Session Title: Vasculitis IV: Diagnosis and Assessment of Disease Activity
Session Type: ACR Concurrent Abstract Session
Session Time: 9:00AM-10:30AM
Background/Purpose: Fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT is, due to its excellent diagnostic accuracy, increasingly used to diagnose large vessel GCA (LV-GCA). However, PET/CT is not always readily available, which may compel the clinician to 1) either delay steroid treatment at the risk of GCA related complications, or 2) to initiate treatment at the expense of diagnostic sensitivity of the 18F-FDG PET/CT study. Therefore, evidence of a possible “18F-FDG PET/CT diagnostic window” after initiation of steroid treatment is needed.
Methods: Twenty treatment-naïve patients (14 women) with a mean age of 69 (range 56-83) years with 18F-FDG PET/CT (PET0) proven LV-GCA were randomized to repeat 18F-FDG PET/CT after either 3 (PET3, n=10) or 10 days (PET10, n=10) of treatment with oral prednisolone 60 mg daily. Prior to treatment, clinical examination and laboratory tests were performed to confirm GCA and exclude differential diagnoses. A temporal artery biopsy (TAB) was performed in all patients. An experienced nuclear medicine physician blinded to patients’ clinical data reviewed the 18F-FDG PET/CT images. LV-GCA was suspected if increased 18F-FDG uptake in the wall of the aorta and/or supra-aortic branches was observed. A semiquantitative approach was applied (a.m. Meller) in which 18F-FDG uptake in 6 vascular regions (see table 1) was graded on a 5-point scale (0 = no uptake, 1 = uptake below or equal to blood pool, 2 = above blood pool but below liver, 3 = above liver, 4 = 2 times above liver). Any score ≥3 was considered consistent with vasculitis. Data was either continuous or binomial. Normality was checked using QQ-plots. McNeemars and Wilcoxon signed-rank test was used to test statistical significance.
Results: Mean CRP and ESR were 77.2 (95% CI: 56.8; 97.7) mg/l and 77.3 (95% CI: 67.3; 87.3) mm/h, respectively. Fourteen of twenty patients fulfilled the ACR criteria for GCA and 13/20 had a positive TAB. Mean number of prednisolone doses before the post-therapeutic 18F-FDG PET/CT were 3.1 (95% CI: 2.9; 3.3) (PET3) and 10.2 (95% CI: 9.6; 10.8) (PET10). Vascular composite score in aorta did not decrease at PET3 whereas a significant decrease was observed in supraaortic branches at PET3 and all vascular domains at PET10 (table 1). Although, 18F-FDG uptake decreased in supra-aortic branches after 3 days, LV-GCA could still be accurately diagnosed in 10/10 patients. By contrast, LV-GCA could only be diagnosed in 5/10 patients after 10 days (PET0 vs. PET10, p=0.03).
Conclusion: In LV-GCA, high-dose steroid treatment for three or ten days differentially attenuates the regional uptake of 18F-FDG but diagnostic properties remains within the first three days. Table 1
|Post-therapeutic LV-GCA diagnosis by 18F-FDG PET/CT|
|Median vascular composite score|
|Aorta€||9 (9-9)||9 (6-9)||9 (9-9)||5 (3-6)*|
|Aortic branches#||6 (5-8)||4.5 (3-7)*||6.5 (6-8)||4 (3-5)*|
|PET positive was defined as vascular 18F-FDG uptake≥3. A vascular composite score in two different vascular domains was calculated by summarizing the grades for selected regions. Medians (interquartile range) in the two groups (PET3 or PET10, n=10 respectively) are presented. *Indicates that post-therapeutic vascular score was significantly different from pre-therapeutic score. €Aortic: Aorta ascendens, aorta descendens and aortic arch. #Aortic branches: Vertebral, carotic and subclavian/axillary artery.|
References 1. Puppo et al. BioMed research international 2014;2014:574248. 2. Stellingwerff MD et al. Medicine 2015 Sep;94(37):e1542.
To cite this abstract in AMA style:Nielsen BD, Tønder Hansen I, Keller KK, Therkildsen P, Hauge EM, Gormsen LC. Attenuation of Fluorine-18-Fluorodeoxyglucose Uptake in Large Vessel Giant Cell Arteritis after Short-Term High-Dose Steroid Treatment – a Diagnostic Window of Opportunity [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/attenuation-of-fluorine-18-fluorodeoxyglucose-uptake-in-large-vessel-giant-cell-arteritis-after-short-term-high-dose-steroid-treatment-a-diagnostic-window-of-opportunity/. Accessed April 17, 2021.
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