Brain developmental abnormalities in Prader-Willi syndrome detected by diffusion tensor imaging.

OBJECTIVE The purpose of this work was to detect brain developmental abnormalities in Prader-Willi syndrome by using diffusion tensor imaging based on a high-field MRI system. METHODS Eight patients with Prader-Willi syndrome and 8 age- and gender-matched normal control subjects were examined using a high-field (3.0 T) MRI system. Trace value and fractional anisotropy were assessed simultaneously in multiple representative brain regions: the deep gray matter (putamen, caudate head, and dorsomedial thalamus) and the white matter structures (frontal and parietal white matter, posterior limb of internal capsule, and corpus callosum). RESULTS In Prader-Willi syndrome patients, trace value was found to be significantly higher in the left frontal white matter and the left dorsomedial thalamus, whereas fractional anisotropy was significantly reduced in the posterior limb of the internal capsule bilaterally, the right frontal white matter, and the splenium of the corpus callosum. The observed diffusivity characteristics indicate developmental abnormalities in these areas, which are highly consistent with the clinical features of Prader-Willi syndrome. CONCLUSIONS The study provides the first objective evidence that Prader-Willi syndrome patients indeed have developmental abnormalities in specific areas of the brain, providing a new window toward understanding the pathophysiology of Prader-Willi syndrome.