Prediction of Abdominal Aortic Aneurysm Growth Using Geometric Assessment of Computerised Tomography Images Acquired During the Aneurysm Surveillance Period.

OBJECTIVE: We investigated the utility of geometric features for future abdominal aortic aneurysms (AAA) growth prediction.
BACKGROUND: Novel methods for growth prediction of AAA are recognised as a research priority. Geometric feature has been applied to predict cerebral aneurysm rupture, but not examined as predictor of AAA growth.
METHODS: Computerised tomography (CT) scans from patients with infra-renal AAAs were analysed. Aortic volumes were segmented using an automated pipeline to extract AAA diameter (APD), undulation index (UI) and radius of curvature (RC). Using a prospectively recruited cohort, we first examined the relation between these geometric measurements to patients' demographic features (n = 102). A separate 192 AAA patients with serial CT scans during AAA surveillance were identified from an ongoing clinical database. Multinomial logistic and multiple linear regression models were trained and optimized to predict future AAA growth in these patients.
RESULTS: There was no correlation between the geometric measurements and patients' demographic features. APD (spearman r = 0.25, p < 0.05), UI (spearman r = 0.38, p < 0.001) and RC (Spearman r = -0.53, p < 0.001) significantly correlated with annual AAA growth. Using APD, UI and RC as three input variables, the area under receiver operating characteristics curve for predicting slow growth (<2.5 mm/year) or fast growth (>5 mm/year) at 12 months are 0.80 and 0.79, respectively. The prediction or growth rate is within 2 mm error in 87% of cases.
CONCLUSIONS: Geometric features of an AAA can predict its future growth. This method can be applied to routine clinical CT scans acquired from patients during their AAA surveillance pathway.