Morphological analysis of hostile neck anatomy in abdominal aortic aneurysm with consecutive 6-months computed tomography angiography - a cohort study

Abstract

Background: The infrarenal neck is a crucial anatomical segment for the repair of abdominal aortic aneurysm (AAA), requiring special attention when hostile neck features are present. The aim of the study was to perform a detailed morphological analysis of neck anatomy, hostility, progression and a prediction of neck length in the presence of AAA.

Methods: In total 625 computed tomography angiographies (CTAs) of 114 patients, diagnosed with infrarenal AAA, were included. CTA-scanning was performed in six month-intervals. Neck characteristics were assessed by determining length, diameter, angulation, shape, calcification and thrombus, and depending on these six parameters necks were classified in non-hostile, single-hostile or multiple-hostile. Moreover, a prediction model for neck length decline was established.

Results: AAAs showed neck deterioration over time, with a 0.6 mm decrease in neck length for 1.0 mm increase in AAA diameter. Multiple-hostile neck characteristics were more common when the maximum AAA diameter exceeded 45 mm (p = 0.003) or when the AAA volume increased to above 100 ml (p = 0.029). At baseline, 39% of patients exhibited multiple-hostile neck anatomy compared to 52% at the last available measurement (p = < 0.001), underlining the continuous progression of neck hostility. Single signs of hostile neck features in patients with AAAs <45 mm predicted for future neck hostility progression in one third of patients.

Conclusion: The neck deteriorates over time as AAA progresses in size, with development of neck hostility even before the maximum aortic diameter reaches the current threshold for repair of 50 mm/55 mm (women/men). The progressive nature of neck anatomy should be carefully considered when surveilling AAA patients and selecting them for future endovascular or open repair.

Keywords: abdominal aortic aneurysm; endovascular aortic repair; hostile neck; infrarenal neck.