Quantitative magnetization transfer characteristics of the human cervical spinal cord in vivo: application to adrenomyeloneuropathy.

[adrenomyeloneuropathy]

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 C 2 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 (2 b )) 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 (2 b ) for volunteers was : 9 +/- 2 micros and the rate of MT exchange (R ) was : WM = 56 +/- 11 Hz , GM = 67 +/- 12 Hz . Neither T (2 b ) nor R showed significant differences between healthy and diseased cords . Comparisons are made between qMT , and conventional MT acquisitions .