiral imaging sequences. These experiments resulted in T(2)* values ranging from 42.9 to 53.8 ms in a ROI including white and gray matter and CSF in a prefrontal brain region, and allowed validation of the quantitative results of the fast single-shot techniques. In functional experiments with motor stimulation mean absolute T(2)* increases during stimulation of 1.1 +/- 0.6 ms and 1.4 +/- 0.9 ms were found with multi-echo EPI and spiral imaging, respectively, averaged over the activated pixels. In addition, absolute T(2)* values and the size of activated areas obtained with both sequences are comparable. In these investigations spiral imaging allowed higher spatial resolution due to more efficient use of available gradient performance.
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Affiliation(s)
- Markus Klarhöfer
- Arbeitsgruppe NMR, Institut für Medizinische Physik, Universität Wien, Vienna, Austria
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Thomas DL, Lythgoe MF, Gadian DG, Ordidge RJ. Rapid simultaneous mapping of T2 and T2* by multiple acquisition of spin and gradient echoes using interleaved echo planar imaging (MASAGE-IEPI). Neuroimage 2002; 15:992-1002. [PMID: 11906239 DOI: 10.1006/nimg.2001.1042] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A new MRI sequence for the rapid simultaneous measurement of T2 and T2* is presented. The technique uses the multiple acquisition of spin and gradient echoes with interleaved echo planar imaging (MASAGE-IEPI). IEPI data sets are sampled during and between a pair of short and long echo time spin echoes, allowing the reconstruction of a set of images with different combinations of T2 and T2* weighting and the calculation of T2 and T2* maps. In the context of neuroimaging, these maps can provide information on cerebral hemodynamics and oxygenation status, either via the deoxyhemoglobin-based BOLD signal or by the effect of exogenous paramagnetic contrast agents. MASAGE-IEPI benefits from the inherent advantages of the IEPI approach, i.e., high time resolution and minimal image distortion, and also has good time efficiency due to the acquisition of multiple image data sets following each excitation pulse. The accuracy of the sequence for the measurement of T2 and T2* is verified on phantoms, and the technique is applied to monitor changing hemodynamics in the rat brain during episodes of hypoxia. Data for the generation of maps of T2 and T2* are acquired with a time resolution of 12 s to accurately define the rapidly changing time course. As increasing emphasis is placed on the role of T2 and T2* in the direct measurement of physiological parameters such as cerebral metabolic rate of oxygen consumption and blood vessel sizes, MASAGE-IEPI offers an efficient method for the measurement of these two important MRI parameters.
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Affiliation(s)
- David L Thomas
- RCS Unit of Biophysics, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom
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Kettunen MI, Gröhn OHJ, Silvennoinen MJ, Penttonen M, Kauppinen RA. Quantitative assessment of the balance between oxygen delivery and consumption in the rat brain after transient ischemia with T2 -BOLD magnetic resonance imaging. J Cereb Blood Flow Metab 2002; 22:262-70. [PMID: 11891431 DOI: 10.1097/00004647-200203000-00003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The balance between oxygen consumption and delivery in the rat brain after exposure to transient ischemia was quantitatively studied with single-spin echo T2-BOLD (blood oxygenation level-dependent) magnetic resonance imaging at 4.7 T. The rats were exposed to graded common carotid artery occlusions using a modification of the four-vessel model of Pulsinelli. T2, diffusion, and cerebral blood volume were quantified with magnetic resonance imaging, and CBF was measured with the hydrogen clearance method. A transient common carotid artery occlusion below the CBF value of approximately 20 mL x 100 g(-1) x min(-1) was needed to yield a T2 increase of 4.6 +/- 1.2 milliseconds (approximately 9% of cerebral T2) and 6.8 +/- 1.7 milliseconds (approximately 13% of cerebral T2) after 7 and 15 minutes of ischemia, respectively. Increases in CBF of 103 +/- 75% and in cerebral blood volume of 29 +/- 20% were detected in the reperfusion phase. These hemodynamic changes alone could account for only approximately one third of the T2 increase in luxury perfusion, suggesting that a substantial increase in blood oxygen saturation (resulting from reduced oxygen extraction by the brain) is needed to explain the magnetic resonance imaging observation.
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Affiliation(s)
- Mikko I Kettunen
- National Bio-NMR Facility and Cognitive Neurobiology Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland
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Beech JS, Williams SC, Campbell CA, Bath PM, Parsons AA, Hunter AJ, Menon DK. Further characterisation of a thromboembolic model of stroke in the rat. Brain Res 2001; 895:18-24. [PMID: 11259755 DOI: 10.1016/s0006-8993(00)03331-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have used magnetic resonance imaging (MRI) techniques to characterise a rat model of thromboembolic stroke. The consequences of acute perfusion deficit associated with a middle cerebral artery occlusion (MCAo) by a newly formed thrombus was mapped by interrogation of the tissue oxygenation status using gradient echo methods and production of T2* maps. Final infarct size was subsequently assessed at 24-h post-ischaemia by histology with 2,3,5-triphenyltetrazolium chloride (TTC) staining. Animals displayed an infarct volume of 178.7+/-84.2 mm(3) (mean+/-S.D.) with a large coefficient of variation (47%) and range of values (85.6--265.5 mm(3)). This variability provided us with an opportunity to assess the relationships between early imaging observations and eventual infarct size. For a single cerebral slice, at the centre of the MCA territory, a relationship between the area of reduced T2* at 1 and 2 h post MCAo correlated highly with final lesion area (Spearman rank correlation, r=0.98, P<0.01, n=9). Lesion volumes in the thromboembolic MCAo model were compared with a 120-min occlusion, 22-h reperfusion protocol using an intraluminal thread MCAo approach. For the thromboembolic model, the total lesion volume was found to be smaller (178.7+/-84.2 vs. 243.3+/-50.1 mm(3), mean+/-S.D., Student's t-test P=0.046) and showed a greater variability (coefficient of variations: 47% vs. 21%). These data underline the relative variability of this embolic model and provide important preliminary information regarding the value of early changes in T2* in predicting eventual infarct size.
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Affiliation(s)
- J S Beech
- Department of Medicine, Division of Anaesthesia, University of Cambridge, Box 93, Level 4, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
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