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Background: The current study proposes simple methods for assessing the performance of robotic devices intended for Magnetic Resonance Imaging (MRI)-guided needle biopsy., Methods: In-house made agar-based breast phantoms containing biopsy targets served as the main tool in the evaluation process of an MRI compatible positioning device comprising a needle navigator. The motion accuracy of mechanical stages was assessed by calliper measurements. Laboratory evaluation of needle targeting included a repeatability phantom test and a laser-based method. The accuracy and repeatability of needle targeting was also assessed by MRI., Results: The maximum error of linear motion for steps up to 10 mm was 0.1 mm. Needle navigation relative to the phantom and alignment with the various biopsy targets were performed successfully in both the laboratory and MRI settings. The proposed biopsy phantoms offered tissue-like signal in MRI and good haptic feedback during needle insertion., Conclusions: The proposed methods could be valuable in the process of validating the accuracy of MRI-guided biopsy robotic devices in both laboratory and real environments., (© 2023 The Authors. The International Journal of Medical Robotics and Computer Assisted Surgery published by John Wiley & Sons Ltd.)

Background: Herein, a robotic system offering Magnetic Resonance-guided Focused Ultrasound (MRgFUS) therapy of thyroid nodules was developed., Methods: The robotic system offers linear motion in 2 PC-controlled axes that navigate a 3 MHz single-element focused transducer. The system, through a C-arm structure attaches to the table of Magnetic Resonance Imaging (MRI) scanners and couples to the neck of patients lying in the supine position. The MRI compatibility of the developed system was assessed inside a 3 T scanner. Benchtop and MRI feasibility studies evaluating the heating performance of the system were executed on excised pork tissue and on homogeneous and thyroid model agar-based phantoms., Results: The MRI compatibility of the system was successfully established. Grid sonications executed using robotic motion inflicted discrete and overlapping lesions on the excised tissue, while magnetic resonance (MR) thermometry successfully monitored thermal heating in agar-based phantoms., Conclusions: The developed system was found to be efficient with ex-vivo evaluation. The system can perform clinical MRgFUS therapy of thyroid nodules and other shallow targets after further in-vivo evaluation., (© 2023 The Authors. The International Journal of Medical Robotics and Computer Assisted Surgery published by John Wiley & Sons Ltd.)

Background: A robotic device featuring three motion axes was manufactured for preclinical research on focussed ultrasound (FUS). The device comprises a 2.75 MHz single element ultrasonic transducer and is guided by Magnetic Resonance Imaging (MRI)., Methods: The compatibility of the device with the MRI was evaluated by estimating the influence on the signal-to-noise ratio (SNR). The efficacy of the transducer in generating ablative temperatures was evaluated in phantoms and excised porcine tissue., Results: System's activation in the MRI scanner reduced the SNR to an acceptable level without compromising the image quality. The transducer demonstrated efficient heating ability as proved by MR thermometry. Discrete and overlapping thermal lesions were inflicted in excised tissue., Conclusions: The FUS system was proven effective for FUS thermal applications in the MRI setting. It can thus be used for multiple preclinical applications of the emerging MRI-guided FUS technology. The device can be scaled-up for human use with minor modifications., (© 2022 The Authors. The International Journal of Medical Robotics and Computer Assisted Surgery published by John Wiley & Sons Ltd.)

Background: Focussed Ultrasound (FUS) combined with microbubbles (MBs) was proven a promising modality for non-invasive blood brain barrier disruption (BBBD). Herein, two devices for FUS-mediated BBBD in rodents are presented., Methods: A two-axes robotic device was manufactured for navigating a single element FUS transducer of 1 MHz relative to the brain of rodents. A second more compact device featuring a single motorized vertical axis was also developed. Their performance was assessed in terms of motion accuracy, MRI compatibility and trans-skull BBBD in wild type mice using MBs in synergy with pulsed FUS., Results: Successful BBBD was evidenced by the Evans Blue dye method, as well as by Fibronectin and Fibrinogen immunostaining. BBB permeability was enhanced when the applied acoustic intensity was increased., Conclusions: The proposed devices constitute a cost-effective and ergonomic solution for FUS-mediated BBBD in small animal models. Further experimentation is needed to examine the repeatability of results and optimise the therapeutic protocol., (© 2022 The Authors. The International Journal of Medical Robotics and Computer Assisted Surgery published by John Wiley & Sons Ltd.)

Background: High-quality methods for Magnetic Resonance guided Focussed Ultrasound (MRgFUS) therapy planning are needed for safe and efficient clinical practices. Herein, an algorithm for full coverage path planning based on preoperative MR images is presented., Methods: The software functionalities of an MRgFUS robotic system were enhanced by implementing the developed algorithm. The algorithm's performance in accurate path planning following a Zig-Zag pathway was assessed on MR images. The planned sonication paths were performed on acrylic films using the robotic system carrying a 2.75 MHz single element transducer., Results: Ablation patterns were successfully planned on MR images and produced on acrylic films by overlapping lesions with excellent match between the planned and experimental lesion shapes., Conclusions: The advanced software was proven efficient in planning and executing full ablation of any segmented target. The reliability of the algorithm could be enhanced through the development of a fully automated segmentation procedure., (© 2022 Cyprus University of Technology. The International Journal of Medical Robotics and Computer Assisted Surgery on behalf of John Wiley & Sons Ltd.)

Background: A robotic system for Magnetic Resonance guided Focussed Ultrasound (MRgFUS) therapy of tumours in the breast, bone, thyroid, and abdomen was developed., Methods: A special C-shaped structure was designed to be attached to the table of conventional magnetic resonance imaging (MRI) systems carrying 4 computer-controlled motion stages dedicated to positioning a 2.75 MHz spherically focussed transducer relative to a patient placed in the supine position. The developed system was evaluated for its MRI compatibility and heating abilities in agar-based phantoms and freshly excised tissue., Results: Compatibility of the system with a clinical high-field MRI scanner was demonstrated. FUS heating in the phantom was successfully monitored by magnetic resonance thermometry without any evidence of magnetically induced phenomena. Cigar-shaped discrete lesions and well-defined areas of overlapping lesions were inflicted in excised tissue by robotic movement along grid patterns., Conclusions: The developed MRgFUS robotic system was proven safe and efficient by ex-vivo feasibility studies., (© 2022 John Wiley & Sons Ltd.)

Background: A prototype robotic system that uses magnetic resonance guided focused ultrasound (MRgFUS) technology is presented. It features three degrees of freedom (DOF) and is intended for thermal ablation of abdominal cancer., Methods: The device is equipped with three identical transducers being offset between them, thus focussing at different depths in tissue. The efficacy and safety of the system in ablating rabbit liver and kidney was assessed, both in laboratory and magnetic resonance imaging (MRI) conditions., Results: Despite these organs' challenging location, in situ coagulative necrosis of a tissue area was achieved. Heating of abdominal organs in rabbit was successfully monitored with MR thermometry., Conclusions: The MRgFUS system was proven successful in creating lesions in the abdominal area of rabbits. The outcomes of the study are promising for future translation of the technology to the clinic., (© 2021 John Wiley & Sons Ltd.)

Background: Robotic-assisted diagnostic and therapeutic modalities require a highly accurate performance to be certified for clinical application. In this paper, three simple methods for assessing the accuracy of motion of magnetic resonance-guided focused ultrasound (MRgFUS) robotic systems are presented., Methods: The accuracy of motion of a 4 degrees of freedom robotic system intended for preclinical use of MRgFUS was evaluated by calliper-based and magnetic resonance imaging (MRI) methods, as well as visually by performing multiple ablations on a plastic film., Results: The benchtop results confirmed a highly accurate motion in all axes of operation. The spatial positioning errors estimated by MRI evaluation were defined by the size of the imaging pixels. Lesions arrangement in discrete and overlapping patterns confirmed satisfactory alignment of motion trajectories., Conclusions: We believe the methods presented here should serve as a standard for evaluating the accuracy of motion of MRgFUS robotic systems., (© 2021 The Authors. The International Journal of Medical Robotics and Computer Assisted Surgery published by John Wiley & Sons Ltd.)

Background: A magnetic resonance image (MRI) guided robotic device for focussed ultrasound therapy of prostate cancer (PC) was developed. The device offers movement in 5 degrees of freedom (DOF) and uses a single-element transducer that operates at 3.2 MHz, has a diameter of 25 mm and focuses at 45 mm., Methods: The MRI compatibility of the system was evaluated in a 1.5 T scanner. The ability of the transducer to create lesions was evaluated in laboratory and MRI settings, on ex vivo pork tissue and in vivo rabbit thigh tissue., Results: Cavitational and thermal lesions were created on the excised pork tissue. In vivo experiments proved the efficacy of the system in ablating muscle tissue without damaging intervening areas., Conclusions: The MRI compatible robotic system can be placed on the table of any commercial MRI scanner up to 7 T. The device has the ability of future use for transrectal focal therapy of PC with the patient in supine position., (© 2021 Cyprus University of Technology. The International Journal of Medical Robotics and Computer Assisted Surgery published by John Wiley & Sons Ltd.)

Background: A magnetic resonance imaging (MRI) compatible robotic system for focused ultrasound was developed for small animal like mice or rats that fits into a 9.4 T MRI scanner (Bruker Biospec 9420, Bruker Biospin, Ettlingen, Germany). The robotic system includes two computer-controlled linear stages., Materials and Methods: The robotic system was evaluated in a mouse-shaped, real-size agar-based mimicking material, which has similar acoustical properties as soft tissues. The agar content was 6% weight per volume (w/v), 4% w/v silica while the rest was degassed water. The transducer used has a diameter of 4 cm, operates with 2.6 MHz and focuses energy at 5 cm., Results: The MRI compatibility of the robotic system was evaluated in a 9.4 T small animal scanner. The efficacy of the ultrasonic transducer was evaluated in the mimicking material using temperature measurements., Conclusions: The proposed robotic system can be utilized in a 9.4 T small animal MRI scanner. The proposed system is functional, compact and simple thus providing a useful tool for preclinical research in mice and rats., (© 2020 John Wiley & Sons Ltd.)

Background: A magnetic resonance image (MRI) guided robotic system dedicated for brain biopsy was developed. The robotic system carries a biopsy needle and a small rectangular unfocused, single element, planar ultrasonic transducer which can be potentially utilized to ablate small and localized brain cancer., Materials and Methods: The robotic device includes six computer-controlled axes. An agar-based phantom was developed which included an olive that mimics brain target. A rectangular ultrasonic transducer operated at 4 MHz was used., Results: The functionality of the robotic system was assessed by means of ultrasound imaging, MRI imaging, and MR thermometry, demonstrating effective targeting. The heating capabilities of the ultrasonic transducer were also evaluated., Conclusions: A functional MRI-guided robotic system was produced which can perform frameless brain biopsy. In the future, if a tumour is proven malignant, the needle can be pulled-out and a small ultrasonic transducer can be inserted to ablate the tumour., (© 2018 John Wiley & Sons, Ltd.)

Introduction: The target of this study was the development of a magnetic resonance imaging (MRI) compatible breast phantom for focused ultrasound which includes plastic (ABS) ribs. The objective of the current study was the evaluation of a focused ultrasound procedure using the proposed phantom that eliminates rib heating., Material and Methods: The proposed phantom was evaluated using two different focused ultrasound exposures. The surrounding breast tissue was mimicked using an agar-silica-evaporation milk gel (2% w/v - 2% w/v - 40% v/v)., Results: The attenuation of the ABS was similar to that of ribs. MR thermometry of focused ultrasound exposures were acquired using the breast/rib phantom. In one exposure focused ultrasound was applied with far-field targeting of the ribs. In the other exposure, the transducer was positioned laterally, thus avoiding exposure of the rib to focused ultrasound., Conclusions: Due to growing interest in using MRI guided focused ultrasound (MRgFUS) for patients with breast cancer, the proposed breast/rib phantom can be utilized as a very useful tool for evaluating ultrasonic protocols., (Copyright © 2017 John Wiley & Sons, Ltd.)

Background: In this paper an MRI-guided focused ultrasound (MRgFUS) robotic system was developed that can be used for conducting experiments in small animals.The target for this robotic system regarding motion was to move a therapeutic ultrasound transducer in two Cartesian axes., Methods: A single element spherically focused transducer of 3 cm diameter, focusing at 7 cm and operating at 0.4 MHz was used. The positioning device incorporates only MRI compatible materials. The propagation of ultrasound is a bottom to top approach. The 2-D positioning device is controlled by custom-made software and a custom-made electronic system which controls the two piezoelectric motors., Results: The system was tested successfully in agar/silica/evaporated milk phantom for various tasks (robot motion, MR compatibility, and MR thermometry). The robotic system is capable of moving the focused ultrasound transducer to perform MR-guided focused ultrasound experiments in small animals., Conclusions: This system has the potential to be deployed as a cost effective solution for performing experiments in small animals., (Copyright © 2017 John Wiley & Sons, Ltd.)

Background: A novel MRI-conditional robot was developed that navigates a focused ultrasound (FUS) transducer. With this robotic system the transducer can access bones. The intended application is pain palliation from bone cancer using thermal ablation using FUS., Methods: The robotic system has four computer-controlled axes (three linear and one angular). The robotic system was manufactured using a digital manufacturing 3D printer, using acrylonitrile butadiene styrene (ABS) plastic. MRI-conditional optical encoders were used to accurately control the robotic system., Results: The robotic system was successfully tested for MRI safety and compatibility, using fast-gradient pulse sequences and a liquid phantom. The robotic system has been tested for its functionality for creating discrete and multiple (overlapping) lesions in a gel phantom., Conclusions: An MRI-conditional FUS robotic system was developed that has the potential to create thermal lesions with the intention of treating bone cancer for the purpose of pain palliation. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

Background: The respiratory motion of abdominal organs is a serious obstacle in high-intensity focused ultrasound (HIFU) treatment with magnetic resonance imaging (MRI) guidance. In this study, a two-dimensional (2D) MRI-conditional motion phantom device was developed in order to evaluate HIFU protocols in synchronized and non-synchronized ablation of moving targets., Materials and Methods: The 2D phantom device simulates the respiratory motion of moving organs in both the left-right and craniocaudal directions. The device consists of MR-conditional materials which have been produced by a three-dimensional (3D) printer., Results: The MRI compatibility of the motion phantom was tested successfully in an MRI scanner. In vitro experiments were carried out to evaluate HIFU ablation protocols that are minimally affected by target motion., Conclusion: It was shown that only in synchronized mode does HIFU produce thermal lesions, as tested on a gel phantom mimicking the moving target. The MRI-conditional phantom device was shown to be functional for its purpose and can be used as an evaluation tool for testing HIFU protocols for moving targets in an MRI environment. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)

Background: A novel MRI-conditional robot that navigates focused ultrasound (FUS) for the treatment of gynaecological tumors endovaginally was developed., Methods: The robotic system has two PC-controlled axes (linear and angular). The robotic system was manufactured using a digital manufacturing 3D printer using acrylonitrile butadiene styrene (ABS) plastic. Evaluation of the device was performed in a 1.5T MRI using excised porcine tissue., Results: The robotic system was successfully tested for MRI safety and compatibility. The robotic system has been tested for its functionality for creating multiple (overlapping) lesions in an in vitro model., Conclusions: An MRI-conditional FUS robotic system was developed that has the potential to create thermal lesions with the intention of treating gynaecological tumors. In the future a third axis will be needed that lifts the robot up or down in order to access vaginas which are at a variable height from the MRI table., (Copyright © 2015 John Wiley & Sons, Ltd.)

Background: This article contains a review of positioning devices that are currently used in the area of magnetic resonance imaging (MRI) guided focused ultrasound surgery (MRgFUS)., Methods: The paper includes an extensive review of literature published since the first prototype system was invented in 1991., Results: The technology has grown into a fast developing area with application to any organ accessible to ultrasound. The initial design operated using hydraulic principles, while the latest technology incorporates piezoelectric motors. Although, in the beginning there were fears regarding MRI safety, during recent years, the deployment of MR-safe positioning devices in FUS has become routine. Many of these positioning devices are now undergoing testing in clinical trials., Conclusion: Existing MRgFUS systems have been utilized mostly in oncology (fibroids, brain, liver, kidney, bone, pancreas, eye, thyroid, and prostate). It is anticipated that, in the near future, there will be a positioning device for every organ that is accessible by focused ultrasound., (Copyright © 2014 John Wiley & Sons, Ltd.)

Background: A prototype magnetic resonance imaging (MRI)-compatible positioning device that navigates a high intensity focused ultrasound (HIFU) transducer is presented. The positioning device has three user-controlled degrees of freedom that allow access to brain targets using a lateral coupling approach. The positioning device can be used for the treatment of brain cancer (thermal mode ultrasound) or ischemic stroke (mechanical mode ultrasound)., Materials and Methods: The positioning device incorporates only MRI compatible materials such as piezoelectric motors, ABS plastic, brass screws, and brass rack and pinion., Result: The robot has the ability to accurately move the transducer thus creating overlapping lesions in rabbit brain in vivo. The registration and repeatability of the system was evaluated using tissues in vitro and gel phantom and was also tested in vivo in the brain of a rabbit., Conclusion: A simple, cost effective, portable positioning device has been developed which can be used in virtually any clinical MRI scanner since it can be placed on the table of the MRI scanner. This system can be used to treat in the future patients with brain cancer and ischemic stroke., (Copyright © 2013 John Wiley & Sons, Ltd.)