Quantitative analysis of inhomogeneity in ventilation SPET

摘要: The aim of this study was to evaluate a method for quantification inhomogeneity in ventilation single-photon emission tomography (SPET). Nine emphysematous patients, nine life-long non-smokers and smokers were included the study. SPET investigation performed after 50 MBq 99mTc-Technegas had been inhaled by each subject supine position. A single-head gamma camera, equipped with general-purpose parallel-hole collimator using 64 projections (20 s each) over 360°, used. Data acquired 128×128 matrices. Attenuation correction applied based upon computed (CT) density maps. Lung regions interest delineated manually on CT images then positioned images. Several attenuation-corrected transaxial slices (thickness 1 cm, spacing 3.5 cm) reconstructed. Each slice divided into several 2×2×1 cm3 elements. Inhomogeneity assessed coefficient variation (CV) pixel counts within these elements (micro-level) CV total (macro-level). Micro-level CVs varied between 1% 41%, whereas they dispersed wide range (1%–600%) patients. In seven smokers, frequency distribution micro-level normal range, other two values pooled mean macro-level clearly separated patients from others. Parametric indicated localisation severity inhomogeneity. We conclude that present enables regional