Yunshan Zhou

Objective To analyze ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) image features in different types of systemic vasculitis and explore its classification and diagnostic significance for systemic vasculitis. Methods Clinical and ¹⁸F-FDG PET/CT imaging data of 71 consecutive patients (34 males, 37 females, mean age 53.4 ± 20.5 years) who were examined at Peking University People’s Hospital and diagnosed with active systemic vasculitis were analyzed retrospectively, and ¹⁸F-FDG PET/CT imaging features of different types of systemic vasculitis were analyzed in patients with positive ¹⁸F-FDG PET/CT findings. Results The proportions of large-, medium-, small-, and variable-vessel vasculitis were 36.6%, 15.5%, 29.6%, and 18.3%, respectively, and 93.0% of patients had positive findings on PET/CT, of which 63.6% had vascular involvement and 53.0% had extravascular involvement. Different types of vasculitis had different lesion sites, distribution patterns, and morphological changes. Large-vessel vasculitis mainly affected the aorta and its branches to the head and neck. Takayasu arteritis showed segmental involvement of the vascular and morphological changes of the vessel wall. Giant cell arteritis manifested as diffuse vascular involvement, which usually involved the temporal artery and the abdominal aorta and its branches. Medium-vessel vasculitis polyarteritis nodosa manifested as diffuse vascular involvement of both lower extremities. Small-vessel vasculitis anti-neutrophil cytoplasmic antibody-associated vasculitis manifested as granulomatous inflammation of extravascular regions. Variable-vessel vasculitis Behcet’s disease involved both blood vessels and extravascular regions. Conclusion Different types of systemic vasculitis show characteristic manifestations in ¹⁸F-FDG PET/CT images, which may be useful for the diagnosis and classification of systemic vasculitis. Key points: • Determining an early diagnosis of systemic vasculitis may be challenging. • Different types of systemic vasculitis show characteristic manifestations in ¹⁸F-FDG PET/CT images. • ¹⁸F-FDG PET/CT may be useful for the diagnosis and classification of systemic vasculitis.

Objective To explore the significance of Fluorine-18 labeled fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in diagnosing connective tissue diseases (CTDs) in fever of unknown origin (FUO) or inflammation of unknown origin (IUO) patients. Methods Clinical and image data of 242 consecutive FUO/IUO patients who underwent PET/CT examination and eventually diagnosed CTDs were retrospectively analyzed, including distribution of diseases, clinical characteristics, and PET/CT imaging findings. The role of FDG PET/CT in differential diagnosis of CTDs was evaluated through clinical questionnaire survey. Results Patients diagnosed as CTDs accounted for 48.1% of FUO/IUO patients. Among them, adult-onset Still’s disease was most frequently diagnosed. Other common diseases included systemic vasculitis, undifferentiated connective tissue disease, rheumatoid arthritis, idiopathic inflammatory myopathy, systemic lupus erythematosus, and polymyalgia rheumatica. On FDG PET/CT examination, 97.9% of the patients had positive findings. Inflammatory lesions were detected in 66.5% and non-specific abnormal uptakes were found in 31.4%. Detected lesions distributed consistently with corresponding susceptible organs and tissues in various diseases. Clinical questionnaire results shown that FDG PET/CT excluded malignant tumors, focal infections, or other typical CTDs in 45.5% of the patients; indicated important diagnostic clues or appropriate biopsy sites in 20.6% of patients; and directly suggested the diagnosis of a CTD in 33.1% of patients. Conclusion FDG PET/CT could reveal inflammatory lesions in organs and tissues that reflect the clinical characteristics in different CTDs, thus providing an objective evidence for differential diagnosis, classification, and treatment decision of these diseases. Key Points • FDG PET/CT is a useful tool for differential diagnosing connective tissue diseases among patients with fever of unknown origin/inflammatory of unknown origin.

Objective: Infections have been implicated in rheumatoid arthritis (RA) development. However, the impact of premorbid infection on initiation and perpetuation of RA has not been well elucidated. Thus, we sought to conduct a large scale on-site survey to study whether premorbid infection may trigger RA and influence status of the disease. Methods: Premorbid infectious events were collected in cohort of 902 RA patients from December 2015 to June 2016. Type of infections prior to RA onset and its possible effects on disease status were analyzed. Result: Three hundred and thirty-four out of 902 patients (37.03%) experienced infections within one month preceding RA onset. The most frequent infections were respiratory (16.08%), intestinal (11.09%) and urinary tract (9.87%) infection, respectively. The infection was associated with increased disease activity. Early onset was found in patients with urinary infection. High disease activity risk was increased in patients who pre-exposure to urinary infection (OR=3.813, 95%CI=1.717-12.418) and upper respiratory infection (OR=2.475, 95%CI= 0.971-6.312). Conclusion: Pre-exposure infections are associated with development of RA. Severe disease status of RA and persistent of active disease status are related to preceding infections.