title: Quantitative magnetization transfer characteristics of the human cervical spinal cord in vivo: application to adrenomyeloneuropathy.
abstract: Magnetization transfer (MT) imaging has assessed myelin integrity in the brain and spinal cord; however, quantitative MT (qMT) has been confined to the brain or excised tissue. We characterized spinal cord tissue with qMT in vivo, and as a first application, qMT-derived metrics were examined in adults with the genetic disorder Adrenomyeloneuropathy (AMN). AMN is a progressive disease marked by demyelination of the white matter tracts of the cervical spinal cord, and a disease in which conventional MRI has been limited. MT data were acquired at 1.5 Tesla using 10 radiofrequency offsets at one power in the cervical cord at C2 in 6 healthy volunteers and 9 AMN patients. The data were fit to a two-pool MT model and the macromolecular fraction (M(ob)), macromolecular transverse relaxation time (T(2b)) and the rate of MT exchange (R) for lateral and dorsal column white matter and gray matter were calculated. M(ob) for healthy volunteers was: WM = 13.9 +/- 2.3%, GM = 7.9 +/- 1.5%. In AMN, dorsal column M(ob) was significantly decreased (P < 0.03). T(2b) for volunteers was: 9 +/- 2 micros and the rate of MT exchange (R) was: WM = 56 +/- 11 Hz, GM = 67 +/- 12 Hz. Neither T(2b) nor R showed significant differences between healthy and diseased cords. Comparisons are made between qMT, and conventional MT acquisitions.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. smith@mri.jhu.edu
authors.forename: Seth A
authors.initials: SA
authors.lastname: Smith
authors.forename: Xavier
authors.initials: X
authors.lastname: Golay
authors.forename: Ali
authors.initials: A
authors.lastname: Fatemi
authors.forename: Asif
authors.initials: A
authors.lastname: Mahmood
authors.forename: Gerald V
authors.initials: GV
authors.lastname: Raymond
authors.forename: Hugo W
authors.initials: HW
authors.lastname: Moser
authors.forename: Peter C M
authors.initials: PC
authors.lastname: van Zijl
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Stanisz
mesh_terms: D000326:Adrenoleukodystrophy / Q000473:pathology* / Q000503:physiopathology*; D000328:Adult; D000465:Algorithms; D002574:Cervical Vertebrae / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000473:pathology* / Q000503:physiopathology*