Usefulness of Testicular Volume, Apparent Diffusion Coefficient, and Normalized Apparent Diffusion Coefficient in the MRI Evaluation of Infertile Men With Azoospermia

OBJECTIVE. The purpose of this article is to assess retrospectively the usefulness of testicular volume, apparent diffusion coefficient (ADC), and normalized ADC as measured using MRI in predicting the histopathologic grade of azoospermia and in differentiating obstructive from nonobstructive azoospermia. MATERIALS AND METHODS. A computerized search generated a list of 30 infertile men with azoospermia who had undergone both scrotal MRI and testis biopsy. MRI-determined testicular volumes, ADCs, and normalized ADCs were compared between infertile men with obstructive azoospermia and those with nonobstructive azoospermia. The normalized ADC was calculated as ADC of the testis divided by the ADC of the bladder lumen. RESULTS. Sixteen men had obstructive azoospermia and 14 had nonobstructive azoospermia. The testicular volume was significantly greater in patients with obstructive azoospermia (8.7-27.6 mL) than in patients with nonobstructive azoospermia (1.8-15.4 mL; p < 0.001). The ROC AUC for distinguishing nonobstructive from obstructive azoospermia using testicular volume was 0.92 (a cutoff value of <= 13.06 mL yielded sensitivity of 85.71% and specificity of 87.5%). Testicular ADC and normalized ADC were significantly lower in patients with obstructive azoospermia (0.329 x 10(-3) to 1.578 x 10(-3) mm(2)/s for ADC; 0.113 to 0.449 for normalized ADC) than in patients with nonobstructive azoospermia (0.801 x 10(-3) to 2.211 x 10(-3) mm(2)/s [p = 0.0094] for ADC; 0.235 to 0.61 [p = 0.0001] for normalized ADC). The ROC AUCs for distinguishing nonobstructive from obstructive azoospermia using testicular ADC and normalized ADC were 0.741 (a cutoff value of > 1.031 x 10(-3) mm(2)/s yielded sensitivity of 92.86% and specificity of 56.25%) and 0.875 (a cutoff value of > 0.425 yielded sensitivity of 78.57% and specificity of 93.75%), respectively. CONCLUSION. Testicular volume, ADC, and normalized ADC, as measured using MRI, are useful in predicting the histopathologic grade of azoospermia and in differentiating obstructive from nonobstructive azoospermia.