Quantitative Aortic Distensibility Measurement Using CT in Patients with Abdominal Aortic Aneurysm: Reproducibility and Clinical Relevance

Abstract

Purpose. To investigate the reproducibility of aortic distensibility (D) measurement using CT and assess its clinical relevance in patients with infrarenal abdominal aortic aneurysm (AAA). Methods. 54 patients with infrarenal abdominal aortic aneurysm were studied to determine their distensibility by using 64-MDCT. Aortic cross-sectional area changes were determined at two positions of the aorta, immediately below the lowest renal artery (level 1.) and at the level of its maximal diameter (level 2.) by semiautomatic segmentation. Measurement reproducibility was assessed using intraclass correlation coefficient (ICC) and Bland-Altman analyses. Stepwise multiple regression analysis was performed to assess linear associations between aortic D and anthropometric and biochemical parameters. Results. A mean distensibility of Dlevel 1. = (1.05 ± 0.22) × 10−5 Pa−1 and Dlevel 2. = (0.49 ± 0.18) × 10−5 Pa−1 was found. ICC proved excellent consistency between readers over two locations: 0.92 for intraobserver and 0.89 for interobserver difference in level 1. and 0.85 and 0.79 in level 2. Multivariate analysis of all these variables showed sac distensibility to be independently related (R2 = 0.68) to BMI, diastolic blood pressure, and AAA diameter. Conclusions. Aortic distensibility measurement in patients with AAA demonstrated high inter- and intraobserver agreement and may be valuable when choosing the optimal dimensions graft for AAA before endovascular aneurysm repair.

A contemporary review of non-invasive methods in diagnosing abdominal aortic aneurysms

“… Above is an example of CT-US fusion measurements with corresponding images along the same plane of the vessel ( 17 ) …”

“…Unlike the other studies looking at aortic anatomical dimensions, Zha et al . ( 17 ) also integrated that of aortic function as characterized by the aneurysmal stiffening as measured by aortic distensibility and its corresponding pulse wave velocity (PWV) to comprehensively evaluate the patients’ AAA. These values were derived by measuring the aortic cross-sectional area changes at two positions: (level 1) immediately below the lowest renal artery and (level 2) at the level of the AAA’s maximal diameter (Fig.…”

“…Zha et al . ( 17 ) described meticulous raw measurements from CT imaging and brachial arterial blood pressure readings, which then had to be incorporated into research software, Matlab (MathWorks, Natwick, MA USA), as well as the use of programming software with Visual C++ (Microsoft, Redmond, WA USA) before multiple contour iterations, and the final contour was adequately defined prior to being able to derive the actual distensibility and PWV measurements. These procedures are probably all too cumbersome and arduous for practical application in the current clinical setting.…”

“…Notably, however, Ruff et al (12) did not specify the age or sex distribution of the population and though they utilized both US and CT, they did not report the quantitative measures of AAA dimensions and their calculated sensitivity/specificity values were estimated with CT imaging after initial screening with US. Claridge et al (13) incorporated the largest sample size, but utilized only CT for (17) Fig. 6.…”

ACR Appropriateness Criteria® Nontraumatic Aortic Disease

“…The CTA 3-D data set can be postprocessed and manipulated perpendicular to the flow lumen, allowing for accurate measurements for longitudinal evaluation of aortic growth and lumen diameters as well as planning for endovascular or surgical treatment [87,94,95]. Even though the maximum diameter of the aorta is the most consistent predictor of future rupture, other CTA findings, such as luminal contrast heterogeneity, intraluminal thrombus volume, aortic wall distensibility, and aneurysm geometry, help identify patients at risk for rupture [96][97][98]. Geometric models from CTA examinations can be used to create computational flow dynamics, which may also be useful in identifying patients with thoracic aortic aneurysms who are at risk for rupture [99].…”