Clinical usefulness of 18FDG-PET in primary lung cancer. Comparison with 201Tl-SPECT

Forty patients with pulmonary nodular lesions had PET imaging performed. Within a week, all patients were investigated with the triple-headed SPECT system and by CT. The PET and SPECT images were compared qualitatively and quantitatively. For quantitative analysis, ROIs were selected in areas of the tumor showing the highest tracer accumulation and in the normal areas of contralateral lung. The tumor to nontumor activity ratio (T/N ratio) was calculated. In thirty-three patients with primary lung cancer, the sensitivity of 18FDG-PFT, 201Tl-SPECT were 93.6%, 84.8%, respectively. In the detection of lung cancer, 18FDG-PET provided a higher sensitivity than 201Tl-SPECT. Neither techniques visualized any lesion in two patients who had bronchioloalveolar carcinoma. Among the patients showing increased tracer accumulation, the T/N ratio was significantly higher with 18FDG-PET than with 201Tl-SPECT. However, there was significant positive correlation between the 18FDG T/N ratio and the 201Tl delayed ratio. We assessed the association between cell differentiation and 18FDG or 201Tl uptake in 17 patients with adenocarcinoma of the lung. Only 18FDG uptake might be associated with cell differentiation of adenocarcinoma. Thirty patients with pulmonary nodular lesion underwent an operation and the results of 18FDG-PET, 201Tl-SPECT were compared between malignant and benign nodules in 18FDG uptake and 201Tl uptake. 18FDG uptake and 201Tl uptake showed no significant differences in malignant nodules or benign nodules. Twenty-one patients underwent thoracotomy and the results of 18FDG-PET, 201Tl-SPECT and CT were compared with the pathological findings of the mediastinal lymph nodes. In the detection of mediastinal lymph node metastasis from lung cancer, sensitivity and specificity were 33.3% and 77.8% for CT, 33.3% and 94.4% for 201Tl SPECT and 66.7% and 88.9% for 18FDG-PET, respectively. (K.H.)