title: Real-time elastography for distinguishing angiomyolipoma from renal cell carcinoma: preliminary observations.
abstract: OBJECTIVE
  The objective of this study was to determine the diagnostic performance of sonoelastography for differentiating angiomyolipomas from renal cell carcinomas.
  
  
  METHODS
  Twenty-eight angiomyolipomas and 19 renal cell carcinomas were prospectively examined with real-time elastography. Lesions were classified according to four elastographic patterns on the basis of the distribution of the blue area (representing no strain and hardest tissue component). The elasticity patterns and the strain ratios of the angiomyolipomas and renal cell carcinomas were evaluated independently by two observers. Diagnostic performance and interobserver agreement were analyzed.
  
  
  RESULTS
  All angiomyolipomas were classified as having a high-strain elastographic pattern (blue areas in < 50% of lesion, considered type 1 or type 2) by both radiologists, whereas 18 of 19 renal cell carcinomas were classified as having a low-strain elastographic pattern (blue areas in ≥ 50% of lesion, considered type 3 or 4) by both radiologists. The respective mean strain ratios measured by two radiologists were 0.15 ± 0.06 and 0.18 ± 0.09 for the angiomyolipomas and 0.64 ± 0.15 and 0.63 ± 0.19 for the renal cell carcinomas. There were significant differences between the elasticity patterns and strain ratios for angiomyolipomas and renal cell carcinomas (p < 0.001). Interobserver agreement was excellent for elasticity patterns and strain ratios, with a weighted kappa coefficient of 0.96 and an intraclass correlation coefficient score of 0.95.
  
  
  CONCLUSIONS
  Our results show that real-time elastography may be useful in differentiating angiomyolipomas from renal cell carcinomas, by use of both elasticity patterns and strain ratios.
authors.affiliation: Department of Radiology, Ankara Atatürk Education and Research Hospital, 06800 Eskişehir Yolu 8.km No: 3 Bilkent, Ankara, Turkey. drsinantan@gmail.com
authors.forename: Sinan
authors.initials: S
authors.lastname: Tan
authors.forename: Muhammed Fuat
authors.initials: MF
authors.lastname: Özcan
authors.forename: Fatih
authors.initials: F
authors.lastname: Tezcan
authors.forename: Serdar
authors.initials: S
authors.lastname: Balci
authors.forename: Mustafa
authors.initials: M
authors.lastname: Karaoğlanoğlu
authors.forename: Bülent
authors.initials: B
authors.lastname: Huddam
authors.forename: Halil
authors.initials: H
authors.lastname: Arslan
mesh_terms: D000328:Adult; D000368:Aged; D018207:Angiomyolipoma / Q000000981:diagnostic imaging*; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D054459:Elasticity Imaging Techniques; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity