Imaging of the epididymis.

Ultrasonography performed with a high-frequency transducer is the modality of choice for evaluating acute and nonacute scrotal disease. Acute epididymitis and epididymo-orchitis are the most common conditions that present with acute scrotal pain. Differentiation of these from testicular torsion is important for determining the appropriate management. High-transducer sonography allows the visualization of the epididymis and its detailed anatomy. We present important sonographic features of epididymitis and epididymo-orchitis caused by infectious and noninfectious etiologies. Features of benign and malignant epididymal lesions, including epididymal cysts, spermatoceles and tubular ectasia, sperm granulomas, adenomatoid tumors, leiomyomas, papillary cyst adenomas, lymphoma, and metastases are also presented. In addition, epididymal trauma and torsion are discussed. The goal of the review is to provide the radiologist with a better understanding of the numerous pathological conditions that occur in the epididymis.