Efficient non-contrast enhanced 3D Cartesian cardiovascular magnetic resonance angiography of the thoracic aorta in 3 min

Abstract

Background The application of cardiovascular magnetic resonance angiography (CMRA) for the assessment of thoracic aortic disease is often associated with prolonged and unpredictable acquisition times and residual motion artefacts. To overcome these limitations, we have integrated undersampled acquisition with image-based navigators and inline non-rigid motion correction to enable a free-breathing, contrast-free Cartesian CMRA framework for the visualization of the thoracic aorta in a short and predictable scan of 3 min. Methods 35 patients with thoracic aortic disease (36 ± 13y, 14 female) were prospectively enrolled in this single-center study. The proposed 3D T2-prepared balanced steady state free precession (bSSFP) sequence with image-based navigator (iNAV) was compared to the clinical 3D T2-prepared bSSFP with diaphragmatic-navigator gating (dNAV), in terms of image acquisition time. Three cardiologists blinded to iNAV vs. dNAV acquisition, recorded image quality scores across four aortic segments and their overall diagnostic confidence. Contrast ratio (CR) and relative standard deviation (RSD) of signal intensity (SI) in the corresponding segments were estimated. Co-axial aortic dimensions in six landmarks were measured by two readers to evaluate the agreement between the two methods, along with inter-observer and intra-observer agreement. Kolmogorov–Smirnov test, Mann–Whitney U (MWU), Bland–Altman analysis (BAA), intraclass correlation coefficient (ICC) were used for statistical analysis. Results The scan time for the iNAV-based approach was significantly shorter (3.1 ± 0.5 min vs. 12.0 ± 3.0 min for dNAV, P = 0.005). Reconstruction was performed inline in 3.0 ± 0.3 min. Diagnostic confidence was similar for the proposed iNAV versus dNAV for all three reviewers (Reviewer 1: 3.9 ± 0.3 vs. 3.8 ± 0.4, P = 0.7; Reviewer 2: 4.0 ± 0.2 vs. 3.9 ± 0.3, P = 0.4; Reviewer 3: 3.8 ± 0.4 vs. 3.7 ± 0.6, P = 0.3). The proposed method yielded higher image quality scores in terms of artefacts from respiratory motion, and non-diagnostic images due to signal inhomogeneity were observed less frequently. While the dNAV approach outperformed the iNAV method in the CR assessment, the iNAV sequence showed improved signal homogeneity along the entire thoracic aorta [RSD SI 5.1 (4.4, 6.5) vs. 6.5 (4.6, 8.6), P = 0.002]. BAA showed a mean difference of < 0.05 cm across the 6 landmarks between the two datasets. ICC showed excellent inter- and intra-observer reproducibility. Conclusions Thoracic aortic iNAV-based CMRA with fast acquisition (~ 3 min) and inline reconstruction (3 min) is proposed, resulting in high diagnostic confidence and reproducible aortic measurements.

Free-breathing, Contrast Agent–free Whole-Heart MTC-BOOST Imaging: Single-Center Validation Study in Adult Congenital Heart Disease

“…When these data were not available, independent review by two experts (consultant cardiologists specialized in ACHD and in MRI in ACHD, each with 15 years of experience), blinded to participant information, was obtained. The data anonymization, randomization, and scoring criteria, as based on previous studies ( 14 – 16 ), are detailed in Appendix S3 .…”

Simultaneous Highly Efficient Contrast‐Free Lumen and Vessel Wall MR Imaging for Anatomical Assessment of Aortic Disease

“…Before visual evaluation, the readers were given training datasets with poor to excellent image quality to calibrate their scores together. Training datasets for the corresponding image quality scores have been demonstrated in a previous study 16 . Following this training session, each reader was blinded to the image acquisition type, reconstruction method, the other readers' evaluations, and clinical history for independent evaluation.…”

“…To further remove respiratory‐induced blurring, a self‐navigated sequence was combined with a respiratory‐resolved reconstruction (XD‐GRASP), resulting in improved image quality compared to self‐navigation alone, enabling whole thoracic aortic imaging with a spatial resolution of 1.7 mm isotropic from a scan with 6 minutes 14,15 . More recently, a highly efficient approach for aortic MR angiography in 3 minutes has been introduced, with a 1.6 mm isotropic resolution 16 . Using a Cartesian trajectory with spiral profile order with 3‐fold acceleration factor and combined with an image‐navigator approach to enable nonrigid respiratory motion correction, images of comparable quality to conventional diaphragmatic navigator gating were obtained, but in a fraction of the scan time 16 …”

“…14,15 More recently, a highly efficient approach for aortic MR angiography in 3 minutes has been introduced, with a 1.6 mm isotropic resolution. 16 Using a Cartesian trajectory with spiral profile order with 3-fold acceleration factor and combined with an image-navigator approach to enable nonrigid respiratory motion correction, images of comparable quality to conventional diaphragmatic navigator gating were obtained, but in a fraction of the scan time. 16 On the other hand, black-blood imaging is generally acquired under breath-hold utilizing two-dimensional (2D) spin-echo sequences in different orientations.…”

“…16 Using a Cartesian trajectory with spiral profile order with 3-fold acceleration factor and combined with an image-navigator approach to enable nonrigid respiratory motion correction, images of comparable quality to conventional diaphragmatic navigator gating were obtained, but in a fraction of the scan time. 16 On the other hand, black-blood imaging is generally acquired under breath-hold utilizing two-dimensional (2D) spin-echo sequences in different orientations. This approach is utilized for evaluation of the aortic wall for hematoma or other causes of thickening, along with the quantification of plaque burden and detection of thrombus.…”