title: MRI in the histologic characterization of testicular neoplasms.
abstract: OBJECTIVE
  The purpose of our study was to investigate the potential role of MRI in the preoperative characterization of the histologic type of testicular tumors and, more specifically, to differentiate seminomatous from nonseminomatous testicular neoplasms.
  
  
  METHODS
  Twenty-one patients with histologically proven germ cell testicular tumors underwent MRI of the scrotum on a 1.5-T unit. T2- and T1-weighted sequences before and after i.v. administration of gadolinium chelate were performed. MRI studies were retrospectively reviewed by two radiologists and findings were correlated with the histopathologic diagnosis. An attempt was made to differentiate seminomatous from nonseminomatous testicular tumors on the basis of signal intensity and homogeneity of the lesions, presence of fibrovascular septa, tumor encapsulation, and patterns of contrast enhancement. Interobserver agreement was assessed using weighted kappa statistics.
  
  
  RESULTS
  MRI findings correctly characterized 19 (91%) of 21 testicular neoplasms (nine seminomatous and 10 nonseminomatous testicular tumors), with excellent interobserver agreement. The presence of an intratesticular lesion of predominantly low signal intensity on T2-weighted images, with septa enhancing more than tumor tissue after contrast material administration, was more suggestive for the diagnosis of a seminoma. Tumors that were markedly heterogeneous both on unenhanced and contrast-enhanced images were indicative of a nonseminomatous neoplasm.
  
  
  CONCLUSIONS
  Our study shows that MRI provides a credible preoperative differentiation of seminomatous from nonseminomatous testicular tumors, with excellent interobserver agreement.
authors.affiliation: Department of Clinical Radiology, University Hospital of Ionnina, Leoforos S. Niarchou, 45500, Platia Pargis, 2, 453 32, Ioannina, Greece. a_tsili@yahoo.gr
authors.forename: Athina C
authors.initials: AC
authors.lastname: Tsili
authors.forename: Constantine
authors.initials: C
authors.lastname: Tsampoulas
authors.forename: Xenofon
authors.initials: X
authors.lastname: Giannakopoulos
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Stefanou
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Alamanos
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Sofikitis
authors.forename: Stavros C
authors.initials: SC
authors.lastname: Efremidis
mesh_terms: D000328:Adult; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009373:Neoplasms, Germ Cell and Embryonal / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018239:Seminoma / Q000473:pathology*; D012680:Sensitivity and Specificity; D013736:Testicular Neoplasms / Q000473:pathology*