Volume-Controlled Histographic Analysis of Pulmonary Parenchyma in Normal and Diffuse Parenchymal Lung Disease: A Pilot Study

Abstract

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 idiopathic 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 maximum (FWHM) were derived from the histogram. We compared normal controls with abnormal groups including emphysema and IPF patients at the same respiration levels. Results: A normal histographic zone with 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 inspiration 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