Magnetic Resonance Imaging in the Diagnosis of Aortic Wall Elastic Properties Disorders and Its Hemodynamics

Background . Vascular stiffness is an important predictor of cardiovascular disease. The vascular wall biomechanical parameters change not only in patients with genetic disorders of the connective tissue. This means that, regardless of etiology, the early detection of a progressive loss of aortic elasticity is of great clinical importance in preventing the development of severe complications. Assessment of aortic biomechanical parameters using magnetic resonance imaging (MRI) is a new level of visualization for aortic diseases allowing to improve surgical tactics and prevent complications. A number of biomechanical parameters determined by aortic MRI demonstrates the process of its wall remodeling, so their analysis will allow to develope an algorithm for the early diagnosis of aneurysms and the threat of acute aortic syndrome. Objective : using aortic MRI data, to evaluate the aortic biomechanical parameters and hemodynamics at pre- and postoperative stages and their impact on the occurrence of complications and relapses in the long-term period. Material and methods . Between 2020 and 2023, in Petrovsky Russian Scientific Center of Surgery, aortic MRI was performed prospectively before and after surgery in 107 patients with diagnoses of ascending aortic aneurysm (55 patients: 48 (87%) males and 7 (13%) females, mean age 79.4±14.91 years) and DeBakey type I and III aortic dissection, chronic stage (52 patients: 44 (85%) males and 8 (15%) females, mean age 54.32±10.41 years). Results . The quantitative data analysis in the postoperative period showed a decrease in the aortic wall elastic properties in the form of extensibility (0.4 [0.34; 0.54] %/mm Hg in the aneurysm group; 0.5 [0.25; 0.55] %/mmHg in the dissection group) and an increase in stiffness in the form of Young’s modulus (0.6 [0.38; 0.68] MPa in the aneurysm group; 0.5 [0.39; 0.83] MPa in the dissection group). Hemodynamic changes in the dissection group after surgery demonstrated a significant increase in values of maximum velocity in the descending aorta (78.6 [66.24; 130.78] cm/sec) and pressure gradient at the celiac trunk level (2.10 [1.76; 6.84] mm Hg). When assessing the pulse wave velocity parameter in both groups, high values were noted with a tendency to increase after surgery (in the aneurysm group, 7.7 [5.7; 20.3] cm/s before surgery versus 8.7 [6.5; 10.65] cm/s after surgery; in the dissection group, 9.7 [6.8; 12.9] versus 12.7 [7.7; 15.7] cm/s, respectively). Conclusion . Monitoring general hemodynamics and blood flow patterns together with an assessment of the aortic wall elasticity will make it possible to identify patients with borderline aortic dilatation. At the same time, studies of the aortic prosthetic segment are of particular interest. The obtained data on hemodynamic changes occuring at the border of the prosthetic and native segments of the operated aorta can confirm and justify the development of a complication in the form of distal stent graft-induced new entry (dSINE).