Influence of hilar deposition in the evaluation of the alveolar epithelial permeability on 99mTc-DTPA aerosol inhaled scintigraphy
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We investigated whether hilar radioaerosol deposition affects the clearance rate of technetium-99m-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA) from peripheral alveolar regions.
Materials and methods
A total of 38 patients underwent 99mTc-DTPA inhalation lung scintigraphy. Six region of interest (ROI) patterns were adopted: ROI 1 was outlined around the entire hemithorax, and ROIs 2–6 were outlined around the hemithorax but excluded square ROIs of different size in the hilar region. Half-times (T½) were calculated with time-activity curves using onecompartment and two-compartment analyses. The T½ of ROIs 1–5 were plotted against the T½ of ROI 6, and regression lines were obtained with the least-squares method. The absolute values of the differences between surveyed values and regression line were calculated. The Wilcoxon test for trend and a single linear regression model were used to determine statistical significance.
There were significant reductions in the absolute values of the differences between surveyed values and regression line from ROIs 1–5 by one-component analysis and the fast component of two-compartment analysis (P < 0.001).
Our results suggest that the deposition of radioaerosol in the hilar region affects the clearance rate of 99mTc-DTPA from the alveoli in damaged lungs. The hilar region should be excluded from ROIs when alveolar epithelial permeability is evaluated.
Key words99mTc-DTPA Lung clearance Alveolar epithelial permeability One-compartment analysis Two-compartment analysis
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