Abstract
BackgroundWhole-heart magnetic resonance angiography (MRA) requires sophisticated methods accounting for respiratory motion. Our purpose was to evaluate the image quality of compressed sensing-based respiratory motion-resolved three-dimensional (3D) whole-heart MRA compared with self-navigated motion-corrected whole-heart MRA in patients with known thoracic aorta dilation.MethodsTwenty-five patients were prospectively enrolled in this ethically approved study. Whole-heart 1.5-T MRA was acquired using a prototype 3D radial steady-state free-precession free-breathing sequence. The same data were reconstructed with a one-dimensional motion-correction algorithm (1D-MCA) and an extradimensional golden-angle radial sparse parallel reconstruction (XD-GRASP). Subjective image quality was scored and objective image quality was quantified (signal intensity ratio, SIR; vessel sharpness). Wilcoxon, McNemar, and paired t tests were used.ResultsSubjective image quality was significantly higher using XD-GRASP compared to 1D-MCA (median 4.5, interquartile range 4.5–5.0 versus 4.0 [2.25–4.75]; p < 0.001), as well as signal homogeneity (3.0 [3.0–3.0] versus 2.0 [2.0–3.0]; p = 0.003), and image sharpness (3.0 [2.0–3.0] vs 2.0 [1.25–3.0]; p < 0.001). SIR with the 1D-MCA and XD-GRASP was 6.1 ± 3.9 versus 7.4 ± 2.5, respectively (p < 0.001); while signal homogeneity was 274.2 ± 265.0 versus 199.8 ± 67.2 (p = 0.129). XD-GRASP provided a higher vessel sharpness (45.3 ± 10.7 versus 40.6 ± 101, p = 0.025).ConclusionsXD-GRASP-based motion-resolved reconstruction of free-breathing 3D whole-heart MRA datasets provides improved image contrast, sharpness, and signal homogeneity and seems to be a promising technique that overcomes some of the limitations of motion correction or respiratory navigator gating.
Highlights
Whole-heart magnetic resonance angiography (MRA) requires sophisticated methods accounting for respiratory motion
Overall subjective image quality was rated significantly higher using the motion-resolved reconstruction compared to motion correction (4.5 versus 4.0, p < 0.001), including signal homogeneity and image sharpness (Table 1)
The improved image quality of the motion-resolved reconstruction resulted in higher diagnostic confidence scores (3.0 versus 2.0, p = 0.016)
Summary
Whole-heart magnetic resonance angiography (MRA) requires sophisticated methods accounting for respiratory motion. Whole-heart magnetic resonance angiography (MRA) has been extensively used as a clinical tool to visualize three-dimensional (3D) cardiac anatomy [1]. Diaphragmatic navigators, the only tool clinically available, have several limitations including unpredictable acquisition time and low scan efficiency, which can render the length of the acquisition excessively long, up to 28 min [7,8,9,10]. Self-navigation, employing a radial trajectory combined with one-dimensional correction, has been one of the most widely used investigational approaches which can provide 100% scan efficiency and predictable acquisition times, enabling the application of this technique even in children with limited compliance [17, 18]. Self-navigation suffers from certain limitations that are related to the 1D motion model used for correction [19], which may not be accurate when a wide range of respiratory motion is present [20]
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