Abstract Introduction Contrast-enhanced (CE) angiography is currently the gold-standard for the evaluation of the aorta in magnetic resonance imaging (MRI). While modern gadolinium-containing contrast agents (CA) have a favorable safety profile, there is great interest in contrast-free techniques due to financial, environmental and safety-issues. Contrast-free steady-state-free-precession (SSFP) sequences for MR-angiography are available but have not been systematically compared to the gold standard of CE-angiography. Methods Between February 2022 and January 2024, a total of 54 patients with an indication for CA angiography of the thoracic aorta have been prospectively included for an intra-individual comparison of CE-angiography with SSFP-angiography before and after CA application. Reformatting and co-registering into corresponding vessel cross-sections, signal to noise ratio (SNR) of the lumen in the ascending aorta as well as maximum diameter measurements at seven prespecified locations (aortic root, sino-tubular Junction (STJ), ascending aorta, proximal aortic arch, medial aortic arch, distal aortic arch, descending thoracic aorta) were performed using an open source DICOM viewing and processing software (Horos, www.horosproject.org). ANOVA was performed to assess mean differences between techniques for SNR. Two-way-ANOVA with post-hoc tests was performed to assess differences in maximum diameter measurements between techniques at all seven measurement locations. A Bland-Altman-analysis was performed for maximum diameter measurements with CE-angiography and SSFP native at the aortic root. Results Five patients had to be excluded due to either incomplete data acquisition or insufficient image quality in one of the three sequences. In the remaining 49 patients, the mean SNR was lower in the CE-angiography compared to both the SSFP-angiography before and after CA application (14.86 vs. 21.3 vs. 22.25, p0.001). While two-way-ANOVA showed statistically significant differences in maximum diameter measurements between the three techniques, the absolute difference was clinically not considered (CE-angio - SSFP native: 0.413 mm, P-value = 0.108 CE-angio - SSFP post CA: 0.558 mm P-value = 0.021). The estimated marginal means for segment-wise measurements are shown in Figure 1. Bland-Altman-Analysis showed minimal bias and acceptable limits of agreement between CE-angiography and SSFP native at the aortic root (Figure 2). Discussion Both SSFP acquisitions showed better signal to noise ratio compared to the CE-angiography, which is partly due to the longer acquisition time. Diameter measuerements showed clinically insignificant lower values for both SSFP acquisitions compared to the CE-angiography, which can be explained by the lower resolution of the CE-angiography with partial-volume-effects. Conclusion SSFP-angiography both before and after CA application is a feasible alternative to CE-angiography in MRI.Estimated Marginal Means Bland-Altman-Plot
Doeblin et al. (Thu,) studied this question.