1
|
Bouchahda N, Jarraya M, Kallala Y, Sassi G, Boussaada M, Bader M, Mahjoub M, Haj H, Zemni I, Betbout F, Gamra H, Hassine M, Messaoud MB. Reproducibility of transthoracic 3D echocardiography in the assessment of mitral valve area in patients with rheumatic mitral stenosis: real time versus ECG-gated 3D echocardiography. THE INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING 2023; 39:2419-2426. [PMID: 37658988 DOI: 10.1007/s10554-023-02939-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 08/18/2023] [Indexed: 09/05/2023]
Abstract
PURPOSE To assess reproducibility of Real time 3D echocardiography (RT3D) and ECG-gated 3D echocardiography (EG3D) when measuring the mitral valve area (MVA) in rheumatic mitral stenosis (MS). METHODS MVA was assessed by three operators in 68 MS patients using RT3D and EG3D. Reproducibility of each technique was determined by calculating the standard error of measurements (SEM). RESULTS SEM was similar between RT3D and EG3D. MVA variability was of 0.4 cm² or 30% of any RT3D or EG3D measured MVA. The minimal change in MVA above which two measurements should be considered to differ significantly for the same operator was of 0.4 cm² for RT3D and 0.5 cm² for EG3D. For two different operators making successive measurements, the minimum significant change was of 0.5 cm² for RT3D and 0.6 cm² for EG3D. The minimum significant difference when switching from RT3D to EG3D or vice versa is of 0.6 cm². Low temporal resolution of 6 Hz has the least variability when using RT3D (0.19 cm² vs. 0.26 cm², p = 0.009) but significantly underestimated MVA (1.3 ± 0.4 cm² vs. 1.4 ± 0.4 cm², p < 10- 3) when compared to EG3D. MVA variability was significantly higher in mild MS when compared to severe MS whether it is RT3D (0.23 cm² vs. 0.18 cm², p = 0.02) or EG3D (0.27 cm² vs. 0.16 cm², p < 0.001). CONCLUSION RT3D and EG3D are equally reproducible in the assessment of MVA in patients with MS. Further measurements standardization is required to have a clinically acceptable estimations of the true 3D MVA and minimal detectable differences.
Collapse
Affiliation(s)
- Nidhal Bouchahda
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia.
| | - Marwa Jarraya
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Yessine Kallala
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Ghada Sassi
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Mehdi Boussaada
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Mouna Bader
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Marwen Mahjoub
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Hassen Haj
- Cardiology Department, TAHER SFAR University Hospital, 5100, Mahdia, Tunisia
| | - Imen Zemni
- Department of preventive Medicine, Faculty of Medicine, University of Monastir, Rue. Avicenne, 5019, Monastir, Tunisia
| | - Fethi Betbout
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Habib Gamra
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Majed Hassine
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| | - Mejdi Ben Messaoud
- Cardiology A Department, Research Laboratory LR12 SP 16 Fattouma, University of Monastir, Bourguiba University Hospital, Rue du 1er juin 1955, 5000, Monastir, Tunisia
| |
Collapse
|
2
|
Hollestelle RVA, Hansen D, Hoeks SE, van Meeteren NLU, Stolker RJ, Maissan IM. Observer Variability as a Determinant of Measurement Error of Ultrasonographic Measurements of the Optic Nerve Sheath Diameter: A Systematic Review. J Emerg Med 2022; 63:200-211. [PMID: 36038435 DOI: 10.1016/j.jemermed.2022.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 03/13/2022] [Accepted: 04/23/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Ultrasonographic measurements of the diameter of the sheath of the optic nerve can be used to assess intracranial pressure indirectly. These measurements come with measurement error. OBJECTIVE Our aim was to estimate observer's measurement error as a determinant of ultrasonographic measurement variability of the optic nerve sheath diameter. METHODS A systematic search of the literature was conducted in Embase, Medline, Web of Science, the Cochrane Central Register of Trials, and the first 200 articles of Google Scholar up to April 19, 2021. Inclusion criteria were the following: healthy adults, B-mode ultrasonography, and measurements 3 mm behind the retina. Studies were excluded if standard error of measurement could not be calculated. Nine studies featuring 389 participants (median 40; range 15-100) and 22 observers (median 2; range 1-4) were included. Standard error of measurement and minimal detectable differences were calculated to quantify observer variability. Quality and risk of bias were assessed with the Guidelines for Reporting Reliability and Agreement Studies. RESULTS The standard error of measurement of the intra- and interobserver variability had a range of 0.10-0.41 mm and 0.14-0.42 mm, respectively. Minimal detectable difference of a single observer was 0.28-1.1 mm. Minimal detectable difference of multiple observers (range 2-4) was 0.40-1.1 mm. Quality assessment showed room for methodological improvement of included studies. CONCLUSIONS The standard errors of measurement and minimal detectable differences of ultrasonographic measurements of the optic nerve sheath diameter found in this review with healthy participants indicate caution should be urged when interpreting results acquired with this measurement method in clinical context.
Collapse
Affiliation(s)
| | - Daniel Hansen
- Department of Anesthesiology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Sanne E Hoeks
- Department of Anesthesiology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | | | - Robert J Stolker
- Department of Anesthesiology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Iscander M Maissan
- Department of Anesthesiology, Erasmus Medical Centre, Rotterdam, The Netherlands
| |
Collapse
|
3
|
Mitchell JR, Kamnitsas K, Singleton KW, Whitmire SA, Clark-Swanson KR, Ranjbar S, Rickertsen CR, Johnston SK, Egan KM, Rollison DE, Arrington J, Krecke KN, Passe TJ, Verdoorn JT, Nagelschneider AA, Carr CM, Port JD, Patton A, Campeau NG, Liebo GB, Eckel LJ, Wood CP, Hunt CH, Vibhute P, Nelson KD, Hoxworth JM, Patel AC, Chong BW, Ross JS, Boxerman JL, Vogelbaum MA, Hu LS, Glocker B, Swanson KR. Deep neural network to locate and segment brain tumors outperformed the expert technicians who created the training data. J Med Imaging (Bellingham) 2020; 7:055501. [PMID: 33102623 PMCID: PMC7567400 DOI: 10.1117/1.jmi.7.5.055501] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/21/2020] [Indexed: 11/17/2022] Open
Abstract
Purpose: Deep learning (DL) algorithms have shown promising results for brain tumor segmentation in MRI. However, validation is required prior to routine clinical use. We report the first randomized and blinded comparison of DL and trained technician segmentations. Approach: We compiled a multi-institutional database of 741 pretreatment MRI exams. Each contained a postcontrast T1-weighted exam, a T2-weighted fluid-attenuated inversion recovery exam, and at least one technician-derived tumor segmentation. The database included 729 unique patients (470 males and 259 females). Of these exams, 641 were used for training the DL system, and 100 were reserved for testing. We developed a platform to enable qualitative, blinded, controlled assessment of lesion segmentations made by technicians and the DL method. On this platform, 20 neuroradiologists performed 400 side-by-side comparisons of segmentations on 100 test cases. They scored each segmentation between 0 (poor) and 10 (perfect). Agreement between segmentations from technicians and the DL method was also evaluated quantitatively using the Dice coefficient, which produces values between 0 (no overlap) and 1 (perfect overlap). Results: The neuroradiologists gave technician and DL segmentations mean scores of 6.97 and 7.31, respectively (p<0.00007). The DL method achieved a mean Dice coefficient of 0.87 on the test cases. Conclusions: This was the first objective comparison of automated and human segmentation using a blinded controlled assessment study. Our DL system learned to outperform its “human teachers” and produced output that was better, on average, than its training data.
Collapse
Affiliation(s)
- Joseph Ross Mitchell
- H. Lee Moffitt Cancer Center and Research Institute, Department of Machine Learning, Tampa, Florida, United States
| | | | - Kyle W Singleton
- Mayo Clinic, Mathematical NeuroOncology Lab, Phoenix, Arizona, United States
| | - Scott A Whitmire
- Mayo Clinic, Mathematical NeuroOncology Lab, Phoenix, Arizona, United States
| | | | - Sara Ranjbar
- Mayo Clinic, Mathematical NeuroOncology Lab, Phoenix, Arizona, United States
| | | | - Sandra K Johnston
- Mayo Clinic, Mathematical NeuroOncology Lab, Phoenix, Arizona, United States.,University of Washington, Department of Radiology, Seattle, Washington, United States
| | - Kathleen M Egan
- H. Lee Moffitt Cancer Center and Research Institute, Department of Cancer Epidemiology, Tampa, Florida, United States
| | - Dana E Rollison
- H. Lee Moffitt Cancer Center and Research Institute, Department of Cancer Epidemiology, Tampa, Florida, United States
| | - John Arrington
- H. Lee Moffitt Cancer Center and Research Institute, Department of Diagnostic Imaging and Interventional Radiology, Tampa, Florida, United States
| | - Karl N Krecke
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Theodore J Passe
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Jared T Verdoorn
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | | | - Carrie M Carr
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - John D Port
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Alice Patton
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Norbert G Campeau
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Greta B Liebo
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Laurence J Eckel
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Christopher P Wood
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Christopher H Hunt
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Prasanna Vibhute
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Kent D Nelson
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Joseph M Hoxworth
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Ameet C Patel
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Brian W Chong
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Jeffrey S Ross
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Jerrold L Boxerman
- Rhode Island Hospital and Alpert Medical School of Brown University, Department of Diagnostic Imaging, Providence, Rhode Island, United States
| | - Michael A Vogelbaum
- H. Lee Moffitt Cancer Center and Research Institute, Department of Neurosurgery, Tampa, Florida, United States
| | - Leland S Hu
- Mayo Clinic, Mathematical NeuroOncology Lab, Phoenix, Arizona, United States.,Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Ben Glocker
- Imperial College, Biomedical Image Analysis Group, London, United Kingdom
| | - Kristin R Swanson
- Mayo Clinic, Mathematical NeuroOncology Lab, Phoenix, Arizona, United States.,Mayo Clinic, Department of Neurosurgery, Phoenix, Arizona, United States
| |
Collapse
|
4
|
Mouawad M, Biernaski H, Brackstone M, Lock M, Yaremko B, Sexton T, Yu E, Dinniwell RE, Lynn K, Hajdok G, Prato FS, Thompson RT, Gelman N, Gaede S. Reducing the dose of gadolinium-based contrast agents for DCE-MRI guided SBRT: The effects on inter and intra observer variability for preoperative target volume delineation in early stage breast cancer patients. Radiother Oncol 2019; 131:60-65. [PMID: 30773188 DOI: 10.1016/j.radonc.2018.11.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/26/2018] [Accepted: 11/29/2018] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND PURPOSE This study aimed to determine the effects of reducing the dose of contrast agent (CA) in a DCE-MRI scan on inter- and intra-observer variability in the context of MRI-guided target volume delineation for stereotactic body radiation therapy of early stage breast cancer patients. This is in hopes of reducing risks to patients due to findings of residual CA in brain and bone. MATERIALS AND METHODS Twenty-three patients receiving neoadjuvant radiation therapy were enrolled. Five observers delineated the gross target volume (GTV) using DCE-MRI for guidance. 14/23 patients received the full clinical dose of CA and 9/23 received half. Clinical target volumes (CTV) were created through a 0.5 cm uniform expansion. Several metrics were used to quantify the inter and intra-observer reliability including differences in delineation volume and the reliability coefficient. RESULTS There were no significant differences in the volume, though half contrast patients had a lower median for both the GTV and CTV (difference of 0.26 cm3 and 1.27 cm3, respectively). All indicated a high degree of agreement between and within observers for both dose groups. However, the full dose group had a greater inter-observer variability, most likely due to the full CA causing more pronounced enhancement in the periphery. CONCLUSIONS Reducing the dose of contrast agent did not significantly alter inter- or intra-observer variability. These results have prompted our centre to reduce the dose of gadolinium in all patients enrolled in the SIGNAL trial.
Collapse
Affiliation(s)
| | | | - Muriel Brackstone
- Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada; London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Michael Lock
- London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Brian Yaremko
- London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Tracy Sexton
- London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Edward Yu
- London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Robert E Dinniwell
- London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Kalan Lynn
- London Health Sciences Centre, London, Canada.
| | | | - Frank S Prato
- Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada.
| | - Robert Terry Thompson
- Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada.
| | - Neil Gelman
- Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada.
| | - Stewart Gaede
- Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada; London Health Sciences Centre, London, Canada.
| |
Collapse
|
5
|
Xue W, Vegunta S, Zwart CM, Aguilar MI, Patel AC, Hoxworth JM, Demaerschalk BM, Mitchell JR. Retrospective Validation of a Computer-Assisted Quantification Model of Intracerebral Hemorrhage Volume on Accuracy, Precision, and Acquisition Time, Compared with Standard ABC/2 Manual Volume Calculation. AJNR Am J Neuroradiol 2017; 38:1536-1542. [PMID: 28596188 DOI: 10.3174/ajnr.a5256] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 04/09/2017] [Indexed: 12/30/2022]
Abstract
BACKGROUND AND PURPOSE Intracerebral hemorrhage accounts for 6.5%-19.6% of all acute strokes. Initial intracerebral hemorrhage volume and expansion are both independent predictors of clinical outcomes and mortality. Therefore, a rapid, unbiased, and precise measurement of intracerebral hemorrhage volume is a key component of clinical management. The most commonly used method, ABC/2, results in overestimation. We developed an interactive segmentation program, SegTool, using a novel graphic processing unit, level set algorithm. Until now, the speed, bias, and precision of SegTool had not been validated. MATERIALS AND METHODS In a single stroke academic center, 2 vascular neurologists and 2 neuroradiologists independently performed a test-retest experiment that involved repeat measurements of static, unchanging intracerebral hemorrhage volumes on CT from 76 intracerebral hemorrhage cases. Measurements were made with SegTool and ABC/2. True intracerebral hemorrhage volumes were estimated from a consensus of repeat manual tracings by 2 operators. These data allowed us to estimate measurement bias, precision, and speed. RESULTS The measurements with SegTool were not significantly different from the true intracerebral hemorrhage volumes, while ABC/2 overestimated volume by 45%. The interrater measurement variability with SegTool was 50% less than that with ABC/2. The average measurement times for ABC/2 and SegTool were 35.7 and 44.6 seconds, respectively. CONCLUSIONS SegTool appears to have attributes superior to ABC/2 in terms of accuracy and interrater reliability with a 9-second delay in measurement time (on average); hence, it could be useful in clinical trials and practice.
Collapse
Affiliation(s)
- W Xue
- From the Department of Biomedical Informatics (W.X., J.R.M.), Arizona State University, Scottsdale, Arizona
| | - S Vegunta
- Moran Eye Center (S.V.), University of Utah, Salt Lake City, Utah
| | - C M Zwart
- Departments of Radiology (C.M.Z., A.C.P., J.M.H.)
| | | | - A C Patel
- Departments of Radiology (C.M.Z., A.C.P., J.M.H.)
| | - J M Hoxworth
- Departments of Radiology (C.M.Z., A.C.P., J.M.H.)
| | | | - J R Mitchell
- From the Department of Biomedical Informatics (W.X., J.R.M.), Arizona State University, Scottsdale, Arizona.,Research (J.R.M.), Mayo Clinic, Scottsdale, Arizona
| |
Collapse
|
6
|
Abstract
Some form of the assessment of observer variability may be the most frequent statistical task in medical literature. Still, very little attempt is made to make the reported methods uniform and clear to the reader. This paper provides overview of various measures of observer variability, and a rationale of why using standard error of measurement (SEM) is preferable to other measures of observer variability. The supplemental file contains examples on how to design a proper repeatability and reproducibility assessment, determine appropriate sample size, and test for significance of its findings.
Collapse
Affiliation(s)
- Zoran B Popović
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA
| | - James D Thomas
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA
| |
Collapse
|
7
|
Qiu W, Yuan J, Rajchl M, Kishimoto J, Chen Y, de Ribaupierre S, Chiu B, Fenster A. 3D MR ventricle segmentation in pre-term infants with post-hemorrhagic ventricle dilatation (PHVD) using multi-phase geodesic level-sets. Neuroimage 2015; 118:13-25. [DOI: 10.1016/j.neuroimage.2015.05.099] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/19/2015] [Accepted: 05/21/2015] [Indexed: 11/15/2022] Open
|
8
|
Qiu W, Yuan J, Kishimoto J, McLeod J, Chen Y, de Ribaupierre S, Fenster A. User-guided segmentation of preterm neonate ventricular system from 3-D ultrasound images using convex optimization. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:542-556. [PMID: 25542486 DOI: 10.1016/j.ultrasmedbio.2014.09.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 09/05/2014] [Accepted: 09/11/2014] [Indexed: 06/04/2023]
Abstract
A three-dimensional (3-D) ultrasound (US) system has been developed to monitor the intracranial ventricular system of preterm neonates with intraventricular hemorrhage (IVH) and the resultant dilation of the ventricles (ventriculomegaly). To measure ventricular volume from 3-D US images, a semi-automatic convex optimization-based approach is proposed for segmentation of the cerebral ventricular system in preterm neonates with IVH from 3-D US images. The proposed semi-automatic segmentation method makes use of the convex optimization technique supervised by user-initialized information. Experiments using 58 patient 3-D US images reveal that our proposed approach yielded a mean Dice similarity coefficient of 78.2% compared with the surfaces that were manually contoured, suggesting good agreement between these two segmentations. Additional metrics, the mean absolute distance of 0.65 mm and the maximum absolute distance of 3.2 mm, indicated small distance errors for a voxel spacing of 0.22 × 0.22 × 0.22 mm(3). The Pearson correlation coefficient (r = 0.97, p < 0.001) indicated a significant correlation of algorithm-generated ventricular system volume (VSV) with the manually generated VSV. The calculated minimal detectable difference in ventricular volume change indicated that the proposed segmentation approach with 3-D US images is capable of detecting a VSV difference of 6.5 cm(3) with 95% confidence, suggesting that this approach might be used for monitoring IVH patients' ventricular changes using 3-D US imaging. The mean segmentation times of the graphics processing unit (GPU)- and central processing unit-implemented algorithms were 50 ± 2 and 205 ± 5 s for one 3-D US image, respectively, in addition to 120 ± 10 s for initialization, less than the approximately 35 min required by manual segmentation. In addition, repeatability experiments indicated that the intra-observer variability ranges from 6.5% to 7.5%, and the inter-observer variability is 8.5% in terms of the coefficient of variation of the Dice similarity coefficient. The intra-class correlation coefficient for ventricular system volume measurements for each independent observer ranged from 0.988 to 0.996 and was 0.945 for three different observers. The coefficient of variation and intra-class correlation coefficient revealed that the intra- and inter-observer variability of the proposed approach introduced by the user initialization was small, indicating good reproducibility, independent of different users.
Collapse
Affiliation(s)
- Wu Qiu
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.
| | - Jing Yuan
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Jessica Kishimoto
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Jonathan McLeod
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Yimin Chen
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Sandrine de Ribaupierre
- Neurosurgery, Department of Clinical Neurologic Sciences, University of Western Ontario, London, Ontario, Canada
| | - Aaron Fenster
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
9
|
Ukwatta E, Yuan J, Buchanan D, Chiu B, Awad J, Qiu W, Parraga G, Fenster A. Three-dimensional segmentation of three-dimensional ultrasound carotid atherosclerosis using sparse field level sets. Med Phys 2013; 40:052903. [PMID: 23635296 DOI: 10.1118/1.4800797] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Three-dimensional ultrasound (3DUS) vessel wall volume (VWV) provides a 3D measurement of carotid artery wall remodeling and atherosclerotic plaque and is sensitive to temporal changes of carotid plaque burden. Unfortunately, although 3DUS VWV provides many advantages compared to measurements of arterial wall thickening or plaque alone, it is still not widely used in research or clinical practice because of the inordinate amount of time required to train observers and to generate 3DUS VWV measurements. In this regard, semiautomated methods for segmentation of the carotid media-adventitia boundary (MAB) and the lumen-intima boundary (LIB) would greatly improve the time to train observers and for them to generate 3DUS VWV measurements with high reproducibility. METHODS The authors describe a 3D algorithm based on a modified sparse field level set method for segmenting the MAB and LIB of the common carotid artery (CCA) from 3DUS images. To the authors' knowledge, the proposed algorithm is the first direct 3D segmentation method, which has been validated for segmenting both the carotid MAB and the LIB from 3DUS images for the purpose of computing VWV. Initialization of the algorithm requires the observer to choose anchor points on each boundary on a set of transverse slices with a user-specified interslice distance (ISD), in which larger ISD requires fewer user interactions than smaller ISD. To address the challenges of the MAB and LIB segmentations from 3DUS images, the authors integrated regional- and boundary-based image statistics, expert initializations, and anatomically motivated boundary separation into the segmentation. The MAB is segmented by incorporating local region-based image information, image gradients, and the anchor points provided by the observer. Moreover, a local smoothness term is utilized to maintain the smooth surface of the MAB. The LIB is segmented by constraining its evolution using the already segmented surface of the MAB, in addition to the global region-based information and the anchor points. The algorithm-generated surfaces were sliced and evaluated with respect to manual segmentations on a slice-by-slice basis using 21 3DUS images. RESULTS The authors used ISD of 1, 2, 3, 4, and 10 mm for algorithm initialization to generate segmentation results. The algorithm-generated accuracy and intraobserver variability results are comparable to the previous methods, but with fewer user interactions. For example, for the ISD of 3 mm, the algorithm yielded an average Dice coefficient of 94.4% ± 2.2% and 90.6% ± 5.0% for the MAB and LIB and the coefficient of variation of 6.8% for computing the VWV of the CCA, while requiring only 1.72 min (vs 8.3 min for manual segmentation) for a 3DUS image. CONCLUSIONS The proposed 3D semiautomated segmentation algorithm yielded high-accuracy and high-repeatability, while reducing the expert interaction required for initializing the algorithm than the previous 2D methods.
Collapse
Affiliation(s)
- E Ukwatta
- Biomedical Engineering Graduate Program and Robarts Research Institute, The University of Western Ontario, London, Ontario N6A 3K7, Canada.
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Ukwatta E, Yuan J, Rajchl M, Qiu W, Tessier D, Fenster A. 3-D carotid multi-region MRI segmentation by globally optimal evolution of coupled surfaces. IEEE TRANSACTIONS ON MEDICAL IMAGING 2013; 32:770-785. [PMID: 23303689 DOI: 10.1109/tmi.2013.2237784] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this paper, we propose a novel global optimization based 3-D multi-region segmentation algorithm for T1-weighted black-blood carotid magnetic resonance (MR) images. The proposed algorithm partitions a 3-D carotid MR image into three regions: wall, lumen, and background. The algorithm performs such partitioning by simultaneously evolving two coupled 3-D surfaces of carotid artery adventitia boundary (AB) and lumen-intima boundary (LIB) while preserving their anatomical inter-surface consistency such that the LIB is always located within the AB. In particular, we show that the proposed algorithm results in a fully time implicit scheme that propagates the two linearly ordered surfaces of the AB and LIB to their globally optimal positions during each discrete time frame by convex relaxation. In this regard, we introduce the continuous max-flow model and prove its duality/equivalence to the convex relaxed optimization problem with respect to each evolution step. We then propose a fully parallelized continuous max-flow-based algorithm, which can be readily implemented on a GPU to achieve high computational efficiency. Extensive experiments, with four users using 12 3T MR and 26 1.5T MR images, demonstrate that the proposed algorithm yields high accuracy and low operator variability in computing vessel wall volume. In addition, we show the algorithm outperforms previous methods in terms of high computational efficiency and robustness with fewer user interactions.
Collapse
Affiliation(s)
- Eranga Ukwatta
- Robarts Research Institute, Western University, London ON, N6A 5K8 Canada.
| | | | | | | | | | | |
Collapse
|
11
|
Tracking cerebral white matter changes across the lifespan: insights from diffusion tensor imaging studies. J Neural Transm (Vienna) 2013; 120:1369-95. [PMID: 23328950 DOI: 10.1007/s00702-013-0971-7] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Accepted: 01/04/2013] [Indexed: 12/13/2022]
Abstract
Delineating the normal development of brain white matter (WM) over the human lifespan is crucial to improved understanding of underlying WM pathology in neuropsychiatric and neurological conditions. We review the extant literature concerning diffusion tensor imaging studies of brain WM development in healthy individuals available until October 2012, summarise trends of normal development of human brain WM and suggest possible future research directions. Temporally, brain WM maturation follows a curvilinear pattern with an increase in fractional anisotropy (FA) from newborn to adolescence, decelerating in adulthood till a plateau around mid-adulthood, and a more rapid decrease of FA from old age onwards. Spatially, brain WM tracts develop from central to peripheral regions, with evidence of anterior-to-posterior maturation in commissural and projection fibres. The corpus callosum and fornix develop first and decline earlier, whilst fronto-temporal WM tracts like cingulum and uncinate fasciculus have protracted maturation and decline later. Prefrontal WM is most vulnerable with greater age-related FA reduction compared with posterior WM. Future large scale studies adopting longitudinal design will better clarify human brain WM changes over time.
Collapse
|
12
|
|
13
|
Fenster A, Chiu B. Evaluation of Segmentation algorithms for Medical Imaging. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2012; 2005:7186-9. [PMID: 17281935 DOI: 10.1109/iembs.2005.1616166] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This paper describes an approach to be used for medical image segmentation evaluation. The process for segmenting organs and structures from medical images is gaining increased importance in the diagnosis of diseases and in guiding minimally invasive surgical and therapeutic procedures. While investigators are continuing to develop novel new segmentation approaches, little attention has been given to the development of a uniform and common framework for and performance metrics to be used in comparing different algorithms, in optimizing algorithms and in evaluating their performance. Choosing an appropriate effectiveness measure of object segmentation is a difficult task and weighting the importance of different possible performance metrics requires matching the metrics to the segmentation objectives. However, in all tasks, it is now believed that three types of metrics must be measured and reported: accuracy, precision and efficiency. In this paper, we review some of these metrics.
Collapse
Affiliation(s)
- Aaron Fenster
- director of the Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5K8, Canada (Phone:
| | | |
Collapse
|
14
|
Fotina I, Lütgendorf-Caucig C, Stock M, Pötter R, Georg D. Critical discussion of evaluation parameters for inter-observer variability in target definition for radiation therapy. Strahlenther Onkol 2012; 188:160-7. [PMID: 22281878 DOI: 10.1007/s00066-011-0027-6] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 10/20/2011] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND PURPOSE Inter-observer studies represent a valid method for the evaluation of target definition uncertainties and contouring guidelines. However, data from the literature do not yet give clear guidelines for reporting contouring variability. Thus, the purpose of this work was to compare and discuss various methods to determine variability on the basis of clinical cases and a literature review. PATIENTS AND METHODS In this study, 7 prostate and 8 lung cases were contoured on CT images by 8 experienced observers. Analysis of variability included descriptive statistics, calculation of overlap measures, and statistical measures of agreement. Cross tables with ratios and correlations were established for overlap parameters. RESULTS It was shown that the minimal set of parameters to be reported should include at least one of three volume overlap measures (i.e., generalized conformity index, Jaccard coefficient, or conformation number). High correlation between these parameters and scatter of the results was observed. CONCLUSION A combination of descriptive statistics, overlap measure, and statistical measure of agreement or reliability analysis is required to fully report the interrater variability in delineation.
Collapse
Affiliation(s)
- I Fotina
- Div. Medical Radiation Physics, Department of Radiotherapy, Medical University Vienna/AKH Vienna, Währinger Gürtel 18-20, Vienna, Austria.
| | | | | | | | | |
Collapse
|
15
|
Ukwatta E, Awad J, Ward AD, Buchanan D, Samarabandu J, Parraga G, Fenster A. Three-dimensional ultrasound of carotid atherosclerosis: Semiautomated segmentation using a level set-based method. Med Phys 2011; 38:2479-93. [DOI: 10.1118/1.3574887] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
16
|
Feasibility of CBCT-based target and normal structure delineation in prostate cancer radiotherapy: multi-observer and image multi-modality study. Radiother Oncol 2010; 98:154-61. [PMID: 21176984 DOI: 10.1016/j.radonc.2010.11.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 11/28/2010] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND PURPOSE In-room cone-beam CT (CBCT) imaging and adaptive treatment strategies are promising methods to decrease target volumes and to spare organs at risk. The aim of this work was to analyze the inter-observer contouring uncertainties of target volumes and organs at risks (oars) in localized prostate cancer radiotherapy using CBCT images. Furthermore, CBCT contouring was benchmarked against other image modalities (CT, MR) and the influence of subjective image quality perception on inter-observer variability was assessed. METHODS AND MATERIALS Eight prostate cancer patients were selected. Seven radiation oncologists contoured target volumes and oars on CT, MRI and CBCT. Volumes, coefficient of variation (COV), conformity index (cigen), and coordinates of center-of-mass (COM) were calculated for each patient and image modality. Reliability analysis was performed for the support of the reported findings. Subjective perception of image quality was assessed via a ten-scored visual analog scale (VAS). RESULTS The median volume for prostate was larger on CT compared to MRI and CBCT images. The inter-observer variation for prostate was larger on CBCT (CIgen=0.57±0.09, 0.61 reliability) compared to CT (CIgen=0.72±0.07, 0.83 reliability) and MRI (CIgen=0.66±0.12, 0.87 reliability). On all image modalities values of the intra-observer reliability coefficient (0.97 for CT, 0.99 for MR and 0.94 for CBCT) indicated high reproducibility of results. For all patients the root mean square (RMS) of the inter-observer standard deviation (σ) of the COM was largest on CBCT with σ(x)=0.4 mm, σ(y)=1.1 mm, and σ(z)=1.7 mm. The concordance in delineating OARs was much stronger than for target volumes, with average CIgen>0.70 for rectum and CIgen>0.80 for bladder. Positive correlations between CIgen and VAS score of the image quality were observed for the prostate, seminal vesicles and rectum. CONCLUSIONS Inter-observer variability for target volume delineation in prostate cancer is larger for CBCT-based contouring compared to CT and MRI. This factor of influence needs to be considered when defining safety margins for CBCT-based Adaptive Radiotherapy (ART).
Collapse
|
17
|
Stroz MJ, Fenster A. Measuring flow-mediated dilation through transverse and longitudinal imaging: comparison and validation of methods. Phys Med Biol 2010; 55:6501-14. [PMID: 20959683 DOI: 10.1088/0031-9155/55/21/011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Three-dimensional ultrasound images (3DUS), having two spatial and one temporal dimension, were taken of the brachial artery during baseline conditions, in the transverse and longitudinal planes. The transverse images were analyzed by three different techniques used to quantify flow-mediated dilation (FMD): (1) measuring vessel area manually (TIMA), (2) measuring vessel area semi-automatically (TISA) and (3) measuring vessel diameter (TID). The inter- and intra-observer variability and transducer repositioning variability of each method were compared to each other and to the variability of measurements taken using the traditional method of measuring vessel FMD through measuring vessel diameter on longitudinal images (LID). The percent coefficient-of-variation describing the inter-observer variability (COV(inter)) was similar for the methods, indicating that each method was equally reproducible by the different observers. The percent coefficient-of-variation describing the intra-observer variability (COV(intra)) and the smallest detectable percent change in diameter (Δd(intra)) for each method indicated that TID was the most precise at measuring vessel diameter, and could measure the smallest changes in diameter between successive measurements (COV(intra) = 0.31%, Δd(intra) = 0.87%). LID performed the poorest (COV(intra) = 0.57%, Δd(intra) = 1.59%). The percent coefficient-of-variation describing transducer repositioning (COV(rep)) and the smallest detectable percent change in FMD over time (ΔFMD) for each method indicated that TIMA was the most reproducible method (COV(rep) = 2.35%, ΔFMD = 6.52%) closely followed by TISA. TID performed the poorest (COV(rep) = 5.37%, ΔFMD = 14.89%). TIMA and TISA were found not to be statistically different so we suggest TISA as the method of choice to maximize reproducibility between measurements over time, as it is faster and simpler to perform. In each experiment it was clear that transverse imaging introduced equal or less variability into diameter measurements as compared to longitudinal imaging and we suggest this imaging plane be used in all assessments of FMD.
Collapse
Affiliation(s)
- Marianne J Stroz
- Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, London, Ontario N6A5K8, Canada.
| | | |
Collapse
|
18
|
Abstract
BACKGROUND Current multiple sclerosis (MS) treatment is only partially effective and not all patients respond well. The goal in this study was to evaluate minocycline for its safety, tolerability, and MRI impact as a potential therapy over 36 months after a three month run-in in ten relapsing-remitting (RR) MS patients. METHODS Clinical assessments were at three month intervals until six months, then at six month intervals. Three Tesla MRI was performed monthly during the run-in and first six months of treatment, then at 12, 24, and 36 months. RESULTS Treatment was safe and well tolerated. Annualized relapse rate was 1.2 during the run-in and 0.25 during treatment. The proportion of active scans was lower during the first six months of treatment (5.6%, p < 0.001) and during the extension (8.7%, p = 0.002) than during the run-in (47.5%). Consistent with these outcomes, mean T2 lesion volume remained stable over three years and percent brain volume change was reduced during year three (-0.37%) of minocycline treatment. CONCLUSIONS This trial is limited by small sample and no control group but suggests that minocycline is safe and potentially beneficial in RRMS. This supports further investigation of its efficacy.
Collapse
|
19
|
Lyshchik A, Hobbs SB, Fleischer AC, Khabele D, Son DS, Gore JC, Price RR. Ovarian volume measurements in mice with high-resolution ultrasonography. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2007; 26:1419-25. [PMID: 17901144 DOI: 10.7863/jum.2007.26.10.1419] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
OBJECTIVE The aim of our study was to evaluate the intraobserver and interobserver variability of ovarian volume measurements in mice with high-resolution 2-dimensional ultrasonography (2DUS) and 3-dimensional ultrasonography (3DUS). METHODS Ovaries of 10 nude mice were visualized with a small-animal ultrasound scanner and a 40-MHz probe. For each ovary, volume was measured 3 times by 2 independent readers using both 2DUS and 3DUS methods. The 2DUS method used a biplane ellipsoid model. The 3DUS method estimated the volume by integrating 10 to 12 parallel image planes of the ovary after semiautomated outlining of the boundaries. For each type of measurement, intraobserver and interobserver standard error of measurement (SEM) values and minimal detectable volume changes were calculated by analysis of variance. RESULTS Two-dimensional ultrasonography showed much poorer reproducibility, with higher absolute intraobserver and interobserver SEM values (0.50 and 0.61 mm3, respectively) than 3DUS (0.20 and 0.35 mm3; P < .01). Relative intraobserver and interobserver SEM values were also much higher for 2DUS (12.20% and 14.88%) than for 3DUS (5.12% and 8.97%; P < .01). The minimal volume changes that could be detected with a 95% confidence level in successive measurements by the same (or different) observers were 33.90% (41.22%) for 2DUS and 14.10% (24.87%) for 3DUS. CONCLUSIONS High-resolution 3DUS can provide a reliable tool for noninvasive, longitudinal ovarian volume measurements in mice.
Collapse
Affiliation(s)
- Andrej Lyshchik
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, CCC-1118 MCN, 1161 21st Ave, Nashville, TN 37232-2675, USA.
| | | | | | | | | | | | | |
Collapse
|
20
|
Court LE, Allen A, Tishler R. Evaluation of the precision of portal-image-guided head-and-neck localization: An intra- and interobserver study. Med Phys 2007; 34:2704-7. [PMID: 17821978 DOI: 10.1118/1.2747050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
There is increasing evidence that, for some patients, image-guided intensity-modulated radiation therapy (IMRT) for head-and-neck cancer patients may maintain target dose coverage and critical organ (e.g., parotids) dose closer to the planned doses than setup using lasers alone. We investigated inter- and intraobserver uncertainties in patient setup in head-and-neck cancer patients. Twenty-two sets of orthogonal digital portal images (from five patients) were selected from images used for daily localization of head-and-neck patients treated with IMRT. To evaluate interobserver variations, five radiation therapists compared the portal images with the plan digitally reconstructed radiographs and reported shifts for the isocenter (approximately C2) and for a supraclavicular reference point. One therapist repeated the procedure a month later to evaluate intraobserver variations. The procedure was then repeated with teams of two therapists. The frequencies for which agreement between the shift reported by the observer and the daily mean shift (average of all observers for a given image set) were less than 1.5 and 2.5 mm were calculated. Standard errors of measurement for the intra- and interobserver uncertainty (SEMintra and SEMinter) for the individual and teams were calculated. The data showed that there was very little difference between individual therapists and teams. At isocenter, 80%-90% of all reported shifts agreed with the daily average within 1.5 mm, showing consistency in the ways both individuals and teams interpret the images (SEMinter approximately 1 mm). This dropped to 65% for the supraclavicular point (SEMinter approximately 1.5 mm). Uncertainties increased for larger setup errors. In conclusion, image-guided patient positioning allows head-and-neck patients to be controlled within 3-4 mm. This is similar to the setup uncertainties found for most head-and-neck patients, but may provide some improvement for the subset of patients with larger setup uncertainties.
Collapse
Affiliation(s)
- Laurence E Court
- Department of Radiation Oncology, Dana-Farber/Brigham & Women's Cancer Center, Boston, Massachusetts 02115, USA.
| | | | | |
Collapse
|
21
|
Landry A, Ainsworth C, Blake C, Spence JD, Fenster A. Manual planimetric measurement of carotid plaque volume using three-dimensional ultrasound imaging. Med Phys 2007; 34:1496-505. [PMID: 17500480 DOI: 10.1118/1.2715487] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We investigated the utility of three manual planimetric methods to quantify carotid plaque volume. A single observer measured 15 individual plaques from 15 three-dimensional (3D) ultrasound (3D US) images of patients ten times each using three different planimetric approaches. Individual plaque volumes were measured (range: 32.6-597.1 mm3) using a standard planimetric approach (M1) whereby a plaque end was identified and sequential contours were measured. The same plaques were measured using a second approach (M2), whereby plaque ends were first identified and the 3D US image of the plaque was then subdivided into equal intervals. A third method (M3) was used to measure total plaque burden (range: 165.1-1080.0 mm3) in a region (+/- 1.5 cm) relative to the carotid bifurcation. M1 systematically underestimated individual plaque volume compared to M2 (V2 = V1 + 14.0 mm3, r = 0.99, p = 0.006) due to a difference in the mean plaque length measured. Coefficients of variance (CV) for M1 and M2 decrease with increasing plaque volume, with M2 results less than M1. Root mean square difference between experimental and theoretical CV for M2 was 3.2%. The standard deviation in the identification of the transverse location of the carotid bifurcation was 0.56 mm. CVs for plaque burden measured using M3 ranged from 1.2% to 7.6% and were less than CVs determined for individual plaque volumes of the same volume. The utility of M3 was demonstrated by measuring carotid plaque burden and volume change over a period of 3 months in three patients. In conclusion, M2 was determined to be a more superior measurement technique than M1 to measure individual plaque volume. Furthermore, we demonstrated the utility of M3 to quantify regional plaque burden and to quantify change in plaque volume.
Collapse
Affiliation(s)
- Anthony Landry
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5K8, Canada
| | | | | | | | | |
Collapse
|
22
|
Breen SL, Publicover J, De Silva S, Pond G, Brock K, O'Sullivan B, Cummings B, Dawson L, Keller A, Kim J, Ringash J, Yu E, Hendler A, Waldron J. Intraobserver and interobserver variability in GTV delineation on FDG-PET-CT images of head and neck cancers. Int J Radiat Oncol Biol Phys 2007; 68:763-70. [PMID: 17379435 DOI: 10.1016/j.ijrobp.2006.12.039] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 12/21/2006] [Accepted: 12/22/2006] [Indexed: 12/22/2022]
Abstract
PURPOSE To determine if the addition of fluorodeoxyglucose positron emission tomography (FDG-PET) data changes primary site gross tumor volumes (GTVs) in head and neck cancers. METHODS AND MATERIALS Computed tomography (CT), contrast-enhanced CT, and FDG-PET-CT scans were obtained in 10 patients with head and neck cancers. Eight experienced observers (6 head and neck oncologists and 2 neuro-radiologists) with access to clinical and radiologic reports outlined primary site GTVs on each modality. Three cases were recontoured twice to assess intraobserver variability. The magnitudes of the GTVs were compared. Intra- and interobserver variability was assessed by a two-way repeated measures analysis of variance. Inter- and intraobserver reliability were calculated. RESULTS There were no significant differences in the GTVs across the image modalities when compared as ensemble averages; the Wilcoxon matched-pairs signed-rank test showed that CT volumes were larger than PET-CT. Observers demonstrated the greatest consistency and were most interchangeable on contrast-enhanced CT; they performed less reliably on PET-CT. CONCLUSIONS The addition of PET-CT to primary site GTV delineation of head and neck cancers does not change the volume of the GTV defined by this group of expert observers in this patient sample. An FDG-PET may demonstrate differences in neck node delineation and in other disease sites.
Collapse
Affiliation(s)
- Stephen L Breen
- Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Zabad RK, Metz LM, Todoruk TR, Zhang Y, Mitchell JR, Yeung M, Patry DG, Bell RB, Yong VW. The clinical response to minocycline in multiple sclerosis is accompanied by beneficial immune changes: a pilot study. Mult Scler 2007; 13:517-26. [PMID: 17463074 DOI: 10.1177/1352458506070319] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Minocycline has immunomodulatory and neuroprotective activities in vitro and in an animal model of multiple sclerosis (MS). We have previously reported that minocycline decreased gadolinium-enhancing activity over six months in a small trial of patients with active relapsing-remitting MS (RRMS). Here we report the impact of oral minocycline on clinical and magnetic resonance imaging (MRI) outcomes and serum immune molecules in this cohort over 24 months of open-label minocycline treatment. Despite a moderately high pretreatment annualized relapse rate (1.3/year pre-enrolment; 1.2/year during a three-month baseline period) prior to treatment, no relapses occurred between months 6 and 24. Also, despite very active MRI activity pretreatment (19/40 scans had gadolinium-enhancing activity during a three-month run-in), the only patient with gadolinium-enhancing lesions on MRI at 12 and 24 months was on half-dose minocycline. Levels of the p40 subunit of interleukin (IL)-12, which at high levels might antagonize the proinflammatory IL-12 receptor, were elevated over 18 months of treatment, as were levels of soluble vascular cell adhesion molecule-1. The activity of matrix metalloproteinase-9 was decreased by treatment. Thus, clinical and MRI outcomes are supported by systemic immunological changes and call for further investigation of minocycline in MS.
Collapse
Affiliation(s)
- R K Zabad
- Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Wirtzfeld LA, Graham KC, Groom AC, Macdonald IC, Chambers AF, Fenster A, Lacefield JC. Volume measurement variability in three-dimensional high-frequency ultrasound images of murine liver metastases. Phys Med Biol 2006; 51:2367-81. [PMID: 16675858 DOI: 10.1088/0031-9155/51/10/002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The identification and quantification of tumour volume measurement variability is imperative for proper study design of longitudinal non-invasive imaging of pre-clinical mouse models of cancer. Measurement variability will dictate the minimum detectable volume change, which in turn influences the scheduling of imaging sessions and the interpretation of observed changes in tumour volume. In this paper, variability is quantified for tumour volume measurements from 3D high-frequency ultrasound images of murine liver metastases. Experimental B16F1 liver metastases were analysed in different size ranges including less than 1 mm3, 1-4 mm3, 4-8 mm3 and 8-70 mm3. The intra- and inter-observer repeatability was high over a large range of tumour volumes, but the coefficients of variation (COV) varied over the volume ranges. The minimum and maximum intra-observer COV were 4% and 14% for the 1-4 mm3 and <1 mm3 tumours, respectively. For tumour volumes measured by segmenting parallel planes, the maximum inter-slice distance that maintained acceptable measurement variability increased from 100 to 600 microm as tumour volume increased. Comparison of free breathing versus ventilated animals demonstrated that respiratory motion did not significantly change the measured volume. These results enable design of more efficient imaging studies by using the measured variability to estimate the time required to observe a significant change in tumour volume.
Collapse
Affiliation(s)
- L A Wirtzfeld
- Biomedical Engineering Graduate Program, University of Western Ontario, London, Ontario, N6A 5B9, Canada.
| | | | | | | | | | | | | |
Collapse
|
25
|
Ding Z, Preiningerova J, Cannistraci CJ, Vollmer TL, Gore JC, Anderson AW. Quantification of multiple sclerosis lesion load and brain tissue volumetry using multiparameter MRI: methodology and reproducibility. Magn Reson Imaging 2005; 23:445-52. [PMID: 15862645 DOI: 10.1016/j.mri.2004.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Accepted: 12/08/2004] [Indexed: 11/27/2022]
Abstract
Quantitative characterization of multiple sclerosis (MS) lesion load is of considerable interest to clinical follow-up studies. Based on fuzzy clustering of multiparameter magnetic resonance images, we have developed a computer-assisted system for volumetric quantification of brain tissue. Tests on patient data show that the system is very efficient, and volumetric measurements characterized are highly reproducible. The high reproducibility and efficiency offer the potential of routine laboratory and clinical use for quantification of MS lesion load.
Collapse
Affiliation(s)
- Zhaohua Ding
- Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37232-2675, USA.
| | | | | | | | | | | |
Collapse
|
26
|
Wei X, Guttmann CRG, Warfield SK, Eliasziw M, Mitchell JR. Has your patient's multiple sclerosis lesion burden or brain atrophy actually changed? Mult Scler 2005; 10:402-6. [PMID: 15327037 DOI: 10.1191/1352458504ms1061oa] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Changes in mean magnetic resonance imaging (MRI)-derived measurements between patient groups are often used to determine outcomes in therapeutic trials and other longitudinal studies of multiple sclerosis (MS). However, in day-to-day clinical practice the changes within individual patients may also be of interest In this paper, we estimated the measurement error of an automated brain tissue quantification algorithm and determined the thresholds for statistically significant change of MRI-derived T2 lesion volume and brain atrophy in individual patients. Twenty patients with MS were scanned twice within 30 min. Brain tissue volumes were measured using the computer algorithm. Brain atrophy was estimated by calculation of brain parenchymal fraction. The threshold of change between repeated scans that represented statistically significant change beyond measurement error with 95% certainty was 0.65 mL for T2 lesion burden and 0.0056 for brain parenchymal fraction. Changes in lesion burden and brain atrophy below these thresholds can be safely (with 95% certainty) explained by measurement variability alone. These values provide clinical neurologists with a useful reference to interpret MRI-derived measures in individual patients.
Collapse
Affiliation(s)
- Xingchang Wei
- Seaman Family MR Research Center, Departments of Radiology and Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
| | | | | | | | | |
Collapse
|
27
|
Court LE, Dong L, Taylor N, Ballo M, Kitamura K, Lee AK, O'Daniel J, White RA, Cheung R, Kuban D. Evaluation of a contour-alignment technique for CT-guided prostate radiotherapy: an intra- and interobserver study. Int J Radiat Oncol Biol Phys 2004; 59:412-8. [PMID: 15145157 DOI: 10.1016/j.ijrobp.2003.10.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2003] [Revised: 09/17/2003] [Accepted: 10/15/2003] [Indexed: 11/25/2022]
Abstract
PURPOSE The recent introduction of integrated CT/linear accelerator systems may mean that daily CT localization can become a reality in the clinic, possibly allowing further dose escalation to the prostate while limiting unwanted doses to the rectum and bladder. However, the implementation of CT localization is currently impeded by the lack of precise and robust techniques to align the treatment plan with the daily CT images. The purpose of this study was to evaluate a manual alignment technique, in which the gross target volume contours are overlaid on the daily CT images and then shifted to match the structures visible in the images. METHODS AND MATERIALS A total of 28 CT image sets were taken before the standard delivery of intensity-modulated radiotherapy for prostate cancer for 2 patients. Seven observers (four radiation oncologists and three medical physicists) manually shifted the gross target volume contours from the treatment plan to best match the daily CT images. One observer repeated the process 1 week later to evaluate intraobserver variations. The experiment was then repeated, but the CT images from the original treatment plan were used as a reference to reduce interobserver uncertainty when aligning the contours. The shifts in prostate position found by different observers, both with and without reference data, were evaluated using a factorial analysis of variance to determine the standard errors of measurement for the intra- and interobserver uncertainty (SEM(intra) and SEM(inter), respectively). The differences in the SEM for the two groups of observers (radiation oncologists and medical physicists), the two alignment techniques (with and without reference information), and the two patients were evaluated using the t test at 90% confidence levels. RESULTS With no reference information, the SEM(inter) using one patient data set (Patient 1) was 0.8 mm, 2.0 mm, and 2.2 mm in the right-left (RL), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. The use of the treatment plan as a reference reduced the SEM(inter) to 0.7 mm, 1.0 mm, and 1.6 mm in the RL, AP, and SI directions, respectively. In Patient 2, localization of the prostate was more difficult; the best SEM(inter) achieved with this patient was 0.8 mm, 1.9 mm, and 2.0 mm in the RL, AP, and SI directions, respectively. The SEM(intra) values with Patient 1 were also slightly better than with Patient 2. When reference data were used, the SEM(intra) value was 0.5 mm, 0.7 mm, and 0.5 mm for Patient 1 and 0.6 mm, 1.0 mm, and 0.7 mm for Patient 2 in the RL, AP, and SI directions, respectively. Despite the larger than expected interobserver variation reported here, the SEM(inter) was smaller than the typical day-to-day variation in prostate position. The contour alignment technique may still be useful to aid daily prostate localization or in a correction scheme to minimize the effect of target positional error. CONCLUSION The interobserver uncertainties associated with aligning the gross target volume contours with daily CT images were sufficiently small that this method may be used for daily CT localization of the prostate. The use of a reference image is important to improve the consistency among different users in this technique.
Collapse
Affiliation(s)
- Laurence E Court
- Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030-4009, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Archibald CJ, Wei X, Scott JN, Wallace CJ, Zhang Y, Metz LM, Mitchell JR. Posterior fossa lesion volume and slowed information processing in multiple sclerosis. Brain 2004; 127:1526-34. [PMID: 15090476 DOI: 10.1093/brain/awh167] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The relationship between performance on information processing efficiency measures and MRI-derived lesion volume including global and regional T2 and T1 lesion volumes was investigated in 20 patients with relapsing-remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS). Processing speed, as measured by the Sternberg Memory Scanning Test, was significantly correlated with posterior fossa lesion volume and slowed reaction time in seven out of eight patients (six out of seven with SPMS) with any lesion volume in the posterior fossa suggesting a 'threshold effect'. Processing capacity as measured by the Salthouse Keeping Track Test was not significantly correlated with the MRI measures. Cognitive performance did not correlate with Expanded Disability Status Scale score, depression or fatigue, and patients performed within normal limits on tests of attention/concentration ability. The significant relationship between posterior fossa lesion volume and memory scanning speed in this study suggests that pathological damage in the posterior fossa may contribute to slowed cognitive processing and may be an important direction for future studies of cognitive function in multiple sclerosis. Lack of correlation of cognitive measures with the other MRI measures may be due to low lesion volume relative to other studies, sample composition, and limited pathological specificity of the MRI measures.
Collapse
Affiliation(s)
- Catherine J Archibald
- Seaman Family MR Research Centre, Foothills Medical Centre, University of Calgary, Calgary, Alberta Canada T2N 2T9.
| | | | | | | | | | | | | |
Collapse
|
29
|
Bosc M, Heitz F, Armspach JP, Namer I, Gounot D, Rumbach L. Automatic change detection in multimodal serial MRI: application to multiple sclerosis lesion evolution. Neuroimage 2003; 20:643-56. [PMID: 14568441 DOI: 10.1016/s1053-8119(03)00406-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2002] [Revised: 04/03/2003] [Accepted: 07/02/2003] [Indexed: 10/27/2022] Open
Abstract
The automatic analysis of subtle changes between MRI scans is an important tool for assessing disease evolution over time. Manual labeling of evolutions in 3D data sets is tedious and error prone. Automatic change detection, however, remains a challenging image processing problem. A variety of MRI artifacts introduce a wide range of unrepresentative changes between images, making standard change detection methods unreliable. In this study we describe an automatic image processing system that addresses these issues. Registration errors and undesired anatomical deformations are compensated using a versatile multiresolution deformable image matching method that preserves significant changes at a given scale. A nonlinear intensity normalization method is associated with statistical hypothesis test methods to provide reliable change detection. Multimodal data is optionally exploited to reduce the false detection rate. The performance of the system was evaluated on a large database of 3D multimodal, MR images of patients suffering from relapsing remitting multiple sclerosis (MS). The method was assessed using receiver operating characteristics (ROC) analysis, and validated in a protocol involving two neurologists. The automatic system outperforms the human expert, detecting many lesion evolutions that are missed by the expert, including small, subtle changes.
Collapse
Affiliation(s)
- Marcel Bosc
- Laboratoire des Sciences de l'Image de l'Informatique et de la Télédetection (LSIIT) UMR-7005 CNRS, 67400, Illkirch, France.
| | | | | | | | | | | |
Collapse
|
30
|
Melhem ER, Herskovits EH, Karli-Oguz K, Golay X, Hammoud DA, Fortman BJ, Munter FM, Itoh R. Defining thresholds for changes in size of simulated T2-hyperintense brain lesions on the basis of qualitative comparisons. AJR Am J Roentgenol 2003; 180:65-9. [PMID: 12490477 DOI: 10.2214/ajr.180.1.1800065] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Our purpose was to define thresholds below which trained reviewers cannot detect changes in the size of T2-hyperintense brain lesions. MATERIALS AND METHODS We generated T2-weighted brain MR images (TR/TE, 4000/80) with simulated hyperintense lesions derived from a real multiple sclerosis plaque. The size of the original multiple sclerosis lesion was varied by scaling up or down the lesion using a bicubic interpolation method. Three hundred seventy-eight composite images, in which two T2-weighted images containing lesions were paired, were presented to three equally trained neuroradiologists to define thresholds below which changes in original lesion size could not be detected. Stepwise logistic regression was used to evaluate the dependency of size thresholds on the original size of the lesion. RESULTS Thresholds ranged from a 5% to 15% increase in the original lesion diameter. For increases greater than 15%, all three reviewers detected the change in lesion size irrespective of the diameter of the original lesion. There was a dependency of the threshold on the diameter of the original lesion (p = 0.02). CONCLUSION Using an MR simulator, we can define thresholds below which changes in original lesion size cannot be reliably detected. These results may guide the design of clinical trials that rely on trained reviewers to assess change in lesion burden.
Collapse
Affiliation(s)
- Elias R Melhem
- Division of Neuroradiology, The Johns Hopkins Medical Institutions, 600 N. Wolfe Street, Baltimore, MD 21287-7619, USA
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Landry A, Fenster A. Theoretical and experimental quantification of carotid plaque volume measurements made by three-dimensional ultrasound using test phantoms. Med Phys 2002; 29:2319-27. [PMID: 12408306 DOI: 10.1118/1.1510130] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
An accurate technique that exhibits low variability has practical importance for the quantification of carotid plaque volume. Such a technique is necessary to monitor plaque progression or regression that may result in response to nonsurgical therapy. In this study, we investigate the accuracy and variability of plaque volume measurement by three-dimensional ultrasound using vascular plaque phantoms over a range of 68.2 mm3 to 285.5 mm3. The agar plaques maintained a consistent cylindrical geometry with variations in the height, length, and echogenicity. The volume of each plaque was determined by water displacement. The three-dimensional (3D) ultrasound (US) images were acquired with a mechanical scanning system which creates a 3D US Cartesian volume, that was manipulated and viewed in any orientation, from a collection of conventional parallel two-dimensional (2D) US images. The plaque volumes were measured by serial 2D manual planimtery. The mean accuracy in plaque volume measurement was 3.1+/-0.9%. Variability in plaque volume measurement was calculated to be 4.0+/-1.0% and 5.1+/-1.4% for intraobserver and interobserver measurements, respectively. We have also developed a theoretical description for the variance in measurement of plaque volume using manual planimetry. Root-mean-square difference between experimentally and theoretically determined values of plaque volume fractional variance was 9%.
Collapse
Affiliation(s)
- Anthony Landry
- Imaging Research Laboratories, John P. Robarts Research Institute, London, Ontario, Canada
| | | |
Collapse
|
32
|
Payne ME, Fetzer DL, MacFall JR, Provenzale JM, Byrum CE, Krishnan KRR. Development of a semi-automated method for quantification of MRI gray and white matter lesions in geriatric subjects. Psychiatry Res 2002; 115:63-77. [PMID: 12165368 DOI: 10.1016/s0925-4927(02)00009-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Brain magnetic resonance imaging (MRI) allows for quantitative assessment of hyperintense foci, which are seen with aging and various diseases. These foci, considered to represent lesions, are important in the study of various psychiatric illnesses, including depression. Few quantitative measures have been developed for such research. The goal of the current study was to develop a reliable and efficient method for quantifying the volumes of gray and white matter lesions in MRI scans of the elderly. Interrater reliability was determined by repeat lesion measures on 16 scans. Semi-automated segmentation was performed that identified potential lesions, and then lesions were manually selected based upon detailed anatomic criteria. The lesion quantification procedure took between 25 and 45 min per scan. Reliability intraclass correlation coefficients (ICCs) were 0.99 for both gray and white matter lesions. Volumetric results were found to be moderately correlated with previous lesion ratings (r-values between 0.37 and 0.62, P<0.0001). Among the 700 scans processed with this method, lesion volumes ranged from 0 to 7.3 ml for gray matter, and from 0.4 to 96.8 ml for white matter. Our method proved to be efficient and reliable for quantifying lesions in MRI scans of the elderly.
Collapse
Affiliation(s)
- Martha E Payne
- Neuropsychiatric Imaging Research Laboratory, Duke University Medical Center, Durham, NC 27710, USA.
| | | | | | | | | | | |
Collapse
|
33
|
Mitchell JR, Rutt BK. Improved contrast in multispectral phase images derived from magnetic resonance exams of multiple sclerosis patients. Med Phys 2002; 29:727-35. [PMID: 12033569 DOI: 10.1118/1.1462637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We describe a method to extract data from multispectral MR exams of patients with Multiple Sclerosis (MS). The technique produces images of "spectral phase" (SP) relative to a reference tissue. SP images allow retrospective suppression of signal in the reference tissue, while maintaining high spatial resolution. Image quality in SP images was determined from MR exams of 5 MS patients selected at random from a clinical trial underway at our institute. Exams consisting of proton density weighted (PDw), T2 weighted (T2w), T1 weighted (T1w), and gadolinium-DTPA enhanced T1w (GAD) images were acquired from each patient. The MR exams were corrected for intensity nonuniformity, then filtered with an algorithm based upon anisotropic diffusion, to reduce noise. Principal component (PC) images and SP images relative to cerebrospinal fluid (SP(CSF)), normal appearing white matter (SP(NAWM)), gray matter (SP(GM)), and temporalis muscle (SP(MUS)) were then calculated. Contrast between tissues and MS lesions in the MR and derived images was then determined by measuring the signal-difference-to-noise ratio (dSNR) between tissues. Our new SP images provided better tissue contrast than the original MR, filtered MR, and PC images. Contrast improved between CSF and NAWM (from 19.5 to 56), CSF and GM (from 15 to 36), GM and NAWM (from 8 to 14), MS lesions and CSF (from 16 to 35), and between MS lesions and NAWM (from 24 to 47). (Maximum contrast in the original MR images compared to maximum contrast in the SP images.) The additional contrast in SP images may aid the quantification and analysis of lesion activity in MR exams of MS patients.
Collapse
Affiliation(s)
- J R Mitchell
- Department of Radiology, Seaman Family MR Research Center, University of Calgary, Alberta, Canada.
| | | |
Collapse
|
34
|
Kraus J, Kuehne BS, Tofighi J, Frielinghaus P, Stolz E, Blaes F, Laske C, Engelhardt B, Traupe H, Kaps M, Oschmann P. Serum cytokine levels do not correlate with disease activity and severity assessed by brain MRI in multiple sclerosis. Acta Neurol Scand 2002; 105:300-8. [PMID: 11939943 DOI: 10.1034/j.1600-0404.2002.1o199.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Chronic and acute dysregulation of the cytokine network has been described in multiple sclerosis (MS). Inflammatory lesions in the central nervous system of MS patients can be assessed by brain magnetic resonance imaging (MRI). This study has been performed to investigate whether changes of cytokines correlate with morphological changes as determined by MRI. MATERIALS AND METHODS We included 46 patients with relapsing-remitting MS in the study. The serum concentrations of tumor necrosis factor-beta (TNF-beta), TNF receptor-1 (TNFR-1; 55 kDa) and TNFR-2 (75 kDa), interleukin-4 (IL-4), interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) were measured by enzyme linked immunosorbent assay in all patients. Each parameter was correlated with clinical findings and brain MRI parameters. We measured both the number (lesion load) and cumulated area (disease burden) of all lesions on brain MRI. In addition, the number and cumulated area of those lesions showing signs of activity [Gadolinium (Gd)-enhancement, perifocal edema] were determined. RESULTS A non-significant trend (P < 0.05) was found only for the correlation of serum IFN-gamma levels and the number of active MRI lesions showing both Gd-enhancement and perifocal edema in the subgroup of patients (n=21) with active lesions. When corrected for multiple comparisons, this correlation was not significant anymore, as it was above the corrected P-value of 0.001. We could not observe any further correlation of cytokine levels and MRI parameters. However, TNF-beta serum levels were significantly (P < 0.05) elevated in the patient subgroups with higher number of lesions and disease burden, respectively. CONCLUSION Our data show that the determination of serum levels of the investigated cytokines and cytokine receptors is not useful as a tool to determine subclinical disease activity and severity as assessed by brain MRI.
Collapse
Affiliation(s)
- J Kraus
- Department of Neurology, Research Group for Multiple Sclerosis and Neuroimmunology, Justus-Liebig University Giessen, Giessen, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Gadeberg P, Gundersen HJG, Taagehøj F, Jakobsen J. MRI volume measurements of hypointense objects. A phantom study using stereological methods. J Neurosci Methods 2002; 114:149-57. [PMID: 11856565 DOI: 10.1016/s0165-0270(01)00513-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Volume estimates made from thick slabs overestimate the volume of a positive contrast particle in a translucent matrix and underestimate its volume if the particle has negative contrast and the matrix is opaque. For T2-weighted MRI high signal objects the bias can be corrected according to simple geometric models. For negative contrast or hypointense objects the magnitude of the bias is unknown and no corrections have yet been put forward. We wanted to determine the bias of MRI measurements of hypointense objects of known diameter surrounded by a positive contrast solution. One, 3 and 5 mm slices with three different contrast concentrations were obtained according to a stereological MRI protocol. Results were compared with the true object size to estimate the bias. A simple correction for the bias could not be developed due to interslice cross-talk. Cross-talk makes an object appear in more MRI slices than corresponding to its physical size and larger than the true diameter. For phantom measurements an empirical correction could be developed, but for measurements of non-ideal objects such as brain structures the validity of the correction would be unpredictable. Besides avoiding or reducing cross-talk, the best way to deal with this bias is to measure the object's maximal contrast from edge to edge, a solution which is not perfect.
Collapse
Affiliation(s)
- Paula Gadeberg
- Department of Neurology, Aarhus University Hospital, Aarhus University, Aarhus, Denmark.
| | | | | | | |
Collapse
|
36
|
Thomas JB, Rutt BK, Ladak HM, Steinman DA. Effect of black blood MR image quality on vessel wall segmentation. Magn Reson Med 2001; 46:299-304. [PMID: 11477633 DOI: 10.1002/mrm.1191] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Black blood MRI has become a popular technique for measuring arterial wall area as an indicator of plaque size. Computer-assisted techniques for segmenting vessel boundaries have been developed to increase measurement precision. In this study, the carotid arteries of four normal subjects were imaged at seven different fields of view (FOVs), keeping all other imaging parameters fixed, to determine whether spatial resolution could be increased at the expense of image quality without sacrificing precision. Wall areas were measured via computer-assisted segmentation of the vessel boundaries performed repeatedly by two operators. Analysis of variance (ANOVA) demonstrated that the variability of wall area measurements was below 1.5 mm(2) for in-plane spatial resolutions between 0.22 mm and 0.37 mm. An inverse relationship between operator variability and the signal difference-to-noise ratio (SDNR) demonstrated that semi-automatic segmentation of the wall boundaries was robust for SDNR >3, defining a criterion above which subjective image quality can be degraded without an appreciable loss of information content. Our study also suggested that spatial resolutions higher than 0.3 mm may be required to quantify normal wall areas to within 10% accuracy, but that the reduced SNR associated with the higher resolution may be tolerated by semi-automated wall segmentation without an appreciable loss of precision.
Collapse
Affiliation(s)
- J B Thomas
- Imaging Research Labs, John P. Robarts Research Institute, University of Western Ontario, London, Canada
| | | | | | | |
Collapse
|
37
|
Ladak HM, Thomas JB, Mitchell JR, Rutt BK, Steinman DA. A semi-automatic technique for measurement of arterial wall from black blood MRI. Med Phys 2001; 28:1098-107. [PMID: 11439479 DOI: 10.1118/1.1368125] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Black blood magnetic resonance imaging (MRI) has become a popular technique for imaging the artery wall in vivo. Its noninvasiveness and high resolution make it ideal for studying the progression of early atherosclerosis in normal volunteers or asymptomatic patients with mild disease. However, the operator variability inherent in the manual measurement of vessel wall area from MR images hinders the reliable detection of relatively small changes in the artery wall over time. In this paper we present a semi-automatic method for segmenting the inner and outer boundary of the artery wall, and evaluate its operator variability using analysis of variance (ANOVA). In our approach, a discrete dynamic contour is approximately initialized by an operator, deformed to the inner boundary, dilated, and then deformed to the outer boundary. A group of four operators performed repeated measurements on 12 images from normal human subjects using both our semiautomatic technique and a manual approach. Results from the ANOVA indicate that the inter-operator standard error of measurement (SEM) of total wall area decreased from 3.254 mm2 (manual) to 1.293 mm2 (semi-automatic), and the intra-operator SEM decreased from 3.005 mm2 to 0.958 mm2. Operator reliability coefficients increased from less than 69% to more than 91% (inter-operator) and 95% (intra-operator). The minimum detectable change in wall area improved from more than 8.32 mm2 (intra-operator, manual) to less than 3.59 mm2 (inter-operator, semi-automatic), suggesting that it is better to have multiple operators measure wall area with our semi-automatic technique than to have a single operator make repeated measurements manually. Similar improvements in wall thickness and lumen radius measurements were also recorded. Since the semi-automatic technique has effectively ruled out the effect of the operator on these measurements, it may be possible to use such techniques to expand prospective studies of atherogenesis to multiple centers so as to increase access to real patient data without sacrificing reliability.
Collapse
Affiliation(s)
- H M Ladak
- Imaging Research Labs, John P. Robarts Research Institute, and Departments of Medical Biophysics and Electrical and Computer Engineering, University of Western Ontario, London N6A 5K8, Canada
| | | | | | | | | |
Collapse
|
38
|
Abstract
Ultrasound is an inexpensive and widely used imaging modality for the diagnosis and staging of a number of diseases. In the past two decades, it has benefited from major advances in technology and has become an indispensable imaging modality, due to its flexibility and non-invasive character. In the last decade, research investigators and commercial companies have further advanced ultrasound imaging with the development of 3D ultrasound. This new imaging approach is rapidly achieving widespread use with numerous applications. The major reason for the increase in the use of 3D ultrasound is related to the limitations of 2D viewing of 3D anatomy, using conventional ultrasound. This occurs because: (a) Conventional ultrasound images are 2D, yet the anatomy is 3D, hence the diagnostician must integrate multiple images in his mind. This practice is inefficient, and may lead to variability and incorrect diagnoses. (b) The 2D ultrasound image represents a thin plane at some arbitrary angle in the body. It is difficult to localize the image plane and reproduce it at a later time for follow-up studies. In this review article we describe how 3D ultrasound imaging overcomes these limitations. Specifically, we describe the developments of a number of 3D ultrasound imaging systems using mechanical, free-hand and 2D array scanning techniques. Reconstruction and viewing methods of the 3D images are described with specific examples. Since 3D ultrasound is used to quantify the volume of organs and pathology, the sources of errors in the reconstruction techniques as well as formulae relating design specification to geometric errors are provided. Finally, methods to measure organ volume from the 3D ultrasound images and sources of errors are described.
Collapse
Affiliation(s)
- A Fenster
- The John P Robarts Research Institute, London, Canada.
| | | | | |
Collapse
|
39
|
Laske C, Oschmann P, Tofighi J, Kuehne SB, Diehl H, Bregenzer T, Kraus J, Bauer R, Chatzimanolis N, Kern A, Traupe H, Kaps M. Induction of sTNF-R1 and sTNF-R2 by interferon beta-1b in correlation with clinical and MRI activity. Acta Neurol Scand 2001; 103:105-13. [PMID: 11227128 DOI: 10.1034/j.1600-0404.2001.103002105.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES To investigate the influence of interferon (IFN) beta-1b on the serum levels of sTNF-R1, sTNF-R2 and TNF-beta in patients with multiple sclerosis (MS) in correlation with clinical and MRI activity. MATERIALS AND METHODS Serum samples were obtained every 3 months from 24 patients treated with 8 x 10(6) U of IFN beta-lb every other day (treatment group) and from 21 patients without any immunomodulatory therapy (control group) over a 15-month observation period. The cytokine levels were measured by ELISA. Cranial MRI was performed every 6 months to determine the burden of disease of every patient. RESULTS In the treatment group we found an obvious increase of sTNFR1 and sTNF-R2 (P < 0.001) and relatively stable serum levels of TNFbeta with no statistical significance (P = 0.56). In the control group, sTNF-R1 showed a significant decrease (P < 0.001) during the same observation period of 15 months. During the 15-month observation period, the MRI-responders group had significant larger mean AUC (area under the concentration-time curve) values of sTNF-R1 (P = 0.04) and sTNF-R2 (P = 0.01) when compared to the group of MRInonresponders. CONCLUSION The present data suggest that IFN beta-1b induces the expression and shedding of TNF-R1 and TNF-R2. The magnitude of an increase of sTNF-Rs may be a marker for the effectiveness of treatment with IFN beta-1b.
Collapse
MESH Headings
- Adjuvants, Immunologic/pharmacology
- Adjuvants, Immunologic/therapeutic use
- Adult
- Antigens, CD/blood
- Antigens, CD/drug effects
- Brain/pathology
- Enzyme-Linked Immunosorbent Assay
- Follow-Up Studies
- Humans
- Interferon-beta/pharmacology
- Interferon-beta/therapeutic use
- Lymphotoxin-alpha/blood
- Magnetic Resonance Imaging
- Male
- Multiple Sclerosis/diagnosis
- Multiple Sclerosis/drug therapy
- Prospective Studies
- Receptors, Tumor Necrosis Factor/blood
- Receptors, Tumor Necrosis Factor/drug effects
- Receptors, Tumor Necrosis Factor, Type I
- Receptors, Tumor Necrosis Factor, Type II
- Sensitivity and Specificity
- Treatment Outcome
Collapse
Affiliation(s)
- C Laske
- Department of Neurology, Justus-Liebig Univ, Giessen, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Blake CC, Elliot TL, Slomka PJ, Downey DB, Fenster A. Variability and accuracy of measurements of prostate brachytherapy seed position in vitro using three-dimensional ultrasound: an intra- and inter-observer study. Med Phys 2000; 27:2788-95. [PMID: 11190962 DOI: 10.1118/1.1326448] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
This paper is a step in investigating whether three-dimensional (3D) ultrasound can be used intraoperatively to replace Computed Tomography (CT) for localization of brachytherapy seeds. In order to quantify the accuracy and variability of seed localization without introducing effects due to tissues, we first report our results with test phantoms. An inter- and intra-observer study was performed to assess the variability of 2 3D ultrasound scan acquisition methods: Tilt 3D scanning and pull-back 3D scanning. Seven observers measured the positions of gold seed markers in an agar phantom twice in each of the three orthogonal image planes. An analysis of variance (ANOVA) was performed to determine the intra- and inter-observer standard errors of measurement (SEM) and the minimum detectable changes in marker position (deltap). Average intra- and inter-observer SEMs for the tilt scan 3D image were 0.36 and 0.40 mm, respectively. Measurements of the pull-back scan 3D image yielded average intra- and inter-observer SEM of 0.46 and 0.49 mm, respectively. A paired difference analysis showed that the lower SEM for the tilt 3D scan image were statistically significant at a significance level of alpha= 0.05. The accuracy of the US measurements was tested by determining marker coordinates from CT images of the phantom in a stereotactic head frame. CT coordinates were matched to the ultrasound (US) coordinates by means of an affine transform. Average matching errors in x, y, and z were 0.02, 0.10, and -0.02 mm, respectively.
Collapse
Affiliation(s)
- C C Blake
- Imaging Research Laboratories, The John P. Robarts Research Institute, London, Ontario, Canada
| | | | | | | | | |
Collapse
|
41
|
Draper KJ, Blake CC, Gowman L, Downey DB, Fenster A. An algorithm for automatic needle localization in ultrasound-guided breast biopsies. Med Phys 2000; 27:1971-9. [PMID: 10984243 DOI: 10.1118/1.1287437] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
An algorithm was developed in order to reduce operator dependence in ultrasound-guided breast biopsy, by automatically locating the needle in the ultrasound image, and displaying its location on the image for the user. Ultrasound images of a typical breast biopsy needle inserted in a tissue-mimicking agar were obtained to test the algorithm. The resulting images were examined by a group of observers who recorded the values of the angle, intercept and tip coordinates of the needle in the image, and inter- and intra-observer variability studies were performed on the results. The results of the algorithm segmentation were compared to the values recorded by the observers, and physical measurements recorded at the time the images were acquired. The algorithm segmentation was precise enough to successfully (when considering angle and tip segmentation) target 90% of tumors of 4.5 mm in diameter situated at the center of the image.
Collapse
Affiliation(s)
- K J Draper
- Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | | | | | | | | |
Collapse
|
42
|
Mao F, Gill J, Downey D, Fenster A. Segmentation of carotid artery in ultrasound images: method development and evaluation technique. Med Phys 2000; 27:1961-70. [PMID: 10984242 DOI: 10.1118/1.1287111] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Segmentation of carotid artery lumen in two-dimensional and three-dimensional ultrasonography is an important step in computerized evaluation of arterial disease severity and in finding vulnerable atherosclerotic plaques susceptible to rupture causing stroke. Because of the complexity of anatomical structures, noise as well as the requirement of accurate segmentation, interactions are necessary between observers and the computer segmentation process. In this paper a segmentation process is described based on the deformable model method with only one seed point to guide the initialization of the deformable model for each lumen cross section. With one seed, the initial contour of the deformable model is generated using the entropy map of the original image and mathematical morphology operations. The deformable model is driven to fit the lumen contour by an internal force and an external force that are calculated, respectively, with geometrical properties of deformed contour and with the image gray level features. The evaluation methodology using distance-based and area-based metrics is introduced in this paper. A contour probability distribution (CPD) method for calculating distance-based metrics is introduced. The CPD is obtained by generating contours of the lumen using a set of possible seed locations. The mean contour can be compared to a manual outlined contour to provide accuracy metrics. The variance computed from the CPD can provide metrics of local and global variability. These metrics provide a complete performance evaluation of an interactive segmentation algorithm and a means for comparing different algorithm settings.
Collapse
Affiliation(s)
- F Mao
- Imaging Research Laboratories, John P. Robarts Research Institute, University of Western Ontario, London, Canada
| | | | | | | |
Collapse
|
43
|
Nadkarni SK, Boughner DR, Drangova M, Fenster A. Three-dimensional echocardiography: assessment of inter- and intra-operator variability and accuracy in the measurement of left ventricular cavity volume and myocardial mass. Phys Med Biol 2000; 45:1255-73. [PMID: 10843104 DOI: 10.1088/0031-9155/45/5/313] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Accurate left ventricular (LV) volume and mass estimation is a strong predictor of cardiovascular morbidity and mortality. We propose that our technique of 3D echocardiography provides an accurate quantification of LV volume and mass by the reconstruction of 2D images into 3D volumes, thus avoiding the need for geometric assumptions. We compared the accuracy and variability in LV volume and mass measurement using 3D echocardiography with 2D echocardiography, using in vitro studies. Six operators measured the LV volume and mass of seven porcine hearts, using both 3D and 2D techniques. Regression analysis was used to test the accuracy of results and an ANOVA test was used to compute variability in measurement. LV volume measurement accuracy was 9.8% (3D) and 18.4% (2D); LV mass measurement accuracy was 5% (3D) and 9.2% (2D). Variability in LV volume quantification with 3D echocardiography was %SEMinter = 13.5%, %SEMintra = 11.4%, and for 2D echocardiography was %SEMinter = 21.5%, %SEMintra = 19.1%. We derived an equation to predict uncertainty in measurement of LV volume and mass using 3D echocardiography, the results of which agreed with our experimental results to within 13%. 3D echocardiography provided twice the accuracy for LV volume and mass measurement and half the variability for LV volume measurement as compared with 2D echocardiography.
Collapse
Affiliation(s)
- S K Nadkarni
- Advanced Imaging Research Laboratories, John P Robarts Research Institute, and University of Western Ontario, London, Canada
| | | | | | | |
Collapse
|
44
|
Raff U, Rojas GM, Hutchinson M, Simon JH. Quantitation of T2 lesion load in patients with multiple sclerosis: a novel semiautomated segmentation technique. Acad Radiol 2000; 7:237-47. [PMID: 10766096 DOI: 10.1016/s1076-6332(00)80473-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES The authors designed a segmentation technique that requires only minimal operator input at the initial and final supervision stages of segmentation and has computer-driven segmentation as the primary determinant of lesion boundaries. The technique was applied to compute total T2-hyperintense lesion volumes in patients with multiple sclerosis (MS). A semi-automated segmentation technique is presented and shown to have a test-retest reliability of <5%. MATERIALS AND METHODS The method used a single segmented section with MS lesions. A probabilistic neural net performed segmentation into four tissue classes after supervised training. This reference section was deconstructed into the entire set of possible 4 x 4-pixel subregions, which was used to segment all-brain sections in steps of 4 x 4-pixel, adjacent image blocks. Intra- and interimage variabilities were tested by using 3-mm-thick, T2-weighted, dual-echo, spin-echo MR images from five patients, each of whom was imaged twice on the same day. Five different reference sections and three temporally separated. training sessions involving the same reference section were used to test the segmentation technique. RESULTS The coefficient of variation ranged from 0.013 to 0.068 (mean +/- standard deviation, 0.037 +/- 0.039) for results from five different reference sections for each brain and from 0.007 to 0.037 (mean, 0.027 +/- 0.021) for brains segmented with the same reference section on three temporally separated occasions. Test-retest (intra-imaging) reliability did not exceed 5% (except for a small lesion load of 1 cm3 in one patient). Interimaging differences were approximately 10%. CONCLUSION The segmentation technique yielded intra-imaging variabilities (2%-3%, except for very small MS lesion loads) that compare favorably with previously published results. New repositioning techniques that minimize imaging-repeat imaging variability could make this approach attractive for resolving MS lesion detection problems.
Collapse
Affiliation(s)
- U Raff
- Department of Neurology, New York University School of Medicine, NYU Medical Center, NY 10016, USA
| | | | | | | |
Collapse
|
45
|
Firbank MJ, Coulthard A, Harrison RM, Williams ED. Partial volume effects in MRI studies of multiple sclerosis. Magn Reson Imaging 1999; 17:593-601. [PMID: 10231186 DOI: 10.1016/s0730-725x(98)00210-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have estimated the accuracy of volume measurements of multiple sclerosis (MS) lesions made using magnetic resonance imaging (MRI) for lesions of comparable diameter to the image slice thickness. We used a phantom containing objects of known volume and obtained images using a range of slice thicknesses. Measurements on the phantom were used to assess a theoretical model, which was then employed to investigate the effects of image dimensions and geometry upon volume measurement accuracy. We observed measured volume to be dependent upon slice thickness. Thin slices gave the most accurate estimate of volume. As slice thickness increased relative to object diameter, the error in the volume measurement increased (to as much as 100%), the volume measured being dependent on the position of the object relative to the slice center. Using a signal intensity threshold value of 50% to outline objects gave results closest to the actual volume. As expected, a lower threshold value tended to give higher volume estimates (up to 100% larger), as did a semi-automated local edge detection technique. For accurate volume measurement, the slice thickness should be no more than a fifth of anticipated object diameter. For typical MS lesions (7 mm in diameter), this implies using a 1.5-mm slice thickness. For serial studies, a repositioning error of 1 mm could lead to differences in the volume measurement of individual lesions of up to 12% between studies for lesions of typical MS size and 5-mm slice thickness. These results emphasize the need for accurate patient repositioning, relatively thin slices, for regular quality assurance checks to ensure that pixel size and slice position are correct and stable over time, and that lesion outlining is performed in a consistent fashion. We would recommend the use of a 3D sequence with 1 mm cubic voxels for accurate measurements of MS lesions.
Collapse
Affiliation(s)
- M J Firbank
- University Department of Radiology, Royal Victoria Infirmary, Newcastle Upon Tyne, UK.
| | | | | | | |
Collapse
|
46
|
Guttmann CR, Kikinis R, Anderson MC, Jakab M, Warfield SK, Killiany RJ, Weiner HL, Jolesz FA. Quantitative follow-up of patients with multiple sclerosis using MRI: reproducibility. J Magn Reson Imaging 1999; 9:509-18. [PMID: 10232508 DOI: 10.1002/(sici)1522-2586(199904)9:4<509::aid-jmri2>3.0.co;2-s] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The reproducibility of an automated method for estimating the volume of white matter abnormalities on brain magnetic resonance (MR) images of multiple sclerosis (MS) patients was evaluated. Twenty MS patients underwent MR imaging twice within 30 minutes. Measurement variability is introduced mainly by MRI acquisition and image registration procedures, which demonstrate significantly worse reproducibility than the image segmentation. The correction of partial volume artifacts is essential for sensitive measurements of overall lesion burden. The average lesion volume difference (bias) between two MR exams of the same MS patient (N = 20) was 0.05 cm3, with a 95% confidence interval between -0.17 and +0.28 cm3, suggesting that the proposed measurement system is suitable for clinical follow-up trials, even in relatively small patient cohorts. The limits of agreement for lesion volume were between -1.3 and +1.5 cm3, implying that in individual patients changes in lesion load need to be at least this large to be detected reliably. This automated method for estimating lesion burden is a reliable tool for the evaluation of MS progression and exacerbation in patient cohorts and potentially also in individual patients.
Collapse
Affiliation(s)
- C R Guttmann
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Kikinis R, Guttmann CR, Metcalf D, Wells WM, Ettinger GJ, Weiner HL, Jolesz FA. Quantitative follow-up of patients with multiple sclerosis using MRI: technical aspects. J Magn Reson Imaging 1999; 9:519-30. [PMID: 10232509 DOI: 10.1002/(sici)1522-2586(199904)9:4<519::aid-jmri3>3.0.co;2-m] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A highly reproducible automated procedure for quantitative analysis of serial brain magnetic resonance (MR) images was developed for use in patients with multiple sclerosis (MS). The intracranial cavity (ICC) was identified on standard dual-echo spin-echo brain MR images using a supervised automated procedure. MR images obtained from one MS patient at 24 time points in the course of a 1-year follow-up were aligned with the images of one of the time points. Next, the contents of the ICC in each MR exam were segmented into four tissues, using a self-adaptive statistical algorithm. Misclassifications due to partial voluming were corrected using a combination of morphologic operators and connectivity criteria. Finally, a connectivity detection algorithm was used to separate the tissue classified as lesions into individual entities. Registration, classification of the contents of the ICC, and identification of individual lesions are fully automatic. Only identification of the ICC requires operator interaction. In each MR exam, the program estimated volumes for the ICC, gray matter (GM), white matter (WM), white matter lesions (WML), and cerebrospinal fluid (CSF). The reproducibility of the system was superior to that of supervised segmentation, as evidenced by the coefficient of variation: CSF supervised 45.9% vs. automated 7.7%, GM 16.0% vs. 1.4%, WM 15.7% vs. 1.3%, and WML 39.5% vs 52.0%. Our results demonstrate that this computerized procedure allows routine reproducible quantitative analysis of large serial MRI data sets.
Collapse
Affiliation(s)
- R Kikinis
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | | | | | | | | | | |
Collapse
|
48
|
Kraus J, Oschmann P, Engelhardt B, Schiel C, Hornig C, Bauer R, Kern A, Traupe H, Dorndorf W. Soluble and cell surface ICAM-1 as markers for disease activity in multiple sclerosis. Acta Neurol Scand 1998; 98:102-9. [PMID: 9724007 DOI: 10.1111/j.1600-0404.1998.tb01727.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The intercellular adhesion molecule-1 (ICAM-1) is a member of the Ig supergene family. ICAM-1 is expressed on various cells like peripheral blood lymphocytes, endothelial cells or thymic cells and the cell surface form is supposed to be shed into a soluble form. The expression of ICAM-1 is induced by cytokines like Interleukin-1, TNF alpha or interferon gamma. The aim of the study was to investigate whether changes of cell surface and soluble ICAM-1 in the cerebrospinal fluid (CSF) and blood are indicative for disease activity in patients with multiple sclerosis (MS). MATERIAL AND METHODS In all patients with relapsing-remitting MS (relapse: n=31, remission: n=11) and controls (n=13) the expression of cell surface ICAM-1 (c-ICAM-1) was determined by two colour flow cytometry. Soluble ICAM-1 (s-ICAM-1) was measured by ELISA. Follow-up examinations were done 3 months later. RESULTS In 31 patients with a current relapse we found significantly decreased expression levels of c-ICAM-1 on leukocytes in CSF (P<0.001) and blood (P<0.10), when compared to those 11 individuals experiencing remission. In contrast we observed significantly (P<0.05) increased levels of s-ICAM-1 in CSF of patients with relapses. Comparing patients who had been in remission for more than 4 weeks (n=11) with remission lasting longer than 3 months (n=28) we detected stable c-ICAM-1 expression on CD3+ T cells in blood. CONCLUSION Our results demonstrate for the first time that c-ICAM-1 on CD3+ T-cells in CSF and blood is an activity marker in MS.
Collapse
Affiliation(s)
- J Kraus
- Department of Neurology, University of Giessen, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Gardner JC, Yazdani F. Correlating Mr Lesions and Functional Deficits in Multiple Sclerosis Patients: Anatomical Atlas Registration. Phys Med Rehabil Clin N Am 1998. [DOI: 10.1016/s1047-9651(18)30250-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
50
|
Tong S, Cardinal HN, McLoughlin RF, Downey DB, Fenster A. Intra- and inter-observer variability and reliability of prostate volume measurement via two-dimensional and three-dimensional ultrasound imaging. ULTRASOUND IN MEDICINE & BIOLOGY 1998; 24:673-681. [PMID: 9695270 DOI: 10.1016/s0301-5629(98)00039-8] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We describe the results of a study to evaluate the intra- and inter-observer variability and reliability of prostate volume measurements made from transrectal ultrasound (TRUS) images, using either the (optimal) height-width-length (HWL) method (V = pi/6 HWL) with two-dimensional (2D) TRUS images (obtained as cross-sections of three-dimensional [3D] TRUS images) or manual planimetry of 3D TRUS images (the 3D US method). In this study, eight observers measured 15 prostate images, twice via each method, and an analysis of variance (ANOVA) was performed. This analysis shows that, with the 3D US method, intra-observer prostate volume estimates have 5.1% variability and 99% reliability, and inter-observer estimates have 11.4% variability and 96% reliability. With the HWL method, intra-observer estimates have 15.5% variability and 93% reliability, and inter-observer estimates have 21.9% variability and 87% reliability. Thus, in vivo prostate volume estimates from manual planimetry of 3D TRUS images have much lower variability and higher reliability than HWL estimates from 2D TRUS images.
Collapse
Affiliation(s)
- S Tong
- Imaging Research Laboratories, J. P. Robarts Research Institute, London, Ontario, Canada
| | | | | | | | | |
Collapse
|