RPM processing and statistical comparison.

<p>(A) For a patient, the glioma tumor volume (green) and residual volume (red) are obtained by segmentation of postoperative MRI FLAIR sequence images. Then the transformation from the patient's brain to standard brain space (MNI152 shown in blue) is calculated by non-linear registration, and the segmented volumes are transformed accordingly. A 3D reconstruction of the brain and volumes in standard brain space are shown. (B) For each patient cohort, summation of the tumor volumes at each voxel provides a tumor localization map (green). Similarly, summation of the residual volumes at each voxel provides a residual localization map (red). The number of patient volumes contained in a voxel is provided as green-scale and red-scale legends. The probability of resection at each voxel is calculated by dividing the number of patients without residual tumor by the number of patients with a glioma at a specific voxel. This results in a resection probability map (RPM) for each hemisphere (here shown for left-sided tumors) to discern contralateral from ipsilateral tumor extension. The RPM legend represents the probability of resection from 0 (red) via 0.5 (yellow) to 1 (green). (C) For statistical comparison of RPMs between cohorts, here the left-hemisphere results are plotted as an example for a single voxel. From these RPMs, the log odds ratio map, adjusted p-value map and q-value map are derived, as detailed in the Methods section. Legends for log odds ratios, p- and q-values are provided. As a calculation example the information for one voxel is included with a probability of resection of 10 out of 12 patients, and 3 out of 10 patients, respectively. This results in a log odds ratio of 10.1, an adjusted p-value of 0.027, and a q-value of 0.45, which is above the arbitrary threshold of 0.2 for false discovery and therefore considered an indifferential resection result at the outlined voxel.