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-e cho magnetic resonance images in 14 adult TS subjects and 14 matched n ormal control subjects. T-2 relaxation times were found to be asymmetr ic throughout the cerebrum of normal control subjects, with difference s seen between T-2 times of corresponding regions of both cerebral hem ispheres that were small in magnitude (2-5%) but of a high degree of s tatistical significance in all regions examined. Our hypothesis of alt ered T-2 relaxation time asymmetries in TS was confirmed in a multivar iate analysis of variance, with post hoc analyses suggesting that grou p differences were attributable to specific asymmetry differences in t he TS insular cortex and frontal white matter. Exploratory analyses re vealed 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 stud ies, and the tissue characteristics that might produce normal and abno rmal relaxation time asymmetries are considered.