Use of apparent diffusion coefficient values to differentiate lymph nodes from testicular tissue in patients with undescended testes

BACKGROUND: This study investigated the anatomical location of non-palpable undescended testes (UTs), which account for approximately 20% of all cases of UTs. Radiological imaging is essential to determine the location of such testes in the abdomen or groin. Other studies have examined the diagnostic performance of diffusion-weighted MRI (DWI) in detecting and localizing non-palpable UTs. However, no study has used apparent diffusion coefficient (ADC) values to differentiate UT tissue. METHODS: This study included consecutive children referred to a pediatric surgery clinic with a prediagnosis of UT. Diffusion-weighted images were used to evaluate lymph nodes (LNs) and testicular tissue. Apparent diffusion coefficient values were measured by placing a circular region of interest at the center. RESULTS: The study enrolled 44 boys (73 testes) who underwent pelvic MRI. Age and testicular volume were significantly positively correlated (P < .001). Testicular ADC values were higher in both inguinal and abdominal locations than in scrotal locations. However, the ADC values of LNs were significantly lower than those of testes. Our ROC analysis revealed that an ADC value < 940 10-3/mm2 could differentiate between LNs and testes (AUC = 0.826, P < .001). CONCLUSION: Measuring ADCs using a DWI imaging sequence is an accurate method of differentiating between testes and LNs. ADVANCES IN KNOWLEDGE: This study is the first to show that ADC values from diffusion-weighted MRI can reliably differentiate non-palpable UTs from LNs. Apparent diffusion coefficient mapping appears to be a novel and accurate tool for detecting testicular localization when conventional assessment is inadequate.