Tumor location and reduction in functional MRI estimates of language laterality

Area of Science:

• Neuroimaging
• Neurosurgery
• Neurology

Background:

• Functional MRI (fMRI) is used to estimate language dominance.
• Tumors near language cortex may distort fMRI results.
• The impact of tumor proximity to specific language areas, like Broca's, is not fully understood.

Purpose of the Study:

• To investigate if brain tumors bias fMRI-based language laterality estimates.
• To determine if tumor proximity to Broca's area has the greatest effect.
• To assess if these effects are independent of known confounding factors.

Main Methods:

• Reviewed 1113 patients, selecting 60 matched for 11 confounders.
• Included patients with left and right hemisphere tumors, anterior and posterior.
• Calculated fMRI laterality indices (LIs) using whole-brain and region of interest (ROI) approaches.

Main Results:

• Tumors near left Broca's area significantly decreased LIs (p=0.02) compared to right.
• This effect was independent of confounders, suggesting tumor bias.
• Wernicke's area LIs did not differ by tumor hemisphere.

Conclusions:

• Tumors near Broca's area lead to more bilateral fMRI language maps.
• Reduced laterality does not necessarily mean no risk to language function post-surgery.
• Findings aid interpretation of fMRI for neurosurgery and understanding functional compensation.