Morphological analysis of hostile neck anatomy in abdominal aortic aneurysm with consecutive 6-month computed...

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.

In total, 625 computed tomography angiographies (CTAs) of 114 patients, diagnosed with infrarenal AAA, were included. CTA-scanning was performed in 6-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.

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.

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.