Role of 99mTc-Octreotide Acetate Scintigraphy in Suspected Lung Cancer Compared with 18F-FDG Dual-Head Coincidence Imaging

Abstract

The aim of this study was to evaluate the clinical value of tomographic (99m)Tc-octreotide acetate (hereafter, (99m)Tc-octreotide) scintigraphy in the detection of patients with suspected lung cancer in comparison with that of (18)F-FDG dual-head coincidence imaging (DHC). Forty-four consecutive patients with suspected pulmonary neoplasms underwent tomographic (99m)Tc-octreotide scintigraphy and (18)F-FDG coincidence imaging using the same gantry. The region of interest was drawn on the entire primary lesion. The tumor-to-normal tissue tracer values for both (99m)Tc-octreotide and (18)F-FDG were determined using region of interests and expressed as T/N(r) and T/N(m), respectively. Final diagnosis was confirmed by histopathologic analysis or clinical follow-up. Thirty-one of the 44 patients had lung cancer-6 with small cell lung cancer (SCLC) and 25 with non-small cell lung cancer (NSCLC). Thirteen of the 44 patients had benign lung lesions. The sensitivity, specificity, positive predictive value, and negative predictive value of (99m)Tc-octreotide were 100%, 75.7%, 90.1%, and 100%, respectively, and of (18)F-FDG DHC were 100%, 46.1%, 83.8%, and 100%, respectively. In the 31 patients with malignant tumors, all 38 abnormal lymph nodes in 20 patients showed abnormal high focal uptake of (18)F-FDG; only 7 patients with 10 regional lymph adenopathies showed moderate uptake of (99m)Tc-octreotide. Thirteen patients with 39 distant sites of abnormal uptake visualized (imaging stage IV) with (99m)Tc-octreotide included 2 patients with brain metastases, 6 patients with pleural invasion and multiple bone metastasis, 2 patients with contralateral internal lung metastasis and pleural invasion, and 3 patients with only multiple bone metastasis. The final diagnosis was confirmed by histopathology or clinical follow-up. The sensitivity of (99m)Tc-octreotide for the detection of lung cancer at the primary lesion was comparable with that of (18)F-FDG coincidence imaging. Tomographic (99m)Tc-octreotide scintigraphy had lower sensitivity for the detection of hilar and mediastinal lymph node metastasis compared with that of (18)F-FDG coincidence PET, but it had high sensitivity for the detection of remote metastatic lesions. However, because of the small population, further investigation is necessary.