A magnetic resonance imaging study in etiology of nonobstructive azoospermia

Background: Testicular magnetic resonance imaging parameters, including apparent diffusion coefficient, fractional anisotropy, magnetization transfer ratio, and normalized metabolite concentrations represent useful noninvasive fingerprints of nonobstructive azoospermia. Nonobstructive azoospermia etiology might correlate with the spermatogenesis status.

Objectives: To assess the possible association between apparent diffusion coefficient, fractional anisotropy, magnetization transfer ratio, and normalised metabolite concentrations with nonobstructive azoospermia etiology.

Materials and methods: This retrospective study included 48 consecutive men with nonobstructive azoospermia and 18 age-matched controls. All participants underwent scrotal magnetic resonance imaging. The testicular apparent diffusion coefficient, fractional anisotropy, magnetization transfer ratio, and normalized metabolite concentrations were calculated. nonobstructive azoospermia men were classified into three groups, based on etiology: group 1, idiopathic; group 2, genetic causes; and group 3, non-genetic causes. Parametric and nonparametric statistical tests were used to evaluate differences in magnetic resonance imaging parameters between nonobstructive azoospermia groups and normal testes (group 4). Regression analysis was performed to assess the most predictive magnetic resonance imaging factor of nonobstructive azoospermia etiology.

Results: Differences in mean apparent diffusion coefficient (p < .001), fractional anisotropy (p < .001), magnetization transfer ratio (p < .001), and normalized concentrations of total choline (p = .005), glucose (p = .012), myo-inositol (p = .024), and lipids (p = .010) were observed among groups. Regression analysis failed to identify the most discriminating magnetic resonance imaging feature for nonobstructive azoospermia etiology.

Discussion and conclusion: Apparent diffusion coefficient, fractional anisotropy, magnetization transfer ratio, and normalized concentrations of total choline, glucose, myo-inositol, and lipids are helpful in discriminating nonobstructive azoospermia etiology. Magnetic resonance imaging may provide useful, noninvasive information on the microstructural and biochemical milieu of nonobstructive azoospermia testes.