Whole-body Cancer Screening Using ¹⁸F-FDG Novel Combined PET/CT Scanner

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In the past decade, functional imaging with ¹⁸F-fluoro-deoxyglucose (FDG) positron emissiooooon tomography (PET) has been the faster growing diagnostic modality in clinical oncology and oncologic research. Whole-body ¹⁸F-FDG PET has spread in cancer screening in Japan and improves the rate of detection of malignancies in cancer screening, although, ¹⁸F-PET lacks precise anatomical information and may cause some false positive and false negative results. In 2004, a combined PET/CT scanner was introduced in Japan and enables the fusion of functional PET images and anatomical CT images within a single examination. Large studies abroad demonstrated PET/CT fusion imaging had the potential to improve the sensitivity, specificity and diagnostic accuracy of malignancies. No whole-body cancer screening using the new combined PET/CT scanner has been reported in Japan. In this study, cancer screening with ¹⁸F-FDG PET/CT was performed.
Subjects A total of 244 asymptomatic Japanese subjects were screened by ¹⁸F-FDG whole-body PET/CT, between August 2004 and January 2005, in our Medical Imaging Centre, MIC. A PET/CT, Discovery LS, was used for cancer screening one hour after ¹⁸F-FDG 5 mCi injection. The results of the whole-body PET/CT image were evaluated to three grades of malignancies, from high suspicion of malignancies, M1, moderate suspicion, M2 to low suspicion, M3. The cases evaluated with M1 grade were followed clinically.
Results Satisfactory fusion images were obtained in whole-body ¹⁸F-FDG PET/CT. Eight subjects, 3.27% of total 244 subjects, were evaluated as high suspicion malignancies, M1 grade. Six cases of eight were diagnosed as malignancies. Three cases of six malignancies were recurrences of malignancies. Others were one malignant lymphoma, lung cancer and breast cancer. With the exception of recurrent cases, detection ratio of malignancy was 1.23% in this cancer screening. Whole-body PET/CT clearly demonstrated localizations of malignancies and metastatic lesions in a single screening.
Discussion Whole-body PET/CT cancer screening appears to be superior to CT and PET alone in cancer detection, localization and staging of malignancies. Further studies on cancer screening using whole-body PET/CT should be conducted to clarify the value of early cancer detection and clinical effectiveness of PET/CT cancer screening.