Functional imaging in a low-field, mobile intraoperative magnetic resonance scanner: expanded paradigms

We previously demonstrated the capability to obtain functional magnetic resonance imaging (MRI) scans of the motor cortex in healthy volunteers using a low-field mobile operating room-based MRI scanner with 0.12-T field strength. Using an expanded (0.15-T), but still mobile, version of this system, our goal was to acquire data showing activation of other areas of functionally important cortex.

Five healthy volunteers were scanned with the low-field scanner using finger tapping, hand touch, silent word generation, text listening, and visual stimulation paradigms. The data was analyzed offline using publicly available software. For comparison, the volunteers were then scanned with a 3-T diagnostic MRI scanner.

Significant cortical activation was demonstrated on 16 out of 22 images obtained on the operating room-based scanner. Motor activation was most robust, followed by silent word generation, text listening, and hand touch paradigms. The correlation coefficients compared favorably with the images obtained on the 3-T scanner. The signal changes were higher for images obtained with the low-field, mobile scanner compared with those performed with the 3-T diagnostic MRI scanner.

Functional MRI scans of multiple cortical areas can be acquired with a low-field strength magnet designed for intraoperative imaging. Further refinement of this technique may allow for the acquisition of true intraoperative functional MRI scans immediately, before, and even during cranial surgery in select patients.