Acute epididymitis in a 9-year-old boy with scrotal pain and redness. Longitudinal US scan shows that the epididymal head and body (arrows) are enlarged and hypoechoic relative to the normal testis (T). Wall thickening (*) and reactive hydrocele (h) are also seen. Power Doppler imaging showed increased perfusion of the epididymis.

http://radiographics.rsna.org/content/25/5/1197.figures-only