Imaging the 'dirty lung'--has high resolution computed tomography cleared the smoke?

The histopathological abnormalities that characterize cigarette smokers' lung damage have been widely studied, but these microscopic changes do not fully explain the radiographic features that have been loosely termed the 'dirty lung'. High resolution computed tomography is not only more sensitive for the detection of early emphysema, it has also provided the imaging correlates of subtle parenchymal changes of smokers, for example, respiratory bronchiolitis - interstitial lung disease. Nevertheless, some aspects of the radiographic 'dirty lung' remain enigmatic.