title: 18F-FDG uptake in main arterial branches of patients with large vessel vasculitis: visual and semiquantitative analysis.
abstract: OBJECTIVE
  Over the last decade, the contribution of (18)F-FDG (FDG) PET/CT imaging to the diagnosis of large vessel vasculitis has been widely investigated. The aim of this study was to evaluate a more extensive role for PET/CT in grading vascular inflammation in patients with different clinical stages of disease.
  
  
  METHODS
  The images of 66 PET/CT studies of 34 patients, performed at diagnosis and/or during follow-up were reviewed. FDG uptake in different regions of aorta and in its major branches was visually (regional Score: rS) and semiquantitatively (regional SUVmean: rSUV) assessed. The global vascular uptake was also evaluated for each study by summing all rSs (summed Score; sS) and averaging rSUVs (averaged SUV; aSUV). FDG uptake in 15 PET/CT studies of control age-matched subjects without signs or symptoms of vasculitis was also analyzed.
  
  
  RESULTS
  Higher levels of regional and global FDG uptake were found at diagnosis in comparison with follow-up studies of 12 patients with complete longitudinal observation (p value range 0.0552-0.0026). In the latter group high values were generally observed when disease relapse or incomplete response to therapy (active disease) occurred, whereas lower uptake was found in studies of remitted patients (p = <0.01), whose FDG levels were similar to those of control subjects. At ROC analysis performed on all image dataset, optimal cut-off levels of regional and global FDG vascular uptake provided a good discrimination between 25 patients at diagnosis and 15 control subjects (aSUV greater than 0.697; PPV = 92.3; NPV = 92.9). Major overlap was observed among FDG levels of 21 patients with active disease and in remission (aSUV greater than 0.653; PPV = 58.3; NPV = 94.1). Similar performances of visual and semiquantitative analyses were found when areas under curves (AUCs) were compared.
  
  
  CONCLUSIONS
  (18)F-FDG PET/CT has a promising role in grading inflammation in patients with large arteries vasculitis. Nevertheless, a cut-off based analysis of FDG vascular uptake is not sufficient to separate patients with active and inactive disease during follow-up.
authors.affiliation: Department of Nuclear Medicine, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, pad. Granelli, Via F. Sforza, 35, 20122, Milan, Italy. mcastell@policlinico.mi.it.
authors.forename: Massimo
authors.initials: M
authors.lastname: Castellani
authors.affiliation: Department of Nuclear Medicine, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, pad. Granelli, Via F. Sforza, 35, 20122, Milan, Italy.|Department of Health Sciences, University of Milan, Milan, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Vadrucci
authors.affiliation: Department of Nuclear Medicine, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, pad. Granelli, Via F. Sforza, 35, 20122, Milan, Italy.
authors.forename: Luigia
authors.initials: L
authors.lastname: Florimonte
authors.affiliation: Referral Center for Systemic Autoimmune Diseases, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Caronni
authors.affiliation: Department of Nuclear Medicine, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, pad. Granelli, Via F. Sforza, 35, 20122, Milan, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Benti
authors.affiliation: Internal Medicine Department, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Bonara
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001011:Aorta / Q000000981:diagnostic imaging* / Q000378:metabolism*; D001692:Biological Transport; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D012372:ROC Curve; D014657:Vasculitis / Q000000981:diagnostic imaging* / Q000378:metabolism*
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Inflammation; Large vessel vasculitis; PET/CT; SUV analysis