Purpose: To determine the amide proton transfer-weighted (APTw) imaging features in testes with age, and to assess the feasibility of APTw magnetic resonance imaging (MRI) in assessing testicular spermatogenic function.

Methods: A total of 23 male patients with clinically confirmed hypospermatogenesis caused by epididymo-orchitis were included in the case group (group A) and another 93 men (age range, 20-80 years) were included in the control group. The control group was divided into four subgroups: group B1 (20-34 years, n = 25), group B2 (35-49 years, n = 23), group B3 (50-64 years, n = 21), and group B4 (65-80 years, n = 24). All participants underwent 3.0T MRI scan, and the APT signal intensity (SI) and apparent diffusion coefficient (ADC) value of each testis were examined. The ADC and APT SI were independently measured by two radiologists blinded to clinical data, and average values were calculated. A power analysis was conducted to determine the required sample size.

Results: APT SI was negatively correlated with age (r = -0.510, P < 0.001), whereas ADC was positively correlated with age (r = 0.317, P = 0.006). The APT SI was significantly higher in group A (1.77 ± 0.41) than in group B1 (1.43 ± 0.21), group B2 (1.37 ± 0.31), group B3 (1.30 ± 0.35), and group B4 (1.20 ± 0.35) (all P < 0.01). The ADC was significantly higher in group A [(0.549 ± 0.091) × 10^-3 mm²/s] compared with group B1 [(0.449 ± 0.047) × 10^-3 mm²/s], group B2 [(0.475 ± 0.022) × 10^-3 mm²/s], and group B3 [(0.488 ± 0.051) × 10^-3 mm²/s] (all P < 0.01), whereas no statistically significant difference was found between group A and group B4 (P > 0.05).

Conclusion: The APT SI of the normal testes decreased with age, whereas a significant elevation of APT SI was detected in patients with hypospermatogenesis caused by epididymo-orchitis.

Clinical significance: Hypospermatogenesis caused by degeneration or inflammation can be differentiated by APT quantity combined with ADC value.

Keywords: MRI; Testis; amide proton transfer; oligospermia; orchitis.

目的： 确定附睾-睾丸炎引起的生精功能减退患者的睾丸酰胺质子转移加权（APTw）成像特征，并评估APTw磁共振成像（MRI）在评估睾丸生精功能方面的可行性。

方法： 总共纳入了23名临床确诊为由附睾-睾丸炎引起的低精子生成症的男性患者作为病例组（A组），另有93名男性（年龄范围，20-80岁）被纳入对照组。对照组分为四个亚组：B1组（20-34岁，n=25）、B2组（35-49岁，n=23）、B3组（50-64岁，n=21）和B4组（65-80岁，n=24）。所有参与者均接受了3.0T MRI扫描，并检测了每个睾丸的APTw信号强度（SI）和表观扩散系数（ADC）值。两位不知道临床数据的放射科医生独立测量了ADC和APTw SI值，并计算平均值。进行了一项功效分析以确定所需样本量。

结果： APTw SI与年龄呈负相关（r = -0.510，P -3 mm²/s]、B2组[(0.475 ± 0.022) × 10^-3 mm²/s] 和B3组[(0.488 ± 0.051) × 10^-3 mm²/s]，差异均具有统计学意义 (P 0.05)。

结论： 正常睾丸的APTw SI随着年龄的增长而下降；然而，在由附睾-睾丸炎引起的低精子生成症患者中检测到APTw SI显著升高。

临床意义： 可以通过结合APTw值和ADC值来区分由于退行性变或炎症导致的低精子生成症。