Study on uptake and dynamics of 123I-IMP in pulmonary diseases

The aim of this study was to assess serial uptake of N-isopropyl-p-[I-123] iodoamphetamine (I-123 IMP) quantitatively in the lung. A total of 53 patients were enrolled in the study, consisting of 34 with lung cancer, 12 with inflammatory disease and 7 with miscellaneous diseases. The findings were compared with those with 99mTc-MAA. The 1- or 2-min I-123 IMP images were analogous to those of 99mTc-MAA in 24 patients. Early I-132 IMP images seemed to be governed by pulmonary arterial blood flow. I-123 IMP was not taken up by cancerous lesions of the lung on both 30 min and 4 hr images. Nor was it taken up by other malignancy. It was taken up by all inflammatory lesions, including pneumonia and infiltrate surrounding lung abscess. Collapse lesions were shown as warm or cold areas on 30 min images and as hot spots on 4 hr images. IMP was not taken up by pleural effusions. Pulmonary arterial blood flow was shown as cold areas at 30 min, and as warm or cold areas at 4 hr. In conclusion, intrathoracic cancerous lesions, cavities and pleural effusions were shown as cold areas on both early and delayed images. Both inflammatory and collapse lesions were shown as hot areas on delayed images. Quantitative assessment of the lesion/contralateral lung count ratios suggested different mechanism in tracer uptake: delayed clearance and delayed fill-in may be involved in the mechanism for inflammation and collapse, respectively. (N.K.)