Population screening for lung cancer

Should we screen for occupational lung cancer with low-dose computed tomography?

OBJECTIVE

The objective of this study was to assess the potential value of screening for occupational lung cancer through the use of low-dose computed tomography (LDCT).

METHODS

A literature review of Medline was conducted to assess: 1) screening studies of occupational lung cancer that used LDCT; 2) screening studies of nonoccupational lung cancer that used LDCT; and 3) position papers of medical professional societies and nongovernmental health organizations that have addressed the value of screening for lung cancer with LDCT.

RESULTS

No screening studies of occupational lung cancer with LDCT were uncovered; however, numerous observational and population-based studies have addressed the value of screening for lung cancer among cigarette smokers. Results of these studies are difficult to interpret in light of numerous biases associated with these types of studies. No randomized, controlled studies on screening for lung cancer have been published at this time. No professional, governmental, or nonprofit health organization recommends screening asymptomatic people at risk of lung cancer with LDCT at this time.

CONCLUSION

In the absence of randomized, controlled studies that can address biases commonly encountered in observational and population-based studies, it is unclear whether LDCT reduces mortality from lung cancer. The National Cancer Institute is sponsoring a randomized, controlled study of over 50,000 current and former smokers with the results expected in 2009.

Stereo CT image compositing methods for lung nodule detection and characterization

RATIONALE AND OBJECTIVES

Stereographic display has been proposed as a possible method of improving performance in reading computed tomographic (CT) examinations acquired for lung cancer screening. Optimizing such displays is important given the large volume of image data that must be evaluated for each of these examinations. This study is designed to explore certain tradeoffs between rendering methods designed for the stereo display of CT images.

MATERIALS AND METHODS

Stereo CT image compositing methods, including distance-weighted averaging, distance-weighted maximum intensity projection (MIP), and conventional MIP, were applied to lung CT images and compared for lung nodule detection and characterization.

RESULTS

Using the Jonckheere test indicated a statistically significant (P < .01) increase in contrast among the three compositing methods. Wilcoxon-Mann-Whitney test showed significant differences in contrast between distance-weighted averaging and conventional MIP (P < .01) and between averaging and distance-weighted MIP (P < .05), but not between distance-weighted MIP and conventional MIP (P > .05). Conventional MIP compositing provided the highest image contrast, but produced ambiguities in local geometric detail and texture, whereas averaging resulted in the lowest contrast, but preserved geometric detail. Distance-weighted MIP partially recovered geometric information, which was lost in images composited by means of conventional MIP.

CONCLUSION

Our results indicate that distance-weighted MIP may be a better choice for nodule detection in stereo lung CT images for its high local contrast and partial preservation of geometric information, whereas compositing by means of distance-weighted averaging is preferable for nodule characterization. The relative clinical value of these compositing methods needs to be evaluated further.