title: Functional pathway-defined MRI diffusion measures reveal increased transverse diffusivity of water in multiple sclerosis.
abstract: The diffusion properties of water are sensitive to microscopic changes in the white matter of multiple sclerosis (MS) patients. Typical MRI measures of disease burden in MS demonstrate modest to poor correlation with disability. Functional MRI and DTI-based fiber tracking were used to define the interhemispheric white matter pathway connecting bilateral supplementary motor areas (SMA) in 16 MS patients sand 16 control subjects. Fractional anisotropy (FA), mean diffusivity (MD), longitudinal (lambda(1)) and transverse diffusivity (lambda(2)) were measured along this pathway in all subjects. Mean FA was 0.587 +/- 0.032 for patients and 0.608 +/- 0.020 for controls (P < 0.02). Mean MD was (0.821 +/- 0.055) x 10(-3) mm(2) s(-1) for patients and (0.770 +/- 0.020) x 10(-3) mm(2) s(-1) for controls (P < 0.004). Mean lambda(1) values were (1.462 +/- 0.099) x 10(-3) mm(2) s(-1) for patients and (1.400 +/- 0.034) x 10(-3) mm(2) s(-1) for controls (P < 0.02). Mean lambda(2) values were (0.500 +/- 0.047) x 10(-3) mm(2) s(-1) for patients and (0.454 +/- 0.027) x 10(-3) mm(2) s(-1) for controls (P < 0.001). In addition, the correlation between the Multiple Sclerosis Functional Composite (MSFC) and transverse diffusivity was -0.341 (P < 0.05). The component test of the MSFC most related to the SMA pathway studied with our MRI method (Nine-hole Peg Test) showed significant correlation with transverse diffusivity (r = 0.392, P < 0.02), indicating that probing functional pathways with MRI measures can lead to a better reflection of disease status.
authors.affiliation: Division of Radiology, The Cleveland Clinic Foundation, 9500 Euclid Ave-U15, Cleveland, OH 44195, USA. mjlowe@sbcglobal.net
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Lowe
authors.forename: Craig
authors.initials: C
authors.lastname: Horenstein
authors.forename: Jochen G
authors.initials: JG
authors.lastname: Hirsch
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie
authors.forename: Lael
authors.initials: L
authors.lastname: Stone
authors.forename: Pallab K
authors.initials: PK
authors.lastname: Bhattacharyya
authors.forename: Achim
authors.initials: A
authors.lastname: Gass
authors.forename: Micheal D
authors.initials: MD
authors.lastname: Phillips
mesh_terms: D000328:Adult; D016880:Anisotropy; D001834:Body Water / Q000502:physiology*; D003337:Corpus Callosum / Q000473:pathology; D003627:Data Interpretation, Statistical; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009044:Motor Cortex / Q000473:pathology; D009103:Multiple Sclerosis / Q000473:pathology*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology; D009412:Nerve Fibers / Q000502:physiology; D009434:Neural Pathways / Q000473:pathology*