Adapting the clinical MRI software environment for real‐time navigation of an endovascular untethered ferromagnetic bead for future endovascular interventions

Abstract

A dedicated software architecture for a novel interventional method allowing the navigation of ferromagnetic endovascular devices using a standard real-time clinical MRI system is shown. Through a specially developed software environment integrating a tracking method and a real-time controller algorithm, a clinical 1.5T Siemens Avanto MRI system is adapted to provide new functionality for potential automated interventional applications. The proposed software architecture was successfully validated through in vivo controlled navigation inside the carotid artery of a swine. Here we present how this MRI-upgraded software environment could also be used in more complex vasculature models through the real-time navigation of a 1.5 mm diameter chrome steel bead in two different MR-compatible phantoms with flowless and quiescent flow conditions. The developed platform and software modules needed for such navigation are also presented. Real-time tracking achieved through a dedicated positioning method based on an off-resonance excitation technique has also been successfully integrated in the software platform while maintaining adequate real-time performance. These preliminary feasibility experiments suggest that navigation of such devices can be achieved Because MR imaging offers many advantages in term of spatial resolution and safety for the patient, modern interventional medicine is now considering this imaging modality as an alternative for upcoming interventional applications. Many standard fluoroscopy catheter procedures can now be executed in an MRI environment (1-3), providing enhanced visual precision for the medical team without patient exposure limitations due to radiation emission. However, all catheter-based procedures, whether offering or not a better quality in visualization, face the same limitations with regard to accessibility and flexibility. Many actual medical interventions would require enhanced targeting of specific organs or physiological sites for the delivery of drug or contrast agents (4 -7). Although catheters can reach some of these specific sites without much complication, many sites remain inaccessible and cannot be reached without involving major invasive surgeries. Moreover, these interventional applications rely on MRI capabilities only for the imaging modality provided by the system without considering using an MRI system as a fully integrated and automated endovascular navigation environment.A recent breakthrough in interventional MRI-guided in vivo procedures demonstrated that real-time MRI systems can offer a well-suited integrated environment for the propulsion, tracking, and control of a ferromagnetic device, which was done in the carotid artery of a living swine (8). The standard imaging environment, however, must be adapted in order to provide such new capabilities. Timing and integration constraints must be overcome to permit the use of a standard MRI system as a new endovascular navigation platform. Unlike some other methods that simply use a DC field flux to create a torque on ...

Automatic slice positioning (ASP) for passive real‐time tracking of interventional devices using projection‐reconstruction imaging with echo‐dephasing (PRIDE)

“…24 or by restricting peak detection within the close vicinity of the vessel anatomy (for example; from previously acquired angiograms). Recently, a similar tracking approach has been presented (25) that is based solely on an off-resonance tissue excitation and may lead to confounding results in the presence of fat tissues. Moreover, the artifact size within the image is approximately 10 cm in length as compared to 1.5 to 2 cm (in both lateral and vertical directions) in the current implementation.…”

MRI-based dynamic tracking of an untethered ferromagnetic microcapsule navigating in liquid

“…A recent breakthrough in interventional MRI-guided in vivo procedures demonstrated that real-time MRI systems can offer a well-suited integrated environment for the imaging, tracking, and control of a ferromagnetic device, which was done in the carotid artery of a living swine [9] . These successful experiments pointed out critical challenges in terms of real-time imaging, tracking, and navigation for future therapeutic applications.…”

MRI magnetic signature imaging, tracking and navigation for targeted micro/nano-capsule therapeutics

“…A recent breakthrough in interventional MRIguided in vivo procedures demonstrated that real-time MRI systems can offer a well-suited integrated environment for the imaging, tracking, and control of a ferromagnetic device, which was done in the carotid artery of a living swine [1]. These successful experiments pointed out critical challenges in terms of real-time imaging, tracking and navigation for future therapeutic applications, that are controlled targeted drug delivery in brain [2], navigable magnetic carriers for implantable biosensors or controlled ultrasensitive imaging for early diagnosis and treatment of diseases [3].…”