Test–Retest Reliability of Multi‐Metabolite Edited MRS at 3T Using PRESS and sLASER

ABSTRACT Purpose Spectral editing is the most common MRS approach for noninvasive in vivo measurement of low‐concentration, strongly overlapped metabolites in the brain, such as γ‐aminobutyric acid (GABA) and glutathione (GSH). Multi‐metabolite editing methods, such as HERMES and HERCULES, enable the editing of multiple J ‐coupled metabolites in a single acquisition without increasing the total scan time. Yet little is known regarding the reliability of these methods. This study assessed the test–retest reliability of HERMES and HERCULES, where volume localization was achieved using both PRESS and sLASER. Methods Sixteen healthy adult volunteers were scanned twice in two separate sessions. Single‐voxel edited MRS data were acquired in the medial parietal lobe using the following sequences: (1) HERMES‐PRESS; (2) HERMES‐sLASER; (3) HERCULES‐PRESS; (4) HERCULES‐sLASER. Spectra were processed and metabolites were quantified relative to tCr. Data quality metrics and reliability statistics were estimated for all four acquisitions. Results HERMES‐sLASER produced lower within‐subject coefficients of variation (CV ws ) for GABA + co‐edited macromolecules (GABA+), GSH, glutamine (Gln), myo ‐inositol (mI), NAA, and total Cho (tCho), suggesting improved reliability compared to HERMES‐PRESS. HERCULES‐sLASER produced better reliability than HERCULES‐PRESS for GABA+, GSH, aspartate, Gln, lactate, mI, NAA, and tCho with lower CV ws . N ‐acetylaspartylglutamate (NAAG) showed higher CV ws for HERCULES‐sLASER, and Glu showed higher CV ws for HERMES‐sLASER and HERCULES‐sLASER. Overall, these findings suggest that sLASER yields lower within‐subject variability than PRESS for several metabolites for both HERMES and HERCULES, supporting improved measurement reliability. Conclusion sLASER yielded better test–retest reliability than PRESS for most metabolites than for multi‐metabolite edited MRS.