Comparison of manual and computer assisted ultrasonic guidance for transparenchymal percutaneous renal needle placement

Abstract

Purpose: We evaluated a novel computer based guidance system for deploying needles into the renal parenchyma. We compared it to current standards, including a fixed needle guide and a freehand technique.

Materials and methods: We performed an in vitro comparison followed by a porcine trial. The in vitro model consisted of a bath of ultrasound medium with suspended metallic targets. We compared the number of attempts and the time needed by the novel guide design with and without its software and a support arm vs the freehand approach. In the porcine model we tested the software guide with and without a support arm for targeting a 5 mm lesion embedded in the renal parenchyma. Impressions of difficulty, time, the number of attempts, needle tip visualization and needle tip divergence were documented.

Results: Compared to freehand targeting the software guide and support arm decreased the number of targeting attempts in the in vitro model from 4.8 to 1.6 (p <0.001) and decreased the time required from 31.8 to 11.4 seconds (p <0.001). In the porcine study needle tip visualization with the software and support arm received an average score of 1.3 vs 1.8 with the software guide alone (p = 0.04). Tip divergence received a score of 1.4 with the arm and 1.8 without it (p = 0.07). Overall contribution received a score of 1.4 with and without the support arm (p = 0.35).

Conclusions: Computer assisted needle deployment decreased the time and number of attempts required to successfully target simulated parenchymal lesions and also decreased the subjective difficulty inherent in the standard freehand approach.