Showing papers by "Robert J. Lederman published in 2007"

Technology preview: X-ray fused with magnetic resonance during invasive cardiovascular procedures.

Abstract: Background: We have developed and validated a system for real-time X-ray fused with magnetic resonance imaging, MRI (XFM), to guide catheter procedures with high spatial precision. Our implementation overlays roadmaps—MRI-derived soft-tissue features of interest—onto conventional X-ray fluoroscopy. We report our initial clinical experience applying XFM, using external fiducial markers, electrocardiogram (ECG)- gating, and automated real-time correction for gantry and table movement. Methods: This prospective case series for technical development was approved by the NHLBI Institutional Review Board and included 19 subjects. Multimodality external fiducial markers were affixed to patients' skin before MRI, which included contrast-enhanced, 3D T1-weighted, or breath-held and ECG-gated 2D steady state free precession imaging at 1.5T. MRI-derived roadmaps were manually segmented while patients were transferred to a calibrated X-ray fluoroscopy system. Image spaces were registered using the fiducial markers and thereafter permitted unrestricted gantry rotation, table panning, and magnification changes. Static and ECG-gated MRI data were transformed from 3D to 2D to correspond with gantry and table position and combined with live X-ray images. Results: Clinical procedures included graft coronary arteriography, right ventricular free-wall biopsy, and iliac and femoral artery recanalization and stenting. MRI roadmaps improved operator confidence, and in the biopsy cases, outperformed the best available alternative imaging modality. Registration errors were increased when external fiducial markers were affixed to more mobile skin positions, such as over the abdomen. Conclusion: XFM using external fiducial markers is feasible during X-ray guided catheter treatments. Multimodality image fusion may prove a useful adjunct to invasive cardiovascular procedures. © 2007 Wiley-Liss, Inc.

Interventional cardiovascular procedures guided by real‐time MR imaging: An interactive interface using multiple slices, adaptive projection modes and live 3D renderings

Abstract: Purpose To develop and test a novel interactive real-time MRI environment that facilitates image-guided cardiovascular interventions. Materials and Methods Color highlighting of device-mounted receiver coils, accelerated imaging of multiple slices, adaptive projection modes, live three-dimensional (3D) renderings and other interactive features were utilized to enhance navigation of devices and targeting of tissue. Results Images are shown from several catheter-based interventional procedures performed in swine that benefit from this custom interventional MRI interface. These include endograft repair of aortic aneurysm, balloon septostomy of the cardiac interatrial septum, angioplasty and stenting, and endomyocardial cell injection, all using active catheters containing MRI receiver coils. Conclusion Interactive features not available on standard clinical scanners enhance real-time MRI for guiding cardiovascular interventional procedures. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.

Transcatheter coronary sinus mitral valve annuloplasty procedure and coronary artery and myocardial protection device

Abstract: A protective device or bridge (20) comprising a central arch (24) is suitable to be placed between an annuplasty device placed in the coronary sinus and an underlying coronary artery to inhibit transmission of compressive force on the coronary artery by the annuplasty device.

Beating heart aortic valve replacement using real-time MRI guidance.

Abstract: ObjectiveThe principal limitations of percutaneous techniques to replace the aortic valve are detailed visualization and durable prostheses. We report the feasibility of using real-time magnetic re...

Blunt atrial transseptal puncture using excimer laser in swine

Abstract: Objectives—We describe a new approach that may enhance safety of atrial transseptal puncture, using a commercially available laser catheter that is capable of perforation only when energized. We test this approach in swine. Background—Despite wide application, conventional needle transseptal puncture continues to risk inadvertent non-target perforation and its consequences. Methods—We used a commercial excimer laser catheter (0.9mm Clirpath, Spectranetics). Perforation force was compared in vitro with a conventional Brockenbrough needle. Eight swine underwent laser transseptal puncture under X-ray fluoroscopy steered using a variety of delivery catheters. Results—The 0.9mm laser catheter traversed in vitro targets with reduced force compared with a Brockenbrough needle. In vitro, the laser catheter created holes that were 25–30% larger than the Brockenbrough needle. Laser puncture of the atrial septum was successful and accurate in all animals, evidenced by oximetry, pressure, angiography, and necropsy. The laser catheter was steered effectively using a modified Mullins introducer sheath and using two different deflectable guiding catheters. The mean procedure time was 15 ± 6 minutes, with an average 3.0 ± 0.8 seconds of laser activation. There were no adverse sequelae after prolonged observation. Necropsy revealed discrete 0.9mm holes in all septae. Conclusion—Laser puncture of the interatrial septum is feasible and safe in swine, using a blunt laser catheter that perforates tissues in a controlled fashion.

High-resolution 3D arteriography of chronic total peripheral occlusions using a T1-W turbo spin-echo sequence with inner-volume imaging.

Abstract: Percutaneous revascularization of peripheral artery chronic total occlusion (CTO) is challenging under X-ray guidance without direct image feedback, due to poor visualization of the obstructed segment and underappreciation of vessel tortuosity. Operators are required to steer interventional devices relatively "blindly," and therefore procedural failure or perforation may occur. Alternatively, MRI may allow complete visualization of both patent and occluded arterial segments. We designed and implemented a 3D high-resolution, T(1)-weighted (T(1)-W) turbo spin-echo (TSE) MRI sequence with inner-volume (IV) imaging to enable detailed peripheral artery CTO imaging. Using this sequence, high-resolution volumes of interest (VOIs) around the vessel were achieved within 5-10 min. This imaging approach may be used for rapid pre- and postprocedural evaluations, and as a 3D roadmap that can be overlaid during real-time X-, MR-, or XMR-guided catheterization. Experiments were successfully performed on a carotid CTO model in swine ex vivo, and in peripheral arteries in normal volunteers and patients in vivo. Delineation of the vascular architecture, including contrast differences between the patent and occluded artery segments, and lesion morphology heterogeneity were visualized.

Advances in interventional cardiovascular MRI

Abstract: Because of its superior soft tissue imaging, MRI has become a valuable diagnostic tool in cardiovascular disease. These strengths make MRI attractive to guide therapeutic catheter-based procedures, both conventional and novel. We review how to configure an interventional MRI suite, how MRI catheter devices differ from conventional radiographic catheters, and finally developments in preclinical and investigational clinical applications.