A multipurpose positioning device for magnetic resonance imaging-guided focused ultrasound surgery

Abstract

Background and Objectives: An magnetic resonance imaging (MRI)-guided focused ultrasound (MRgFUS) positioning device was developed with 3 identical Cartesian stages. The robotic system can be utilized to move a focused ultrasound transducer for performing various MR-guided applications. Materials and Methods: A single element spherically focused transducer of 4 cm diameter, focusing at 10 cm, and operating at 1.14 MHz was used during the evaluation of the robotic system. The propagation of ultrasound was either lateral or superior to inferior. MRI thermometry algorithms were developed to assess the thermal effects of MRgFUS. The proposed robotic system was developed using a three-dimensional printer. Results: The system was tested successfully in a gel phantom for various tasks (robot motion, functionality, and MR compatibility). Controlled thermal lesions were created in the gel phantom. The lesion creation was monitored successfully using MRI thermometry. Conclusions: The system was tested successfully for its functionality and its MR compatibility. This system has the potential to be used for focused ultrasound applications in the brain, breast, abdominal, and thyroid.

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

“…Although the simple design of the device is based on previously proposed systems developed by our group, 71,74,[76][77][78]80 with one such recent system offering the potential for top to bottom MRgFUS therapy of thyroid tumours, 76 the herein system offers advanced characteristics. The current prototype has been designed for use on thyroid tumours and not on multiple, potentially deeper, targets as the previously developed system.…”

“…Considering the thickness and depth of the thyroid gland, the robotic system, with the appropriate application of power, can controllably ablate thyroid nodules without affecting nearby organs. Moreover, due to the thin nature of the gland, a Y‐axis for adjusting the focusing height of the transducer and providing motion along the Y imaging plane of the MRI, as previously employed in other MRgFUS robotic systems, 71,74,76–78,80 was not required herein. Additionally, the formed lesions provided a visual representation of the accuracy of robotic motion through the formation of almost square overlapping lesions as well as uniformly distant discrete lesions.…”

“…Considering the thickness and depth of the thyroid gland, the robotic system, with the appropriate application of power, can controllably ablate thyroid nodules without affecting nearby organs. Moreover, due to the thin nature of the gland, a Y-axis for adjusting the focusing height of the transducer and providing motion along the Y imaging plane of the MRI, as previously employed in other MRgFUS robotic systems,71,74,[76][77][78]80 was not required herein. Additionally, the formed lesions provided a visual representation of the accuracy of robotic motion through the formation of almost square overlapping lesions as well as uniformly distant discrete lesions.F I G U R E 1 1 (A) Axial thermal maps acquired at different timepoints during sonications at an acoustic power of 45 W for a sonication time of 60 s at 30 mm focal depth as overlayed on the magnitude images of the agar-based thyroid phantom, and (B) Timeseries temperature increase recorded in the focal spot within the agar-based thyroid phantom during sonications.…”

Focused ultrasound heating in brain tissue/skull phantoms with 1 MHz single-element transducer

“…The study further provides insights on the feasibility of precisely delivering FUS through a skull mimic of 1-mm thickness as a potential method for the treatment of unresectable brain tumors. At the same time, the findings of such experiments play an essential role in the protocol optimization of MRI-compatible FUS robotic systems [ 43 – 54 ].…”