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International audience; 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.

International audience; Currently, localized cancer treatment is one of the focused research interests of Physicians. Indeed, with the advent of sensor and actuator technologies with the feasibility of integrating multiple systems, treatment and diagnosis have gained more interest in incorporating Magnetic Resonance Imaging (MRI) due to better soft-tissue contrast. In this paper, the authors report the development of the MR-based Cooperative Brachytherapy (CoBra) robot design for in-bore patient prostate intervention, in terms of diagnosis and treatment of localized cancers. The presented CoBra system is characterized by three main MR-compatible components: a suitable leg-support ensuring patient stabilization, a versatile robotized needle guide, and an automated implant driver to deposit precisely radioactive seeds. In fact, ergonomically in-bore needle placement is a challenging problem, whereas the CoBra robot aims to help in in-bore intra-operative intervention under closed-loop control based on imagery feedback. This feedback might be exploited judiciously for tracking online the biological target during changes after needle insertions. Within this framework, the paper discusses the CoBra robot with a focus on kinematics design, modeling, instrumentation, control, and MRI in-bore robot tests, with respect to the adopted clinical workflow. Also, Preliminary experimental results simulating an adaptive prostate LDR-BT under 3 Tesla MRI are given to validate the proposed concept.

We present the CoBra (Cooperative Brachytherapy) project 2018 - 2022. The CoBra purposes an integrated concept to perform localized cancer treatment and biopsy of soft-tissues under real-time (RT) MRI guidance [1]. The robot executes needle insertion within the MRI-scanner, performing adaptive prostate brachytherapy under RT-imaging. An active steerable-needle under closed-loop control is used to achieve precise positioning of the seeds with the increased reach of the needle to pubic arch and organs-at-risk occluded areas. Dose calculation under RT-MRI is achieved by the generation of synthetic-CT datasets based on a Machine-learning algorithm. Needle trajectory planning based on a steerable needle with minimal entry points is optimized by an algorithm depending upon the target, seed plan, and prostate contours attained from MRI. A bio-inspired active phantom (BIP) is designed for concept validation. The CoBra project is funded by the EU Interreg 2 Seas programme, led by the University of Lille partnering with multiple institutions and industrial observers.

Background Breast cancer is one of the most common cancer diagnosed among US women. Early and accurate diagnosis using breast biopsy techniques is essential in detecting cancer. Methods In this paper, we present a new cable-driven robot for MRI-guided breast biopsy. A compact three degree-of-freedom (DOF) semi-automated robot driven by ultrasonic motors is designed with non-magnetic materials. Next, a novel insertion trajectory planning algorithm based on the breast holder that we created is proposed and designed, which can help radiologists locate the lesion and calculate the insertion trajectory. To improve the accuracy of insertion, kinematic analysis and accuracy compensation methods are introduced. Results An experimental study based on image recognition and positioning is performed to validate the performance of the new robot. The results show that the mean position accuracy is 0.7 ± 0.04 mm. Conclusions Application of the new robot can improve breast biopsy accuracy and reduce surgery time.

Purpose: A new version of a grid-template-mimicking MR-compatible robot is developed to assist during in-gantry MRI-guided focal laser ablation of prostate cancer. This robot replaces the grid template and provides higher positioning resolution, and allows autonomous needle alignment directly from the targeting and navigation software, with the needle insertion manually performed for safety. Method: A substantially more compact solution is designed and prototyped to allow comfortable accommodation between the patient’s legs while in MRI bore. The controller software was reconfigured and embedded into the custom navigation and multi-focal ablation software, OncoNav (NIH). OncoNav performs robot-to-image registration, target planning, controlling the robot, ablation planning, and 3D temperature analysis for monitoring. For free space accuracy study, 5 targets were selected across the workspace and the robot was commanded 5 times to each target. Then, a thermochromic phantom study was designed consisting of acrylamide gel and color changing ink for testing the overall workflow. 4 spherical metal fiducials were embedded in the phantom at different locations. After each targeting, laser ablation was applied in two of the targets. Finally, the phantom was sliced for gross observation of guidance and treatment accuracy. Results: in-the-air accuracy was 0.38±0.27 mm. The overall targeting accuracy including robot, registration, and insertion error was 2.17±0.47 mm in phantom. Ablation successfully covered ellipsoids around the targets. The workflow was acceptably smooth. Conclusions: The new robot can accurately assist in targeting small targets followed by focal laser ablation. Sterility and regulatory hurdles will be addressed with specific design approaches as the next step.

Purpose: A novel grid-template-mimicking MR-compatible robot was developed for in-gantry MRI-guided focal laser ablation of prostate cancer. Method: A substantially compact robot was designed and prototyped to meet in-gantry lithotomy ergonomics and allow for accommodation in the perineum. The controller software was reconfigured and integrated with the custom-designed navigation and multi-focal ablation software. Three experiments were conducted: (1) free space accuracy test, (2) phantom study under computed tomography (CT) guidance for image-guided accuracy test and overall workflow, and (3) magnetic resonance imaging (MRI)-guided focal laser ablation of an ex vivo prostate. The free space accuracy study included five targets that were selected across the workspace. The robot was then commanded five times to each target. The phantom study used a gel phantom made with color changing thermos-chromic ink, and four spherical metal fiducials were deployed with the robot. Then, laser ablation was applied, and the phantom was sliced for gross observation. For an MR-guided ex vivo test, a prostate from a donor who died of prostate cancer was obtained and multi-focally ablated using the system within the MRI gantry. The tissue was sliced after ablation for validation. Results: free-space accuracy was 0.38 &plusmn, 0.27 mm. The overall system targeting accuracy under CT guidance (including robot, registration, and insertion error) was 2.17 &plusmn, 0.47 mm. The planned ablation zone was successfully covered in both acrylamide gel phantom and in human prostate tissue. Conclusions: The new robot can accurately facilitate fiber targeting for MR-guided focal laser ablation of targetable prostate cancer.

The use of magnetic resonance imaging (MRI) for guiding robotic surgical devices has shown great potential for performing precisely targeted and controlled interventions. To fully realize these benefits, devices must work safely within the tight confines of the MRI bore without negatively impacting image quality. Here we expand on previous work exploring MRI guided robots for neural interventions by presenting the mechanical design and assessment of a device for positioning, orienting, and inserting an interstitial ultrasound-based ablation probe. From our previous work we have added a 2 degree of freedom (DOF) needle driver for use with the aforementioned probe, revised the mechanical design to improve strength and function, and performed an evaluation of the mechanism’s accuracy and effect on MR image quality. The result of this work is a 7-DOF MRI robot capable of positioning a needle tip and orienting it’s axis with accuracy of 1.37 ± 0.06mm and 0.79° ± 0.41°, inserting it along it’s axis with an accuracy of 0.06 ± 0.07mm, and rotating it about it’s axis to an accuracy of 0.77° ± 1.31°. This was accomplished with no significant reduction in SNR caused by the robot’s presence in the MRI bore, ≤ 10.3% reduction in SNR from running the robot’s motors during a scan, and no visible paramagnetic artifacts.

This proposal focuses on the interventional MRI technology and the MRI compatible robots which are used to overcome some limitation of the MRI. In the introduction part, the development and the limitation of the current MRI interventions are introduced and a possible solution, MRI compatible robotic assistance, is proposed. In the design part, the specification of the MRI robot is discussed, including the MRI compatible material, the motor and encoder, the control unit and the combination of haptic sensor. Finally, the possible future application of the MRI compatible interventional robots is introduced.

This paper presents the development, preclinical evaluation, and preliminary clinical study of a robotic system for targeted transperineal prostate biopsy under direct interventional magnetic resonance imaging (MRI) guidance. The clinically integrated robotic system is developed based on a modular design approach, comprised of surgical navigation application, robot control software, MRI robot controller hardware, and robotic needle placement manipulator. The system provides enabling technologies for MRI-guided procedures. It can be easily transported and setup for supporting the clinical workflow of interventional procedures, and the system is readily extensible and reconfigurable to other clinical applications. Preclinical evaluation of the system is performed with phantom studies in a 3 Tesla MRI scanner, rehearsing the proposed clinical workflow, and demonstrating an in-plane targeting error of 1.5[Formula: see text]mm. The robotic system has been approved by the institutional review board (IRB) for clinical trials. A preliminary clinical study is conducted with the patient consent, demonstrating the targeting errors at two biopsy target sites to be 4.0[Formula: see text]mm and 3.7[Formula: see text]mm, which is sufficient to target a clinically significant tumor foci. First-in-human trials to evaluate the system’s effectiveness and accuracy for MR image-guided prostate biopsy are underway.

The paper reports an important achievement in MRI instrumentation, a pneumatic, fully actuated robot located within the scanner alongside the patient and operating under remote control based on the images. Previous MRI robots commonly used piezoelectric actuation limiting their compatibility. Pneumatics is an ideal choice for MRI compatibility because it is decoupled from electromagnetism, but pneumatic actuators were hardly controllable. This achievement was possible due to a recent technology breakthrough, the invention of a new type of pneumatic motor, PneuStep (1), designed for the robot reported here with uncompromised MRI compatibility, high-precision, and medical safety. MrBot is one of the “MRI stealth” robots today (the second is described in this issue by Zangos et al.). Both of these systems are also multi-imager compatible, being able to operate with the imager of choice or cross-imaging modalities. For MRI compatibility the robot is exclusively constructed of nonmagnetic and dielectric materials such as plastics, ceramics, crystals, rubbers and is electricity free. Light-based encoding is used for feedback, so that all electric components are distally located outside the imager’s room. MRI robots are modern, digital medical instruments in line with advanced imaging equipment and methods. These allow for accessing patients within closed bore scanners and performing interventions under direct (in scanner) imaging feedback. MRI robots could allow e.g. to biopsy small lesions imaged with cutting edge cancer imaging methods, or precisely deploy localized therapy at cancer foci. Our robot is the first to show the feasibility of fully automated in-scanner interventions. It is customized for the prostate and operates transperineally for needle interventions. It can accommodate various needle drivers for different percutaneous procedures such as biopsy, thermal ablations, or brachytherapy. The first needle driver is customized for fully automated low-dose radiation seed brachytherapy. This paper gives an introduction to the challenges of MRI robot compatibility and presents the solutions adopted in making the MrBot. Its multi-imager compatibility and other preclinical tests are included. The robot shows the technical feasibility of MRI-guided prostate interventions, yet its clinical utility is still to be determined.

This paper presents a surgical master-slave tele-operation system for percutaneous interventional procedures under continuous magnetic resonance imaging (MRI) guidance. This system consists of a piezoelectrically actuated slave robot for needle placement with integrated fiber optic force sensor utilizing Fabry-Perot interferometry (FPI) sensing principle. The sensor flexure is optimized and embedded to the slave robot for measuring needle insertion force. A novel, compact opto-mechanical FPI sensor interface is integrated into an MRI robot control system. By leveraging the complementary features of pneumatic and piezoelectric actuation, a pneumatically actuated haptic master robot is also developed to render force associated with needle placement interventions to the clinician. An aluminum load cell is implemented and calibrated to close the impedance control loop of the master robot. A force-position control algorithm is developed to control the hybrid actuated system. Teleoperated needle insertion is demonstrated under live MR imaging, where the slave robot resides in the scanner bore and the user manipulates the master beside the patient outside the bore. Force and position tracking results of the master-slave robot are demonstrated to validate the tracking performance of the integrated system. It has a position tracking error of 0.318mm and sine wave force tracking error of 2.227N.

We present a pneumatic actuated robotic assistant system for transapical aortic valve replacement under MRI guidance in a beating heart. This is a minimally invasive procedure that is currently performed manually inside the MRI bore. A robotic assistance system that integrates an interactive real-time MRI system, a robotic arm with a newly developed robotic valve delivery module, as well as user interfaces for the physician to plan the procedure and manipulate the robot, would be advantageous for the procedure. An Innomotion arm with hands-on cooperative interface was used as a device holder. A compact MRI compatible robotic delivery module was developed for delivering both balloon-expandable and self-expanding prostheses. A compact fiducial that can be placed close to the volume of interest and requires a single image plane was used for image-based robot registration. The system provides different user interfaces at various stages of the procedure. We present the development and evaluation of the components and the system in ex-vivo experiments.

This paper reports our work on developing a robotic surgical system for transapical beating heart aortic valve replacement (AVR) under interactive real-time magnetic resonance imaging (rtMRI) guidance. Our system integrates a real-time MRI system, a compound MRI robot, as well as an interface for the surgeon to plan the procedure and manipulate the robot. The compound robot consists of a positioning module and a valve delivery module. A 5-DOF Inno-motion positioning arm provides and maintains direct access to the native aortic valve. A newly developed 3-DOF robotic valve delivery module allows the surgeon to remotely control bioprosthetic valve delivery with MRI guidance. Preliminary evaluation of the parameters of the robotic system demonstrates it can provide sufficient capability to successfully assist the surgeon.