The relation between apparent diffusion coefficient and clinical stage of clear-cell renal cell carcinoma.

PURPOSE: The utility of the apparent diffusion coefficient (ADC) in patients with clear-cell renal cell carcinoma (RCC) for distinguishing between the four clinical stages was assessed. METHODS: Forty-nine patients with pathologically proven RCCs (I, II, III, IV; 27, 5, 10, 7) were included. The ADC was compared between each stage. RESULTS: The difference of ADC between stage I and the more advanced stages (III and IV) was statistically significant. CONCLUSIONS: When ADC in primary tumor site of clear-cell RCC would be higher than the cutoff level, the stage might not be an advanced stage (III or IV).

Comparison of utility of tumor size and apparent diffusion coefficient for differentiation of low- and high-grade clear-cell renal cell carcinoma.

BACKGROUND: There is a significant correlation between tumor size and tumor grade for clear-cell renal cell carcinoma (RCC) in pathology. Thus, apparent diffusion coefficient (ADC) of clear-cell RCC might be influenced by tumor size. PURPOSE: To compare the utility of tumor size and ADC for distinguishing low-grade from high-grade clear-cell RCC. MATERIAL AND METHODS: Forty-nine patients undergoing preoperative magnetic resonance imaging were retrospectively assessed. ADC values were calculated using b-value combinations of 0 and 800 s/mm(2) at 1.5 T. Two radiologists in consensus measured ADC values via small region of interest (ROI) (mean ROI area, 88.8 mm(2); range, 80-108 mm(2)) placement on an area of solid tumor on a single slice. Maximum tumor diameter was measured at the maximum tumor area. A single pathologist reviewed all pathological slides to determine the nuclear grade according to the Fuhrman classification. The utility of ADC, tumor size, and ADC/size ratio for distinguishing low-grade from high-grade tumors was assessed. Receiver-operating characteristic (ROC) analysis and regression analysis of the each index were performed. The correlation between ADC and tumor size was also investigated. RESULTS: The 49 clear-cell RCC included 34 low-grade and 15 high-grade tumors. The differences of ADC, tumor size, and ADC/size ratio between high-grade and low-grade tumors were statistically significant (P <0.05). The area under the ROC curve of ADC, tumor size, and ADC/size ratio were 0.802, 0.763, and 0.804 respectively. However, using regression analysis, only ADC (P <0.05) was statistically significant index as independent risk factors for high-grade clear-cell RCC. Moreover, weak significant correlation was observed between tumor size and ADC (R(2) = 0.3865, P <0.01). CONCLUSION: There was a weak significant correlation between tumor size and ADC value of clear-cell RCC. Using ROC and regression analysis, ADC was statistically significant index for distinguishing low-grade from high-grade clear-cell RCC more than tumor size and ADC/size ratio.