RESUMO
PURPOSE: To evaluate the clinical usefulness of a home-made histographic analysis system using a lung volume controller. MATERIALS AND METHODS:Our study involved ten healthy volunteers, ten emphysema patients, and two idio-pathic pulmonary fibrosis (IPF) patients. Using a home-made lung volume controller, images were obtained in the upper, middle, and lower lung zones at 70%, 50%, and 20% of vital capacity. Electron beam tomography was used and scanning parameters were single slice mode, 10-mm slice thickness, 0.4-second scan time, and 35 -cm field of view. Using a home-made semi-automated program, pulmonary parenchyma was isolated and a histogram then obtained. Seven histographic parameters, namely mean density (MD), density at maximal frequency (DMF), maximal ascending gradient (MAG), maximal ascending gradient density (MAGD), maxi-mal descending gradient (MDG), maximal descending gradient density (MDGD), and full width at half maxi-mum (FWHM) were derived from the histogram. We compared normal controls with abnormal groups includ-ing emphysema and IPF patients at the same respiration levels. RESULTS: A normal histographic zone with +/-1 standard deviation was obtained. Histographic curves of normal controls shifted toward the high density level, and the width of the normal zone increased as the level of inspi-ration decreased. In ten normal controls, MD, DMF, MAG, MAGD, MDG, MDGD, and FWHM readings at a 70% inspiration level were lower than those at 20% (p<0.05). At the same level of inspiration, histograms of emphysema patients were located at a lower density area than those of normal controls. As inspiration status decreased, histograms of emphysema patients showed diminished shift compared with those of normal con-trols. At 50% and 20% inspiration levels, the MD, DMF, and MAGD readings of emphysema patients were significantly lower than those of normal controls (p<0.05). Compared with those of normal controls, his-tograms of the two IPF patients obtained at three inspiration levels were located in an area of higher density. CONCLUSION: Using a home-made histographic analysis system which included a lung volume controller, pa-tients with diffuse parenchymal lung disease could be distinguished from normal controls. The method may be useful for the diagnosis and follow up of diffuse parenchymal lung diseases.