Diffusion-weighted imaging-guided resection of intracerebral lesions involving the optic radiation.

In this paper we report our experience with diffusion-weighted imaging (DWI) for optic radiation (OR) visualization during resection of tumors. We hypothesize that intraoperative OR visualization helps to maintain patients' visual fields. DWI studies were performed together with T1-weighted postcontrast magnetic resonance imaging (MRI) in four patients with lesions in or adjacent to the OR (glioblastoma, oligo-astrocytoma, cavernoma, and metastasis; n = 1 each). The OR was identified from one of six DWI data acquisitions, segmented and reconstructed three-dimensionally. The image data were neuronavigationally transferred into the operative field, and provided the neurosurgeon with information on lesion site and adjacent OR localization. Preoperative and postoperative neuroophthalmological testing included, among others, perimetry to define the value of diffusion-weighted image guidance during OR lesion resection. Three lesions were removed completely. In one case, low-grade tumor parts infiltrating the OR were intentionally left. No persistent visual field deficits were induced. In one patient, a transient homonymous hemianopia attributable to postoperative swelling completely resolved under steroid medication. The authors conclude that intraoperative OR visualization, realized by neuronavigationally displayed DWI data, might prove to be helpful to maintain patients' visual fields.