Undescended testis: evaluation by magnetic resonance imaging. 
We describe our experience of prospective magnetic resonance imaging (MRI) study in patients of undescended testis, with a 1.5 T equipment using body coil.  There were thirty two patients, aged 1.5 to 14 years with a mean age of nine years.  Surgical follow up was obtained for thirty one patients.  We were able to indicate the position of 26 testes in 22 patients and absence of five testes in three patients.  MRI was falsely positive and negative for five and two testes, respectively.  Testicular tissue at ectopic site was identified by presence of characteristic signal intensity pattern, mediastinum testis and its location along empty spermatic canal in cases of inguinal testis either singly or in combination.  MRI was able to detect atrophic changes in four testes, confirmed on surgery.  The study concludes that MR imaging is useful in the localization and tissue characterization of a non palpable testis.  However, it is not sensitive enough for complete exclusion of the diagnosis of an undescended testis.  Thus a surgical or laproscopic exploration may be needed further in selective cases for the management of patient.