Increased accumulation of iodine-123-IMP in the pulmonary inflammatory lesion surrounding a lung cancer

Binding cells of 125I-iodoamphetamine in rat liver

We recently reported that transrectal or intestinal portal scintigraphy with 123I-iodoamphetamine (IMP) could be a useful method for the non-invasive and quantitative evaluation of the portosystemic shunt in portal hypertension, but what cells in the liver trap IMP has not been clarified. This study was aimed at elucidating whether IMP was extracted by parenchymal cells, sinusoidal endothelial cells, Kupffer cells or fat storing cells. Each type of liver cell was isolated from rats and cultured. The cells were incubated with 125I-IMP and the radioactivity of the lysate was determined. Nonspecific binding was assessed in the presence of an excess of unlabeled IMP, and specific binding was determined by subtracting the nonspecific from total binding. Specific binding observed in parenchymal cells, endothelial cells and Kupffer cells was 70.2 +/- 0.4, 4.2 +/- 1.4 and 2.3 +/- 0.8 pmol/well, respectively, but no specific binding was observed in fat storing cells. The binding in parenchymal cells was much higher than that in endothelial cells or Kupffer cells (p < 0.005). In addition, the binding to parenchymal cells reached equilibrium within 20 min and was not saturable over the concentration range tested (0.5-10 microM). These findings indicate that IMP is mostly extracted by parenchymal cells in the liver.

New design of N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) lung imaging in the patient with lung cancer

N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) was injected intravenously into primary non small cell lung carcinoma patients (n = 17). The average pixel count ratios of the cancerous area to the whole lung was measured in the initial and delayed images. In the initial image, this ratio was less than 1.0 for the entire group of patients, and was thought to reflect decreased blood flow in the cancerous tissues. The rate of counts within a ROI in the delayed image to counts in the same ROI in the initial image was also calculated and called the remain rate. The remain rate (delayed count/initial count) was significantly higher in the cancerous area than in the whole lung (0.65 +/- 0.30, median 0.62, 0.38 +/- 0.05, median 0.38, p < 0.01). This observation was thought to be due to a relative decrease in the blood flow and the accumulation of IMP, which forms pools within the alveolar spaces of the cancerous areas. The image prepared with the remain rate revealed a hot image in the cancerous regions, even when this was not apparent in the delayed image. The remain rate image may therefore be useful in the identification of cancerous areas in lung tissue if it is used in comparison with the initial image.

Lung scintigraphy with [123I]IMP in patients with pulmonary tuberculosis

Lung scintigraphy using N-isopropyl-p-[123I]iodoamphetamine (IMP) was performed on 26 patients with pulmonary tuberculosis. Early (5 min after injection) and late images (4 h after injection) were obtained with a large-field gamma-camera equipped with a digital computer. Lung scintigraphy using [99mTc]MAA (MAA) was also done. Although early IMP images showed the same findings as [99mTc]MAA, images, a discrepancy between delayed IMP images and [99mTc]MAA images was seen in some patients. Increment of activities seen in late images was demonstrated in most patients whose chest x-ray findings included exudative inflammatory changes. Uptake and clearance of IMP was considered to be affected by the active phase of pulmonary tuberculosis.

The influence of age on N-isopropyl-p-[123I]iodoamphetamine accumulation in the human heart

Variations in heart intensity in the 30 min and 4 hr chest images of the radiolabelled lipophilic amine, N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) were observed in 130 patients with lung diseases, aged 23 to 85 yrs. The heart intensity had a significant positive linear correlation with age (r = 0.43 at 30 min, 0.66 at 4 hr). The ratio of 4 hr heart intensity to 30 min heart intensity also had a positive linear correlation (r = 0.59), suggesting slower clearance of the radioactivity from the heart in older than in younger patients during this interval. Other parameters including sex, EKG findings, liver function, blood pressure, the presence of diabetes mellitus and smoking history had no relationship to heart intensity. A significant difference between heart intensities in bronchogenic carcinoma and pneumonia patient groups might be probably due to the age difference between the two groups. Therefore heart intensity in the 4 hr 123I-IMP image may reflect certain metabolic and/or myocardial change(s) with aging.

Differentiation of bronchogenic carcinoma from secondary changes, obstructive pneumonitis and/or collapse by I-123 IMP lung imaging

Serial lung images with N-isopropyl-p-[I-123]-iodoamphetamine (I-123 IMP) were obtained to assess the imaging findings and to clarify the lesion to uptake relationships in 74 lesions in 73 patients with various histological types of bronchogenic carcinoma. A decreased uptake area was observed in all 74 lesions in the initial one or two-min I-123 IMP image. The initial image was analogous to a Tc-99m MAA lung perfusion image in 70 patients in whom both lung imaging procedures were performed. The imaging findings changed following this initial phase. At 4 hr, the lesion was depicted as either areas of decreased uptake or increased uptake or a combination of the two. Comparison between the lesion findings in the 4-hr I-123 IMP images, radiograms and removed specimens revealed that areas of decreased uptake corresponded to the cancerous portions of the lung mass or pleural effusion and areas of increased uptake corresponded to inflammatory portions including obstructive pneumonitis and/or collapse. Thus, the 4-hr I-123 IMP lung images can be used to discriminate the cancerous portion from associated secondary changes, obstructive pneumonitis and/or collapse.