Abstract
PurposeTo develop an accelerated and nonrigid motion‐compensated technique for efficient isotropic 3D whole‐heart coronary magnetic resonance angiography (CMRA) with Cartesian acquisition.MethodsHighly efficient whole‐heart 3D CMRA was achieved by combining image reconstruction from undersampled data using compressed sensing (CS) with a nonrigid motion compensation framework. Undersampled acquisition was performed using a variable‐density Cartesian trajectory with radial order (VD‐CAPR). Motion correction was performed in two steps: beat‐to‐beat 2D translational correction with motion estimated from interleaved image navigators, and bin‐to‐bin 3D nonrigid correction with motion estimated from respiratory‐resolved images reconstructed from undersampled 3D CMRA data using CS. Nonrigid motion fields were incorporated into an undersampled motion‐compensated reconstruction, which combines CS with the general matrix description formalism. The proposed approach was tested on 10 healthy subjects and compared against a conventional twofold accelerated 5‐mm navigator‐gated and tracked acquisition.ResultsThe proposed method achieves isotropic 1.2‐mm Cartesian whole‐heart CMRA in 5 min ± 1 min (~8× acceleration). The proposed approach provides good‐quality images of the left and right coronary arteries, comparable to those of a twofold accelerated navigator‐gated and tracked acquisition, but scan time was up to about four times faster. For both coronaries, no significant differences (P > 0.05) in vessel sharpness and length were found between the proposed method and reference scan.ConclusionThe feasibility of a highly efficient motion‐compensated reconstruction framework for accelerated 3D CMRA has been demonstrated in healthy subjects. Further investigation is required to assess the clinical value of the method.
Highlights
Coronary artery disease (CAD) remains the leading cause of death worldwide, affecting both men and women in developed and developing countries
We propose a motion-compensated reconstruction framework for accelerated 3D Coronary magnetic resonance angiography (CMRA), which combines a compressed sensing (CS)-based undersampled reconstruction with the nonrigid motion compensation strategy proposed by Cruz et al [19,31], to further accelerate the scan and, enable isotropic Cartesian CMRA acquisitions
Motion correction was achieved in two steps: 1) 2D image navigators (iNAVs) are used to estimate beat-to-beat translational motion, which is used to group data into respiratory bins and correct for intra-bin 2D translational motion in k-space; 2) These highly undersampled bins are reconstructed, by solving a total variation (TV)-based CS problem using MFISTA, and used to estimate 3D bin-to-bin nonrigid motion
Summary
Coronary artery disease (CAD) remains the leading cause of death worldwide, affecting both men and women in developed and developing countries. Respiratory 1D self-navigation techniques have been proposed as an alternative approach to compensate for respiratory motion while increasing scan efficiency [7,8,9,10] These methods estimate the translational displacement of the heart due to respiration in the SI direction directly from the data. Several motion compensation approaches have been recently proposed to achieve high scan efficiency and correct for more complex motion in fully sampled free-breathing acquisitions, allowing reduced and predictable scan times These approaches correct for beat-to-beat translational motion based on two-dimensional (2D) or three-dimensional (3D) image navigators (iNAVs) [11,12,13,14] or correct for more complex affine motion, estimating motion from iNAVs [15] or the data itself [16,17,18]. A method has been proposed that combines beat-to-beat 2D translational correction with bin-to-bin 3D nonrigid motion correction [19]
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