Login to Access Video or Poster Abstract: MP52-13
Sources of Funding: This research was supported by the Intramural Research Program of the National Cancer Institute, NIH

Introduction

The aim of the study is to test the feasibility of a low cost, patient-specific template that allows for angulated insertion of needles during transperineal MR-guided biopsy and treatment for prostate cancer. Currently, transperineal MR-guided biopsy can be performed with a standard straight grid, or with a robotic device. The straight grid does not incorporate information on patient-specific anatomy or disease, and renders it difficult to avoid structures such as the pubic arch. Robotic devices are not currently in widespread use due to regulatory issues, and can be prohibitively expensive. We propose a two-plate template in which guide holes drilled mid-procedure, using an MR image registered with 3D imaging software, allow for accurate direction of biopsy needles to specific tumor locations.

Methods

The two-plate template was attached to a platform in a fixed position relative to a prostate phantom. A 3T MR image of the template (with gadolinium fiducials) and the phantom was obtained, and the template and phantom were registered to MRI coordinates. The MR images were uploaded onto a custom-made module in 3D slicer. Four fiducials were localized in the image and registered to their physical locations on the template, allowing the user to plan needle trajectories and calculate insertion depths to the targets. These trajectories can be manually translocated as necessary in order to minimize contact with other trajectories and nearby structures. The disposable plates were placed into a portable milling machine, which then drilled the corresponding guide holes according to the plan. The plates were replaced into the template frame, and biopsy needles were inserted into the phantom at the angle constrained by the guide holes. The phantom, template, and needles were imaged via CT scan for confirmation of placement accuracy.

Results

Three MRI-visible targets were identified in the image. Mean and standard deviation of error was 2.83mm ±1.42 for user 1 and 4.70mm ±3.66 for user 2.

Conclusions

It is feasible to use a patient-specific template for low-cost, angulated transperineal MR-guided prostate biopsy. The method has potential applications not only in prostate biopsy, but also in other forms of targeted therapy. Future studies will consider further tests of accuracy, efficiency, convenience, and applicability.

Funding

This research was supported by the Intramural Research Program of the National Cancer Institute, NIH