Evaluation of the relationship between atherosclerotic thoracic aortic calcification and quantitative flow parameters using 4D flow MRI.

Atherosclerosis causes abnormal blood flow. Four-dimensional (4D) magnetic resonance imaging (MRI) is a recently developed technique that can be used to quantify abnormal blood flow. Several blood flow parameters may reflect thoracic aortic calcification (TAC). The aim of this study was to evaluate the relationship between quantitative blood flow parameters and TAC, using 4D flow MRI. We retrospectively evaluated patients with TAC and divided them into no, mild, and severe TAC groups using the Agatston score which is usually used to evaluate coronary artery calcification (0, < 400, and ≥ 400, respectively). The following blood flow parameters were calculated for all patients: mean thoracic aorta volume (mTAV), energy loss (EL), vorticity, and helicity (average (ave), maximum (max), and minimum (min) values for each of the latter three). The values for EL, vorticity, and helicity were also divided by the mTAV values. The correlations between the Agatston score and the blood flow parameters were also determined. Data for 272 patients were analyzed; 98 patients with no TAC, 68 patients with mild TAC; and 106 patients with severe TAC. Significant differences between the groups were found for mTAV, and certain measurements for EL, vorticity, and helicity. Several blood flow parameters were significantly weakly positively correlated with the Agatston score (e.g., vorticity ave and min, helicity left screw ave/mTAV, helicity left screw min/mTAV). Other parameters were significantly weakly negatively correlated with the Agatston score (e.g., vorticity max/mTAV, Hel max/mTAV). 4D MRI offers promising potential for evaluating TAC through quantitative blood flow parameters. Nevertheless, careful interpretation is needed to understand which physiological aspects these parameters reflect, given the study's limitations, such as age-related confounding and modest associations. Further studies are needed to determine whether these quantitatively measuring parameters can be clinically useful for diagnosis, severity grading, and prediction thoracic calcification.