Within-session test-retest reproducibility and reliability of auditory cortex GABA+ in individuals with tinnitus using MEGA-sLASER at 3T

Motivation: The measurement of GABA+ using in vivo proton magnetic resonance spectroscopy requires adequate reproducibility and reliability for its use in clinical research and as a potential biomarker. Goal(s): We aimed to determine the within-session test-retest reproducibility and reliability of GABA+ in the auditory cortex of individuals with tinnitus. Approach: A MEGA-sLASER sequence for GABA+ measurement using two consecutive within-session blocks was performed on 38 participants over 2 scanning days. Results: GABA+ quantification in the auditory cortex demonstrated similar reproducibility and reliability when using either a total creatine (tCr) or water reference (GABA+/tCr: CV=5.6%, ICC=0.69, 95% CI [0.52-0.80]; GABA+/water: CV=5.6%; ICC=0.73, 95% CI [0.58-0.83]). Impact: Auditory cortex GABA+ quantification with MEGA-sLASER in a clinical population with GABA+ abnormalities in the region of interest can be achieved with reproducibility and reliability that is comparable to what has been reported in other brain regions of healthy controls.