The split sign: The MRI equivalent of the bell clapper deformity.

OBJECTIVE:: We sought to define the MRI findings in the bell clapper deformity (BCD) and to retrospectively evaluate its diagnostic ability.

METHODS:: The cases of eight patients who underwent MRI and surgery for acute scrotum between January 2010 and January 2017 were evaluated. We recorded whether hyperintense fluid on T2 -weighted images (T2WI) existed between the posterior aspect of the epididymis and the scrotal wall ("split sign") and investigated if it correlated with BCD in surgical findings.

RESULTS:: In one patient without hydrocele, readers were unable to evaluate the anatomy of the tunica vaginalis. Among seven patients with hydrocele, five had the split sign and all were surgically confirmed as BCD. In two patients with hydrocele but no split sign, one had normal scrotal anatomy and the other had a BCD with a necrotic testis adherent to the scrotal wall.

CONCLUSION:: The split sign on MRI corresponded well to the lack of fixation of the epididymis to the scrotal wall and detected BCD with high sensitivity (5/6).

ADVANCES IN KNOWLEDGE:: A hyperintense area on T2 weighted image between the posterior aspect of the epididymis and scrotal wall ('split sign') is a useful MRI finding for diagnosing BCD.