Amit Manohar Saindane MD, Presenter: Nothing to Disclose

Meng Law MD, Abstract Co-Author: Nothing to Disclose

Yulin Ge MD, Abstract Co-Author: Nothing to Disclose

Glyn Johnson PhD, Abstract Co-Author: Nothing to Disclose

Robert Ivin Grossman MD, Abstract Co-Author: Nothing to Disclose

Hypoperfusion of the normal-appearing white matter in multiple sclerosis (MS) may be related to primary ischemia or secondary to hypometabolism from Wallerian degeneration. Diffusion tensor imaging (DTI) has been used to study such processes affecting white matter microstructure. This study was performed to evaluate the relationship between perfusion and diffusion changes in normal-appearing corpus callosum of patients with relapsing-remitting MS (RR-MS).

Eleven RR-MS patients and eleven age-matched controls underwent conventional MR imaging at 1.5-T, perfusion MRI, and DTI. Gradient-echo echo-planar perfusion MR images were acquired during the first pass of a standard dose bolus of gadopentetate dimeglumine. Absolute cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) were computed. DTI data were acquired with a pulsed gradient, double spin-echo, echo-planar technique in six directions. Mean diffusivity (MD) and fractional anisotropy (FA) maps were calculated. After visual coregistration of perfusion and DTI images, two regions of interest were placed in the central body and in bilateral areas of genu and splenium of the corpus callosum. Spearman rank correlation coefficients (r) were calculated using mean diffusion and perfusion measures in each region.

Across all regions of the RR-MS group, mean MD was 0.808 (SD = 0.074), mean FA was 0.737 (SD = 0.081), and mean CBF was 15.7 ml/100g/min (SD = 5.9). Within bilateral areas of splenium and central body of the corpus callosum of RR-MS patients, CBF was significantly correlated with MD (r = 0.840 to 0.899; all P < 0.01), but not significantly correlated with FA. No significant correlations between diffusion and perfusion metrics were found in the genu of the corpus callosum or in any of the regions of controls.

In areas of normal-appearing corpus callosum of RR-MS patients, decreasing perfusion is correlated with decreasing MD, and is not significantly related to FA. These findings support the concept of primary ischemia in MS rather than secondary hypoperfusion due to Wallerian degeneration, where decreased perfusion would be expected to correlate with increased MD and decreased FA.

Saindane, A, Law, M, Ge, Y, Johnson, G, Grossman, R, Correlation of Diffusion Tensor and Dynamic Perfusion MR Imaging Metrics in Normal-appearing Corpus Callosum: Support for Primary Hypoperfusion in Multiple Sclerosis.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4408799.html