The Clinical Impact of Using 18F-FDG-PET/CT in the Diagnosis of Suspected Vasculitis: The Effect of Dose and Timing of Glucocorticoid Treatment

Kirsi Taimen,Soile P Salomäki,Pirjo Nuutila,Anne Roivainen,Jukka Kemppainen,Laura Pirilä,Markku Mali,Sami Kajander,Ulla Hohenthal,Marko Seppänen,Antti Palomäki

doi:10.1155/2019/9157637

Kirsi Taimen, Soile P Salomäki + Show 9 more

Open Access

https://doi.org/10.1155/2019/9157637

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Abstract

18F-Fluorodeoxyglucose positron-emission tomography (18F-FDG-PET) with computed tomography (CT) is effective for diagnosing large vessel vasculitis, but its usefulness in accurately diagnosing suspected, unselected vasculitis remains unknown. We evaluated the feasibility of 18F-FDG-PET/CT in real-life cohort of patients with suspicion of vasculitis. The effect of the dose and the timing of glucocorticoid (GC) medication on imaging findings were in special interest. 82 patients with suspected vasculitis were evaluated by whole-body 18F-FDG-PET/CT. GC treatment as prednisolone equivalent doses at the scanning moment and before imaging was evaluated. 38/82 patients were diagnosed with vasculitis. Twenty-one out of 38 patients had increased 18F-FDG accumulation in blood vessel walls indicating vasculitis in various sized vessels. Vasculitis patients with a positive vasculitis finding in 18F-FDG-PET/CT had a significantly shorter duration of GC use (median = 4.0 vs 7.0 days, P=0.034), and they used lower GC dose during the PET scan (median dose = 15.0 mg/day vs 40.0 mg/day, p=0.004) compared to 18F-FDG-PET/CT-negative patients. Vasculitis patients with a positive 18F-FDG-PET/CT result had significantly higher C-reactive protein (CRP) than patients with a negative 18F-FDG-PET/CT finding (mean value = 154.5 vs 90.4 mg/L, p=0.018). We found that 18F-FDG-PET/CT positivity was significantly associated with a lower dose and shorter duration of GC medication and higher CRP level in vasculitis patients. 18F-FDG-PET/CT revealed clinically significant information in over half of the patients and was effective in confirming the final diagnosis.

Highlights

Less is known about how 18F-FDG-PET/computed tomography (CT) performs in other types of vasculitis than large-vessel vasculitis (LVV). ere is some evidence that PET may be useful in detecting small-vessel vasculitis [10, 11]. e ongoing multinational Diagnostic and Classification Criteria for Vasculitis (DCVAS) study aims to validate diagnostic criteria and to improve classification criteria for primary systemic vasculitis [12]
Is study is part of the Positron Emission Tomography of Infection and Vasculitis (PETU) study, which is registered as a clinical trial (NCT01878721). e PETU study researched different branches of infectious and inflammatory diseases which are reported separately [19,20,21,22]
We evaluated the American College of Rheumatology (ACR) criteria for GCA, granulomatous polyangiitis (GPA), eosinophilic granulomatous polyangiitis (EGPA), microscopic polyangiitis (MPA), and polyarteritis nodosa (PAN)

Summary

Materials and Methods

Vasculitis suspicion was raised by an experienced specialist based on the clinical symptoms and signs of the patient. Vasculitis was confirmed or excluded by a consensus-based decision made by the specialists, while taking notice of the medical history, results of clinical examination, extensive laboratory work, 18F-FDG-PET/CT result, other imaging modalities, response to GC therapy, and follow-up. E final diagnosis was based on the clinical picture as well as on the imaging findings of different sizes of affected vessels and histology. After an average of 57 minutes (range 44–79 minutes), a whole-body PET acquisition (3 min/bed position) was performed following lowdose CT (kV 120, Smart mA range 10–80) In some patients, this was followed by a diagnostic contrast-enhanced CT scan (kV 120, Smart mA range 100–440) during the arterial phase after an automated i.v. injection of contrast agent.

Results

Unknown diagnosis

Duration of GC treatment

Conclusions