Quantitative Proton Spectroscopy of the Testes at 3 T: Toward a Noninvasive Biomarker of Spermatogenesis
The aim of this study was to compare testicular metabolite concentrations between fertile control subjects and infertile men.Materials and Methods
Single voxel proton magnetic resonance spectroscopy (1H-MRS) was performed in the testes with and without water suppression at 3 T in 9 fertile control subjects and 9 infertile patients (8 with azoospermia and 1 with oligospermia). In controls only, the T1 and T2 values of water and metabolites were also measured. Absolute metabolite concentrations were calculated using the unsuppressed water signal as a reference and correcting for the relative T1 and T2 weighting of the water and metabolite signals.Results
Testicular T1 values of water, total choline, and total creatine were 2028 ± 125 milliseconds, 1164 ± 105 milliseconds, and 1421 ± 314 milliseconds, respectively (mean ± standard deviation). T2 values were 154 ± 11 milliseconds, 342 ± 53 milliseconds, and 285 ± 167 milliseconds, respectively. Total choline concentration was lower in patients (mean, 1.5 mmol/L; range, 0.9–2.1 mmol/L) than controls (mean, 4.4 mmol/L; range, 3.2–5.7 mmol/L; P = 4 × 10−5). Total creatine concentration was likewise reduced in patients (mean, 1.1 mmol/L; range, undetectable −2.7 mmol/L) compared with controls (mean, 3.6 mmol/L; range, 2.5–4.7 mmol/L; P = 1.6 × 10−4). The myo-inositol signal normalized to the water reference was also lower in patients than controls (P = 4 × 10−5).Conclusions
Testicular metabolite concentrations, measured by proton spectroscopy at 3 T, may be valuable as noninvasive biomarkers of spermatogenesis.