ABNORMAL MAGNETIC-RESONANCE-IMAGING T-2 RELAXATION-TIME ASYMMETRIES IN TOURETTES-SYNDROME

Recent imaging studies in Tourette's syndrome (TS) have reported a los s of normal asymmetry in basal ganglia volumes. Our recent report of r educed midline sagittal cross-sectional area in TS suggests that alter ed lateralization may be widespread throughout the TS cerebrum. We rep ort here our analyses of cerebral asymmetries of T-2 (transverse or sp in-spin) relaxation times derived from multi-echo/multi-planar/spin-ec ho magnetic resonance images in 14 adult TS subjects and 14 matched no rmal control subjects. T-2 relaxation times were found to be asymmetri c throughout the cerebrum of normal control subjects, with differences seen between T-2 times of corresponding regions of both cerebral hemi spheres that were small in magnitude (2-5%) but of a high degree of st atistical significance in all regions examined. Our hypothesis of alte red T-2 relaxation time asymmetries in TS was confirmed in a multivari ate analysis of variance, with post hoc analyses suggesting that group differences were attributable to specific asymmetry differences in th e TS insular cortex and frontal white matter. Exploratory analyses rev ealed group differences in T-2 times of the amygdala and red nucleus, as well as significantly lower ferritin levels in the TS group. These findings are discussed in relation to the previous TS volumetric studi es, and the tissue characteristics that might produce normal and abnor mal relaxation time asymmetries are considered.