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National Center for Image Guided Therapy

Enabling Technologies for MRI-Guided Prostate Interventions R01-CA111288

In this collaboration between the Brigham and Women's Hospital, Johns Hopkins University, and Acoustic MedSystems, research teams are developing a technology platform for precise transperineal needle placement into the prostate for both diagnostic and therapeutic purposes to be used inside conventional (high-field closed) MRI scanners under real-time image guidance and monitoring. This system will be uniformly applicable to a wide range of MRI scanners, supporting long bore, short bore, and open magnets of high and low fields alike. The initial applications will be prostate biopsy and low-dose-rate brachytherapy performed by a multi-disciplinary team of physicians. The technology will translate to outside the specialized research hospital.

To date, the teams have developed an MRI-compatible needle placement manipulator for MRI-guided prostate biopsy and brachytherapy, including a Z-shaped fiducial frame for patient-robot registration, 3D Slicer features to provide a user interface to control and monitor the manipulator, and technological support to AcousticMed to develop commercial navigation software. The team has also integrated a whole body 3T MRI scanner (GE Excite HD 3T, GE Healthcare) with open source surgical navigation software 3D Slicer to perform real-time interactive MR imaging that allows the continuous acquisition of 2D images from the selected imaging plane.

During real-time MR imaging, acquired images are immediately reconstructed and transferred to navigation software via the Ethernet and displayed on a screen. To capture images of the needle throughout the procedure, the imaging plane can be controlled according to the needle position measured from encoders of the robot. Clinicians can perform “closed-loop” needle guidance whereby the action made by the robot is captured by the MR image and immediately fed back to physicians to aid their decisions.

A phantom study demonstrated real-time imaging using this mechanism with a frame rate of 0.3 fps and maximum latency of 1.7s (excl. acquisition time). As a foundation of the integration, the team defined OpenIGTLink, an open protocol to establish communication among robot, navigation software, and MRI scanner. The protocol can handle various kinds of data including image, coordinate data, and command-to- control robotic and imaging devices. In doing so, OpenIGTLink software allows for the transfer various types of data among software and devices to better enable image-guided therapy.

This collaboration has a mission to optimize MR for image guidance within the prostate. Historically, closed high-field MRI scanners, the most superior imaging systems, have been unavailable for interventions as the strong magnetic field and confined physical space present formidable challenges, including difficulties such as needle deflection, tissue deformation, and target motion. Realizing this, the research teams established the clinical feasibility of MR-guided transperineal prostate biopsy and brachytherapy (BWH), the Hopkins team created an in-MRI prostate robot in human trials for biopsy and seed placement, and the Acoustic MedSystems group developed a commercial prostate cancer brachytherapy suite that is now in over 60 healthcare settings worldwide.

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