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Introduction. 18F-FDG-PET visualises inflammation. Both atherosclerosis and giant cell arteritis cause vascular inflammation, but distinguishing the two may be difficult. The goal of this study was to assess interobserver agreement and diagnostic accuracy of 18F-FDG-PET for the detection of large artery involvement in giant cell arteritis (GCA). Methods. 31 18F-FDG-PET/CT scans were selected from 2 databases. Four observers assessed vascular wall 18F-FDG uptake, initially without and subsequently with predefined observer criteria (i.e., vascular wall 18F-FDG uptake compared to liver or femoral artery 18F-FDG uptake). External validation was performed by two additional observers. Sensitivity and specificity of 18F-FDG-PET were determined by comparing scan results to a consensus diagnosis. Results. The highest interobserver agreement (kappa: 0.96 in initial study and 0.79 in external validation) was observed when vascular wall 18F-FDG uptake higher than liver uptake was used as a diagnostic criterion, although agreement was also good without predefined criteria (kappa: 0.68 and 0.85). Sensitivity and specificity were comparable for these methods. The criterion of vascular wall 18F-FDG uptake equal to liver 18F-FDG uptake had low specificity. Conclusion. Standardization of image assessment for vascular wall 18F-FDG uptake promotes observer agreement, enables comparative studies, and does not appear to result in loss of diagnostic accuracy compared to nonstandardized assessment. [ABSTRACT FROM AUTHOR]

Objective To determine the current status of positron emission tomography (PET) as a tool for diagnosis and monitoring of peripheral inflammatory arthritis (IA). Methods For conducting this systematic review, the PubMed (Medline), Embase, and Cochrane Library databases were searched until December 31, 2012. Studies of PET for diagnosis and/or therapy monitoring of peripheral IA were included. Data were summarized qualitatively using best evidence synthesis. Results Eighteen articles met our inclusion criteria. The majority of studies were feasibility studies with varying methods applied. All studies demonstrated that PET visualized IA with high sensitivity, corresponding to clinical assessments. PET outcome of clinically active IA also matched that of ultrasound and magnetic resonance imaging. PET differentiates from other modalities by (quantitative) imaging of molecular sites in the synovium. The first studies reporting on the potential clinical applications of PET to image subclinical synovitis in preclinical RA and during therapy have been published. The results are promising, but the number and study populations of these studies are still limited. Conclusion Thus far, a limited number of PET studies addressing IA imaging have been published. The PET modality seems to offer highly sensitive and potentially specific imaging of IA at the (quantitative) molecular level. Clinical application studies for early diagnostics and therapy monitoring are arising, but these topics should be further explored in future studies with larger cohorts. For integration in clinical practice, aspects such as radiation burden and cost-effectiveness should also be taken into account. [ABSTRACT FROM AUTHOR]