title: Combined late gadolinium-enhanced and double-echo chemical-shift MRI help to differentiate renal oncocytomas with high central T2 signal intensity from renal cell carcinomas.
abstract: OBJECTIVE
  The purpose of our study was to evaluate the combination of dynamic contrast-enhanced T1-weighted and double-echo gradient-echo MR imaging to distinguish renal oncocytoma with high T2 signal intensity centrally from renal cell carcinoma (RCC).
  
  
  METHODS
  Between 2006 and 2011, 63 renal tumors (59 patients) presenting with a high signal intensity (SI) central area on T2-weighted sequences were imaged with dynamic contrast-enhanced sequences, including phases later than 5 minutes after contrast injection, and double-echo chemical-shift sequences were selected from our institutional database. Two experienced radiologists visually assessed presence and distribution of signal enhancement of central areas after injection and measured SI changes on opposed-phase images for calculation of the SI index and tumor-to-spleen ratio. Cutoff values were derived from the receiver operating characteristic (ROC) curve.
  
  
  RESULTS
  There were 19 oncocytomas (16 patients), 43 RCCs (42 patients), and one leiomyoma. Complete late enhancement of the central area was observed in 14 oncocytomas (74%) and in five RCCs (12%) (p = 0.05). The combination of complete enhancement and SI index lower than 2% (p = 0.02) or tumor-to-spleen ratio higher than -6% (p = 0.001) provided sensitivity of 36% and 55%, specificity of 95% and 97%, positive predictive value of 67% and 86%, and negative predictive value of 84% and 88%, respectively, for diagnosis of oncocytomas.
  
  
  CONCLUSIONS
  Absence of central area SI inversion or presence of a signal drop on chemical-shift imaging may rule out the diagnosis of oncocytoma.
authors.affiliation: Department of Radiology, Pellegrin Hospital, Pl Amélie Raba Léon, 33076 Bordeaux, France. francoiscornelis@hotmail.com
authors.forename: François
authors.initials: F
authors.lastname: Cornelis
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Lasserre
authors.forename: Thomas
authors.initials: T
authors.lastname: Tourdias
authors.forename: Colette
authors.initials: C
authors.lastname: Deminière
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Ferrière
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Bras
authors.forename: Nicolas
authors.initials: N
authors.lastname: Grenier
mesh_terms: D018249:Adenoma, Oxyphilic / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000175:diagnosis*; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis*; D007889:Leiomyoma / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media