title: A positron emission tomography/computed tomography (PET/CT) evaluation of asymptomatic abdominal aortic aneurysms: another point of view.
abstract: BACKGROUND
  To assess the prevalence of increased (18)F-fluorodeoxyglucose (FDG) uptake in aneurysmal walls, adopting a case-control approach in a population of asymptomatic patients with abdominal aortic aneurysm (AAA).
  
  
  METHODS
  This study included 40 males (mean age: 74 years, range: 59-93 years), consecutive, white Caucasian patients, with asymptomatic infrarenal AAA. The mean diameter of AAA was 4.9 cm (range: 4.8-5.4 cm), detected by computed tomography (CT) scan. Control Subjects: 44 age-matched controls subjects (mean age: 71 years, range: 59-85 years, 24 males, 20 females) who were selected according to a case-control criterion among a population of patients without any clinical evidence of atherosclerotic disease. Patients and controls underwent simultaneous FDG-positron emission tomography (PET) and CT imaging from the skull base to the femoral neck by using an integrated PET/CT scanner. PET/CT studies were analysed both visually and quantitatively. For quantitative analysis, circular CT-based regions of interest (ROIs) were drawn on the AAA, on all the aortic segments, and on the large vessel included in the study (carotid, subclavian, and iliac arteries). FDG uptake was quantified by calculating the mean and maximum standardized uptake values (SUVs) within each ROI and normalizing for the blood-pool SUV to obtain the final target-to-background ratio. Arterial calcium load was graded according to a semiquantitative five-point scale based on calcification of the arterial ring.
  
  
  RESULTS
  Metabolic activity in the aneurysmal aortic segment was even lower with respect to both the adjacent--nonaneurysmal--samples of patient group and the corresponding arterial segments of control subjects (P < 0.001 and P < 0.01, respectively). In visual analysis, no patients showed an increased focal uptake of degree adequate to identify the aneurysmal arterial wall. AAA patients showed significantly higher values of total calcium load (ACL) than controls in ascending aorta and subclavian and iliac arteries (P < 0.01), and only in AAA patient group, a significant correlation was present between values of ACL in both iliac arteries and abdominal aorta on one side and wall metabolic activity in the same arteries on the other (P < 0.05).
  
  
  CONCLUSIONS
  In conclusion, our results suggest that FDG hot spot, as well an increased diffuse uptake of FDG, in PET/CT studies is an extremely rare finding in patients with AAA of diameter close to surgical indications.
authors.affiliation: Division of Vascular and Endovascular Surgery, IRCCS San Martino University Hospital-IST, University of Genoa, Genoa, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Palombo
authors.forename: Silvia
authors.initials: S
authors.lastname: Morbelli
authors.forename: Giovanni
authors.initials: G
authors.lastname: Spinella
authors.forename: Bianca
authors.initials: B
authors.lastname: Pane
authors.forename: Cecilia
authors.initials: C
authors.lastname: Marini
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Rousas
authors.forename: Michela
authors.initials: M
authors.lastname: Massollo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cittadini
authors.forename: Dario
authors.initials: D
authors.lastname: Camellino
authors.forename: Gianmario
authors.initials: G
authors.lastname: Sambuceti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18