Focused ultrasound robotic system for very small bore magnetic resonance imaging

Abstract

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, realsize 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.

Robotic system for magnetic resonance imaging‐guided focused ultrasound treatment of thyroid nodules

“…MRI-compatible piezoelectric ultrasonic motors were utilised for actuating motion in the two mechanical positioning stages of the robot, following their vast employment in other preclinical MRIcompatible robotic devices for HIFU treatment. [70][71][72][73][74][75][76][77][78] The linear motion in the X and Z axes was achieved using simple plastic jackscrews with mounted plate mechanisms, following the vast experience of our group in the design of MRgFUS positioning devices using piezoelectric motors. [70][71][72][73][74][75][76][77][78] It is noted that all materials employed in the Although the composite agar-based thyroid model phantom exhibited tissue-like appearance on MR imaging and successfully validated the thermal heating performance of the system for the intended application, future improvements could be potentially performed, resulting in a phantom that more realistically mimics the human properties of the thyroid.…”

“…[70][71][72][73][74][75][76][77][78] The linear motion in the X and Z axes was achieved using simple plastic jackscrews with mounted plate mechanisms, following the vast experience of our group in the design of MRgFUS positioning devices using piezoelectric motors. [70][71][72][73][74][75][76][77][78] It is noted that all materials employed in the Although the composite agar-based thyroid model phantom exhibited tissue-like appearance on MR imaging and successfully validated the thermal heating performance of the system for the intended application, future improvements could be potentially performed, resulting in a phantom that more realistically mimics the human properties of the thyroid. Both the thyroid model and surrounding neck tissue phantoms were developed with an agar-base that is known to mechanically resemble human soft tissue.…”

“…MRI‐compatible piezoelectric ultrasonic motors were utilised for actuating motion in the two mechanical positioning stages of the robot, following their vast employment in other preclinical MRI‐compatible robotic devices for HIFU treatment 70–78 . The linear motion in the X and Z axes was achieved using simple plastic jackscrews with mounted plate mechanisms, following the vast experience of our group in the design of MRgFUS positioning devices using piezoelectric motors 70–78 . It is noted that all materials employed in the development of the robotic system are non‐magnetic to allow proper functioning within the MRI environment.…”

Robotic device for transcranial focussed ultrasound applications in small animal models

“…Overall, the proposed systems are easy to make at an affordable price and were developed based on the knowledge gained from our previously introduced robotic systems. [28][29][30][31][32][33]…”

“…Especially for very small animals such as mice, the accuracy benefits of the proposed experimental setup are of high importance. Overall, the proposed systems are easy to make at an affordable price and were developed based on the knowledge gained from our previously introduced robotic systems 28–33 …”