- Oral presentation
- Open Access
The spatial and temporal fidelity in real-time MRI in patients with sinus rhythm and arrhythmias
© Contijoch et al.; licensee BioMed Central Ltd. 2014
- Published: 16 January 2014
- Ejection Fraction
- Temporal Resolution
- Radial Projection
- Vary Exposure Time
- Cardiac Motion Artifact
Irregularly irregular arrhythmia is difficult to image with conventional cine CMR because arrhythmia rejection and registration-based reconstruction result in cardiac motion artifacts or unachievable breath-hold durations. Undersampled radial trajectories, combined with a suitable non-Cartesian reconstruction algorithm, have the potential to overcome these problems by sampling a small number of radial projections without loss of temporal fidelity associated with temporal regularization. Despite the large number of available real-time reconstruction algorithms and sampling trajectories, there are very few reports regarding optimal values for basic reconstruction parameters such as image exposure time (radial projections per image frame) and temporal resolution (view sharing). Our goal was to address the problem of spatial and temporal fidelity in real-time MRI using automatic active contour segmentation in subjects with sinus rhythm and also patients with irregularly irregular arrhythmias.
Short-axis stacks of images were acquired in 20 subjects using standard retrospective gated bSSFP cine imaging and a golden-angle radial bSSFP trajectory (total views = 4000, views per image = 34) reconstructed into 128 × 128 images via conjugate gradient-SENSE based iterative reconstruction (Gadgetron). Golden-angle radial acquisitions can be reconstructed with a variable number of projections (quantified as the exposure time Te of each frame). In addition, projections can be shared between two adjacent frames resulting in higher reconstructed temporal resolution. Two datasets were reconstructed with varying exposure time (Te = 28 - 840 ms) and temporal resolution (Tr = 2.8 - 96.2 ms) to evaluate the effect on ejection fraction (EF). Global function was assessed via semi-automated segmentation of all phases and all left ventricular slices (ITK-SNAP, Philadelphia PA) in the short-axis stack and EDV, ESV, SV, and EF were measured.
Accurate volume assessment at high spatiotemporal fidelity is possible in patients with irregular arrhythmias with real-time CMR and active contour segmentation. Our estimated values for optimal image exposure time and temporal resolution will guide future consensus regarding these basic reconstruction parameters.
K99-HL108157, R01-HL103723, T32HL007954, T32-EB009384.
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