Abstract
BackgroundWe aimed to assess the feasibility of 3 dimensional (3D) respiratory and ECG gated, gadolinium enhanced magnetic resonance angiography (MRA) on a 3 Tesla (3 T) scanner for imaging pulmonary veins (PV) and left atrium (LA). The impact of heart rate (HR) and rhythm irregularity associated with atrial fibrillation (AF) on image and segmentation qualities were also assessed.Methods101 consecutive patients underwent respiratory and ECG gated (ventricular end systolic window) MRA for pre AF ablation imaging. Image quality (assessed by PV delineation) was scored as 1 = not visualized, 2 = poor, 3 = good and 4 = excellent. Segmentation quality was scored on a similar 4 point scale. Signal to noise ratios (SNRs) were calculated for the LA, LA appendage (LAA), and PV. Contrast to noise ratios (CNRs) were calculated between myocardium and LA, LAA and PV, respectively. Associations between HR/rhythm and quality metrics were assessed.Results35 of 101 (34.7%) patients were in AF at time of MRA. 100 (99%) patients had diagnostic studies, and 91 (90.1%) were of good or excellent quality. Overall, mean ± standard deviation (SD) image quality score was 3.40 ± 0.69. Inter observer agreement for image quality scores was substantial, (kappa = 0.68; 95% confidence interval (CI): 0.46, 0.90). Neither HR adjusting for rhythm [odds ratio (OR) = 1.03, 95% CI = 0.98,1.09; p = 0.22] nor rhythm adjusting for HR [OR = 1.25, 95% CI = 0.20, 7.69; p = 0.81] demonstrated association with image quality. Similarly, SNRs and CNRs were largely independent of HR after adjusting for rhythm. Segmentation quality scores were good or excellent for 77.3% of patients: mean ± SD score = 2.91 ± 0.63, and scores did not significantly differ by baseline rhythm (p = 0.78).Conclusions3D respiratory and ECG gated, gadolinium enhanced MRA of the PVs and LA on a 3 T system is feasible during ventricular end systole, achieving high image quality and high quality image segmentation when imported into electroanatomic mapping systems. Quality is independent of HR and heart rhythm for this free breathing, radiation free, alternative strategy to current MRA or CT based approaches, for pre AF ablation imaging of PVs and LA.
Highlights
We aimed to assess the feasibility of 3 dimensional (3D) respiratory and ECG gated, gadolinium enhanced magnetic resonance angiography (MRA) on a 3 Tesla (3 T) scanner for imaging pulmonary veins (PV) and left atrium (LA)
PV isolation guided by image integration was associated with reduced atrial fibrillation (AF) recurrence in comparison with PV isolation guided by three dimensional (3D) electroanatomical mapping alone based on registry data from 573 patients undergoing catheter ablation for paroxysmal AF [10]; randomized trials of AF ablation guided by 3D electroanatomical mapping alone versus with image integration have shown no difference in AF outcomes [8,9]
In our study, we found that free breathing 3D respiratory and ECG gated gadolinium enhanced MRA of the LA and PVs on a 3 T system is both feasible and reproducible, achieving diagnostic images in almost all patients (99%) and good or excellent diagnostic quality images in 90% of patients
Summary
We aimed to assess the feasibility of 3 dimensional (3D) respiratory and ECG gated, gadolinium enhanced magnetic resonance angiography (MRA) on a 3 Tesla (3 T) scanner for imaging pulmonary veins (PV) and left atrium (LA). Computerized tomography (CT) or cardiovascular magnetic resonance (CMR) evaluation of the left atrium (LA) and pulmonary vein (PV) anatomy prior to catheter ablation is considered appropriate [3]. Such imaging provides accurate visualization of highly variable PV and LA anatomy, facilitates image integration with electroanatomic mapping systems, and demonstrates the atrioesophageal relationship that is important for risk assessment of thermal esophageal injury. Integration of preacquired cardiac images with electroanatomic mapping to guide catheter ablations is feasible and inconsistently reported to improve procedural success, reduce procedure duration, fluoroscopy time and occurrence of PV stenosis, compared to conventional electroanatomic mapping alone [4,5,6,7,8,9,10]. PV isolation guided by image integration was associated with reduced AF recurrence in comparison with PV isolation guided by three dimensional (3D) electroanatomical mapping alone based on registry data from 573 patients undergoing catheter ablation for paroxysmal AF [10]; randomized trials of AF ablation guided by 3D electroanatomical mapping alone versus with image integration have shown no difference in AF outcomes [8,9]
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