Optic Radiation Diffusion Tensor Imaging Tractography: An Alternative and Simple Technique for the Accurate Detection of Meyer's Loop.

Abstract

The optic radiation (OR) is a white matter bundle with a very complex anatomy. Its anterior component bends sharply around the tip of the temporal horn, forming the Meyer's loop (ML), the sparing of which during surgery is crucial to preserve visual function. Defining its exact anatomy and accurately identifying its position remain challenging, even with diffusion tensor imaging (DTI) tractography and the most refined tracking procedure. We have developed an alternative tracking technique to detect the ML position. We performed DTI studies in 26 patients undergoing resection of a temporo-parieto-occipital lesion. We then reconstructed the ORs of each patient using 2 techniques (the first developed by our team, the other taken from the literature), using the same tracking software and parameters. We evaluated the accuracy of each technique measuring 3 distances that define the ML position. We created 5 data groups and compared the 2 techniques. Finally, we compared our results with the results from 8 anatomic dissection studies and other tractographic studies. Our findings show that our technique allows a more accurate definition of the ML position. We found a statistically significant (P < 0.05) difference for all the distances between the 2 techniques; our results resemble those obtained in dissection studies. Our technique is also easy to perform and repeatable. Our tracking technique may be of marked interest for the evaluation and anatomic definition of the ML position, particularly for neurosurgeons approaching the anterior temporal region.