Background/Purpose: 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computerized tomography (CT) [PET/CT] has been proposed as a useful tool to diagnose and monitor activity of large vessel vasculitis (LVV), but its precise role remains debated. The objective of this study was to determine the value of PET-CT in the assessment of disease activity in LVV. To this end, PET/CT findings were correlated with clinical indices including ITAS (Indian Takayasu activity score) and Kerr/National Institute of Health, serum acute-phase reactants (ESR, CRP) levels as well as interleukin-6 (IL-6) and the soluble IL-6 receptor (sIL-6R).
Methods: 78 patients with LVV (giant cell arteritis, Takayasu arteritis or idiopatic aortitis) underwent a total of 204 PET/CT scans. PET/CT scans were reviewed by a nuclear medicine physician without knowledge of clinical information. Vascular uptake was graded using a 4-point semiquantitative scale where grade 0=no uptake, grade 1=less than liver uptake, grade 2=similar to liver uptake, grade 3=higher than liver uptake. Visual analysis was performed on 14 vessel segments. PET/CT scans were considered negative if vascular FDG uptake was grade 0-1, moderately positive if vascular uptake was grade 2, and markedly positive if vascular uptake was grade 3 in at least one vessel. ITAS, Kerr/NIH scores, ESR, CRP, IL-6 and sIL-6R values were obtained within 20 days of PET/CT scans.
Results: 43% of 204 PET-CT were negative, 31% were moderately positive, and 26% were markedly positive. We found a significant association between the intensity of the uptake and both ESR and CRP levels. Significantly higher ESR values were observed in the patients with markedly positive PET/CT (49.4 + 36.5 mm/1st h) compared with those with moderately positive (27+ 21 mm/1st h, p = 0.0001) and inactive scans ( 22.7 + 15.9 mm/1st h, p=0.0001), respectively. CRP levels were 0.8+1.0 mg/dL in patients with inactive scans, 1.3+ 2.2 mg/dL in patients with moderately positive (p=0.001) and 3.0 + 3.6 in patients with markedly positive scans (p = 0.0001). Significantly higher levels of IL-6 were measures in patients with markedly positive scans (10.0 + 8.9 pg/ml) compared to those with inactive scans (8.1+18.5 pg/ml, p=0.013). No association was found between sIL-6R levels and intensity of vascular FDG uptake. However, there was a significant association between the intensity of vascular FDG uptake and both ITAS and Kerr/NIH scores.
Patients with markedly positive scans had more frequently (50%) active vasculitis according to the ITAS compared with those with moderately active (31.7%) and inactive scans (28.1%) (p=0.003). Likewise, vasculitis was judged to be active according to the Kerr/NIH index in 50% of patients with markedly positive scans, 22% of those with moderately positive scans, and 14.6% with inactive scans (p=0.0001).
Conclusion: Our findings show a strong association between vascular FDG uptake and clinical activity and traditional inflammatory markers. A weaker association was found between vascular FDG uptake and IL-6 levels. These data suggest that PET/CT may be a useful tool for evaluating disease activity in patients with LVV.
Disclosure:
G. Pazzola,
None;
L. Magnani,
None;
L. Boiardi,
None;
N. Pipitone,
None;
A. Versari,
None;
D. Formisano,
None;
O. Addimanda,
None;
R. Meliconi,
None;
L. Pulsatelli,
None;
G. Bajocchi,
None;
P. Macchioni,
None;
M. G. Catanoso,
None;
N. Possemato,
None;
I. Padovano,
None;
A. Lo Gullo,
None;
C. Salvarani,
None.
« Back to 2012 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/evaluation-of-disease-activity-using-fdg-pet-ct-in-patients-with-large-vessel-vasculitis/