Role of Gadolinium-DTPA in the assessment of renal tumors with magnetic resonance

To investigate the role of Gd-DTPA in the MR study of renal cancers, 30 patients affected with primary (28) or recurrent (2) renal cancers were submitted to high-field MRI (1.5 T). T1- and T2-weighted and Gd-DTPA-enhanced T1-weighted sequences were always acquired. Based on qualitative and quantitative criteria (calculation of the signal-to-noise ratio in the tumor mass and of the signal-difference-to-noise ratio between tumor and renal parenchyma), Gd-DTPA influence was studied on the following variables: signal intensity and tumor demonstration, detectability of morphostructural features of tumor tissue and staging accuracy. As for the latter variable, MR results were compared with the results of anatomical and surgical staging (28 cases). Relative to unenhanced T1- and T2-weighted sequences, on Gd-DTPA-enhanced sequences 80% of the lesions were markedly hypointense relative to renal parenchyma and they were better demonstrated in 93% of cases. The S/N and the SD/N ratios were higher on Gd-DTPA-enhanced than on unenhanced images. After Gd-DTPA administration, the intratumoral necrotic areas, the walls and the septations of the cystic masses and the boundaries between tumors and renal parenchyma were better demonstrated. Staging accuracy was the same (90%) on both Gd-DTPA-enhanced T1-weighted and unenhanced images. Therefore, Gd-DTPA, although failing to increase staging accuracy, improves tumor depiction and demonstrates the morphostructural features of the mass. Since Gd-DTPA caused no side-effects, Gd-DTPA-enhanced T1-weighted sequences can replace T2-weighted sequences, whose acquisition time is definitely longer.