Korean J Radiol.  2023 Jun;24(6):553-563. 10.3348/kjr.2022.1001.

Functional Magnetic Resonance Imaging and Diffusion Tensor Imaging for Language Mapping in Brain Tumor Surgery: Validation With Direct Cortical Stimulation and Cortico–Cortical Evoked Potential

• Kang KM
• Kim KM
• Kim IS
• Kim JH
• Kang H
• Ji SY
• Dho YS
• Oh H
• Park HP
• Seo HG
• Kim SM
• Choi SH
• Park CK

• KMID: 2542863
• DOI: http://doi.org/10.3348/kjr.2022.1001

Abstract

Objective
Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging-derived tractography (DTI-t) contribute to the localization of language areas, but their accuracy remains controversial. This study aimed to investigate the diagnostic performance of preoperative fMRI and DTI-t obtained with a simultaneous multi-slice technique using intraoperative direct cortical stimulation (DCS) or corticocortical evoked potential (CCEP) as reference standards.
Materials and Methods
This prospective study included 26 patients (23–74 years; male:female, 13:13) with tumors in the vicinity of Broca’s area who underwent preoperative fMRI and DTI-t. A site-by-site comparison between preoperative (fMRI and DTI-t) and intraoperative language mapping (DCS or CCEP) was performed for 226 cortical sites to calculate the sensitivity and specificity of fMRI and DTI-t for mapping Broca’s areas. For sites with positive signals on fMRI or DTI-t, the true-positive rate (TPR) was calculated based on the concordance and discordance between fMRI and DTI-t.
Results
Among 226 cortical sites, DCS was performed in 100 sites and CCEP was performed in 166 sites. The specificities of fMRI and DTI-t ranged from 72.4% (63/87) to 96.8% (122/126), respectively. The sensitivities of fMRI (except for verb generation) and DTI-t were 69.2% (9/13) to 92.3% (12/13) with DCS as the reference standard, and 40.0% (16/40) or lower with CCEP as the reference standard. For sites with preoperative fMRI or DTI-t positivity (n = 82), the TPR was high when fMRI and DTI-t were concordant (81.2% and 100% using DCS and CCEP, respectively, as the reference standards) and low when fMRI and DTI-t were discordant (≤ 24.2%).
Conclusion
fMRI and DTI-t are sensitive and specific for mapping Broca’s area compared with DCS and specific but insensitive compared with CCEP. A site with a positive signal on both fMRI and DTI-t represents a high probability of being an essential language area.

Keyword

Functional MRI; Broca’s area; Diffusion tensor imaging; Direct cortical stimulation; Cortico–cortical evoked potential