Diffusion tensor imaging and fiber tractography of the normal epididymis.

PURPOSE: To evaluate the feasibility of diffusion tensor imaging (DTI) and fiber tractography (FT) of the normal epididymis and to determine normative apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values. METHODS: Twenty-eight healthy volunteers underwent MRI of the scrotum, including DTI on a 3.0 T system. For each anatomic part of the epididymis (head, body and tail) free-hand regions of interest were drawn and the mean ADC and FA were measured by two radiologists in consensus. Parametric statistical tests were used to determine intersubject differences in ADC and FA between the anatomic parts of each normal epididymis and between bilateral epididymides. Fiber tracts of the epididymis were reconstructed using the MR Diffusion tool. RESULTS: The mean ADC and FA of the normal epididymis was 1.31 × 10-3 mm2/s and 0.20, respectively. No differences in ADC (p = 0.736) and FA (p = 0.628) between the anatomic parts of each normal epididymis were found. Differences (p = 0.020) were observed in FA of the body between the right and the left epididymis. FT showed the fiber tracts of the normal epididymis. Main study's limitations include the following: small number of participants with narrow age range, absence of histologic confirmation and lack of quantitative assessment of the FT reconstructions. CONCLUSION: DTI and FT of the normal epididymis is feasible and allow the noninvasive assessment of the structural and geometric organization of the organ.

3.0 T diffusion tensor imaging and fiber tractography of the testes in nonobstructive azoospermia.

PURPOSE: To assess the role of 3.0 T Diffusion Tensor Imaging (DTI) and Fiber Tractography (FT) of the testes in the work-up of nonobstructive azoospermia (NOA). METHODS: This prospective study included consecutive NOA men and controls. A 3.0 T scrotal MRI was performed, including DTI. The testicular apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were calculated. FT reconstructions were created. The Kruskal-Wallis test, followed by pairwise comparisons, assessed differences in testicular ADC and FA between NOA histologic phenotypes (group 1: hypospermatogenesis; group 2: maturation arrest; and group 3: Sertoli cell-only syndrome) and normal testes. The Mann-Whitney-U test compared ADC and FA between NOA testes with positive and negative sperm retrieval. Visual assessment of the testicular fiber tracts was performed. Fiber tracts fewer in number, of reduced thickness, disrupted and/or disorganized were considered "abnormal". Chi-square tests and binary logistic regression analysis assessed variations in testicular fiber tracts morphology. RESULTS: Twenty-nine NOA men (mean age: 39 ± 5.93 years) and 20 controls (mean age: 26 ± 5.83 years) were included for analysis. Higher ADC (p < 0.001) and FA (p < 0.001) was observed in NOA testes compared to controls. Differences in FA were found between groups 1 and 3 (0.07 vs 0.10, p = 0.26) and groups 2 and 3 (0.07 vs 0.10, p = 0.03), but not between groups 1 and 2 (p = 0.66). An increase in FA was observed in NOA testes with Sertoli cell-only syndrome compared to hypospermatogenesis and maturation arrest. FA was higher in NOA testes with negative results for the presence of sperm compared to those with positive results (0.09 vs 0.07, p = 0.006). FT showed "abnormal" fiber tracts in NOA testes (p < 0.001). CONCLUSION: 3.0 T DTI and FT provide an insight into deranged spermatogenesis in NOA testes.

Dynamic contrast-enhanced MRI in the assessment of testicular perfusion in infertile men with clinical varicocele.

BACKGROUND: Varicocele represents the most common correctable cause of male infertility. The presence of non-invasive imaging parameters providing evidence as to which patients with varicocele are at risk for infertility would be important. PURPOSE: To explore the role of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) using semi-quantitative parameters in the assessment of testicular perfusion in infertile men with clinical varicocele. MATERIAL AND METHODS: The study cohort included 11 infertile men with clinical varicocele and six controls, with prior paternity. Subtraction DCE-MRI was performed after gadolinium administration, using a three-dimensional fast field-echo sequence. Time-signal intensity curves were created and semi-quantitative parameters were calculated. The independent samples t-test was used to compare basic T1 perfusion parameters between infertile testes with clinical varicocele and normal testes. Logistic regression analysis was performed to assess the most significant predictor of the diagnosis of clinical varicocele. RESULTS: Both testes with clinical varicocele and normal testes enhanced moderately and homogeneously, with a linear increase of enhancement throughout the examination. Higher mean values of maximum enhancement (P = 0.026), maximum relative enhancement (P = 0.024), and wash-in rate (P = 0.013) were detected in the testes of infertile men with clinical varicocele, compared to the normal population. The wash-in rate proved the most significant predictor of the diagnosis of clinical varicocele (P = 0.013). CONCLUSION: DCE-MRI may provide a valuable insight into the testicular perfusion of infertile men with clinical varicocele. The wash-in rate proved a strong and independent predictor of the diagnosis of clinical varicocele.

A preliminary study of the biochemical environment of infertile testes with clinical varicocele.

PURPOSE: To investigate the role of proton magnetic resonance spectroscopy. (1H-MRS) in the assessment of the biochemical environment of testes in infertile men with clinical varicocele. METHODS: In this prospective IRB approved study, 13 infertile men with clinical varicocele and 11 age-matched controls were assessed. 1H-MRS was performed using a single voxel point-resolved spectroscopy (PRESS) sequence with TR/TE: 2000/25 ms. Normalized metabolite concentrations, defined as ratios of the calculated metabolite concentrations relative to total creatine (tCr) concentration were compared between infertile testes with clinical varicocele and normal testes using nonparametric statistical tests. Logistic regression analysis was performed to assess the most significant predictor for the diagnosis of varicocele. RESULTS: Several metabolic peaks were found in both infertile testes with clinical varicocele and normal testes. Most prominent peaks were the following: total choline (tCho), tCr, myo-inositol (mI), Glx, and total lipids and macromolecules resonating at 0.9 ppm (TLM09), 1.3 ppm (TLM13) and 2.0 ppm (TLM20). Lower normalized concentrations of tCho (P = 0.001), mI (P = 0.012), Glx (P = 0.011), TLM09 (P = 0.027), TLM13 (P = 0.035) and TLM20 (P = 0.021) were found in infertile testes with clinical varicocele compared with normal men. Total Cho proved the most significant predictor for the diagnosis of clinical varicocele (P = 0.001). CONCLUSIONS: 1H-MR spectra of infertile testes with clinical varicocele showed decrease in normalized concentrations of tChol, ml, Glx and lipids. 1H-MRS of the testes might be used as a noninvasive marker of deranged spermatogenesis in infertile men with clinical varicocele.

Testicular Apparent Diffusion Coefficient and Magnetization Transfer Ratio: Can These MRI Parameters Be Used to Predict Successful Sperm Retrieval in Nonobstructive Azoospermia?

OBJECTIVE. The aim of our study was to assess if testicular apparent diffusion coefficient (ADC) and magnetization transfer ratio (MTR) can be used as MRI parameters to predict the presence of spermatozoa retrieved after microdissection testicular sperm extraction (mTESE) in men with nonobstructive azoospermia (NOA). MATERIALS AND METHODS. The study included 49 men with NOA and 45 age-matched control subjects. Participants underwent scrotal MRI between June 2013 and January 2017, 1 day before mTESE. Testicular volume (TV), ADC, and MTR were measured. NOA testes were classified as follows: group 1, testes with higher Johnsen score of ≥ 8; and group 2, testes with higher Johnsen score of < 8. Nonparametric statistical tests were used to assess differences in TV, ADC, and MTR between men with NOA and control subjects, the two NOA groups, and NOA testes with positive sperm retrieval and NOA testes with negative sperm retrieval. RESULTS. TV (p < 0.001) was reduced and both ADC (p < 0.001) and MTR (p = 0.013) were increased in NOA testes compared with normal testes. A positive correlation between higher Johnsen score and TV (p < 0.001) and a negative correlation between higher Johnsen score and both ADC (p = 0.015) and MTR (p = 0.003) were found. TV (p < 0.001) was reduced in NOA testes with failed sperm retrieval compared with NOA testes with positive sperm retrieval. On the contrary, ADC (p = 0.011) and MTR (p = 0.045) were significantly increased in NOA testes with negative sperm retrieval. CONCLUSION. On the basis of our preliminary data, TV, ADC, and MTR might represent useful MRI parameters in the workup of patients with NOA by helping to predict the presence of spermatozoa after mTESE.