Elsevier

Journal of Vascular Surgery

Volume 56, Issue 3, September 2012, Pages 802-807
Journal of Vascular Surgery

Basic research study
Inflammation in the walls of asymptomatic abdominal aortic aneurysms is not associated with increased metabolic activity detectable by 18-fluorodeoxglucose positron-emission tomography

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Objective

We hypothesized that the general inflammation observed in the wall of large, asymptomatic abdominal aortic aneurysms (AAAs) could be detected in vivo by 18-fluorodeoxglucose (FDG) positron-emission tomography (PET) and, if so, that this method could be used to study if active inflammation is an early pathogenetic finding in small AAAs detected by screening.

Methods

In this prospective clinical study, 12 men were examined with FDG-PET computed tomography. Seven had large asymptomatic AAAs (range, 52-66 mm) that required surgery, and five had small AAAs (range, 34-40 mm) under surveillance. In the surgery group, biopsy specimens were taken from the aneurysm wall for histologic examinations.

Results

Compared with normal segments of the aorta, liver, and blood and compared with healthy controls matched for age and sex, no increased FDG uptake, measured as standardized uptake value, was detected in any of the large or small AAAs. The SUVmean difference between infrarenal aorta and blood was −0.3 for cases and −0.1 for controls (P = .06). The corresponding differences between the infrarenal aorta and liver was −0.8 and −0.8 (P = .91) and between infrarenal aorta and suprarenal aorta was −0.2 and −0.1 for cases and controls, respectively (P = .20). The histologic examination of the aneurysm walls showed high inflammatory cell infiltration with T lymphocytes, B lymphocytes, and macrophages.

Conclusions

The chronic inflammation observed in the wall of asymptomatic AAAs was not sufficiently metabolically active to result in an increased glucose metabolism detectable by FDG-PET by means of this standard protocol. To study the importance of inflammation in the pathogenesis of AAAs in vivo, PET tracers other than FDG need to be developed.

Clinical Relevance

The etiology of abdominal aortic aneurysms (AAAs) is mostly unknown. Histologic studies have revealed a chronic inflammation in the media of the aortic wall, and recent studies indicate that this inflammation may be detectable by means of 18F-fluorodeoxglucose (FDG) positron-emission tomography (PET)/computed tomography (CT). However, previous reports have predominantly evaluated symptomatic large AAAs, whereas studies on small asymptomatic AAAs are rare. In this study, we hypothesized that the inflammation observed in the wall of large asymptomatic AAAs could be detected in vivo by FDG-PET/CT and, if so, that this method could be used to study if active inflammation is an early pathogenetic finding in small AAAs.

Cited by (0)

This study received funding Swedish Research Council (Grant K2010-65X-20406-04-3) and an Amersham research grant.

Author conflict of interest: none.

The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest.