MRI-compatible needle guidance toolkit to streamline arthrography procedures: phantom accuracy study

In this paper we introduce a novel and enabling MRI-compatible needle guidance toolkit intended to streamline arthrography procedures, eliminating the need for ionizing radiation exposure during this diagnostic procedure. We developed a flexible 2D grid template with unique patterns in which each point on the grid can be uniquely represented and denoted with respect to surrounding patterns. This MRI-visible non-repeating grid template sits on top of the patient’s skin in the region of interest and allows the radiologist to visualize the skin surface in the MR images and correlates each point in MR image with the corresponding point on the grid. In this manner, the radiologist can intuitively find the entry point on the skin according to their plan. An MRI-compatible handheld positioning device consisting of a needle guide, two baseline bubble inclinometers, and an MRI-compatible stabilizer arm allows the radiologist to adjust the orientation of the needle in two directions. The radiologist selects an entry point on MR images, identifies a grid location through which the needle would be projected to pass on the image, and then reproduces this needle position and angulation using the MRI-compatible handheld device and the physical grid. To evaluate the accuracy of needle targeting with the MRI-compatible needle guidance toolkit, we used the kit to target 10 locations in a phantom in a Philips Achieva 1.5T MRI. The average targeting error was 2.2±0.7 mm. Average targeting procedure time was around 20 minutes for each target.