Current situation and cost-effectiveness of 18F-FDG PET/CT for the diagnosis of fever of unknown origin and inflammation of unknown origin: A single-center, large-sample study from China.

PURPOSE: 18F-FDG PET/CT has an important role in the evaluation of fever of unknown origin (FUO) and inflammation of unknown origin (IUO). Our study was to investigate the current status of the inclusion of 18F-FDG PET/CT within FUO/ IUO diagnostic work-up and evaluate the cost-effectiveness of it in China. METHODS: A total of 741 FUO/IUO patients admitted to our hospital from January 2012 to December 2019 were retrospectively reviewed. The clinical characteristic, medical expenses to reach diagnosis and the proportion of definite etiological diagnosis achieved upon hospital discharge were compared between patients examined by 18F-FDG PET/CT (18F-FDG PET/CT group) and patients not examined by 18F-FDG PET/CT (non-18F-FDG PET/CT group). RESULTS: The mean age, proportion of critically-ill patients, proportion of rheumatologic diseases, the number of examinations and hospitalisation days to reach diagnosis in the 18F-FDG PET/CT group were significantly higher than those in the non-18F-FDG PET/CT group. The mean medical costs of 18F-FDG PET/CT group were significantly higher than those of non-18F-FDG PET/CT group, whereas the proportion of definite etiological diagnosis achieved upon hospital discharge of 18F-FDG PET/CT group was significantly higher than that of non-18F-FDG PET/CT group. The mean hospitalisation days and mean medical costs before diagnosis were significantly lower in patients who undertook 18F-FDG PET/CT ≤ 7 days after hospital admission than those in patients who undertook 18F-FDG PET/CT > 7 days after hospital admission. CONCLUSIONS: 18F-FDG PET/CT is mostly used in critically-ill and hard-to-diagnose FUO/IUO patients currently in China, which may conceal its cost-effective advantage. While the early use of 18F-FDG PET/CT according to patient characteristics and etiological clues could help to reduce hospitalization stay, limit medical costs, thus producing its diagnostic effect to the great extent.

[18F-FDG imaging by coincidence circuit SPECT with low-dose CT in preoperative assessment of pulmonary lesions].

OBJECTIVE: To assess the clinical diagnostic value of 18F-FDG imaging by coincidence circuit SPECT with low-dose CT in differential diagnosis of pulmonary lesions and mediastinal lymph node involvement, which can not be definitely diagnosed based on regular CT image in patients with non-small-cell lung cancer (NSCLC). METHODS: By using GE-Millennium VG with Hawkeye, 18F-FDG imaging was carried out in 48 patients with suspected lung cancer. Clinical value of 18F-FDG imaging for diagnosing malignancy was evaluated through comparison with the final pathological results. Mediastinal lymph node involvement was also assessed through lesion-by-lesion comparison with pathologic results in 74 lymph node regions from 24 patients. RESULTS: Final pathologic diagnoses of these patients were 36 malignancies consisting of 20 adenocarcinomas, 12 squamous cell carcinomas, 3 small cell carcinomas and I large cell carcinoma; 12 benign tumors including 6 pneumonias, 2 tuberculosis, 2 hamatomas, 1 cyst and 1 neurofibroma. Of 48 patients, uptake of 18F-FDG in the chest was found to be abnormal in 40. Correct diagnosis were made in 34 malignancies and 6 false positive lesions were excluded based on morphology and 18F-FDG uptake status of the lesion. There were 6 false positive and 2 false negative cases. Furthermore, extrathoracic metastases which were not showed on previous CT image in 4 patients including one in the adrenal gland and 3 in the bone were detected by 18F-FDG imaging. The sensitivity, specificity and accuracy of the 18F-FDG imaging for differentiating malignant tumor from benign was 94.4%, 50.0% and 83.3%, respectively. Squamous cell carcinoma was found to uptake more FDG than adenocarcinoma. For determination of mediastinal lymph node involvement, the sensitivity, specificity and accuracy of 18F-FDG imaging was 57.9% , 90.9% and 82.4%, respectively through lesion-by-lesion comparison; whereas, which was 61.5%, 81.8% and 70.8%, respectively, based on case-by-case comparison. CONCLUSION: 18F-FDG imaging by coincidence circuit SPECT with low-dose CT is quite helpful in differential diagnosis for patient with undetermined lesion on regular CT image, but it is limited for staging of lung cancer in the patients with non-small cell lung cancer.