Accurate prediction of isocitrate dehydrogenase -mutation status of gliomas using SLOW-editing magnetic resonance spectroscopic imaging at 7 T MR

Abstract

Background 2-Hydroxy-glutarate (2HG) is a metabolite that accumulates in IDH-mutated gliomas and can be detected non-invasively using MR-spectroscopy. However, due to the low concentration of 2HG, established magnetic resonance spectroscopic imaging (MRSI) techniques at low-field have limitations with respect to signal-to-noise and to spatial resolution that can be obtained within clinically acceptable measurement-times. Recently a tailored editing-method for 2HG detection at 7T named SLOW-EPSI was developed. The underlying prospective study aimed to compare SLOW-EPSI to established techniques at 7T and 3T for IDH-mutation status determination. Methods The applied sequences were MEGA-SVS and MEGA-CSI at both field strengths and SLOW-EPSI at 7T only. Measurements were performed on a MAGNETOM-Terra 7T MR-scanner in clinical-mode using a Nova 1Tx32Rx head-coil and on a 3T MAGNETOM-Prisma scanner with a standard 32-channel head-coil. Results Fourteen patients with suspected glioma were enrolled. Histopathological confirmation was available in 12 patients. IDH-mutation was confirmed in 9 out of 12 cases and 3 cases were characterized as IDH-wildtype. SLOW-EPSI at 7T showed highest accuracy for IDH-status prediction (91.7% accuracy, 11 of 12 predictions correct with 1 false negative case). At 7T, MEGA-CSI had an accuracy of 58.3% and MEGA-SVS an accuracy of 75%. At 3T, MEGA-CSI showed an accuracy of 63.6% and MEGA-SVS of 33.3%. The co-edited cystathionine was detected in 2 out of 3 oligodendroglioma cases with 1p/19q co-deletion. Conclusion Depending on the pulse sequence, spectral editing can be a powerful tool for noninvasive determination of the IDH-status. SLOW-editing EPSI sequence is the preferable pulse sequence when used at 7T for IDH-status characterization.