Magnetic resonance urography: Proposal for a new method for the morphological evaluation of the renal collecting system and preliminary clinical experience

In this study we propose a new imaging modality for the evaluation with MRI of the renal collecting system in patients without obstructive uropathy, using fat-suppressed Turbo Spin-Echo sequences, after drug-induced distention of the pyelo-calyceal system. With these sequences, it is possible to obtain the complete cancellation of the parenchymal signal and to enhance the fluid signal. These acquisitions were post-processed with the MIP algorithm in order to obtain images very similar to intravenous urography. The maximum filling of the renal collecting system was obtained with 250 ml i.v. administration of saline solution within 2-3 minutes and afterwards the injection of a diuretic. 9 normal volunteers and 16 patients with renal pathologies underwent MRI-Urography. We obtained an excellent evaluation of the renal collecting system; the anatomical definition was greatly improved after the administration of the diuretic, especially in the evaluation of the calyceal systems. MRI-Urography allows a morphological study of renal collecting system also in patients with non-obstructed urinary tract.