Diagnostic value of [18F]FDG-PET/CT for treatment monitoring in large vessel vasculitis: a systematic review and meta-analysis

Abstract

Purpose Monitoring disease activity in patients with large vessel vasculitis (LVV) can be challenging. [18F]FDG-PET/CT is increasingly used to evaluate treatment response in LVV. In this systematic review and meta-analysis, we aimed to summarize the current evidence on the value of [18F]FDG-PET/CT for treatment monitoring in LVV. Methods PubMed/MEDLINE and the Cochrane library database were searched from inception through October 21, 2020. Studies containing patients with LVV (i.e. giant cell arteritis, Takayasu arteritis and isolated aortitis) that received treatment and underwent [18F]FDG-PET/CT were included. Screening, full-text review and data extraction were performed by 2 investigators. The risk of bias was examined with the QUADAS-2 tool. Meta-analysis of proportions and diagnostic test accuracy was performed by a random-effects model and bivariate model, respectively. Results Twenty-one studies were included in the systematic review, of which 8 studies were eligible for meta-analysis. Arterial [18F]FDG uptake decreased upon clinical remission in longitudinal studies. High heterogeneity (I2 statistic 94%) precluded meta-analysis of the proportion of patients in which the scan normalized during clinical remission. Meta-analysis of cross-sectional studies indicated that [18F]FDG-PET/CT may detect relapsing/refractory disease with a sensitivity of 77% (95%CI 57–90%) and specificity of 71% (95%CI 47–87%). Substantial heterogeneity was observed among the cross-sectional studies. Both variation in clinical aspects and imaging procedures contributed to the heterogeneity. Conclusion Treatment of LVV leads to reduction of arterial [18F]FDG uptake during clinical remission. [18F]FDG-PET/CT has moderate diagnostic accuracy for detecting active LVV. [18F]FDG-PET/CT may aid treatment monitoring in LVV, but its findings should be interpreted in the context of the clinical suspicion of disease activity. This study underlines the relevance of published procedural recommendations for the use of [18F]FDG-PET/CT in LVV.

Whole-Body [18F]FDG PET/CT Can Alter Diagnosis in Patients with Suspected Rheumatic Disease

“…However, with the jugular vein serving as a reference, similar results were obtained (Supplementary Materials Figure S1), further demonstrating that blood pool and liver may be suitable for calculation of target-to-background ratios in the context of GCA/PMR, which is in line with recommendations of current guidelines [8]. Nonetheless, a recent meta-analysis demonstrated that [ 18 F]FDG had only moderate accuracy in detecting active sites of disease in LVV, thereby indicating that PET-based findings should be carefully interpreted in the context of clinical and laboratory parameters [35]. As such, the results of the present proof-of-concept study and herein provided ratios must definitely be confirmed in larger prospective, multi-centric settings, preferably by using phantom studies to provide harmonized semi-quantitative values among multiple PET centers [36].…”

Semi-Quantitative and Quantitative [18F]FDG-PET/CT Indices for Diagnosing Large Vessel Vasculitis: A Critical Review

“…In these trials, consistency and congruency of imaging characteristics are of utmost importance since patients are often imaged at different time points or during treatment. Indeed, a recent systematic review suggested that TBR-based semi-quantitative indices might potentially be more responsive to change than composite scores based on visual assessment [ 36 ]. The best parameter to be applied in clinical studies is yet to be determined, and well-designed clinical trials may provide an answer to the value and indication of quantitative PET in LVV.…”

Functionally Heterogenous Macrophage Subsets in the Pathogenesis of Giant Cell Arteritis: Novel Targets for Disease Monitoring and Treatment

“…Recently, imaging techniques such as ultrasonography, detecting the "halo" sign in inflamed cranial and axillary arteries of GCA patients, and 18 F-Fluorodeoxyglucose PET/CT (FDG-PET/CT) are emerging as more sensitive and specific diagnostic tools for GCA [97][98][99]. Although vasculitic lesions as detected by these imaging methods often improve upon treatment-induced remission, vascular abnormalities may still persist despite clinical remission [100,101]. This observation could reflect ongoing smoldering inflammation in the vessel or perhaps post-inflammatory vascular remodeling.…”

“…Apart from blood biomarkers, positron emission tomography combined with computed tomography (PET/CT) is emerging as a potent diagnostic tool for GCA. Visualization of inflammation via [ 18 F]FDG-PET imaging is now a useful tool for diagnosis and monitoring of treatment in GCA [101]. However, [ 18 F]FDG-PET imaging still shows a number of disadvantages.…”

“…[ 18 F]FDG-PET scan relies on glucose uptake of metabolically active immune cells and stromal cells. Treatment with GCs was shown to reduce glycolysis in immune cells and therefore may downmodulate the vascular wall uptake of FGD [101]. Higher [ 18 F]FDG uptake in aging vessels due to changes in metabolic activity, persistent vessel wall remodeling, and atherosclerotic calcifications may also pose a problem in the diagnosis of an aging disease such as GCA [119,120].…”