title: Qualitative and quantitative MDCT features for differentiating clear cell renal cell carcinoma from other solid renal cortical masses.
abstract: OBJECTIVE
  The purpose of this study was to differentiate clear cell renal cell carcinoma (RCC) from other solid renal masses on four-phase MDCT.
  
  
  METHODS
  Our study cohort included all pathologically proven solid renal masses that underwent pretreatment four-phase MDCT at our institution from 2001 to 2012. Both retrospective qualitative analysis (blinded dual-radiologist evaluation of morphologic features: enhancement pattern, lesion contour, neovascularity, and calcification) and quantitative analysis (mean absolute and relative attenuation and changes in attenuation across phases) were performed. ANOVA with post-hoc analysis, Pearson chi-square tests, and ROC analysis were used.
  
  
  RESULTS
  One hundred fifty-six consecutive patients (99 men, 57 women) with a mean age of 62.7 years (range, 26-91 years) had 165 solid renal masses (median size, 3.0 cm): 86 clear cell RCCs, 36 papillary RCCs, 10 chromophobe RCCs, 23 oncocytomas, and 10 lipid-poor angiomyolipomas. Kappa for interradiologist agreement regarding morphologic features was 0.33-0.76. There were significant associations between histologic subtype and enhancement pattern (p < 0.001), lesion contour (p < 0.014), and neovascularity (p < 0.001). Clear cell RCC had the highest mean relative corticomedullary attenuation (p < 0.02). Clear cell RCC had greater deenhancement than oncocytoma (p < 0.001); deenhancement less than 50 HU or relative corticomedullary attenuation greater than 0% differentiated clear cell RCC from oncocytoma with a positive predictive value of 90%. Lipid-poor angiomyolipoma had the highest mean absolute unenhanced attenuation (p < 0.01); absolute unenhanced attenuation greater than 45 HU and relative corticomedullary attenuation less than 10% differentiated lipid-poor angiomyolipoma from clear cell RCC with a negative predictive value of 97%.
  
  
  CONCLUSIONS
  Four-phase MDCT renal attenuation profiles enable differentiation of clear cell RCC from other solid renal cortical masses, most notably papillary RCC and lipid-poor angiomyolipoma.
authors.affiliation: 1 Department of Radiological Sciences, David Geffen School of Medicine at UCLA, Ronald Reagan UCLA Medical Center, 757 Westwood Plaza, Ste 1638, Los Angeles, CA 90095.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Lee-Felker
authors.forename: Ely R
authors.initials: ER
authors.lastname: Felker
authors.forename: Nelly
authors.initials: N
authors.lastname: Tan
authors.forename: Daniel J A
authors.initials: DJ
authors.lastname: Margolis
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Young
authors.forename: James
authors.initials: J
authors.lastname: Sayre
authors.forename: Steven S
authors.initials: SS
authors.lastname: Raman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: clear cell renal cell carcinoma; lipid-poor angiomyolipoma; multiphasic MDCT; oncocytoma; papillary renal cell carcinoma