Subacute scrotal pain: evaluation of torsion versus epididymitis with MR imaging.

Torsion knot and whirlpool patterns result from the twisting of the spermatic cord, which produces distortion of cord structures. These two findings, along with spermatic cord vascularity, were used to prospectively differentiate testicular torsion from epididymitis in 11 patients with subacute scrotal pain who underwent magnetic resonance (MR) imaging. The final diagnosis was established clinically in four patients and surgically in five. MR imaging enabled the recognition of each entity without error. Retrospective review of findings highlighted other potential discriminating features, the most important of which were testicular size and vascularity. Because of its ability to highlight vessels and detail normal and abnormal intrascrotal anatomy, MR imaging in this small series enabled the differentiation of subacute torsion from epididymitis with 100% accuracy. This high degree of accuracy warrants further investigation.