Sequence design and software environment for real-time navigation of a wireless ferromagnetic device using MRI system and single echo 3D tracking

Real-time software platform design for in-vivo navigation of a small ferromagnetic device in a swine carotid artery using a magnetic resonance imaging system

Using an 1.5T Siemens clinical Magnetic Resonance Imaging system (MRI), a 1.5 mm diameter ferromagnetic bead is moved across a pre-planned path in the carotid artery of a 25 kg living swine. The software architecture for the navigation and path planning is herein described. Using the real-time feedback capabilities of recent MRIs, the device is moved, controlled and tracked using the magnetic gradients coils already present for imaging purposes. Navigation of the ferromagnetic device has been achieved with a peak velocity of about 13 cm/s through a set of pre established 11 waypoints. The dedicated software architecture presented in this paper lies in a modified real-time MRI imaging sequence. The dedicated architecture permits the navigation of the ferromagnetic bead with an operating frequency of 24 Hz Real-time control of the magnetic core is achieved through the implementation of a simple 2D PID controller incorporated in the presented software platform.

Medical and technical protocol for automatic navigation of a wireless device in the carotid artery of a living swine using a standard clinical MRI system

A 1.5 mm magnetic sphere was navigated automatically inside the carotid artery of a living swine. The propulsion force, tracking and real-time capabilities of a Magnetic Resonance Imaging (MRI) system were integrated into a closed loop control platform. The sphere was released using an endovascular catheter approach. Specially developed software is responsible for the tracking, propulsion, event timing and closed loop position control in order to follow a 10 roundtrips preplanned trajectory on a distance of 5 cm inside the right carotid artery of the animal. Experimental protocol linking the technical aspects of this in vivo assay is presented. In the context of this demonstration, many challenges which provide insights about concrete issues of future nanomedical interventions and interventional platforms have been identified and addressed.

Bidimensional MRI-based navigation system using a PID controller

The feasibility of using 2D real-time control to navigate ferromagnetic entities in an MRI bore for novel medical interventions is assessed. Preliminary experimental results confirm that a simple PID controller can be suitable for several applications where targeting out-of-reach locations within the cardiovascular system is essential.