Value of volume measurements in evaluating abdominal aortic aneurysms growth rate and need for surgical treatment.
OBJECTIVE
To examine whether indices other than the traditionally used abdominal aortic aneurysm (AAA) maximum diameter, such as AAA volume, intraluminal thrombus (ILT) thickness and ILT volume, may be superior to evaluate aneurismal enlargement.


METHODS
Thirty-four small AAAs (initially presenting a maximum diameter <5.5cm which is the threshold for surgical repair) with an initial and a follow-up CT were examined. Median increase and percentile annual change of these variables was calculated. Correlation between growth rates as determined by the new indices under evaluation and those of maximum diameter were assessed. AAAs were divided according to outcome (surveillance vs. elective repair after follow-up which is based on the maximum diameter criterion) and according to growth rate (high vs. low) based on four indices. Contingency between groups of high/low growth rate regarding each of the four indices on one hand and those regarding need for surgical repair on the other was assessed.


RESULTS
A strong correlation between growth rates of maximum diameter and those of AAA and ILT volumes could be established. Evaluation of contingency between groups of outcome and those of growth rate revealed significant associations only for AAA and ILT volumes. Subsequently AAAs with a rapid volumetric increase over time had a likelihood ratio of 10 to be operated compared to those with a slower enlargement. Regarding increase of maximum diameter, likelihood ratio between AAAs with rapid and those with slow expansion was only 3.


CONCLUSIONS
Growth rate of aneurysms regarding 3Dimensional indices of AAA and ILT volumes is significantly associated with the need for surgical intervention while the same does not hold for growth rates determined by 2Dimensional indices of maximum diameter and ILT thickness.
Department of Vascular Surgery, University of Crete Medical School, Heraklion, Greece. Electronic address: kontopodisn@yahoo.gr.
Nikolaos
N
Kontopodis
Institute of Applied and Computational Mathematics, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece. Electronic address: emmetaxa@gmail.com.
Eleni
E
Metaxa
Institute of Applied and Computational Mathematics, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece. Electronic address: yannisp@iacm.forth.gr.
Yannis
Y
Papaharilaou
Vascular Surgery Department, "Demokritus" University of Thrace Medical School, Alexandroupolis, Greece. Electronic address: efstratiosgeorg@gmail.com.
Efstratios
E
Georgakarakos
Interventional Radiology Unit, Department of Radiology, University of Crete Medical School, Heraklion, Crete, Greece. Electronic address: tsetis@med.uoc.gr.
Dimitris
D
Tsetis
Department of Vascular Surgery, University of Crete Medical School, Heraklion, Greece. Electronic address: ioannou@med.uoc.gr.
Christos V
CV
Ioannou
D000368:Aged; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery; D018450:Disease Progression; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008137:Longitudinal Studies; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D018579:Patient Selection; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity
AAA diameter; AAA expansion; AAA volume; Intraluminal thrombus thickness; Intraluminal thrombus volume; Rupture risk