Perfusion CT of Renal Tumors: Usefulness in the Characterization of Tumor Type and Grade

PURPOSE: To correlate preoperative CT perfusion data with histological vascularization features of different renal lesions including clear cell renal cell carcinoma(RCC), chromofobe RCC, angiomyolipoma, oncocytoma and cystic lesions.METHOD AND MATERIALS: patients (15 M, 6 F; mean age 61 yrs) were prospectively enrolled and underwent a 120-ss perfusion 64-row MDCT examination afterinjection of 60cc of a 370 mgI/ml solution at 5 cc/s. The diagnosis at pathology of the resected or biopsy specimen was obtained in 20 cases: 12 clear cell RCC (7G1-G2 and 5 G3-G4), 3 chromofobe RCC, 3 oncocytoma, 1 angiomyolipoma, 1 cystic lesion. One patient was put on follow up because of the presumptive benignnature of his cystic lesion, unchanged at 18 months follow-up. Perfusion, peak enhancement integral (PEI), time to peak (TTP) and blood volume (BV) of focallesions and normal renal cortex and medullary were measured. The perfusion parameters between RCC, cortex and medullary were compared using ANOVA test;unpaired t-test was used to compare perfusion parameters between the different renal lesions examined, paired t-test was used to compare perfusion parametersin the two kidneys. Statistical significance was assigned at the 5% level.RESULTS: Significant difference was found for all perfusion parameters except PEI comparing normal renal cortex, medullary and renal carcinoma (clear cell andchromofobe RCC). A significant difference was observed in perfusion and BV between oncocytoma and RCC (97.96 vs 157.50mLx100g/min, p=0.0447; 74.61 vs46.44mL/100 g, p=0.0045). A very significant difference was observed between RCCs of different grade (G1-G2 vs G3-G4) in perfusion and TTP for all carcinomas(116.74 vs 218.64mLx100g/min, p<0.0001, 23.27 vs 12.46s, p=0.0377) and in perfusion and BV for clear cell RCC (129.65 vs 201.75mLx100g/min, p=0.0027;37.23 vs 55.86mL/100g, p=0.0092).CONCLUSION: From our experience, CT perfusion can have a role in the characterization of renal masses and in the discrimination between different grades ofRCC, with the goal of optimizing patient treatment and evaluating the effects of chemotherapy, anti-angiogenic therapy or local treatments.CLINICAL RELEVANCE/APPLICATION: CT perfusion might aid in the characterization of renal masses, and noninvasively differentiate between different grades ofRCC, with the goal of optimizing patient treatment.