MR imaging evaluation of renal cell carcinoma

Background: This study examines the minimally required imaging protocol needed for detection and staging of renal cell carcinoma (RCC). Methods: In 81 patients (21 women, 60 men; mean age = 62 years) with 85 RCCs, T1-weighted (T1WI), contrast-enhanced T1-weighted (Gd-T1WI), T2-weighted (T2WI), and gradient recalled echo–fast low flip angle shot (GRE/FLASH) images were evaluated alone and in combination. Surgical–pathological findings were available in all patients and were considered the standard of reference. Results: Tumor detection for lesions smaller than 3 cm was better on Gd-T1WI than on any other sequence, but only the comparison with noncontrast T1WI and GRE/FLASH was statistically significant (detection: T1WI = 33%, Gd-TIWI = 80%, T2WI = 60%, GRE = 47%). The respective accuracies of T1WI, Gd-T1WI, T2WI, and GRE/FLASH images were 81%, 78%, 71%, and 62% for evaluating local tumor extension; 90%, 88%, 89%, and 85% for lymphadenopathy; and 89%, 81%, 91%, and 95% for renal vein thrombus. The combination of T1WI and GRE sequences rendered the highest overall staging accuracy. Conclusion: For tumor detection, contrast-enhanced T1WI is necessary for lesions smaller than 3 cm. For tumor staging, although the addition of GRE results in significant improvement in the evaluation of venous thrombus, any combination of two sequences will result in similar accuracy, and the use of multiple sequences is not necessary.