High levels of 18F-FDG uptake in aortic aneurysm wall are associated with high wall stress.
BACKGROUND
Functional imaging using positron emission tomography (PET) showed increased metabolic activities in the aneurysm wall prior to rupture, whereas separate studies using finite element analysis techniques found the presence of high wall stresses in aneurysms that subsequently ruptured. This case series aimed to evaluate the association between wall stress and levels of metabolic activities in aneurysms of the descending thoracic and abdominal aorta.


METHODS
Five patients with aneurysms in the descending thoracic aorta or abdominal aorta were examined using positron emission tomography-computed tomography (PET-CT). Patient-specific models of the aortic aneurysms were reconstructed from CT scans, and wall tensile stresses at peak blood pressure were calculated using the finite element method. Predicted wall stresses were qualitatively compared with measured levels of 18F-fluoro-2-deoxy-glucose (18F-FDG) uptakes in the aneurysm wall.


RESULTS
The distribution of wall stress in the aneurysm wall was highly non-uniform depending on the individual geometry. Predicted high wall stress regions co-localised with areas of positive 18F-FDG uptake in all five patients examined. In the two ruptured cases, the locations of rupture corresponded well with regions of elevated metabolic activity and high wall stress.


CONCLUSIONS
These preliminary observations point to a potential link between high wall stress and accelerated metabolism in aortic aneurysm wall and warrant further large population-based studies.
Xu
X Y
XY
Department of Chemical Engineering, Imperial College London, UK.
Borghi
A
A
Nchimi
A
A
Leung
J
J
Gomez
P
P
Cheng
Z
Z
Defraigne
J O
JO
Sakalihasan
N
N
D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging* / Q000378:metabolism; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging* / Q000378:metabolism; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000378:metabolism; D017545:Aortic Aneurysm, Thoracic / Q000000981:diagnostic imaging* / Q000378:metabolism; D001019:Aortic Rupture / Q000000981:diagnostic imaging* / Q000378:metabolism; D001696:Biomechanical Phenomena; D018450:Disease Progression; D005260:Female; D020342:Finite Element Analysis; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000378:metabolism; D013314:Stress, Mechanical; D013718:Tensile Strength; D014057:Tomography, X-Ray Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18