Ratio of aortic to left ventricle SSFP blood signal in a single 3-chamber view correlates with aortic stenosis severity

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): UK research and Innovation [UKRI Centre for Doctoral Training in AI for Healthcare]. Background Aortic stenosis (AS) is the most common valvular heart disease in developed countries with prevalence increasing with age. CMR is an important tool for the evaluation of AS, co-existing aortic disease and concurrent myocardial abnormalities. Whilst a 3-chamber aortic valve view is standard for most cardiac protocols, a full evaluation of the aortic valve including short-axis cine imaging of the valve and flow imaging in the ascending aorta incurs additional time penalty and is not necessary for all patients. We noted that the SSFP signal of blood in the ascending aorta on a standard 3-chamber view was often reduced in those with aortic stenosis. Our aim was to compare the aortic to left ventricular (LV) blood ratio of SSFP signal with existing gold-standard imaging biomarkers of aortic stenosis. Methods Retrospective analysis of 53 patients with varying aortic stenosis severity. We manually measured a 1–2cm2 region of interest (ROI) in the aorta and LV in end-systole (Figure 1). We compared the signal intensity in the aorta ROI to the LV ROI (Ao:LV) with echocardiography parameters including dimensionless index (DI) and aortic valve maximum velocity (Vmax). Pearson correlation coefficient (R) was used to compare methods. Results Patients (n=53, median age 67 [24–91], 33/53 male) included none or trace AS (n=14), mild AS (n=12), moderate AS (n=8) and severe AS (n=19) according to echocardiography. Median time between CMR and echocardiography was 43 days [1–917]. There was a reasonable correlation (R=0.785, −0.771 respectively) between blood Ao:LV ratio of SSFP signal with DI and Vmax (Figure 2). Conclusion The ratio of blood signal seen in SSFP 3-chamber cine images gives a reasonable approximation to aortic stenosis severity measured using gold-standard echocardiography strategies. It is potentially automatable and may allow identification of the subset of patients whose scans would be enhanced by need of dedicated aortic valve imaging.