Imaging of tumor extension of renal cell carcinomas by magnetic resonance tomography. Improvement of tumor-tissue contrast by means of Gd-DTPA-enhanced spin-echo-sequences and concomitant fat suppression

Purpose: To evaluate the use of contrast-enhanced T1-weighted images with fat suppression (T1 FS) to improve the contrast-to-noise ratio of renal cancer and renal parenchyma as well as perirenal fat. Methods: 25 patients with histologically proven unilateral renal cancer after nephrectomy were examined before surgery. In addition to plane and contrast-enhanced T1-weighted as well as T2-weighted spin-echo images, all patients had T1 FS immediately after administration of Gd-DTPA in two planes. The contrast-to-noise ratio was calculated using circular regions-of-interest which outlined the tumor, the renal parenchyma, pyelon, and the perirenal fat. Results: T1 FS significantly improved the contrast-to-noise ratio of renal cancer and renal parenchyma compared to all conventional spinecho sequences (p<0.001; Wilcoxon-Test). Compared to contrast-enhanced T1-weighted images without fat-suppression T1 FS yielded a higher CNR of the tumor, the perirenal fat and the pyelon. Another advantage was the absence of the chemical-shift artifact which is mostly pronounced in T2-weighted images and a reduced number of observed artifacts due to breathing. Conclusion: T1 FS should replace conventional contrast-enhanced T1-weighted spin-echo images in the work-up of renal cancer using MRI. (orig.)