MR-safe robotic needle driver for real-time MRI-guided minimally invasive procedures: a feasibility study

This article reports on the development and feasibility testing of an MR-safe robotic needle driver. The needle driver is pneumatically actuated and designed for automatic insertion and extraction of needles along a straight trajectory within the MRI scanner.

All parts use plastic resins and composite materials to ensure MR-safe operation. A needle could be clamped in the needle carriage using a pneumatically operated clamp. The clamp is designed to be easily attached and detached from the needle driver. Clamps with different opening sizes could accommodate a range of needles from 18 to 22 gauge. To mimic the manual procedure of needle insertion, a pneumatically operated rack-and-pinion mechanism simultaneously translates and rotates the needle carriage along a helical slot. Signal-to-noise ratio (SNR) and 2-D geometric distortion were measured to evaluate the MRI compatibility. Targeting was measured with an electromagnetic tracker. We also evaluated the maximum force that could be generated at the tip of the needle with different clamping pressures using a force sensor.

We recorded the maximum percentage change in SNR for multiple configurations of needle drivers as 6.6% and the maximum geometric distortion at 0.24%. The needle driver's mean positioning accuracy for 105 targets at 50 mm depth was 2.38 ± 1.00 mm in a composite tissue phantom. The angulation error for the straight trajectory was 0.51°, and the mean linear trajectory deviation was statistically negligible. The measured force at the needle tip was 1.17N, 1.6N, and 2.12N at 30, 40, and 50 psi, respectively.

This preliminary study showed that the prototype of our robotic needle driver works as intended for the insertion and extraction of the needle. The driver is MR-safe and serves as a suitable platform for MRI-guided interventions.