Image Based Grading of Emphysema

Abstract

Emphysema is permanent abnormal enlargement of alveolar walls due to destruction of the alveolar tissues and thereby affecting the gas exchange process of lungs. Grading is usually done to rank the severity of the disease. This paper is a comprehensive review of the imaging based methods used to monitor the emphysema severity. This article aims at the identification of the best imaging method for emphysema grading. Correlation of imaging outcome with pulmonary function parameters is analyzed. Time frame of reviewed articles included is from 2002 to till date. In this review, the classification methods employed for grading emphysema are examined. The best grading method was chosen based on the superior performance obtained in comparison to all the existing work available so far in grading the severity of emphysema. Three-dimensional CT densitometry is found to be highly significant with a correlation coefficient of r = 0.97 at significance value, p < 0.001 for the classification of moderate to very severe emphysema as compared to pulmonary function test (PFT). Further research needs to be done to identify methods for evaluating the progress of emphysema during its mild stage.