How Reliable is Proton MRS for Measuring Brain Creatine?

Proton magnetic resonance spectroscopy ( 1 H MRS) is gaining attention for its role in determining total creatine (tCr) concentrations in the brain. However, the trustworthiness of repeated 1 H MRS measurements has been questioned. A study delved into how well 1 H MRS can reliably and repeatedly measure tCr concentrations in different brain regions, such as the midbrain, visual cortex, and frontal cortex. Eighteen healthy adults, aged 20-32, participated in the study. Half were female. They underwent 1 H magnetic resonance imaging and spectroscopy at 3 tesla. Intra-session measurements were taken without moving the participants or the voxel (a small 3D region of interest). Inter-session measurements were done with participants and voxel repositioning between repeated scans.The 1 H MRS data, totaling 174 spectra, was analyzed using TARQUIN and OSPREY. Voxel fractions (grey/white matter and cerebrospinal fluid) were determined through segmentation. Results showed that tCr concentrations can be measured reliably and repeatedly using 1 H MRS, with errors less than 2%. Significant regional differences in tCr concentrations were also found across the human brain. The study provided new data on the minimum detectable changes in tCr concentrations and discussed the sources of error in repeated 1 H MRS, including the impact of the analysis package on tCr quantification. It also offered suggestions to improve the interpretation and clinical value of future research. More studies are needed to confirm these findings in other settings and populations.