[Urography with magnetic resonance: a new method for the study of the renal collecting system in patients without...

A new MR technique is proposed to study the renal collecting system and the proximal ureteral portion in patients without obstructive uropathy, using fat-suppressed Turbo Spin Echo sequences, after drug-induced distension of the urinary tract. Nine normal volunteers and 16 patients (11 with renal stones, 1 with bilateral pyeloureteral junction stenosis, 1 with renal ptosis, 1 with ureteral hyperkinesia, 1 with renal tumor and 1 with a symptomatic renal cyst) were submitted to MR-Urography, performed with a 3D non-breath-hold fat-suppressed Turbo SE sequence (TR = 3000 ms, TE = 800 ms, 6 acquisitions, Turbo Factor = 128, Matrix = 128 x 256 or 256 x 256, acquisition time = 5 min 15 sec or 10 min 36 sec) on the coronal plane. With these acquisition parameters, parenchymal signal can be completely suppressed while enhancing fluid signal. These acquisitions were post-processed with the MIP algorithm to obtain very similar images to those of conventional urography. The maximum filling of the renal collecting system was obtained with the i.v. administration of 250 ml saline solution within 2-3 minutes and then the i.v. injection of 20 mg furosemide. The renal collecting system was optimally depicted in all the volunteers and the patients, except for 2 cases because of malfunctioning respiratory gating. Anatomical detailing was really improved after the diuretic administration, especially in the study of the major caliceal systems. To conclude, MR-Urography permits accurate morphological detailing of the renal collecting system also in patients without obstructive uropathy.