A Multicenter Trial With a Somatostatin Analog 99mTc Depreotide in the Evaluation of Solitary Pulmonary Nodules

The affinity of various malignant neoplasms including small cell and non-small cell lung cancer for peptide analogs of somatostatin has been well documented. Depreotide is such an analog and can be complexed with technetium-99m (99mTc depreotide) for optimal imaging properties. Using this radiopharmaceutical, solitary pulmonary nodules (SPN) were previously evaluated in a successful phase II/III trial. The results of the larger multicenter phase III study using 99mTc depreotide to differentiate malignant and benign etiologies in SPN are now presented. Patients with SPN ≤ 6 cm on chest radiograph were referred for evaluation. One hundred fourteen individuals who had an absence of a benign pattern of calcification on CT scan, age > 30 years, and no demonstrable radiographic stability for the prior 2 years were studied. All underwent single-photon emission CT (SPECT) with 99mTc depreotide and subsequent tissue histologic examination. Three nuclear medicine specialists blinded to histologic findings examined the SPECT images and scored them as positive or negative based on the presence or absence of activity in the radiographic region of the SPN. The final result was determined by the majority score, which was then compared with the histologic result. Of the 114 individuals studied, 88 had a histologic result compatible with malignant neoplasm. 99mTc depreotide scintigraphy correctly identified 85 of this group, with three false-negative determinations compared with histology. There were seven false-positive determinations, including six granulomas and one hamartoma. 99mTc depreotide scintigraphy correctly excluded malignancy in 19 of 26 patients with benign histologic findings. The sensitivity of this method was 96.6% with a specificity of 73.1%. 99mTc depreotide scintigraphy is a safe and useful method for the noninvasive evaluation of SPN with a sensitivity and accuracy comparable to that reported for fluorine-18 fluorodeoxyglucose positron emission tomography.