Journal Article

In Vivo Strain Analysis of Dilated Ascending Thoracic Aorta by ECG-Gated CT Angiographic Imaging

Pilato, Michele, Di Giuseppe, Marzio, Pasta, Salvatore, Raffa, Giuseppe M., Agnese, Valentina, Bellavia, Diego, Gentile, Giovanni

2017

Overview

Accurate assessment of aortic extensibility is a requisite first step for elucidating the pathophysiology of an ascending thoracic aortic aneurysm (ATAA). This study aimed to develop a framework for the in vivo evaluation of the full-field distribution of the aortic wall strain by imaging analysis of electrocardiographic- (ECG) gated thoracic data of 34 patients with ATAA. Seven healthy controls (i.e., non-aneurysmal aorta) from patients who underwent ECG-gated CT angiography for coronary artery diseases were included for comparison. To evaluate the systolic function, ECG-gated computed tomography (CT) angiography was used to generate patient-specific geometric meshes of the ascending aorta, and then to estimate both the displacement and strain fields using a mathematical algorithm. Results evidenced stiff behavior for the aneurysmal aorta compared with that of the healthy ascending aorta of the controls, with patients over 55 years of age displaying significantly lower extensibility. Moreover, the patient risk as quantified by the ratio of in vivo strain to the ruptured one increased significantly with increased systolic blood pressure, older age, and higher pressure-strain modulus. Statistical analysis also indicated that an increased pressure-strain modulus is a risk factor for ATAAs with bicuspid aortic valve, suggesting a different mechanism of failure in these patients. The approach here proposed for the in vivo evaluation of the aortic wall strain is simple and fast, with promising applicability in routine clinical imaging, and could be used to develop a rupture potential criterion on the basis of the aortic aneurysm extensibility.

• Publisher: Springer US,Springer Nature B.V
• Subject: Aged / Aged, 80 and over / Aneurysms / Angiography / Aorta / Aorta, Thoracic - diagnostic imaging / Aorta, Thoracic - physiopathology / Aortic Aneurysm, Thoracic - diagnostic imaging / Aortic Aneurysm, Thoracic - physiopathology / Aortic aneurysms / Aortic valve / Biochemistry / Biological and Medical Physics / Biomedical and Life Sciences / Biomedical Engineering and Bioengineering / Biomedicine / Biophysics / Blood pressure / Cardiac-Gated Imaging Techniques - methods / Classical Mechanics / Compressive Strength / Computed tomography / Computed Tomography Angiography - methods / Computer Simulation / Coronary artery / Coronary vessels / EKG / Elastic Modulus / Elasticity Imaging Techniques - methods / Extensibility / Failure mechanisms / Female / Heart valves / Humans / In vivo methods and tests / Male / Medical imaging / Middle Aged / Models, Cardiovascular / Patients / Radiographic Image Interpretation, Computer-Assisted - methods / Reproducibility of Results / Risk factors / Rupturing / Sensitivity and Specificity / Statistical analysis / Strain analysis / Stress, Mechanical / Tensile Strength / Thorax