title: Comparison of Utility of Histogram Apparent Diffusion Coefficient and R2* for Differentiation of Low-Grade From High-Grade Clear Cell Renal Cell Carcinoma.
abstract: OBJECTIVE
  The purpose of this study was to compare histogram analysis of apparent diffusion coefficient (ADC) and R2* for differentiating low-grade from high-grade clear cell renal cell carcinoma (RCC).
  
  
  METHODS
  Forty-six patients with pathologically confirmed clear cell RCC underwent preoperative BOLD and DWI MRI of the kidneys. ADCs based on the entire tumor volume were calculated with b value combinations of 0 and 800 s/mm(2). ROI-based R2* was calculated with eight TE combinations of 6.7-22.8 milliseconds. Histogram analysis of tumor ADCs and R2* values was performed to obtain mean; median; width; and fifth, 10th, 90th, and 95th percentiles and histogram inhomogeneity, kurtosis, and skewness for all lesions.
  
  
  RESULTS
  Thirty-three low-grade and 13 high-grade clear cell RCCs were found at pathologic examination. The TNM classification and tumor volume of clear cell RCC significantly correlated with histogram ADC and R2* (ρ = -0.317 to 0.506; p < 0.05). High-grade clear cell RCC had significantly lower mean, median, and 10th percentile ADCs but higher inhomogeneity and median R2* than low-grade clear cell RCC (all p < 0.05). Compared with other histogram ADC and R2* indexes, 10th percentile ADC had the highest accuracy (91.3%) in discriminating low- from high-grade clear cell RCC. R2* in discriminating hemorrhage was achieved with a threshold of 68.95 Hz. At this threshold, high-grade clear cell RCC had a significantly higher prevalence of intratumor hemorrhage (high-grade, 76.9%; low-grade, 45.4%; p < 0.05) and larger hemorrhagic area than low-grade clear cell RCC (high-grade, 34.9% ± 31.6%; low-grade, 8.9 ± 16.8%; p < 0.05).
  
  
  CONCLUSIONS
  A close relation was found between MRI indexes and pathologic findings. Histogram analysis of ADC and R2* allows differentiation of low- from high-grade clear cell RCC with high accuracy.
authors.affiliation: 1 Department of Radiology, First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Rd, Nanjing, China, 210000.
authors.forename: Yu-Dong
authors.initials: YD
authors.lastname: Zhang
authors.affiliation: 1 Department of Radiology, First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Rd, Nanjing, China, 210000.
authors.forename: Chen-Jiang
authors.initials: CJ
authors.lastname: Wu
authors.affiliation: 1 Department of Radiology, First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Rd, Nanjing, China, 210000.
authors.forename: Qing
authors.initials: Q
authors.lastname: Wang
authors.affiliation: 1 Department of Radiology, First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Rd, Nanjing, China, 210000.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: 1 Department of Radiology, First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Rd, Nanjing, China, 210000.
authors.forename: Xiao-Ning
authors.initials: XN
authors.lastname: Wang
authors.affiliation: 1 Department of Radiology, First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Rd, Nanjing, China, 210000.
authors.forename: Xi-Sheng
authors.initials: XS
authors.lastname: Liu
authors.affiliation: 1 Department of Radiology, First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Rd, Nanjing, China, 210000.
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Shi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000473:pathology; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D012189:Retrospective Studies; D047368:Tumor Burden
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: DWI; MRI; blood oxygen level dependent (BOLD); clear cell renal cell carcinoma