Novel system for real-time integration of 3-D echocardiography and fluoroscopy for image-guided cardiac interventions: Preclinical validation and clinical feasibility evaluation

© 2015 IEEE. Real-time imaging is required to guide minimally invasive catheter-based cardiac interventions. While transesophageal echocardiography allows for high-quality visualization of cardiac anatomy, X-ray fluoroscopy provides excellent visualization of devices. We have developed a novel image fusion system that allows real-time integration of 3-D echocardiography and the X-ray fluoroscopy. The system was validated in the following two stages: 1) preclinical to determine function and validate accuracy; and 2) in the clinical setting to assess clinical workflow feasibility and determine overall system accuracy. In the preclinical phase, the system was assessed using both phantom and porcine experimental studies. Median 2-D projection errors of 4.5 and 3.3 mm were found for the phantom and porcine studies, respectively. The clinical phase focused on extending the use of the system to interventions in patients undergoing either atrial fibrillation catheter ablation (CA) or transcatheter aortic valve implantation (TAVI). Eleven patients were studied with nine in the CA group and two in the TAVI group. Successful real-time view synchronization was achieved in all cases with a calculated median distance error of 2.2 mm in the CA group and 3.4 mm in the TAVI group. A standard clinical workflow was established using the image fusion system. These pilot data confirm the technical feasibility of accurate real-time echo-fluoroscopic image overlay in clinical practice, which may be a useful adjunct for real-time guidance during interventional cardiac procedures

Three-dimensional CT overlay in comparison to CartoMerge for pulmonary vein antrum isolation

\u3cp\u3eINTRODUCTION: Three-dimensional (3D) navigation systems are widely used for pulmonary vein antrum isolation (PVAI). To circumvent left atrial (LA) mapping, 3D CT reconstructions of the LA can be superimposed directly (CT overlay) on the fluoroscopy image to guide ablation catheters and to mark ablation sites.\u3c/p\u3e\u3cp\u3eMETHODS AND RESULTS: Sixty-eight patients (pts) with symptomatic AF refractory to medical therapy were randomly assigned to CT overlay (group 1, n = 38) or CartoMerge (group 2, n = 30). In group 1 registration of the CT image was performed with contrast injections in 2 orthogonal projections. In group 2, visualization of all pulmonary vein (PV) ostia was done by PV angiography, followed by merging of the CT image and the Carto shell. We compared procedural success, procedure time, fluoroscopy time and radiation burden, measured as dose area product (DAP). Baseline characteristics were comparable in both groups. Procedural success, defined as disappearance of PV potentials in all PVs, was achieved in 37/38 (97%) of group 1 patients and 27/30 (90%) patients in group 2 (P = NS). Total procedure time was significantly shorter in group 1 compared to group 2 (129 +/- 34 vs 181 +/- 30 min, P < 0.0001). Although fluoroscopy time tended to be longer in the CT overlay group (47 +/- 16 vs 40 +/- 13 min, P = 0.06), proper use of diaphragmation resulted in comparable radiation values for both groups (DAP 53 +/- 27 vs 56 +/- 35 Gy cm(2), P = 0.76).\u3c/p\u3e\u3cp\u3eCONCLUSIONS: CT overlay for PV isolation is feasible and may, in comparison to conventional LA navigation systems, shorten procedural time without increases in radiation burden.\u3c/p\u3

Cardiac unfold: A novel technique for image-guided cardiac catheterization procedures

X-ray fluoroscopically-guided cardiac catheterization procedures are commonly carried out for the treatment of cardiac arrhythmias, such as atrial fibrillation (AF) and cardiac resynchronization therapy (CRT). X-ray images have poor soft tissue contrast and, for this reason, overlay of a 3D roadmap derived from pre-procedure volumetric image data can be used to add anatomical information. However, current overlay technologies have the limitation that 3D information is displayed on a 2D screen. Therefore, it is not possible for the cardiologist to appreciate the true positional relationship between anatomical/functional data and the position of the interventional devices. We prose a navigation methodology, called cardiac unfold, where an entire cardiac chamber is unfolded from 3D to 2D along with all relevant anatomical and functional information and coupled to real-time device tracking. This would allow more intuitive navigation since the entire 3D scene is displayed simultaneously on a 2D plot. A real-time unfold guidance platform for CRT was developed, where navigation is performed using the standard AHA 16-segment bull’s-eye plot for the left ventricle (LV). The accuracy of the unfold navigation was assessed in 13 patient data sets by computing the registration errors of the LV pacing lead electrodes and was found to be 2.2 ± 0.9 mm. An unfold method was also developed for the left atrium (LA) using trimmed B-spline surfaces. The method was applied to 5 patient data sets and its utility was demonstrated for displaying information from delayed enhancement MRI of patients that had undergone radio-frequency ablation

An integrated platform for image-guided cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an effective procedure for patients with heart failure but 30% of patients do not respond. This may be due to sub-optimal placement of the left ventricular (LV) lead. It is hypothesized that the use of cardiac anatomy, myocardial scar distribution and dyssynchrony information, derived from cardiac magnetic resonance imaging (MRI), may improve outcome by guiding the physician for optimal LV lead positioning. Whole heart MR data can be processed to yield detailed anatomical models including the coronary veins. Cine MR data can be used to measure the motion of the LV to determine which regions are late-activating. Finally, delayed Gadolinium enhancement imaging can be used to detect regions of scarring. This paper presents a complete platform for the guidance of CRT using pre-procedural MR data combined with live x-ray fluoroscopy. The platform was used for 21 patients undergoing CRT in a standard catheterization laboratory. The patients underwent cardiac MRI prior to their procedure. For each patient, a MRI-derived cardiac model, showing the LV lead targets, was registered to x-ray fluoroscopy using multiple views of a catheter looped in the right atrium. Registration was maintained throughout the procedure by a combination of C-arm/x-ray table tracking and respiratory motion compensation. Validation of the registration between the three-dimensional (3D) roadmap and the 2D x-ray images was performed using balloon occlusion coronary venograms. A 2D registration error of 1.2 ± 0.7mm was achieved. In addition, a novel navigation technique was developed, called Cardiac Unfold, where an entire cardiac chamber is unfolded from 3D to 2D along with all relevant anatomical and functional information and coupled to real-time device detection. This allowed more intuitive navigation as the entire 3D scene was displayed simultaneously on a 2D plot. The accuracy of the unfold navigation was assessed off-line using 13 patient data sets by computing the registration error of the LV pacing lead electrodes which was found to be 2.2 ± 0.9mm. Furthermore, the use of Unfold Navigation was demonstrated in real-time for four clinical cases. © 2012 Institute of Physics and Engineering in Medicine

Extended-field-of-view three-dimensional transesophageal echocardiography using image-based X-ray probe tracking

International audienceThe use of ultrasound imaging for guidance of cardiac interventional procedures is limited by the small field of view of the ultrasound volume. A larger view can be created by image-based registration of several partially overlapping volumes, but automatic registration is likely to fail unless the registration is initialized close to the volumes' correct alignment. In this article, we use X-ray images to track a transesophageal ultrasound probe and thereby provide initial position information for the registration of the ultrasound volumes. The tracking is possible using multiple X-rays or just a single X-ray for each probe position. We test the method in a phantom experiment and find that with at least 50% overlap, 88% of volume pairs are correctly registered when tracked using three X-rays and 86% when using single X-rays. Excluding failed registrations with errors greater than 10 mm, the average registration accuracy is 2.92 mm between ultrasound volumes and 4.75 mm for locating an ultrasound volume in X-ray space. We conclude that the accuracy and robustness of the registrations are sufficient to provide useful images for interventional guidance

Three-modality registration for guidance of minimally invasive cardiac interventions

Image guidance of minimally invasive cardiac interventions can be augmented by registering together different imaging modalities. In this paper, we propose a method to combine three modalities: X-ray fluoroscopy, trans-esophageal ultrasound and pre-procedure MRI or CT. The registration of the pre-procedure image involves a potentially unreliable manual initialisation of its position in an X-ray projection view. The method therefore includes an automatic correction using the esophagus location as an additional constraint. We test the method in a phantom experiment and find that initialising the pre-procedure image with up to 9mm offset from its correct position results in a 92% registration success rate. The esophagus constraint improves the capture range in the out-of-plane direction, which simplifies the manual initialisation

New image processing and noise reduction technology allows reduction of radiation exposure in complex electrophysiologic interventions while maintaining optimal image quality : a randomized clinical trial

Background Despite their carcinogenic potential, X-rays remain indispensable for electrophysiologic (EP) procedures. Objective The purpose of this study was to evaluate the dose reduction and image quality of a novel X-ray technology using advanced image processing and dose reduction technology in an EP laboratory. Methods In this single-center, randomized, unblinded, parallel controlled trial, consecutive patients undergoing catheter ablation for complex arrhythmias were eligible. The Philips Allura FD20 system allows switching between the reference (Allura Xper) and the novel X-ray imaging technology (Allura Clarity). Primary end-point was overall procedural patient dose, expressed in dose area product (DAP) and air kerma (AK). Operator dose, procedural success, and necessity to switch to higher dose settings were secondary end-points. Results A total of 136 patients were randomly assigned to the novel imaging group (n = 68) or the reference group (n = 68). Baseline characteristics were similar, except patients in the novel imaging group were younger (58 vs 65 years,

Dynamic coronary roadmapping during percutaneous coronary intervention: a feasibility study

Abstract Background A novel software (“Dynamic Coronary Roadmap”) was developed, which offers a real-time, dynamic overlay of the coronary tree on fluoroscopy. Once the roadmap has been automatically generated during angiography it can be used for navigation during percutaneous coronary interventions (PCI). As a feasibility study, we aimed to investigate the feasibility of real-time dynamic coronary roadmapping and consecutive coronary overlay during elective PCI. Methods and results We studied 936 overlay runs, created following the same amount of angiographies, which were generated during 36 PCIs. Feasibility of dynamic coronary roadmapping was analyzed using a dedicated software tool. Roadmap quality (correct dynamic imaging of the vessels without relevant artefacts or missing parts) was distinguished from overlay quality (congruence of dynamic coronary roadmapping and coronary anatomy). Additionally, we assessed procedural success and the occurrence of major cardiac and cerebrovascular events (MACCE). Roadmap quality was defined as “fit for use” in 99.5%. In 97.4% of runs overlay quality was deemed “fit for use”. Overall, we observed low inter and intra observer variability (ICC R = 0.84 for roadmap quality and R = 0.75 for overlay quality). Procedural success rate was 100%. MACCE occurred in two (5.6%) patients during post-interventional in-hospital stay and were not software-related. Conclusions Dynamic coronary roadmapping provides in > 98% of cases sufficient roadmap quality with an anatomically correct overlay of the coronary vessels with good inter and intra observer variability. Future randomized studies are warranted to test possible advantages like procedure time reduction and less consumption of contrast medium

MOESM1 of Dynamic coronary roadmapping during percutaneous coronary intervention: a feasibility study

Additional file 2. . Table S1. Baseline characteristics and procedural data of patients undergoing PCI with the use of dynamic coronary roadmapping