Assessment of injuries in pyramidal tracts and cerebellar peduncles using three-dimensional anisotropy contrast MRI in patients with brain tumors in posterior fossa

The purpose of this study is to evaluate neuronal tracts in patients with infratentorial brain tumors using three-dimensional anisotropy contrast (3DAC) imaging technique. Twenty-one patients with infratentorial tumors underwent echo-planar diffusion-weighted imaging (DWI). Gray-scale DWIs in each of the three orthogonal diffusion gradients were transformed and color-coded with three primary colors to compose a 3DAC image. Morphological changes of neuronal tracts were assessed. Fine anatomical structures of neuronal tracts were visible on 3DAC images, including pyramidal tracts, medial leminsci, and superior and middle cerebellar peduncles. Pathological findings of these tracts were categorized as compression or displacement, alteration of fiber directionality, involvement in tumor invasion or perifocal edema, and loss of anisotropy characterized by fading of color. Among these, only loss of anisotropy correlated with tract-related clinical deficits. Three-DAC imaging is useful in evaluating infratentorial neuronal tracts, and in providing useful information to determine surgical strategy in patients with infratentorial brain tumors. (author)