Electronic reference for absolute quantification of brain metabolites by 1H-MRS on clinical whole-body imaging.

BACKGROUND AND PURPOSE The electronic reference to access in vivo concentrations (ERETIC) method is a promising technique for absolute concentration quantification by brain proton magnetic resonance spectroscopy ((1)H-MRS). However, in its usual form, the technique cannot be implemented in most clinical MR scanners. For this reason, we propose a new strategy for transmitting the ERETIC signal before localized spectroscopy acquisition, thereby allowing its use in clinical MR scanners. METHODS ERETIC signal acquisition, using a dedicated sequence, was carried out immediately before the MR sequence. This approach was evaluated on phantoms of known metabolite concentrations and in 10 healthy volunteers. The results were then compared with those obtained using the water signal as reference. RESULTS Measurements in vitro showed that the standard deviations measured by the ERETIC method were similar to those using the water-signal reference method. Also, values for metabolite concentrations in vivo were in good agreement with those found in the literature for normal white matter in human brains. Concentrations obtained by ERETIC showed good linear correlation compared with the values obtained by the water-signal reference method. CONCLUSION Our preliminary study shows that the ERETIC method appears to be a reliable technique that can overcome most of the drawbacks observed with other absolute quantification methods. However, further studies involving larger patient groups are needed to confirm these findings.