A new management algorithm for impalpable undescended testis with gadolinium enhanced magnetic resonance angiography

Purpose: We evaluated the diagnostic accuracy of preoperative localization of impalpable undescended testis using ultrasound and gadolinium (Gd) enhan ced magnetic resonance angiography (MRA). Materials and Methods: Ultrasound and Gd-MRA were performed prospectively i n 21 boys (23 impalpable testes) with cryptorchidism before laparoscopy and surgical exploration. Gd-MRA was done using a 1.5 Tesla magnetic resonance scanner with a turbo field echo technique after bolus intravenous injectio n of 0.4 mmol./kg. body weight of Gd diethylenetriaminepentaacetic acid. A total of 10 dynamic scans were acquired during 15 minutes after Gd injectio n to cover the early arterial and delayed venous phases. All patients subse quently underwent diagnostic laparoscopy and definitive surgery. Results: Ultrasound correctly localized 9 of 10 intracanalicular testes but failed to reveal any intra-abdominal or vanishing testes. In contrast, Gd- MRA correctly localized 4 intra-abdominal, all 10 intracanalicular and 8 ca nalicular vanishing testes. In 1 patient with an intra-abdominal vanishing testis ultrasound and Gd-MRA failed to make the diagnosis. When correlated with the findings of subsequent laparoscopy and surgical exploration, Gd-MR A had a diagnostic sensitivity of 96% and a specificity of 100% for localiz ing impalpable undescended testes. Based on Gd-MRA and ultrasound findings laparoscopy could have been avoided in 18 of 23 cases (78%). No adverse eff ect was associated with Gd use in this study. Conclusions: Gd-MRA accurately diagnoses vanishing testes and reliably diff erentiates intraabdominal from intracanalicular impalpable testes, allowing definite preoperative planning of the surgical approach and avoiding unnec essary laparoscopy. A new management algorithm for impalpable testis in pat ients with cryptorchidism is proposed based on ultrasound and Gd-MRA findin gs.