[MRI-guided percutaneous nephrostomy of the contrast-enhanced, nondilated upper urinary tract: initial experimental results]. / MR-tomographisch gesteuerte perkutane Nephrostomie des kontrastangehobenen, nicht dilatierten oberen Harntraktes: Erste experimentelle Ergebnisse.

PURPOSE: To evaluate technique and practicability of MR-guided percutaneous nephrostomy (MRPCN) in an animal model. METHODS: In three domestic pigs, a unilateral percutaneous nephrostomy tube was placed into the nondilated collecting system using exclusively MR-guidance with a standard 1.5 T scanner. The urinary tract was visualized by intravenous injection of Gd-DTPA and low-dose furosemide. The entire interventional procedure was controlled using a T1-weighted "dual stack" 2 D TFE sequence in two orthogonal planes. RESULTS: In all three animals, the puncture needle was safely directed into the nondilated target calyx. Even slight deviations of the needle from the optimal path were readily detected on both MR image planes which enabled immediate correction. This technique successfully achieved a "first attempt" puncture of the targeted calyx in each animal. Over a nitinol guidewire a 5 F catheter was placed into the renal pelvis. Its dysprosium labelled tip was accurately delineated on contrast-enhanced MR images. CONCLUSIONS: Percutaneous nephrostomy under MR guidance is a very feasible technique for puncturing the nondilated pelvicalyceal system. This procedure offers some advantages over the current standard modalities.