Reproducibility of localized 2D correlated MR spectroscopy

The test-retest reliability of two-dimensional (2D) correlated spectroscopy (COSY) was studied on a whole-body 1.5T MRI scanner. Single-voxel localized 2D proton spectra were recorded in vitro as well as in vivo using a recently implemented localized chemical shift correlated spectroscopic (L-COSY) sequence. A total of 40 in vitro and 40 human brain (10 volunteers, four times each) 2D L-COSY spectra were recorded. The coefficients of variation (CVs) of selected brain metabolites (raw volume integrals) recorded in 10 healthy volunteers were less than 9% for creatine, choline, and N-acetyl aspartate, and less than 17% for myo-inositol, glutamine/glutamate, aspartate, and threonine/lactate. The 2D metabolite ratios and the raw volume integrals of 2D diagonal and cross peaks in healthy human brain were very well reproduced. The intraclass correlation coefficients were greater than 0.4 (P < 0.05) for the major metabolites, indicating that the 2D peak volumes were stable enough within individuals to detect reliable differences between normal subjects.