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OP0306 Evaluation of Disease Activity Using FDG PET-CT in Patients with Large Vessel Vasculitis
  1. G. Pazzola1,
  2. L. Magnani1,
  3. L. Boiardi1,
  4. N. Pipitone1,
  5. F. Muratore1,
  6. A. Versari2,
  7. D. Formisano3,
  8. O. Addimanda1,
  9. R. Meliconi4,
  10. L. Pulsatelli5,
  11. G. Bajocchi1,
  12. M. Catanoso1,
  13. I. Padovano1,
  14. N. Possemato1,
  15. A. Lo Gullo1,
  16. C. Salvarani1
  1. 1Rheumatology Unit
  2. 2Nuclear Medicine Unit
  3. 3Scientific Directorate, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy, Reggio Emilia
  4. 4Rheumatology Unit
  5. 5Department of Immunorheumatology and tissue regeneration, Istituto Ortopedico Rizzoli, Bologna, Italy

Abstract

Background 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.

Objectives 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 (Kerr/NIH), serum acute-phase reactants (ESR, C-reactive protein [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 215 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. 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 215 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. 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).

Conclusions 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 of Interest None Declared

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