Caudate nucleus abnormalities in obsessive-compulsive disorder: measurements of MRI signal intensity.

A previous magnetic resonance imaging (MRI) study from our group reported increased size of the right caudate nucleus in obsessive-compulsive patients compared with control subjects. To test the hypothesis of a structural abnormality underlying such volume alteration, MRI signal intensity (SI), as an index of T1 relaxation values, was measured in the caudate nucleus of the same sampling data. Results showed higher SI values in the left caudate nucleus compared with the right in the patient group, whereas no asymmetry was found in the control group.