The purpose of this study is to determine whether Positron Emission Tomography imaging can help to predict the evolutivity of AAA treated with endovascular prosthesis.

Background:

Abdominal Aorta Aneurysm(AAA) is a frequently occurring atherothrombotic disease, linked to male gender and aging. Due to the current aging of the population, the incidence of rupture may be increasing. The clinical evaluation of AAA usually includes a morphological assessment(size and localization) for diagnosis, open surgery or endovascular prosthesis (EVAR) may be indicated to prevent the onset of a rupture which is often lethal. Unfortunately, the durability of endovascular repair of AAA remains uncertain and the rupture risk or endoleaks onset requires continuous surveillance and the conventional imaging by CT scan often fails to predict this negative progression.

Our hypothesis is that the therapeutic efficacity of endovascular surgery in the AAA is linked to the restoration of effective compartmentalization between the blood and the outer wall (removal of the thrombosis interface and blood pressure constraint). Thus, success of EVAR must be followed by the disappearance of adventitial inflammation visualized by metabolic activity in FDG-PET (18FDG uptake) and a normalization of biological markers of the injury. Conversely, the inefficacy of endovascular therapy should result in the persistence of an inflammatory metabolic activity in relation to the saccular endoleak and a persistent elevation of plasma biomarkers.

Primary objective:

The general aim of this pilot study is to assess the effect of endoprosthesis treatment on PET scan functional imaging of AAA.

Materials and method:

Seven French Hospitals will recruit 50 patients presenting a large AAA scheduled for EVAR (Endovascular prosthesis) within one month. A 18FDG PET scan will be added to their conventional follow up (CT scan, usual blood sampling, ECG…) i.e. within one month before endovascular surgery (inclusion visit), at one month and 6 month of follow-up.

Furthermore, biological markers of the inflammation, proteolysis and coagulation potentially related to morphology and evolution of AAA will be investigated by the U698 (National Institute for Medical Research) Unit, implementing already existing database from others cohorts of patients with AAA, including biological samples conserved both by the Nancy clinical investigation center and the (U698) National Institute for Medical Research Unit.

Study duration for a patient: 26 months

Perspectives:

This pilot study will help to assess the effect of EVAR in terms of it functional inflammatory response and determine the required sample size for a future project. Since aneurysm expansion rate varies widely among patients and even for one single patient over time, studying metabolic adventitial immuno-inflammatory activity using 18FDG PET imaging will provide new major informations about the efficacity of endovascular therapy in AAA. Plasma assays will help to identify intermediate biological markers of aneurysm evolutivity after endovascular therapy. Those complementary functional and biological criteria are of paramount importance to improve therapeutic management and prognosis of AAA.

Inclusion Criteria:

• Large AAA scheduled for endovascular surgery within one month
• Written informed consent

Exclusion Criteria:

• Evolutive neoplasm
• Chronic liver disease
• Connective tissue diseases: rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, Crohn's disease, polymyositis/dermatomyositis, mixed connective tissue disease
• Crohn's disease
• Evolutive tuberculosis
• Contraindication to CT scan
• Pregnancy and breastfeeding
• Women of child bearing potential
• Patient unable to understand the study aims
• Patient unable to comply with scheduled visit
• Participation in other investigational studies.