MRI-Guided Robotic Prostate Biopsy

Prostate cancer is one of the most common malignancies and the second leading cause of cancer death in men [1]. Approximately 52,300 new cases of prostate cancer are detected in the UK every year, that’s more than 140 every day. Magnetic resonance imaging (MRI) has been widely used in the diagnosis of prostate cancer, as it can offer high-resolution tissue imaging at arbitrary orientations and monitor therapeutic agents, surgical tools, and tissue properties. Therefore, a robot - under the guidance of MRI - can target the tumor regions with high accuracy to obtain the biopsy samples for diagnosis, thus reducing unnecessary gland punctures and maximizing the utility of a minimally invasive system. However, as MR scanners require a strong magnetic field, ferromagnetic materials are precluded as they can cause a hazard to the device and patients, and paramagnetic materials can generate their own magnetic field which will distort the image quality. As a result, MR-safe actuators are required to power the robot. Plus, due to the limited size of the MR bores, the robot operating inside should be as compact as possible [2]. In this paper, a robotic system for MRI-guided prostate biopsy is proposed. Comparing with the existing designs, it has a compact size, with the workspace covering the whole prostate. The use of pneumatically powered actuators can avoid the influence of electromagnetic interference. The working principle, mathematical model, and mechanism design are presented. The needle insertion experiment under an MR environment was conducted.