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Objective To explore the clinical value of 18F-fluorodeoxyglucose (FDG) PET/CT in assessing antineutrophil cytoplasmic antibody-associated vasculitis (AAV).Methods Fifteen patients (7 males,8 females,age (66±11) years) with AAV between January 2015 and June 2017 were retrospectively analyzed.There were 6 patients diagnosed as granulomatosis with polyangiitis (GPA),7 diagnosed as microscopic polyangiitis (MPA) and 2 diagnosed as eosinophilic granulomatosis with polyangiitis (EGPA).All patients underwent 18 F-FDG PET/CT and the image features were observed and analyzed.The maximum standardized uptake value (SUVmax) of the positive lesion was measured.The relationship between the SUVmax and C reactive protein (CRP) was analyzed with Pearson correlation.The SUVmax and the number of lesion sites were compared by two-sample t test between the CRP-elevated and CRP-normal patients.Results A total of 56 lesions in the 14 of 15 AAV patients were detected by PET/CT.The positive findings distributed in 15 tissues and organs,including the nasopharynxes (n =9),lungs (n =9),kidneys (n =8),spleen (n =6),lymph nodes (n =6),bone marrow (n =4),skin (n =3),prostate (n =2),aortas (n =2),vertebral soft tissues (n =2),orbita (n =1),parotid gland (n =1),thyroid gland (n =1),liver (n =1) and pancreas (n=1).The 60.7％ (34/56) of lesions were clinically unsuspected occult lesions.GPA lesions mainly invaded the nasopharynxes,lungs and kidneys;MPA lesions mainly invaded the kidneys and spleen;EGPA lesions mainly invaded the nasopharynxes,lymph nodes and bone marrow.There was no significant correlation between the level of CRP and the SUVmax of AAV lesions (r=0.462,P＞0.05).No differences in the SUVmax were observed between patients with elevated CRP levels and those with normal CRP levels (t=1.451,P＞0.05).But more lesion sites were observed in patients with elevated CRP (t=3.456,P＜0.05).Conclusions 18F-FDG PET/CT shows positive findings in multiple sites in AAV patients,including clinically unsuspected sites.This imaging technique may be a useful tool for diagnosis and evaluation of AAV.
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Objective To study the 18F-FDG PET/CT features of tuberculous and malignant diffuse peritoneal lesions and to discuss the diagnostic value of 18F-FDG PET/CT in diagnosing and differentiating the lesions. Methods The 18F-FDG PET/CT features of 72 patients with tuberculous peritonitis,28 primary serous papillary carcinoma of the peritoneum and 135 peritoneal metastases confirmed by clinic and/or histopathology, were retrospectively reviewed. The peritoneal thickening features of tuberculous and malignant peritoneal lesions were observed. The maximal standardized uptake value (SUVmax) of peritoneal lesions and ascites, ascites SUVmax/liver SUVmax (T/NT) were compared between tuberculous peritonitis and cancerous peritonitis. The ROC curve was used to analyze the diagnostic efficiency of T/NT, SUVmax of peritoneal lesions and ascites. Results The typical 18F-FDG PET/CT features of tuberculous peritonitis were uniformity thickening of parietal peritoneum, mesenteric and omental stain like changes, widely and even distribution of the peritoneal 18F-FDG, while the cancerous peritonitis was obvious uneven thickening of parietal peritoneum, mesenteric and omental nodules and pie-shape changes, uneven distribution of the peritoneal 18F-FDG. The degree of 18F-FDG uptake was increased in all peritoneal lesions, and there was no significant difference between the tuberculous group (SUVmax=10.53±5.44) and the cancerous group (SUVmax=11.45±6.78, t=1.017, P>0.05). The 18F-FDG concentration in malignant ascites (SUVmax=1.88±0.65,T/NT=0.73± 0.18) was obvious higher than that of tuberculous ascites (SUVmax=1.67±0.69,T/NT=0.57±0.27, t=2.243 and 5.045,both P<0.05). The area under the ROC curve of T/NT, SUVmax of ascites, SUVmax of peritoneal lesions were 0.707, 0.593, 0.536, respectively. Conclusion The 18F-FDG PET/CT imaging can reflect the morphology and metabolic changes of peritoneal lesions. It is important to combine the SUVmax of ascites in order to improve the efficiency of diagnosing the diffuse peritoneal diseases.