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Objectives: To evaluate diagnostic accuracy for active Takayasu arteritis (TAK) for two novel 18 F-fluorodeoxyglucose PET-CT parameters, the inflammatory volume (MIV) and total inflammatory glycolysis (TIG), to quantitate volume of metabolically-active arterial tissue., Methods: From a cohort of TAK (n = 36, 35 immunosuppressive-naïve), images of PET-CTs were reviewed for mean and maximum standardized uptake value (SUV mean and SUV max ), target-to-blood pool ratio (TBR), target-to-liver ratio (TLR), and PET Vasculitis Activity Score (PETVAS). Regions of interest were drawn to semiautomatically calculate MIV in areas of 18 F-fluorodeoxyglucose uptake ≥ 1.5 SUV mean after excluding physiological tracer uptake. TIG was calculated by multiplying MIV with SUV mean . PET-CT parameters, ESR, CRP, and clinical disease activity scores were compared against the gold standard of physician global assessment of disease activity (PGA, active/inactive)., Results: Using dichotomized cut-offs for active TAK at SUV max (≥ 2.21), SUV mean (≥ 1.58), TBR (≥ 2.31), TLR (≥ 1.22), PETVAS (various cut-offs), ESR (≥ 40 mm/hour), and CRP (≥ 6 mg/L), the novel indices MIV (≥ 1.8) and TIG (≥ 2.7) performed similar [area under the receiver operating characteristics curve (AUC) 0.873 for both] to SUV max (AUC 0.841) and SUV mean (AUC 0.851), and better than TBR (AUC 0.773), TLR (AUC 0.773), PETVAS [≥ 5.5 (AUC 0.750), ≥ 10 (AUC 0.636), ≥ 15 (AUC 0.546)], ESR (AUC 0.748), or CRP (AUC 0.731). MIV and TIG had similar agreement with PGA or CRP as with SUV max or SUV mean , and better agreement than TBR, TLR, or PETVAS cut-offs., Conclusions: MIV and TIG performed similarly, therefore, are viable alternatives to existing PET-CT parameters to assess TAK disease activity in this preliminary report. Key Points • MIV and TIG performed similar to SUV max and SUV max for disease activity assessment in TAK. • MIV and TIG distinguished active TAK better than TBR, TLR, PETVAS cut-offs, ESR, or CRP. • MIV and TIG had better agreement with PGA or CRP than TBR, TLR, or PETVAS cut-offs., (© 2023. The Author(s), under exclusive licence to International League of Associations for Rheumatology (ILAR).)

The objective of the study is to investigate the value of 18 F-fluorodeoxyglucose-positron emission tomography/computed tomography ( 18 F-FDG-PET/CT) for assessment of the activity of Takayasu's arteritis (TA) and the correlation between acute-phase reactive proteins (ARPs) and standard uptake value (SUV). Analyses of the clinical characteristics and 42 18 F-FDG-PET/CT scans in 39 TA patients were undertaken. The degree of FDG uptake in the blood vessel walls was assessed quantitatively by SUV. TA activity was analyzed by physician global assessment (PGA). Clinical and 18 F-FDG-PET/CT characteristics were compared between patients with clinically active and clinically inactive TA. Maximum SUV (SUV max ), mean SUV (SUV mean ), and SUV ratio (SUV ratio ) were significantly higher in the clinically active group than in the clinically inactive group (3.63 ± 1.96 vs. 1.82 ± 0.43, p = 0.007; 2.07 ± 0.71 vs. 1.43 ± 0.32, p = 0.009; 2.08 ± 1.17 vs. 0.95 ± 0.19, p = 0.000). Analyses of receiver operating characteristic (ROC) curves revealed a cutoff value of SUV max of 2.21, with sensitivity and specificity of 86.2 and 90.0%, respectively, for clinically active TA. The SUV ratio cutoff was 1.27 with a sensitivity and specificity of 79.3 and 100.0%, respectively. SUV ratio was slightly superior to SUV max and ARPs in the area under the curve (AUC) comparison. SUV max and SUV ratio showed a significant increasing trend with increasing US National Institutes of Health (NIH) score and levels of ARPs, interleukin-6, and serum amyloid-A protein. 18 F-FDG-PET/CT is a promising non-invasive, quantitative measurement with high sensitivity and specificity for determining TA activity.

Purpose: The object of this study was to assess whether 18 F-fluorodeoxyglucose PET/CT (FDG PET/CT) provides novel information in patients with Takayasu's arteritis (TA) in addition to that provided by current activity assessment, to analyse the effects of possible confounders, such as arterial grafts, and to verify whether PET/CT could be informative in lesions <4 mm thick., Methods: We studied 30 patients with TA, evaluated from October 2010 to April 2014 by both PET/CT and magnetic resonance imaging (MRI). All arterial lesions were evaluated by PET both qualitatively (positive/negative) and semiquantitatively (maximum standardized uptake value, SUV max ), and the thickness of lesions in the MRI field of view was evaluated. In a per-patient analysis, the relationships between the PET data and acute-phase reactants and NIH criteria for active TA were evaluated. In a per-lesion analysis, the relationships between the PET features of each lesion and MRI morphological data were evaluated. The effects of the presence of arterial grafts were also evaluated., Results: Increased FDG uptake was seen in 16 of 30 patients (53%) and in 46 of 177 vascular lesions (26%). Significant periprosthetic FDG uptake was seen in 6 of 7 patients (86%) with previous vascular surgery and in 10 of 11 of grafts (91%). Graft-associated uptake influenced the PET results in three patients (10%) and the SUV max values in five patients (17%). Of 39 lesions with significant FDG uptake, 15 (38%) were <4 mm thick. Lesion thickness was correlated with lesion SUV max in FDG-avid lesions only. FDG arterial uptake was not associated with systemic inflammation or NIH criteria., Conclusions: PET/CT reveals unique and fundamental features of arterial involvement in TA. PET/CT may be useful in the assessment of local inflammatory and vascular remodelling events independent of systemic inflammation during follow-up, even in lesions in which the arterial wall is <4 mm. The presence of arterial grafts is a potential confounder. Prospective studies are required to correlate PET findings with relevant clinical outcomes.

Objective: To evaluate (18)F-fluorodeoxyglucose ((18)F-FDG) uptake on positron emission tomography-computed tomography (PET-CT) and serum levels of different cytokines and matrix metalloproteinases (MMPs) in patients with Takayasu arteritis (TA) and associations with disease activity., Methods: Serum levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-2, IL-6, IL-8, IL-12, IL-18, MMP-3 and MMP-9 were measured in 36 TA patients and 36 controls. Maximum standard uptake value (SUVmax) of (18)F-FDG in arterial walls was determined by PET-CT scans. TA patients were classified as active disease, inactive disease and possible active disease., Results: Serum IL-6 and MMP-3 levels were higher in TA patients than in controls (p<0.001). Serum IL-6 was higher in patients with active disease and in patients with possible active disease than in inactive disease (p<0.0001). Patients with active disease had higher serum TNFα levels than patients with inactive disease (p=0.049) while patients with possible active disease presented higher IL-18 levels than patients with inactive disease (p=0.046). Patients with active disease had higher SUVmax values than those with inactive disease (p=0.042). By receiver operating characteristic (ROC) curve SUVmax was predictive of active disease in TA and values ≥1.3 were associated with disease activity (p=0.039). Serum TNF-α levels were higher in patients with SUVmax≥1.3 than <1.3 (p=0.045) and controls (p=0.012). Serum IL-6 levels were higher in patients with SUVmax≥1.3 than in controls (p<0.001). No differences regarding other biomarkers were found between TA patients and controls., Conclusions: Higher serum IL-6 and TNFα levels as well as higher (18)F-FDG uptake in arterial wall are associated with active TA., (Copyright © 2015 Elsevier Editora Ltda. All rights reserved.)