Noninvasive electrical conductivity measurement by MRI: a test of its validity and the electrical conductivity characteristics of glioma

This study noninvasively examined the electrical conductivity (sigma) characteristics of diffuse gliomas using MRI and tested its validity. MRI including a 3D steady-state free precession (3D SSFP) sequence was performed on 30 glioma patients. The sigma maps were reconstructed from the phase images of the 3D SSFP sequence. The sigma histogram metrics were extracted and compared among the contrast-enhanced (CET) and noncontrast-enhanced tumour components (NCET) and normal brain parenchyma (NP). Difference in tumour sigma histogram metrics among tumour grades and correlation of sigma metrics with tumour grades were tested. Validity of sigma measurement using this technique was tested by correlating the mean tumour sigma values measured using MRI with those measured ex vivo using a dielectric probe. Several sigma histogram metrics of CET and NCET of diffuse gliomas were significantly higher than NP (Bonferroni-corrected p ae .045). The maximum sigma of NCET showed a moderate positive correlation with tumour grade (r = .571, Bonferroni-corrected p = .018). The mean tumour sigma measured using MRI showed a moderate positive correlation with the sigma measured ex vivo (r = .518, p = .040). Tissue sigma can be evaluated using MRI, incorporation of which may better characterise diffuse gliomas. aEuro cent This study tested the validity of noninvasive electrical conductivity measurements by MRI. aEuro cent This study also evaluated the electrical conductivity characteristics of diffuse glioma. aEuro cent Gliomas have higher electrical conductivity values than the normal brain parenchyma. aEuro cent Noninvasive electrical conductivity measurement can be helpful for better characterisation of glioma.