ECG and navigator‐free four‐dimensional whole‐heart coronary MRA for simultaneous visualization of cardiac anatomy and function

Abstract

Purpose To develop a cardiac and respiratory self-gated 4D coronary MRA technique for simultaneous cardiac anatomy and function visualization. Methods A contrast-enhanced, ungated spoiled gradient echo sequence with self-gating (SG) and 3DPR trajectory was used for image acquisition. Data was retrospectively binned into different cardiac and respiratory phases based on information extracted from SG projections using principal component analysis. Each cardiac phase was reconstructed using a respiratory motion-corrected self-calibrating SENSE framework, and those belong to the quiescent period were retrospectively combined for coronary visualization. Healthy volunteer studies were conducted to evaluate the efficacy of the SG method, the accuracy of the left ventricle (LV) function parameters and the quality of coronary artery visualization. Results SG performed reliably for all subjects including one with poor ECG. The LV function parameters showed excellent agreement with those from a conventional cine protocol. For coronary imaging, the proposed method yielded comparable apparent SNR and coronary sharpness and lower apparent CNR on three subjects compared with an ECG and navigator-gated Cartesian protocol and an ECG-gated, respiratory motion-corrected 3DPR protocol. Conclusion A fully self-gated 4D whole-heart imaging technique was developed, potentially allowing cardiac anatomy and function assessment from a single measurement.

Free breathing whole-heart 3D CINE MRI with self-gated Cartesian trajectory

“…Examples of self-gated 3D non-Cartesian trajectories include 3D spiral phyllotaxis [17], [18], 3D Projection Reconstruction (PR) [19] and 3D stack of stars golden radial trajectory [20], [21]. For better signal contrast between blood and myocardium, especially required for coronary imaging, preparation pulses and fat saturation pulses are interspersed in the data acquisition [17], [18], [19]. For spiral phyllotaxis [17], [18] and 3D PR [19] trajectories, the respiratory self-navigation is usually obtained from a k-space readout along the superior inferior (SI) direction, regularly interleaved in the acquired data.…”

Two-dimensional XD-GRASP provides better image quality than conventional 2D cardiac cine MRI for patients who cannot suspend respiration

“…The assessment of this new approach is currently underway and will be validated in patient studies in future works. In addition, the motion detection can also be improved in 3D imaging, where a self-navigation readout can be periodically inserted during data acquisitions for motion detection, as previously demonstrated in [28]. These potential directions will be further explored in future work.…”

Fully automated left ventricle function analysis with self-gated 4D MRI

“…From each dataset, a 16-phase whole-heart cine series was reconstructed using the methods proposed in [1]. Then, the following steps were taken to automatically derive the LV volume from the 16-phase series: first, an unbiased template was constructed by iteratively averaging all cardiac phases with motion correction; second, the template LV was segmented out using atlas-based joint label fusion [2] with a diffeomorphic registration [3]; finally, the template LV segmentation was warped back to the 16 phases using the inverse transforms and corrective learning [4].…”