Contrast inhomogeneity in CT angiography of the abdominal aortic aneurysm

• Authors: Elizabeth George, Brigham and Women’s Hospital; Andreas A. Giannopoulos, Brigham and Women’s Hospital; Ayaz Aghayev, Brigham and Women’s Hospital; Saurabh Rohatgi, Emory University; Amir Imanzadeh, Brigham and Women’s Hospital; Antonios P. Antoniadis, Guy’s and St Thomas NHS Foundation; Kanako K. Kumamaru, Juntendo University; Yiannis S. Chatzizisis, University of Nebraska Medical Center; Ruth Dunne, Brigham and Women’s Hospital; Michael Steigner, Brigham and Women’s Hospital; Michael Hanley, University of Virginia Health System; Edwin C. Gravereaux, Brigham and Women’s Hospital; Frank J. Rybicki, University of Ottawa; Dimitrios Mitsouras, Brigham and Women’s Hospital
• Journal Title: Journal of Cardiovascular Computed Tomography
• Volume: Volume 10, Number 2
• Publisher: Elsevier | 2016-03-01, Pages 179-183
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1016/j.jcct.2015.11.006
• Subjects: Health Sciences, Radiology; Health Sciences, Medicine and Surgery
• Keywords: Science & Technology; Life Sciences & Biomedicine; Cardiac & Cardiovascular Systems; Radiology, Nuclear Medicine & Medical Imaging; Cardiovascular System & Cardiology; CT angiography; Abdominal aortic aneurysm; Risk stratification; Contrast inhomogeneity; Aneurysm growth; COMPUTED-TOMOGRAPHY ANGIOGRAPHY; FOR-VASCULAR-SURGERY; PRACTICE GUIDELINES; RISK-FACTORS; SURVEILLANCE; RUPTURE; SOCIETY; STRESS; METAANALYSIS; ASSOCIATION

Abstract

Background If undetected, infrarenal Abdominal Aortic Aneurysm (AAA) growth can lead to rupture, a high-mortality complication. Some AAA patients exhibit inhomogeneous luminal contrast attenuation at first-pass CT angiography (CTA). This study assesses the association between this observation and aneurysm growth. Methods Sixty-seven consecutive pre-repair AAA CTAs were included in this retrospective study. The “Gravitational Gradient” (GG), defined as the ratio of the mean attenuation in a region-of-interest placed posteriorly to that in a region-of-interest placed anteriorly within the lumen of the aortic aneurysm on a single axial slice, and the maximum aneurysm diameter were measured from each CT data set. “AAA Contrast Inhomogeneity” was defined as the absolute value of the difference between the GG and 1.0. Univariate and multivariate logistic regression was used to assess the association of aneurysm growth >0.4 and >1.0 cm/year to AAA Contrast Inhomogeneity, aneurysm diameter, patient characteristics and cardiovascular co-morbidities. Results AAA Contrast Inhomogeneity was not correlated to aneurysm diameter (p=0.325). In multivariable analysis that included initial aneurysm diameter and AAA Contrast Inhomogeneity, both factors were significantly associated with rapid aneurysm growth (initial diameter: p=0.0029 and 0.011, and, AAA Contrast Inhomogeneity: p=0.045 and 0.048 for growth >0.4 cm/year and >1 cm/year respectively). Conclusions AAA Contrast Inhomogeneity is a common observation in first-pass CTA. It is associated with rapid aneurysm growth, independent of and incremental to aneurysm diameter.