Preclinical evaluation of an MRI-compatible pneumatic robot for angulated needle placement in transperineal prostate interventions.

PURPOSE:

To evaluate the targeting accuracy of a small profile MRI-compatible pneumatic robot for needle placement that can angulate a needle insertion path into a large accessible target volume.

METHODS:

We extended our MRI-compatible pneumatic robot for needle placement to utilize its four degrees-of-freedom (4-DOF) mechanism with two parallel triangular structures and support transperineal prostate biopsies in a closed-bore magnetic resonance imaging (MRI) scanner. The robot is designed to guide a needle toward a lesion so that a radiologist can manually insert it in the bore. The robot is integrated with navigation software that allows an operator to plan angulated needle insertion by selecting a target and an entry point. The targeting error was evaluated while the angle between the needle insertion path and the static magnetic field was between -5.7° and 5.7° horizontally and between -5.7° and 4.3° vertically in the MRI scanner after sterilizing and draping the device.

RESULTS:

The robot positioned the needle for angulated insertion as specified on the navigation software with overall targeting error of 0.8 ± 0.5mm along the horizontal axis and 0.8 ± 0.8mm along the vertical axis. The two-dimensional root-mean-square targeting error on the axial slices as containing the targets was 1.4mm.

CONCLUSIONS:

Our preclinical evaluation demonstrated that the MRI-compatible pneumatic robot for needle placement with the capability to angulate the needle insertion path provides targeting accuracy feasible for clinical MRI-guided prostate interventions. The clinical feasibility has to be established in a clinical study.