Test–Retest Reliability of the Brain Metabolites GABA and Glx With JPRESS, PRESS, and MEGA‐PRESS MRS Sequences in vivo at 3T

BACKGROUND: The optimization of magnetic resonance spectroscopy (MRS) sequences allows improved diagnosis and prognosis of neurological and psychological disorders. Thus, to assess the test-retest and intersequence reliability of such MRS sequences in quantifying metabolite concentrations is of clinical relevance. PURPOSE: To evaluate the test-retest and intersequence reliability of three MRS sequences to estimate GABA and Glx = Glutamine+Glutamate concentrations in the human brain. STUDY TYPE: Prospective. SUBJECTS: Eighteen healthy participants were scanned twice (range: 1 day to 1 week between the two sessions) with identical protocols. FIELD STRENGTH/SEQUENCE: 3T using a 32-channel SENSE head coil in the PCC region; PRESS, JPRESS, and MEGA-PRESS sequences. ASSESSMENT: Metabolite concentrations were estimated using LCModel (for PRESS and MEGA-PRESS) and ProFit2 (for JPRESS). STATISTICAL TESTS: The test-retest reliability was evaluated by Wilcoxon signed-rank tests, Pearson's r correlation coefficients, intraclass-correlation coefficients (ICC), coefficients of variation (CV), and by Bland-Altman (BA) plots. The intersequence reliability was assessed with Wilcoxon signed-rank tests, Pearson's r correlation coefficients, and BA plots. RESULTS: For GABA, only the MEGA-PRESS sequence showed a moderate test-retest correlation (r = 0.54, ICC = 0.5, CV = 8.8%) and the BA plots indicated good agreement (P > 0.05) for all sequences. JPRESS provided less precise results and PRESS was insensitive to GABA. For Glx, the r and ICC values for PRESS (r = 0.87, ICC = 0.9, CV = 2.9%) and MEGA-PRESS (r = 0.70, ICC = 0.7, CV = 5.3%) reflect higher correlations, compared with JPRESS (r = 0.39, ICC = 0.4, CV = 20.1%). DATA CONCLUSION: MEGA-PRESS and JPRESS are suitable for the reliable detection of GABA, the first being more precise. The three sequences included in the study can measure Glx concentrations. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:1181-1191.