MR Imaging-guided Percutaneous Nephrostomy and Use of MR-compatible Catheters in the Nondilated Porcine Urinary Tract

PURPOSE: To investigate technique and practicability of MR-guided percutaneous nephrostomy (MRPCN) and to test magnetic resonance (MB)-compatible catheters inside the urinary tract. MATERIALS AND METHODS: In 10 healthy pigs, a percutaneous nephrostomy tube was placed into the nonobstructed pelvicaliceal system with use of exclusive MR guidance with a standard 1.5-T magnet. The urinary tract was visualized by intravenous injection of Gd-DTPA in combination with low-dose furosemide, The procedure was controlled with use of a T1-weighted turbo gradient-echo sequence in two orthogonal planes. The equipment for MRPCN included an 18-gauge MR-compatible puncture needle, a nitinol guide wire, and different 5-F MR catheters. RESULTS: In all 10 animals, the puncture needle was safely directed into the nondilated target calix, Slight deviations of the needle were detected on both MR image planes, which enabled immediate! correction. This technique achieved a "first attempt" puncture of the targeted calix in each animal. MR images accurately demonstrated the dysprosium labelled tip of the different inserted catheters, It proved essential to inject a gadolinium-insaline solution via these catheters to preserve the endoluminal contrast enhancement as long as necessary. Balloon catheters were directed and inflated inside the ureter under exclusive MR guidance, Complications such as perforation and leakage were visualized by MR imaging. CONCLUSIONS: MRPCN is a promising technique for puncturing the pelvicaliceal system, The ability to successfully enter the urinary tract, even when it is nondilated, underscores the accuracy achievable with multiplanar MR imaging.