Uptake of Tc-99m hexakis 2-methoxy isobutyl isonitrile in lung or mediastinal lesions by SPECT

The uptake of Tc-99m hexakis 2-methoxy isobutyl isonitrile (99mTc-MIBI) was evaluated in 18 patients with various lung or mediastinal lesions by SPECT. The patients consisted of seven with lung cancers, three with lung cancers who were treated with chemotherapy and were disease free, and one each with malignant lymphoma, esophageal cancer, thyroid cancer involving the mediastinum, malignant thymoma, pneumonia, granuloma, sarcoidosis and neurinoma. SPECT imaging (30 min, 600 MBq) was performed after intravenous injection. Strong uptake of 99mTc-MIBI was noted in all malignant tumors except malignant lymphoma. The mean tumor to normal lung tissue uptake ratio (T/N ratio) was 2.26. The mean in lung cancer was 2.31. Slight accumulation was present in pneumonia and granuloma (mean T/N=1.24). No accumulation was present in a case of non-Hodgkin's lymphoma and neurinoma. Moderate uptake was noted in one case of sarcoidosis (T/N=1.46). No abnormal accumulation of 99mTc-MIBI was seen in post-therapeutic lung cancer. These results suggested that 99mTc-MIBI SPECT could be useful in differentiating between malignant and benign lesions. (author)