A comparison of 2-hydroxyglutarate detection at 3 T and 7 T with long-TE semi-LASER

Journal article

Abnormally high levels of the ‘oncometabolite’ 2-hydroxyglutarate (2-HG) occur in many grade II and III gliomas and correlate with mutations in the genes of isocitrate dehydrogenase (IDH) isoforms. In vivo measurement of 2-HG in patients, using MR spectroscopy, has largely been carried out at 3 T, yet signal overlap continues to pose a challenge for 2-HG detection. To combat this, several groups have proposed MRS methods at ultra-high field (≥ 7 T) where theoretical increases in signal-to-noise ratio and spectral resolution could improve 2-HG detection. Long-TE semi-LASER (TE = 110 ms) is a promising method for improved 2-HG detection in vivo at either 3 T or 7 T owing to the use of broadband adiabatic localisation. Using previously published semi-LASER methods at 3 T and 7 T, this study directly compares the detectability of 2-HG in phantoms and in vivo across nine patients. Cramér-Rao Lower Bounds (CRLBs) of 2-HG fitting were found to be significantly lower at 7 T (6 ± 2)% compared to 3 T (15 ± 7)% (p = 0.0019), yet were larger at 7 T in an IDH-wildtype patient. Although no increase in SNR was detected at 7 T (77 ± 26) compared to 3 T (77 ± 30), the detection of 2-HG was greatly enhanced through an improved spectral profile and increased resolution at 7 T. 7 T had a large effect on pairwise fitting correlations between GABA and 2-HG (p = 0.004) and resulted in smaller coefficients. The increased sensitivity for 2-HG detection using long-TE acquisition at 7 T may allow for more rapid estimation of 2-HG (within a few spectral averages) along with other associated metabolic markers in glioma.

Authors: Berrington, A; Voets, N; Larkin, S; de Pennington, N; Mccullagh, J

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: NMR in Biomedicine
• Volume: 31
• Issue: 3
• Pages: 1-9
• Publication date: 2018-01-05
• Acceptance date: 2017-11-22
• DOI: 10.1002/nbm.3886
• EISSN: 1099-1492
• ISSN: 0952-3480