Volume growth of abdominal aortic aneurysms correlates with baseline volume and increasing finite element analysis-derived rupture risk.
BACKGROUND
The diagnosis and management of abdominal aortic aneurysms (AAAs) currently relies on the aortic maximal diameter, which grows in an unpredictable manner. Infrarenal aortic volume has recently become clinically feasible to measure, and an estimate of biomechanical rupture risk derived from finite element analysis, the peak wall rupture index (PWRI), has been shown to predict AAA rupture. Our objective was to ascertain how well volume growth correlates with baseline volume and increasing PWRI, compared with the maximal diameter.


METHODS
We retrospectively identified 41 AAA patients (nine women, 32 men) at our institution who had undergone two computed tomography angiographies with an interval of 8 to 17 months. Digital three-dimensional reproductions of the aneurysms were segmented from the 82 computed tomography angiographies. AAA diameter, volume, and PWRI were measured and calculated with finite element analysis software. Growth rates of diameter and volume were related to baseline diameter and volume as well as to change rates of PWRI. Significant growth was defined as growth exceeding our interobserver 95% limits of agreement.


RESULTS
Diameter growth rate did not correlate with baseline diameter (r = 0.15, 95% confidence interval [CI], -0.17 to 0.45), but volume growth rate correlated with baseline volume (r = 0.56; 95% CI, 0.30-0.75). The correlation between baseline volume and volume growth rate was stronger than the correlation between baseline diameter and diameter growth rate (95% CI, 0.086-0.71). Increasing PWRI correlated with volume growth rate (r = 0.70; 95% CI, 0.40-0.87) but not with diameter growth rate (r = 0.044; 95% CI, -0.44 to 0.51), and the difference between the correlation coefficients was significant (95% CI, 0.11-1.16).


CONCLUSIONS
Volume better predicts aneurysm growth rate and correlates stronger with increasing estimated biomechanical rupture risk compared with diameter. Our results support the notion of monitoring all three dimensions of an AAA.
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. Electronic address: moritz.lindquist.liljeqvist@ki.se.
Moritz
M
Lindquist Liljeqvist
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; Department of Vascular Surgery, Karolinska University Hospital, Stockholm, Sweden.
Rebecka
R
Hultgren
Department of Solid Mechanics, School of Engineering Sciences, Royal Institute of Technology, Stockholm, Sweden.
T Christian
TC
Gasser
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; Department of Vascular Surgery, Karolinska University Hospital, Stockholm, Sweden.
Joy
J
Roy
D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging*; D017544:Aortic Aneurysm, Abdominal / Q000150:complications / Q000000981:diagnostic imaging*; D001019:Aortic Rupture / Q000000981:diagnostic imaging / Q000209:etiology*; D001027:Aortography / Q000379:methods*; D019540:Area Under Curve; D000072226:Computed Tomography Angiography / Q000379:methods*; D018450:Disease Progression; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013548:Sweden; D013997:Time Factors