Diffusion tensor imaging parameters in testes with nonobstructive azoospermia: DTI in the Evaluation of NOA

BACKGROUND: The development of noninvasive imaging parameters having the capacity to identify the population of men with nonobstructive azoospermia (NOA) where a successful sperm retrieval outcome is of great clinical significance. PURPOSE/HYPOTHESIS: To assess differences of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in NOA testes with impaired spermatogenesis and the possible association with the presence of spermatozoa after testicular sperm extraction (TESE). STUDY TYPE: Retrospective. POPULATION: Twenty NOA men (35 testes) and 21 age-matched controls (36 testes). FIELD STRENGTH/SEQUENCE: 1.5T, T1 WI-SE T2 WI-FSE FS SS-EP-DTI. ASSESSMENTS: The MRI data were analyzed by two radiologists in consensus. The average ADC and FA of testicular parenchyma was measured. NOA testes were classified as NOA with higher Johnsen score (JS) ≥8 (group 1) and JS <8 (group 2). STATISTICAL TESTS: Parametric and nonparametric statistical tests were used to compare ADC and FA between NOA groups and normal testes (group 3) and to evaluate a possible association with the presence of spermatozoa after TESE. RESULTS: Differences in ADC were found between groups 1 and 2 (P = 0.043) and groups 2 and 3 (P = 0.004), but not between groups 1 and 3 (P = 0.418). Higher values of FA were found both in NOA testes with JS ≥8 (P < 0.001) and JS <8 (P < 0.001) compared to controls. ADC (P = 0.096) and FA (P = 0.516) did not demonstrate differences in NOA testes with or without spermatozoa at TESE. DATA CONCLUSION: Both ADC and FA are increased in NOA testes compared to a normal population. ADC was proven to be a more useful diagnostic adjunct tool in the identification of the population of NOA men with foci of advanced spermatogenesis. However, DTI parameters were not predictive of sperm retrieval after TESE. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1318-1325.