VOXELWISE ANALYSIS OF SPATIAL DISTRIBUTION OF POSTOPERATIVE ISCHEMIA IN DIFFUSE GLIOMA

Abstract

BACKGROUND Surgical treatment of diffuse glioma is performed to reduce tumor mass effect and to pave the way for adjuvant (chemo)radiotherapy. As a complication of surgery, ischemic lesions are often found in the postoperative setting. Not only can these lesion induce neurological deficits, but their volume has also been associated with reduced survival time. Prior studies suggest areas with a singular vascular supply to be more prone to postoperative ischemic lesions, although the precise cause is yet unknown. The aim of this study was to explore the volumetric and spatial distributions of postoperative ischemic lesions and their relation to arterial territories in glioma patients. MATERIAL AND METHODS We accessed a retrospective database of 144 adult cases with WHO grade II-IV supratentorial gliomas, who received surgery and postoperative MRI within 3 days in 2012–2014. We identified 93 patients with postoperative ischemia, defined as new confluent diffusion restriction on DWI. Ischemic lesions were manually delineated and spatially normalized to stereotaxic MNI space. Voxel-based analysis (VBA) was performed to compare presence and absence of postoperative ischemia. False positive results were eliminated by family-wise error correction. Areas of ischemia were labeled using an arterial territory map, the Harvard-Oxford cortical and subcortical atlases and the XTRACT white matter atlas. RESULTS Median volume of confluent ischemia was 3.52cc (IQR 2.15–5.94). 23 cases had only ischemic lesion in the left hemisphere, 46 in the right hemisphere and 24 bilateral. Median volume was 3.08cc (IQR 1.35–5.72) in left-sided lesions and 2.47cc (1.01–4.24) in right-sided lesions. Volume of ischemic lesions was not associated with survival after 1, 2 or 5 years. A cluster of 125.18cc was found to be significantly associated with development of postoperative ischemia. 73% of this cluster was situated in the arterial territory of the right middle cerebral artery (MCA), limited by the border of the posterior cerebral artery (PCA), and the watershed area between the right MCA and the right anterior cerebral artery (ACA). Significant areas were located in the frontal lobes, spanning into the right temporo-occipital region, and predominantly included right and left thalamus, caudate nucleus, putamen, pallidum, as well as right temporal gyri and insular cortex, and parts of the right corticospinal tract, longitudinal fasciculi and superior thalamic radiation. CONCLUSION We found slightly more and larger ischemic lesions in the right than left hemisphere after glioma resection. A statistically significant cluster of voxels of postoperative ischemia was found in the territory of the right MCA and watershed area of the right ACA. Exploration of the spatial distribution of these lesions could help elucidate their etiology and form the basis for predicting clinically relevant postoperative ischemia.