Imaging Features And Clinical Value Of Extrapulmonary Tuberculosis With ¹⁸F-FDG PET/CT

Objective China is a country with high incidence of tuberculosis（TB）.TB is a systemic disease that affects all organs and systems.TB often shows high ¹⁸F-FDG uptake on PET/CT imaging,it is often misdiagnosed as malignant lesions,which brings difficulties in the diagnosis.This study retrospectively analyzed the diagnosis of extrapulmonary tuberculosis patients with ¹⁸F-FDG PET/CT imaging in our hospital.To analyze the diagnostic value and imaging characteristics of ¹⁸F-FDG PET/CT in extrapulmonary tuberculosis,in order to better understand the characteristics of tuberculosis in ¹⁸F-FDG PET/CT imaging and improve the accuracy of application diagnosis.Methods We retrospectively analyzed patients with extrapulmonary tuberculosis in our hospital from January 2013 to December 2016.The diagnosis was confirmed by pathological diagnosis or clinical follow-up.PET images were analyzed visually and semi-quantitatively with standardized uptake Value.The site and systemic distribution of tuberculosis lesions were calculated.This paper tried to summarize the clinical characteristics and imaging features of extrapulmonary tuberculosis in ¹⁸F-FDG PET/CT,in order to improve the diagnosis of this disease.Results 1.A total of 174 patients with extrapulmonary tuberculosis were recruited.According to the system and number of lesions involved,three distinct patterns were identified:Single system involvement（27.0%）,multiple extrapulmonary systems involvement（23.6%）,involved in the pulmonary and extrapulmonary sites（49.4%）.There was no significant difference in SUVmax between the three groups（p=0.816）.2.According to locations,the lesions were classified into 6 basic types,including lymph node tuberculosis,pleural tuberculosis,pericardial tuberculosis,peritoneal tuberculosis,osteoarticular tuberculosis,organ tuberculosis.（1）Lymphatic tuberculosis with lymph node enlargement coalesced calcified,and ring-shaped FDG avidity was found in some of the lymph nodes.（2）Most of the pleura were diffuse irregular thickening,some of which were nodules or masses.The most common pattern of FDG uptake was streaklike surrounding the pleura.（3）The patients with tuberculous pericarditis showed pericardial thickening and ring-shaped diffuse FDG uptake in the pericardia.Most of them had small-to-large amount of pericardial,pleural effusion,mediastinal lymph nodes enlargement.（4）Tuberculous peritonitis:the liver/spleen and parietal peritoneum were uniformity thickening,and the pattern of FDG uptake was streaklike surrounding the peritoneal surface of the liver/spleen and parietal.Omental and mesenteric stainsed changed,widely and diffusely distribution of the peritoneal FDG.But some of the omentum changed as a cake.（5）Osteoarticular tuberculosis:Most of bone tuberculosis were osteolytic bone destruction with high FDG uptake.The imaging features of spinal tuberculosis were as follows,continuous vertebral body involvement,paraspinal cold abscess formation,intervertebral disc involvement,bone destruction area with dead bone or bone fragments.（6）Organ tuberculosis:The incidence of organ tuberculosis is low,and the imaging characteristics are lacking in specificity.most of the solid organ tuberculosis（annex,liver,pancreas,spleen,adrenal gland,prostate,etc.）showed low density or equal density.The manifestations of intracranial tuberculosis were equal or high density shadow,with or without increased metabolism.Ileocecal tuberculosis was characterized by thickening of the intestinal wall and narrowing of the intestinal cavity.3.In this group of 174 patients with extrapulmonary tuberculosis,129 cases were diagnosed correctly by PET/CT imaging,the accuracy was 74.1%,and the misdiagnosis rate was 25.9%.45 cases were misdiagnosed in this study,including lung cancer with metastasis（n=15）,lymphoma（n=12）,ovarian cancer（n=4）,lymph node metastasis（n=3）,sarcoidosis（n=2）,peritoneal carcinoma（n=1）,prostate cancer（n=1）,primary malignant bone tumor（n=1）,colon cancer（n=1）,orbital malignant tumor（n=1）,pleural malignancy（n=1）,thymoma（n=1）,pancreatic cancer（n=1）,and pulmonary fungal infection（n=1）.Conclusions PET/CT can comprehensively and non-invasively evaluate the violation of systemic organs in patients with extrapulmonary tuberculosis,determine the activity of the lesions,and guide the clinical selection of biopsy sites,and provide assistance for the early diagnosis and treatment of extrapulmonary tuberculosis.