NI-66COLOR CODED MAPS OF WHITE MATTER TRACTS: NO NEED FOR TRACTOGRAPHY

BACKGROUND/PURPOSE: White matter tracts can be observed using tractograms generated from diffusion tensor imaging (DTI). However, the dependence of these tract images on subjective variables, including how seed points are placed and the preferred level of fractional anisotropy, introduces interobserver inconsistency and potential lack of reliability. We propose that color coded maps (CCM) generated from DTI can be a preferred method for the visualization of important white matter tracts. METHODS: DTI was acquired in 25 patients with brain tumors. Lesions included 15 tumors of glial origin, 9 metastatic tumors, two meningiomas, and one cavernous angioma. Tractograms of the pyramidal and/or optic radiations, based on tumor location, were created by marking seed regions of interest using known anatomical locations. We compared the degree of tract involvement and white matter alteration between CCMs and tractograms. Neurological outcomes were obtained from chart reviews. RESULTS: The pyramidal tract was evaluated in 20/25 patients, the visual tracts were evaluated in 10/25, and both tracts were evaluated in 5/25. In 19/25 studies, the same patterns of white matter alternations were found between the CCM and tractograms. In the 6 patients where patterns differed, 2 tractograms were not useful in determining pattern alteration; in the remaining 4/6, no practical difference was seen in comparing the studies. Two patients were lost to follow up. Thirteen patients were neurologically improved or remained intact after intervention. In these, 10 of the 13 patients showed displaced white matter tracts on CCM. Twelve patients had no improvement of their preoperative deficit. In 9 of these 12 patients, CCM showed white matter disruption. CONCLUSION: CCMs provide a convenient, practical, and objective method of visualizing white matter tracts, obviating the need for potentially subjective and time-consuming tractography. CCMs are at least as reliable as tractograms in predicting neurological outcomes after neurosurgical intervention.