Air trapping in chest imaging refers to retention of extra fueloline in all or a part of the lung, especially for the duration of expiration, both because of entire or partial airway obstruction or because of nearby abnormalities in pulmonary compliance. It may from time to time be determined in regular individuals. Air trapping is a descriptor utilized in lung CT visible as a reduced attenuation of pulmonary parenchyma, specially manifested as a much less than regular growth in attenuation for the duration of expiratory acquisition. This look has to be differentiated from the reduced attenuation of hypo perfusion secondary to regionally accelerated pulmonary arterial resistance. The concurrent presence of absence or bronchiectasis and interstitial lung sickness can be beneficial to slender the differential possibilities. Air trapping, additionally referred to as fueloline trapping, is a strange retention of air with inside the lungs wherein it's miles hard to exhale completely. It is determined in obstructive lung illnesses along with asthma, bronchiolitis obliterans syndrome and persistent obstructive pulmonary illnesses along with emphysema and persistent bronchitis. Air trapping isn't a analysis however is a presentation of an illness, and may be a manual to an appropriate differential. On excessive decision CT air trapping has a regular imaging look, despite the fact that frequently assessment with each most inhalation and exhalation, or inspiratory and expiratory views, are wanted for a greater particular analysis. One of its standard imaging styles is mosaic attenuation. In the conventional presentation, the lung will seem regular at thought, however on exhalation, the diseased quantities of the lung that have misplaced connective tissue draw back will stay lucent even as the wholesome quantities of the lung becomes greater dense because of atelectasis. This facilitates distinguish it from mosaic attenuation because of patchy fibrosis, as takes place with nonspecific interstitial pneumonia, and in early ordinary interstitial pneumonitis (the hallmark imaging analysis of interstitial lung sickness) wherein there may be no alternate with thought and expiration. Unfortunately, their take a look at had numerous limitations. Although emphysema is now detectable with using CT, it's miles hard to quantify airway obstruction and air trapping in sufferers with COPD. However, numerous researchers have attempted to quantify the diploma of air trapping the use of densitometric strategies on expiratory or paired inspiratory and expiratory CT in diverse obstructive lung diseases. It has been suggested that the location of air trapping does now no longer display an growth in CT attenuation and stays greater radiolucent than the encompassing ordinary pulmonary tissue. Therefore, the exclusion of the pixels much less than –950 H on each inspiratory and expira-tory CT is perfect for the quantification of air trapping without impact of the volume of emphysema. Actually, with inside the mild to extreme emphysema group, relative quantity change860–950 became the most effective parameter that associated with the end result of PFTs related to airway obstruction and air trapping. Meanwhile, no massive correlations have been visible among the outcomes of PFTs reflecting airway disorder and relative quantity change that is the parameter consisting of voxels with attenuation values much less than –950 H concerning the volume of emphysema. Quantitative CT evaluation has been used to evaluate the relative efficacy of medicine on small airway hyperreactivity and local air trapping. The assessment of drug efficacy with inside the peripheral airlines is important, and development in the direction of particular remedy for COPD is probably multiplied via way of means of transferring past the size of airflow drawback to an appropriate prognosis of the particular objectives liable for the airflow drawback.