Is ¹⁸F‐fluorodeoxyglucose positron emission tomography scanning a reliable way to assess disease activity in takayasu arteritis?

Abstract

Objective. 18 F-fluorodeoxyglucose-positron emission tomography (FDG-PET) scanning has been proposed as a new way of assessing disease activity in Takayasu arteritis (TA), but previous studies have used the nonvalidated National Institutes of Health (NIH) global activity criteria, and thus might be biased. This study was undertaken to determine the value of PET scanning for assessment of disease activity in TA, by comparing PET scan data with clinical, biologic, and magnetic resonance imaging (MRI) data assessed separately.Methods. Twenty-eight patients with TA (according to the American College of Rheumatology criteria) underwent a total of 40 PET scans. Images were reviewed by 2 pairs of independent nuclear medicine physicians and assessed for pattern and intensity of vascular uptake. TA activity data were obtained within 15 days of the PET scans.Results. PET scanning revealed abnormal vascular uptake in 47% of the 40 examinations. The uptake intensity grade was 0 in 7 scans, grade 1 in 7 scans, grade 2 in 13 scans, and grade 3 in 13 scans. Morphologic analysis was conducted by grading the pattern of the vascular uptake as diffuse (73%), segmental (20%), or focal (13%). There was a trend toward an association between clinically active disease and the semiquantitative assessment of FDG uptake (P ‫؍‬ 0.08). We found no statistical association between levels of acute-phase reactants and intensity of uptake. There was no significant association between the semiquantitative assessment of FDG uptake and the presence of vascular wall thickening (P ‫؍‬ 0.23), gadolinium uptake (P ‫؍‬ 0.73), or the presence of vascular wall edema (P ‫؍‬ 0.56).Conclusion. Our findings indicate that there is no association between FDG vascular uptake intensity and clinical, biologic, or MRI assessment of disease activity. Previous studies using the nonvalidated NIH global activity criteria are likely biased.

18F‐fluorodeoxyglucose–positron emission tomography scanning is more useful in followup than in the initial assessment of patients with Erdheim‐Chester disease

“…There is preliminary evidence that PET scanning could be useful in evaluating patients with Langerhans' cell histiocytosis (23) and other inflammatory diseases, such as sarcoidosis (24) or primary large-vessel arteritides (15). In these diseases, FDG uptake is believed to be related to the high density of activated macrophages present in inflammatory lesions.…”

“…FDG uptake was considered significant in large vessels only when the maximum SUV (SUV max ) was equal to or exceeded the mean SUV in the liver. The intensity of vascular uptake was expressed quantitatively using the vascular uptake index, which is defined as the ratio of the vascular SUV max divided by the mean SUV in the liver, as described previously (15).…”

FDG Uptake by Prosthetic Arterial Grafts in Large Vessel Vasculitis Is Not Specific for Active Disease

“…Determining whether low grade 18 F-FDG-uptake represents active arteritis requiring treatment escalation, noninflammatory remodelling, or local glucose analogue uptake without major clinical relevance is challenging. Clinical studies offer contrasting conclusions concerning the relationship between 18 F-FDG uptake and disease activity biomarkers [9][10][11][12]. Adding to this complexity, our study of 18 F-FDG-PET/CT scans performed on 26 patients more than six months after arterial graft surgery demonstrates that 18 F-FDG avidity of the prosthetic graft exceeds that of the native aorta.…”

“…Relatively poor correlation between 18 F-FDG uptake and disease activity markers is reported [9], while other studies suggest a closer relationship [10][11][12]. Although the intense linear arterial wall 18 F-FDG uptake seen in active LVV may be reduced by immunosuppression [13], it is not uncommon to find low-grade uptake in those with clinically inactive disease and normal acute phase reactants [9]. Persistent 18 F-FDG uptake might reflect residual arterial wall inflammation, vascular remodelling, progressive fibrosis or atherogenesis, and discriminating these is complicated by the lack of available biopsy material.…”

“…Second, whilst in active TA the sensitivity and specificity of 18 F-FDG-PET/CT may be high [3], opinion is divided concerning its sensitivity for detecting partially-treated or relapsing disease [8]. Relatively poor correlation between 18 F-FDG uptake and disease activity markers is reported [9], while other studies suggest a closer relationship [10][11][12]. Although the intense linear arterial wall 18 F-FDG uptake seen in active LVV may be reduced by immunosuppression [13], it is not uncommon to find low-grade uptake in those with clinically inactive disease and normal acute phase reactants [9].…”