Presurgical Brain Mapping of the Ventral Somatomotor Network in Patients With Brain Tumors Using Resting-State fMRI

AJNR Am J Neuroradiol. 2017 May;38(5):1006-1012. doi: 10.3174/ajnr.A5132. Epub 2017 Mar 31.

Abstract

Background and purpose: Resting-state fMRI readily identifies the dorsal but less consistently the ventral somatomotor network. Our aim was to assess the relative utility of resting-state fMRI in the identification of the ventral somatomotor network via comparison with task-based fMRI in patients with brain tumor.

Materials and methods: We identified 26 surgically naïve patients referred for presurgical fMRI brain mapping who had undergone both satisfactory ventral motor activation tasks and resting-state fMRI. Following standard preprocessing for task-based fMRI and resting-state fMRI, general linear model analysis of the ventral motor tasks and independent component analysis of resting-state fMRI were performed with the number of components set to 20, 30, 40, and 50. Visual overlap of task-based fMRI and resting-state fMRI at different component levels was assessed and categorized as full match, partial match, or no match. Rest-versus-task-fMRI concordance was calculated with Dice coefficients across varying fMRI thresholds before and after noise removal. Multithresholded Dice coefficient volume under the surface was calculated.

Results: The ventral somatomotor network was identified in 81% of patients. At the subject level, better matches between resting-state fMRI and task-based fMRI were seen with an increasing order of components (53% of cases for 20 components versus 73% for 50 components). Noise-removed group-mean volume under the surface improved as component numbers increased from 20 to 50, though ANOVA demonstrated no statistically significant difference among the 4 groups.

Conclusions: In most patients, the ventral somatomotor network can be identified with an increase in the probability of a better match at a higher component number. There is variable concordance of the ventral somatomotor network at the single-subject level between resting-state and task-based fMRI.

MeSH terms

  • Brain Mapping / methods*
  • Brain Neoplasms / diagnostic imaging*
  • Brain Neoplasms / surgery
  • Female
  • Humans
  • Linear Models
  • Magnetic Resonance Imaging / methods*
  • Male
  • Neural Pathways / diagnostic imaging*
  • Somatosensory Cortex / diagnostic imaging*