Improvement in Image Quality and Efficiency of Non-contrast Thoracic MR Angiography: Comparison of a Highly Accelerated Dixon-based Technique with the Conventional Fat-suppressed Technique.

PURPOSE: To compare the image quality and acquisition time of thoracic great vessels using a novel, 3D isotropic non-contrast-enhanced MR angiography that combines respiratory compensation, electrocardiogram-triggering, compressed sensing, and Dixon water-fat separation at 3T (CS-MRA) to a conventional MRA employing parallel imaging and spectral attenuated inversion recovery (cMRA).

METHODS

This study included 20 healthy volunteers and 19 patients with thoracic vascular diseases. All scans were performed on a 3T MRI scanner using a T2-prepared 3D fast low angle shot (FLASH) sequence. Visual image quality of thoracic great vessels was assessed using a 4-point scale. Quantitative parameters including SNR, contrast-to-noise ratio (CNR), contrast ratio (CR), and coefficient of variation (CV) were evaluated. Aortic diameters were measured, and reproducibility was assessed using Bland-Altman analysis and the intraclass correlation coefficient (ICC). Image acquisition times were also compared.

RESULTS

Visual assessment demonstrated significantly higher scores with CS-MRA compared to cMRA across all evaluated thoracic vessels in both volunteers and patients (median score: 3 vs. 2, P < 0.05). Quantitative analysis showed that CS-MRA yielded significantly higher SNR, CNR, and CR (P < 0.05 for all), along with better signal homogeneity (lower CV). CS-MRA showed excellent intra- and inter-observer agreement for aortic diameter measurements, with ICCs ≥ 0.91 in volunteers and ≥ 0.95 in patients. CS-MRA also achieved significantly shorter acquisition times (volunteers: 5.3 ± 1.4 min vs. 6.0 ± 1.7 min, P < 0.01; patients: 5.1 [4.6-6.3] min vs. 6.9 [5.0-9.6] min, P < 0.01).

CONCLUSION

CS-MRA provides superior image quality, comparable measurement reproducibility, and significantly reduced acquisition times compared to cMRA. These findings support the clinical utility of CS-MRA as an efficient and reliable non-contrast technique for thoracic vascular evaluation.