Functional activity within brain tumors: a magnetic source imaging study

Area of Science:

• Neurosurgery
• Neuroscience
• Medical Imaging

Background:

• Intra-axial brain tumors can infiltrate or border functional cortical areas.
• Accurate localization of functional cortex is vital for surgical planning to minimize neurological deficits.

Purpose of the Study:

• To compare the prevalence of functional cortical activity within radiologically defined abnormal tissue in low-grade versus high-grade gliomas.
• To assess the necessity of preoperative functional imaging for optimizing tumor resection.

Main Methods:

• Retrospective analysis of 106 patients with intra-axial cerebral lesions near eloquent cortex.
• Preoperative magnetic source imaging (MSI) using a dual 37-channel biomagnetometer.
• Analysis of evoked magnetic fields from somatosensory and auditory stimuli to identify neuronal sources.

Main Results:

• Functional activity was found within the tumor lesion in 18% of Grade 2, 17% of Grade 3, and 8% of Grade 4 gliomas.
• 24.5% of patients were at risk for neurological deficits due to functional tissue proximity.
• High-grade lesions were more frequently associated with functional cortex at margins or in peritumoral edema.

Conclusions:

• Intra-axial brain tumors, irrespective of grade, can involve or border functional cortex.
• Functionally viable cortex involvement was greater in low-grade gliomas compared to high-grade lesions.
• Preoperative functional imaging and intraoperative mapping are essential for safe and maximal tumor resection.