title: Comparison of biexponential and monoexponential DWI in evaluation of Fuhrman grading of clear cell renal cell carcinoma.
abstract: OBJECTIVE
  Clear cell renal cell carcinoma (ccRCC) is the most common primary malignant urologic tumor. The Fuhrman grading system is an independent indicator for aggressiveness and prognosis of ccRCC. We aimed to assess the possible diagnostic role of biexponentially and monoexponentially fitted signal attenuation for the Fuhrman grading.
  
  
  METHODS
  A total of 33 patients with ccRCC underwent multiple b values (0, 20, 50, 100, 150, 250, 400, 600, 800, 1000 s/mm2) diffusion-weighted imaging (DWI). Biexponential parameters (fast ADC [ADCf], slow ADC [ADCs], and fraction of ADCf [f]) and monoexponential apparent diffusion coefficient were calculated, and correlated with the Fuhrman grade of ccRCC respectively. The performance of biexponential parameters in differentiating Fuhrman low- and high-grade tumors was assessed and compared with ADC value by receiver operating characteristic analysis.
  
  
  RESULTS
  Qualified images and diffusion-weighted parameters were obtained for all patients. The ADCf and f value were positively correlated, whereas ADCs and ADC value were negatively correlated with Fuhrman grade. Significant differences were observed in ADCf (P < 0.001), ADCs (P = 0.005), and f values (P < 0.001) of high- and low-grade ccRCCs. When differentiating Fuhrman low-grade tumors from high-grade, the ADCf revealed an area under receiver operating characteristic curve of 0.959, which was higher than the ADC value (0.789; P = 0.046), while ADCs (0.807) and f (0.833) showed no significant difference from ADC (P = 0.85 for ADCs, P = 0.73 for f).
  
  
  CONCLUSIONS
  Biexponential DWI provides additional parameters for ccRCC. ADCf is more accurate compared with the ADC value in characterizing Fuhrman grade of ccRCC.
authors.affiliation: Department of Radiology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China. 25278721@qq.com.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Shen
authors.forename: Liangping
authors.initials: L
authors.lastname: Zhou
authors.forename: Xiaohang
authors.initials: X
authors.lastname: Liu
authors.forename: Xiaoqun
authors.initials: X
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011379:Prognosis; D012372:ROC Curve; D012680:Sensitivity and Specificity