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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.

SUBMITTER: Gutierrez LF

PROVIDER: S-EPMC2677196 | biostudies-literature | 2007 Nov

REPOSITORIES: biostudies-literature

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

Gutiérrez Luis F LF Silva Ranil de Rd Ozturk Cengizhan C Sonmez Merdim M Stine Annette M AM Raval Amish N AN Raman Venkatesh K VK Sachdev Vandana V Aviles Ronnier J RJ Waclawiw Myron A MA McVeigh Elliot R ER Lederman Robert J RJ

Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions 20071101 6

<h4>Background</h4>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.<h4>Me ...[more]

PMID: 18022851

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Project description:BackgroundDecisions in the management of aortic stenosis are based on the peak pressure drop, captured by Doppler echocardiography, whereas gold standard catheterization measurements assess the net pressure drop but are limited by associated risks. The relationship between these two measurements, peak and net pressure drop, is dictated by the pressure recovery along the ascending aorta which is mainly caused by turbulence energy dissipation. Currently, pressure recovery is considered to occur within the first 40-50 mm distally from the aortic valve, albeit there is inconsistency across interventionist centers on where/how to position the catheter to capture the net pressure drop.MethodsWe developed a non-invasive method to assess the pressure recovery distance based on blood flow momentum via 4D Flow cardiovascular magnetic resonance (CMR). Multi-center acquisitions included physical flow phantoms with different stenotic valve configurations to validate this method, first against reference measurements and then against turbulent energy dissipation (respectively n = 8 and n = 28 acquisitions) and to investigate the relationship between peak and net pressure drops. Finally, we explored the potential errors of cardiac catheterisation pressure recordings as a result of neglecting the pressure recovery distance in a clinical bicuspid aortic valve (BAV) cohort of n = 32 patients.ResultsIn-vitro assessment of pressure recovery distance based on flow momentum achieved an average error of 1.8 ± 8.4 mm when compared to reference pressure sensors in the first phantom workbench. The momentum pressure recovery distance and the turbulent energy dissipation distance showed no statistical difference (mean difference of 2.8 ± 5.4 mm, R2 = 0.93) in the second phantom workbench. A linear correlation was observed between peak and net pressure drops, however, with strong dependences on the valvular morphology. Finally, in the BAV cohort the pressure recovery distance was 78.8 ± 34.3 mm from vena contracta, which is significantly longer than currently accepted in clinical practise (40-50 mm), and 37.5% of patients displayed a pressure recovery distance beyond the end of the ascending aorta.ConclusionThe non-invasive assessment of the distance to pressure recovery is possible by tracking momentum via 4D Flow CMR. Recovery is not always complete at the ascending aorta, and catheterised recordings will overestimate the net pressure drop in those situations. There is a need to re-evaluate the methods that characterise the haemodynamic burden caused by aortic stenosis as currently clinically accepted pressure recovery distance is an underestimation.

Project description:BackgroundThe use of ultrasound for procedural guidance is an essential skill in emergency medicine (EM) and a required Accreditation Council for Graduate Medical Education (ACGME) competency for residents. Resident learners develop their skill set through hands-on training and may benefit from an intervention that encourages proper technique, bolsters confidence, and improves procedural success. Clear Guide ONE, a Food and Drug Administration-approved technology, overlays real-time virtual instrument navigation onto ultrasound displays to allow visualization of expected instrument trajectory prior to needle puncture, ensuring alignment with the target.ObjectivesThis study investigated computer-assisted instrument guidance as an educational tool for residents in a simulation environment. Primarily, the study evaluated residents' procedural speed and accuracy using ultrasound with and without the guidance device.MethodsA total of 34 residents were observed performing ultrasound-guided needle placement in ballistic gel models with and without computer assistance in a simulation-based observational crossover study. Scan time before needle insertion, time to target, total procedure time, number of needle redirections, and procedural accuracy were measured. A total of 104 observations were recorded with 52 in each group. Paired-sample t-test analysis was used to compare group performance. Secondary outcomes were derived from survey data assessing resident opinions about the device.ResultsThe computer-guidance group significantly outperformed the ultrasound-alone group in mean time to target, number of needle redirections, and procedural accuracy. There was no significant difference in mean scan time before needle insertion or total procedure time. Fifty percent of residents preferred the guidance system. Most residents (67%, n = 23) reported that the device increased confidence and the majority (94%, n = 32) reported perceived improvement in speed, accuracy, or both.ConclusionsUse of computer assistance technology for sonographic instrument guidance was successful in improving procedural accuracy, number of needle redirections, and time to target performance metrics and was well received by residents. This educational study suggests that this technology may emerge as a valuable tool in training EM residents to utilize ultrasound for procedures.

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

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

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