MR-guided percutaneous nephrostomy of the nondilated upper urinary tract in a porcine model

OBJECTIVE: The purpose of this study was to assess the safety and feasibility of MR-guided percutaneous nephrostomy of the nondilated contrast-enhanced upper urinary tract in a porcine model. SUBJECTS AND METHODS: Six MR-guided percutaneous nephrostomies of the nondilated upper urinary tract were performed in four domestic farm pigs (body weight range, 20-25 kg) using a 0.2-T system. Ten minutes after IV administration of 0.2 mmol/kg of gadodiamide and 0.4 mg/kg of furosemide, a fast T1-weighted sequence was used to guide insertion of an 18-gauge MR-compatible needle into a predetermined calix. After confirmation of needle position using a turbo spin-echo T1-weighted sequence, a 0.035-inch catheter coated with superparamagnetic iron oxide was inserted during MR monitoring. Insertion was followed by tract dilatation and insertion of a 4-French sheath. The final position of the sheath was confirmed by injection of diluted superparamagnetic iron oxide into the collecting system. RESULTS: Needle insertion was successful for all six procedures, with no complications. Instrumentation time ranged from 4 to 13 min (mean, 6+/-4 min). Sheath placement was successful in five of six kidneys. Placement time ranged from 6 to 28 min (mean, 16+/-9 min). CONCLUSION: MR-guided percutaneous nephrostomy of the nondilated contrast-enhanced upper urinary tract in a porcine model is feasible and safe.