CT Based Histogram Assisted Emphysema Severity Quantification

Emphysema is defined as loss of lung tissue and considered one of the main reasons for causing COPD (Chronic Obstructive Pulmonary Disease). Thus a proper differentiation between emphysematous and healthy lung tissues is a big necessity. This paper aims to discuss a novel approach to assess the emphysema severity through chest CT image analysis. From the histogram of the segmented lung region of a chest CT image a single intensity threshold in Hounsfield Units (HU) is taken into account to determine the relative no. of pixels with low attenuation values below it. This parameter has been widely used to measure the severity of emphysema from CT images. The study considers RA-910 HU, the pixel index or emphysema index as the intensity threshold to measure the proportion of pixels with densities or attenuation values or HU lesser than it, which usually refer to regions contributing emphysema. CT images of 5 subjects (both COPD and non-COPD smokers and non-smokers) were processed and used for quantitative analysis in this study to get a fundamental hold of the degree of severity of emphysema.