Review of Clinical and Technological Consideration for MRI-Guided Robotic Prostate Brachytherapy

Abstract

Low Dose Rate Brachytherapy (LDR-BT) is a technique for treating localized prostate cancer by implanting radioactive seeds. In conventional practice, the delivery of seeds is performed using transrectal ultrasonography (TRUS) imaging for implant guidance and checked using computed-tomography for post-implant dosimetry. In the case of TRUS, accuracy can be compromised due to sub-optimal imaging. Magnetic Resonance Imaging (MRI), however, is known to provide better soft-tissue contrast, therefore, increasing the ability to detect small lesions; for that reason, the integration of intraoperative MRI in BT workflows has been investigated over the last two decades. The fusion of preoperative MR-images during TRUS-brachytherapy is possible. However, the image registration process introduces a source of uncertainty. Manual, real-time intra-operative LDR-BT is challenging under MRI due to confined space and procedural workflows. This motivates the development of MRI-compatible robots for prostate BT, with potential advantages of improved source placement accuracy and final dosimetry. In this paper, the state-of-art of technological components in MRI compatible robots, especially for LDR-BT, has been presented. This systematic review helps us to position an ongoing Cooperative Brachytherapy project, developing a real-time MRI-guided robot for adaptive LDR-BT. The design approach includes integrating separate modules: imaging, dose planning, needles, and robot.

Cooperative Brachytherapy Robotic Concept for Localized Cancer Treatment Under Real-Time MRI

“…A detailed survey on MRI robots for prostate intervention can be found in [3], [4], and [5]. DiMaio et al [6] demonstrated the first robotized concept for prostate intervention under MRI, proving the clinical efficacy of MRI.…”

“…In addition, real-time intraoperative intervention can also get the benefit of a reduction in edema due to the multi-insertion through the perineum as it will reduce the insertion and re-insertion of needles for needle tip-verification, and reduce the overall procedure time. At present, most of the robotized systems are limited to needle positioning with manual needle intervention in an MRIenvironment [5]. Limited number of developments actually tested for clinical studies, e.g., [21], [22] (as needle placement for manual biopsy).…”

“…Limited number of developments actually tested for clinical studies, e.g., [21], [22] (as needle placement for manual biopsy). These developments still left researchers with the motivation to automate solutions for in-bore intraoperative localized treatment or diagnosis [5]. Due to clinical restrictions and ethical issues, it is mandatory to keep the physician in the loop.…”

“…The robots developed particularly for prostate brachytherapy, compatible with the MRI environment and with possible extension towards clinical testing, are summarized in Table I, and a detailed classification can be found in [5]. In this paper, the authors present a concept for adaptive robotized LDR-BT under real-time MRI [24], [25].…”

“…Also, the paper proposes a technological solution for autonomous and teleoperated adaptive BT under MRI intra-operatively. To perform the preliminary tests of adaptive-BT, a bio-inspired active prostate phantom (BIP) has been developed [26], emulating the prostate's motions and deformations 5 .…”