PURPOSE: Classic computed tomography (CT) in its qualitative mode has been useful to pulmonologists and others in medicine since the early 1970s. Serial applications in lung cancer detection and in large clinical trials such as the National Lung Screening Trial (NLST) are well known. We have begun to analyze some of the NLST database for quantitative changes in patients with emphysema.
METHODS: Quantitative analysis of HRCT can be achieved using a software program, either intrinsic to the CT manufacturer's equipment or as an add-on. It has been technically available since 1984. For this study we used Pulmo-CMS CT analysis. Quantitative CT analysis can more reproducibly measure lung volume and density changes over time, expressed in Hounsfield units or some derivative.
RESULTS: In the left hand image Pulmo-CMS demonstrates diffusely distributed emphysema quantitatively. On the right, a narrow lung window image, the enhanced contrast allows the numerous large regions of loss of parenchyma to be easily seen radiographically using qualitative settings. With less obvious and extensive involvement quantitative analysis may prove more sensitive in emphysema detection and in follow-up studies over time quantitative analysis is more useful to measure progressive density loss more reproducibly.
CONCLUSION: Computed tomography with the Pulmo-CMS software may allow quantatative assessment of the degree of pulmonary emphysema in a format that is more diagnostically sensitive than with standard computed tomography.
CLINICAL IMPLICATIONS: Quantitative CT analysis is readily available today. Its applications to clinical medicine would perhaps most obviously be seen if there were disease-modifying therapy that affected the otherwise natural course of progressive loss of CT density over time.
DISCLOSURE: Daniel Ouellette, No Product/Research Disclosure Information; Grant monies (from industry related sources) We have received research sponsorship from Roche pharmaceuticals who may have an interest in the topic being presented.