Value of 18F-FDG-PET/CT in diagnosis of classic fever of unknown origin / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To evaluate the application of (18)F-FDG PET/CT in diagnosis of classic fever of unknown origin.</p><p><b>METHODS</b>A total of 27 consecutive patients with classic fever of unknown origin (FUO) (19 men, 8 women; aged 24-82 y) underwent (18)F-FDG PET/CT scans. The images were interpreted by visual inspection and semiquantitative analysis(standardized uptake value, SUV). Final diagnosis was based on histopathology or clinical follow-up.</p><p><b>RESULTS</b>The cause of FUO was confirmed by followed investigations in 21 of 27 cases after PET/CT scan, including 10 cases of infection, 4 of noninfectious inflammation, 4 of malignancies and 3 of miscellaneous disorders; and remaining 6 cases were still confirmed FUO. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 100.0 %, 83.3%, 83.3%, 100.0% and 96.3%, respectively.</p><p><b>CONCLUSION</b>For patients with fever of unknown origin, (18)F-FDG-PET/CT can be a sensitive, reliable imaging modality. It is suggested that (18)F-FDG-PET/CT should be considered earlier in detecting the causes of FUO, which is difficultly diagnosed by conventional modalities.</p>

Malignant tumor with false negative 18F-FDG PET image / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the FDG uptake characteristics, the factors affecting 18F-FDG uptake and the extra CT diagnostic value of 18F-FDG PET/CT scan in the malignant tumor with false negative 18F-FDG PET image.</p><p><b>METHODS</b>The data of PET/CT image in 17 patients with various kinds of cancers were reviewed and analyzed by visual observation and semi-quantity analysis ( SUV). The results were compared with the CT and histopathological diagnosis, respectively.</p><p><b>RESULTS</b>Of 6 well-differentiated HCC patients confirmed by histopathological diagnosis, one had two lesions in the right lobe of the liver. One of these two lesions showed low FDG uptake on 18F-FDG PET scan and low density on CT scan. The other one was not shown on either 18F-FDG PET or plain CT scan. But on enhanced CT scan, these two lesions were found to be inhomogeneous with high density at arterial phase. The false negative 18F-FDG PET images of one gastric signet ring cell carcinoma in the gastric fundus with right adnexa metastasis, 3 renal cell carcinoma, one greater omentum and peritoneal metastatic adenocarcinoma and one well-differentiated prostate cancer were caused by normal physical uptake in the digestive tract or FDG retention in the urinary system due to normal excretion. The size of three metastases was smaller than or equal to 1 cm in diameter, however, two primary lesions of these metastases showed high FDG uptake and only one was negative on either 18F-FDG PET or CT scan. In this series, 68.8% of the primary tumors and 66.7% of metastases were found to show abnormal density on CT scan, and 31. 2% of the primary tumors and 33. 3% of metastases were not detectable on either PET or CT images.</p><p><b>CONCLUSION</b>False negative 18F-FDG PET in malignant tumor may be correlated with the pathologic type, differentiation degree and the lesion size. Combining CT information with PET or paying attention to the scan methods during 8 F-FDG PET examination may reduce the rate of false negative 18F-FDG PET diagnosis in various kinds of malignant tumors.</p>