Resting-state Functional Magnetic Resonance Imaging in Presurgical Functional Mapping: Sensorimotor Localization

Abstract

This article compares resting-state functional magnetic resonance (fMR) imaging with task fMR imaging for presurgical functional mapping of the sensorimotor (SM) region. Before tumor resection, 38 patients were scanned using both methods. The SM area was anatomically defined using 2 different software tools. Overlap of anatomic regions of interest with task activation maps and resting-state networks was measured in the SM region. A paired t-test showed higher overlap between resting-state maps and anatomic references compared with task activation when using a maximal overlap criterion. Resting state-derived maps are more comprehensive than those derived from task fMR imaging.

Keywords: Functional MR (fMR); Multilayer perceptron (MLP); Resting-state fMR (RS-fMR); Resting-state networks (RSN); Sensorimotor network (SMN); Task fMR (T-MR).

Figure 1

Brodmann Primary SensoriMotor (B-SM) Anatomical Region of Interest (ROI) Brodmann Areas 1, 2, 3, and 4 surface-based labels in the Population-Average, Landmark- and Surface-based (PALS) atlas were projected to a volume ribbon 1.5mm above and 1.5mm below the mean PALS midthickness surface in atlas space, and then dilated to a distance of 10mm. This ROI requires no exclusions, but does not precisely localize the subject’s PSM.

Figure 2

Quality Control Scenes for FreeSurfer Pre-/Post-Central Parcels. After creating template scenes, captures like this were generated for all subjects to determine which hemispheres had usable pre-/post-central parcellations for the overlap computations.

Figure 3

Surface Views Across a Range of Jaccard Overlap Indices Task activation maps (left) and MLP probability maps (right) are shown for subjects with low, medium, and high overlap with FS-SM on the patient’s native mesh inflated surface. Green borders delimit FS-SM ROI (left and right columns). Task (left columns): Dark blue borders encircle regions exceeding the task threshold with maximum overlap. Task maps are scaled to 2.7, the mean of max overlap thresholds across subjects. MLP (right columns): Blue borders encircle regions exceeding the MLP threshold with maximum overlap. MLP probability maps are scaled 0.7 to 1.0.

Figure 4

Volume Views Across a Range of Overlap Indices Top row: Task activation map (left) and MLP probability map (right) are shown for a patient with low FS-SM overlap laid over the patient’s MPRAGE image. Task activation maps are scaled to 2.7, which is the mean maximum overlap threshold across subjects. MLP probability maps (right) are scaled 0.7 to 1.0. Corresponding views for subjects with medium and high overlap are also shown.