Diffusion tensor imaging of cerebral white matter: a pictorial review of physics, fiber tract anatomy, and tumor imaging patterns.

We review the normal anatomy of the white matter (WM) tracts as they appear on directional diffusion tensor imaging (DTI) color maps, which will almost certainly be available to the general radiologist as part of a commercial DTI software package in the near future. Anatomic drawings and gross dissection photographs are correlated with the directional DTI color maps to review the anatomy of those tracts readily seen in most cases. We also include several correlative examples of so-called tractograms in which specific tracts are traced and displayed by using computer-graphical techniques (1). Since several excellent reviews focusing on tractography and other sophisticated DTI postprocessing techniques are already published (2–4), we focus on the directional eigenvector color maps. A brief review of the basic principles underlying DTI is also included; several more comprehensive reviews are available for the reader who wishes to delve deeper into the technical aspects of DTI (5, 6). Finally, we briefly review the DTI patterns that result when a cerebral neoplasm involves WM tracts; knowledge of these patterns becomes critically important when neurosurgeons use DTI in planning tumor resections, as they frequently do at our institution (7, 8).