Optic Radiation Delineated by Tractography During Surgery
Optic radiation tractography during temporal lobe epilepsy surgery may reduce visual field deficits
WEDNESDAY, Sept. 14 (HealthDay News) -- Optic radiation during anterior temporal lobe resection (ATLR) for refractory temporal lobe epilepsy (TLE) can be delineated by diffusion tensor imaging (DTI) tractography, and propagated onto postoperative images during neurosurgery, according to a study published online Sept. 2 in the Annals of Neurology.
Gavin P. Winston, B.M., B.Ch., from the University College of London Institute of Neurology, and colleagues investigated whether incorporating DTI tractography into interventional magnetic resonance imaging (MRI) is feasible for delineating optic radiation to guide surgery. A total of 20 patients undergoing ATLR for refractory TLE underwent structural MRI scans, DTI, and visual field assessment before and three to 12 months after surgery. Optic radiation tractography was carried out on preoperative images, and was propagated onto postoperative images. The extent of anteroposterior damage to Meyer's loop was determined, and visual loss quantified by Goldmann perimetry.
The investigators identified visual field deficit (VFD) in 12 patients (average VFD, 39 percent of upper quadrant). Fewer than three minutes were taken for image registration, which predicted that the Meyer's loop was 4.4 to 18.7 mm anterior and 0.0 to 17.6 mm posterior to the resection margin in patients with and without VFD, respectively. There was a significant correlation between Meyer's loop and the degree of VFD, which explained 55 percent variance in this measure.
"The technique is fast enough to propagate accurate preoperative tractography onto intraoperative scans acquired during neurosurgery, with the potential to reduce the risk of VFD," the authors write.
One of the study authors disclosed financial ties to the pharmaceutical, health care, and medical device industries.