Usefulness of combined FDG-PET with CT or tumour markers in lung cancer diagnosis.

BACKGROUND: The synergy between in vitro and in vivo imaging was investigated in this study. PATIENTS AND METHODS: Comparison of fluorodeoxyglucose positron-emission tomography (FDG-PET) and computerised tomography (CT) included 62 patients (group 1), while that for comparison of FDG-PET and serum tumour markers included 26 patients (group 2). RESULTS: In group 1, FDG-PET had positive and negative predictive values of 81% and 80% respectively, compared to 73.7% and 71.4% for CT, respectively. Combined imaging showed 100% sensitivity and 100% specificity. In group 2, FDG-PET and CEA were both positive in 42.9%, and only CEA was falsely negative in all other cases. FDG-PET and TPA were both positive in 47.6%, and in 52.4% only FDG-PET was positive. NSE and SCC had 100% specificity; their sensitivity was 38% and 25%, respectively. CONCLUSION: FDG-PET diagnosis was improved by CT. Because the serum tumour markers were falsely negative in more than 50% and there were no falsely negative results for FDG-PET, combined imaging may allow reduction of cut-off values for conventional serum tumour markers.