Feasibility of fluorodeoxyglucose dual-head gamma camera coincidence imaging in the evaluation of lung cancer: Comparison with FDG PET

The purpose of this study was to elucidate the feasibility of fluorodeoxygl ucose gamma camera coincidence imaging (FDG GCI) in the evaluation of lung cancer in comparison with FDG PET. Methods: Twenty-three patients with rece ntly diagnosed lung cancer were examined with both FDG PET and FDG GCI on t he same day. Pulmonary lesions were analyzed visually and semiquantitativel y using the ratio of lesion-to-background counts (L/B ratio). The L/B ratio of FDG PET without attenuation correction (AC) was also calculated and com pared. Nodal stations were only visually analyzed. Results: FDG GCI and FDG PET could detect 22 and 23, respectively, of 23 pulmonary lesions by visua l analysis (95.7% versus 100%). The L/B ratio of FDG GCI was 4.26 +/- 2.55, and significantly lower than that of FDG PET (9.29 +/- 4.95; P < 0.01). Th e L/B ratio of FDG PET was significantly higher with AC than that without A C (9.29 +/- 4.95 vs. 6.66 +/- 4.65; P < 0.01). When the L/B ratio threshold was set at 5.0 for FDG PET and 2.7 for FDG GCI, their sensitivity was 87.0 % and 73.9%, respectively. Of the 3 and 6 patients with false-negative resu lts on semiquantitative analysis, the lesions in 3 patients on FDG PET and 4 patients on FDG GCI were less than or equal to 2.0 cm in greatest diamete r, respectively. In the assessment of mediastinal involvement, FDG PET was 77.8% sensitive, 78.6% specific and 78.3% accurate, whereas FDG GCI was 77. 8% sensitive, 92.9% specific and 87.0% accurate. In the hilar regions, FDG PET was 100% sensitive, 84.2% specific and 87.0% accurate, whereas FDG GCI was 75.0% sensitive, 89.5% specific and 87.0% accurate. Conclusion: In this study, FDG GCI yielded results comparable to FDG PET on visual analysis to detect pulmonary lesions and lymph node metastases. However, the lesion-to -background contrasts of pulmonary lesions and nodal involvement were lower in FDG GCI than in FDG PET. Comparison between the L/B ratio of FDG PET wi th and without AC indicated that, with AC, FDG GCI would be closer to FDG P ET in the evaluation of lung cancer.