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

Abstract

<b>OBJECTIVE.</b> 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). <b>MATERIALS AND METHODS.</b> 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. <b>RESULTS.</b> TV (<i>p</i> < 0.001) was reduced and both ADC (<i>p</i> < 0.001) and MTR (<i>p</i> = 0.013) were increased in NOA testes compared with normal testes. A positive correlation between higher Johnsen score and TV (<i>p</i> < 0.001) and a negative correlation between higher Johnsen score and both ADC (<i>p</i> = 0.015) and MTR (<i>p</i> = 0.003) were found. TV (<i>p</i> < 0.001) was reduced in NOA testes with failed sperm retrieval compared with NOA testes with positive sperm retrieval. On the contrary, ADC (<i>p</i> = 0.011) and MTR (<i>p</i> = 0.045) were significantly increased in NOA testes with negative sperm retrieval. <b>CONCLUSION.</b> 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.