MR imaging of undescended testis

Twenty three undescended testes in 18 boys were prospectively evaluated for location with palpation (n=23), MRI (n=23), US (n=21) and CT (n=17). All patients underwent operation and/or laparoscopy, which confirmed the location in 13 cases with 16 testes; 6 in the puboscrotal, 6 in the intracanalicular and 4 in the intraabdominal regions. Of 16 undescended testes, 13 were correctly identified on MRI. Sensitivity of MRI (81%) was superior to those of palpation (31%), US (62%), and CT (59%). Three testes, two in the abdominal and one in the intracanalicular regions, were failed to be detected by MRI. MRI can demonstrate the gubernaculum testis and/or the spermatic cord particularly on the coronal images. These structures are helpful to identify the testis and to differentiate it from inguinal lymph nodes or fluid-filled bowel loops. In three out of 4 atrophic undescended testes with nodular shape, MRI showed small nodules of lower signal intensity, suggesting atrophic testes. Mediastinum testis was depicted in only two out of 10 undescended testes (20%) on MRI. Authors conclude that among currently available imaging modalities MRI is the most sensitive and non-invasive to evaluate the patients with undescended testes, and the promising method to predict the function of the testes. (author)