Redux testis: a potential pitfall in testicular imaging. 
The use of radionuclide testicular imaging to assess testicular perfusion has been shown to be a valuable diagnostic procedure in the evaluation of the acute scrotum.  However, if images are not evaluated in conjunction with physical findings falsely negative examinations can occur.  A case of torsion of a retractile testicle (redux testis) is presented to demonstrate this potential limitation.  To our knowledge this has not been reported previously.