Introduction: Multi-detector computed tomography (MDCT) has established concerning analysis and quantification of vascular calcification in various vessels. We used MDCT for assessment of plaque architecture in smaller (<50 mm) and larger (≥50 mm) infrarenal abdominal aortic aneurysms (AAA).
Material & Methods: Study included 42 patients (<50 mm: n=20; ≥50 mm: n=22), who all underwent MDCT. Two readers performed quantitative and qualitative analysis, including calculation of calcium scores and measurement of plaque size and thickness. Calcium scores were calculated; t-tests were done to look for statistical differences between calcium scores and density ratios (=calcium score/aortic cross-sectional area). Cardiovascular risk factors were compared in patients with smaller and larger aneurysms.
Results: Calcium scores significantly rose with AAA diameter (mean value in smaller aneurysms: 488.8±375.7; in larger aneurysms: 1,687 ± 923; p< 0.001), but no considerable difference was seen in density ratios. Plaque architecture changed: while larger aneurysms mainly contained thin (1 or 2 mm) or intermediate (3 or 4 mm) plaques in circular or mixed grouped-circular arrangement, smaller aneurysms had thicker (≥5 mm) plaques that covered less than half of vessel circumference. On average, subjects had more than 2 cardiovascular risk factors with hypertension being the most frequent one. Number of cardiovascular risk factors present increased with AAA size, in larger aneurysms patients had 3.0 ± 1.2 risk factors compared to a mean of 1.8 ± 1.1 in smaller aneurysms (p=0.001).
Conclusion: Plaque pattern is different in smaller and larger AAA with thicker and more grouped plaques present in smaller AAA, which might have a stabilizing function on vessel wall.