TY - JOUR
T1 - Sub-millimeter imaging of brain-free water for rapid volume assessment in atrophic brains
AU - Gao, Katherine C.
AU - Nair, Govind
AU - Cortese, Irene C.M.
AU - Koretsky, Alan
AU - Reich, Daniel S.
N1 - Funding Information:
This study was supported by the Intramural Research Program of the National Institute of Neurologic Disorders and Stroke (NINDS), National Institutes of Health. We are grateful to the Neuroimmunology Clinic (especially Joan Ohayon and Kaylan Fenton) for performing neurological exams on our participants, the National Institute of Mental Health (NIMH)/NINDS Functional Magnetic Resonance Facility, Tianxia Wu (NINDS), Colin Shea (NINDS), John Ostuni (NINDS), and Souheil Inati (NIMH).
PY - 2014/10/15
Y1 - 2014/10/15
N2 - Introduction: Cerebral atrophy occurs in healthy aging, and in disease processes such as multiple sclerosis (MS), it correlates with disability accumulation. Imaging measurements of brain atrophy are commonly based on tissue segmentation, which is susceptible to classification errors and inconsistencies. High-resolution imaging techniques with strong contrast between brain parenchyma and cerebrospinal fluid (CSF) might allow fully automated, rapid, threshold-based determination of the free water in the brain. We hypothesized that total brain-free-water (BFW) volume and BFW volume expressed as a normalized fraction of the intracranial volume ("BFW fraction"), determined from heavily T2-weighted images, would be useful surrogates for cerebral atrophy and therefore would correlate with clinical measures of disability in MS. Methods: Whole brains of 83 MS cases and 7 healthy volunteers were imaged with a 4.7-min, heavily T2-weighted sequence on a 3T MRI scanner, acquiring 650-μm isotropic voxels. MS cases were clinically assessed on the Expanded Disability Status Scale (EDSS), Scripps Neurological Rating Scale (SNRS), Paced Auditory Serial Addition Test (PASAT), 9-Hole Peg Test (9HPT), Symbol Digit Modalities Test (SDMT), and 25-Foot Timed Walk. Twelve of the MS cases were rescanned within an average of 1.8months to assess reproducibility. Automated calculations of BFW volume and BFW fraction were correlated with clinical measures of disability upon adjusting for age and sex. Results were compared to data from T1-based approaches (SIENAX and Lesion-TOADS). Results and discussion: BFW volume was automatically derived from heavily T2-weighted images with no need for separate skull stripping. BFW volume and fraction had mean scan-rescan coefficients of variation of 1.5% and 1.9%, respectively, similar to the T1-based approaches tested here. BFW fraction more strongly correlated with clinical measures than T1-derived results. Among those clinical measures, modality-specific disability scores, such as SDMT and 9HPT, were more strongly associated with BFW fraction than composite measures, such as EDSS and SNRS. Conclusion: The BFW method robustly estimates cerebral atrophy in an automated, fast, and reliable manner, and as such may prove a useful addition to imaging protocols for clinical practice and trials.
AB - Introduction: Cerebral atrophy occurs in healthy aging, and in disease processes such as multiple sclerosis (MS), it correlates with disability accumulation. Imaging measurements of brain atrophy are commonly based on tissue segmentation, which is susceptible to classification errors and inconsistencies. High-resolution imaging techniques with strong contrast between brain parenchyma and cerebrospinal fluid (CSF) might allow fully automated, rapid, threshold-based determination of the free water in the brain. We hypothesized that total brain-free-water (BFW) volume and BFW volume expressed as a normalized fraction of the intracranial volume ("BFW fraction"), determined from heavily T2-weighted images, would be useful surrogates for cerebral atrophy and therefore would correlate with clinical measures of disability in MS. Methods: Whole brains of 83 MS cases and 7 healthy volunteers were imaged with a 4.7-min, heavily T2-weighted sequence on a 3T MRI scanner, acquiring 650-μm isotropic voxels. MS cases were clinically assessed on the Expanded Disability Status Scale (EDSS), Scripps Neurological Rating Scale (SNRS), Paced Auditory Serial Addition Test (PASAT), 9-Hole Peg Test (9HPT), Symbol Digit Modalities Test (SDMT), and 25-Foot Timed Walk. Twelve of the MS cases were rescanned within an average of 1.8months to assess reproducibility. Automated calculations of BFW volume and BFW fraction were correlated with clinical measures of disability upon adjusting for age and sex. Results were compared to data from T1-based approaches (SIENAX and Lesion-TOADS). Results and discussion: BFW volume was automatically derived from heavily T2-weighted images with no need for separate skull stripping. BFW volume and fraction had mean scan-rescan coefficients of variation of 1.5% and 1.9%, respectively, similar to the T1-based approaches tested here. BFW fraction more strongly correlated with clinical measures than T1-derived results. Among those clinical measures, modality-specific disability scores, such as SDMT and 9HPT, were more strongly associated with BFW fraction than composite measures, such as EDSS and SNRS. Conclusion: The BFW method robustly estimates cerebral atrophy in an automated, fast, and reliable manner, and as such may prove a useful addition to imaging protocols for clinical practice and trials.
KW - Atrophy
KW - Cerebrospinal fluid
KW - Magnetic resonance imaging
KW - Multiple sclerosis
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U2 - 10.1016/j.neuroimage.2014.06.014
DO - 10.1016/j.neuroimage.2014.06.014
M3 - Article
C2 - 24945671
AN - SCOPUS:84904065883
SN - 1053-8119
VL - 100
SP - 370
EP - 378
JO - NeuroImage
JF - NeuroImage
ER -