Correlation Of Tumor Aggressiveness With Enhancement Features On CT In Clear Cell Renal Cell Carcinoma

OBJECTIVE. The purpose of this study was to develop a method of measuring enhancement of renal cell carcinoma on contrast-enhanced CT and to assess the relation between tumor enhancement and Fuhrman grade in clear cell renal cell carcinoma.MATERIALS AND METHODS. A single-institution retrospective review was conducted on the clinical, radiological and pathological records of 255 patients who underwent radical or partial nephrectomy and received a histologic diagnosis of clear cell renal cell carcinoma. Various radiological features and parameters were measured and recorded from contrast-enhanced CT images, including tumor diameter, tumor enhancement patterns, presence of intratumoral calcification, cystic or solid appearance of the lesion, tumor margin regularity, etc. A method of measuring tumor enhancement was developed. Four parameters representing tumor enhancement(TEV1, REV1, TEV2, REV2) were defined to study the association between tumor enhancement and Fuhrman grade and their ability to predict Fuhrman grade. Various clinical and radiological variables were included in a multivariate analysis to find independent predictive factors of high Fuhrman grade. 45 patients were prospectively accrued to validate the aforementioned conclusion.RESULTS. The median age of the 255 clear cell renal cell carcinoma patients were 59 years. 196(76.9%) were male and 59(23.1%) were female. The Fuhrman grade was 1, 2, 3 and 4 in 24(9.4%), 188(73.7%), 40(15.7%) and 3(1.2%) patients. All the four enhancement parameters were significantly different among different Fuhrman grades(p<0.001). The higher the Fuhrman grade, the lower the enhancement parameters. TEV1, REV1, TEV2 and REV2 were lower in high Fuhrman grade(Fuhrman 3-4) clear cell renal cell carcinoma than in low Fuhrman grade(Fuhrman 1-2) tumors(p<0.001). When the enhancement parameters were used to predict high Fuhrman grade, the area under curve on the ROC curve for TEV1, REV1, TEV2 and REV2 were 0.882, 0.926, 0.847 and 0.871, respectively. When 0.65 was used as the cutoff value, REV1 had a sensitivity and specificity of 0.84 and 0.93 in predicting high Fuhrman grade. REV1 as well as other clinical and radiological variables were included in a multivariate analysis as potential predictive factors of high Fuhrman grade. The logistic regression showed that advanced age, irregular margin of the lesion and low REV1 value were independent predictive factors of high Fuhrman grade. In the validation cohort, the criteria of REV1≤0.65 had a sensitivity and specificity of 0.84 and 0.87 in predicting high Fuhrman grade.CONCLUSION. Tumor enhancement of clear cell renal cell carcinoma on multiphase contrast-enhanced CT images is negatively associated with Fuhrman grade. Advanced age, irregular margin of the lesion and low enhancement were independently predictive of high Fuhrman grade. This method of evaluation would be helpful in the assessment of tumor aggressiveness and could provide useful information in clinical decisionmaking.