Lung cancer screening

The association of incidentally detected heart valve calcification with future cardiovascular events

Objectives

This study aims to investigate the prognostic value of incidental aortic valve calcification (AVC), mitral valve calcification (MVC) and mitral annular calcification (MAC) for cardiovascular events and non-rheumatic valve disease in particular on routine diagnostic chest CT.

Methods

The study followed a case-cohort design. 10410 patients undergoing chest CT were followed for a median period of 17 months. Patients referred for cardiovascular disease were excluded. A random sample of 1285 subjects and the subjects who experienced an endpoint were graded for valve calcification by three reviewers. Cox-proportional hazard analysis was performed to evaluate the prognostic value.

Results

515 cardiovascular events were ascertained. Compared with patients with no valve calcification, patients with severe AVC, MVC or MAC had respectively 2.03 (1.48–2.78), 2.08 (1.04–4.19) and 1.53 (1.13–2.08) increased risks of experiencing an event during follow-up. For valve endpoints the hazard ratios were respectively 14.57 (5.19–40.53), 8.78 (2.33–33.13) and 2.43 (1.18–4.98).

Conclusion

Incidental heart valve calcification, detected on routine chest CT is an independent predictor of future cardiovascular events. The study emphasises how incidental imaging findings can contribute to clinical care. It is a step in the process of composing an evidence-based approach in the reporting of incidental subclinical findings.

Lung cancer screening update

PURPOSE OF REVIEW

Lung cancer is a health problem of global proportions. Despite intensive research over many years, the prognosis is still very poor. For the surgery to be effective, tumours need to be recognized early. Computed tomography (CT) is significantly more sensitive than chest radiograph for identifying small, asymptomatic lung cancers. Although low-dose CT screening observational trials have demonstrated that survival for all tumour types and sizes detected were extremely high, there is no clear evidence that low-dose CT screening reduces deaths from lung cancer. Only the results of ongoing randomized controlled trials can reveal a real benefit of screening in terms of mortality reduction.

RECENT FINDINGS

We summarize the protocols and the preliminary results of the lung cancer screening randomized controlled trial and the problems linked to the detection of suspected early cancer.

SUMMARY

Today, we cannot already prove the ultimate mortality benefit of lung cancer screening with low-dose CT nor we can confirm that this approach is not harmful. We are waiting the final analysis of randomized controlled trials for lung cancer mortality. Even if is widely accepted that pooling data of randomized controlled trials could be of help to get powerful results in terms of mortality reduction in shorter follow-up time, this opportunity is still under evaluation.

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.

Evaluation of lung MDCT nodule annotation across radiologists and methods

RATIONALE AND OBJECTIVES

Integral to the mission of the National Institutes of Health-sponsored Lung Imaging Database Consortium is the accurate definition of the spatial location of pulmonary nodules. Because the majority of small lung nodules are not resected, a reference standard from histopathology is generally unavailable. Thus assessing the source of variability in defining the spatial location of lung nodules by expert radiologists using different software tools as an alternative form of truth is necessary.

MATERIALS AND METHODS

The relative differences in performance of six radiologists each applying three annotation methods to the task of defining the spatial extent of 23 different lung nodules were evaluated. The variability of radiologists' spatial definitions for a nodule was measured using both volumes and probability maps (p-map). Results were analyzed using a linear mixed-effects model that included nested random effects.

RESULTS

Across the combination of all nodules, volume and p-map model parameters were found to be significant at P < .05 for all methods, all radiologists, and all second-order interactions except one. The radiologist and methods variables accounted for 15% and 3.5% of the total p-map variance, respectively, and 40.4% and 31.1% of the total volume variance, respectively.

CONCLUSION

Radiologists represent the major source of variance as compared with drawing tools independent of drawing metric used. Although the random noise component is larger for the p-map analysis than for volume estimation, the p-map analysis appears to have more power to detect differences in radiologist-method combinations. The standard deviation of the volume measurement task appears to be proportional to nodule volume.

Novel Strategies for the Early Detection and Prevention of Lung Cancer

Lung cancer is the leading cause of cancer death in the United States. Despite evidence of molecular abnormalities in biological specimens, progress in this disease is hampered by the lack of diagnostic markers useful for clinical practice. The majority of patients with lung cancer are still diagnosed at an advanced stage, when prognosis is poor. This article reviews new strategies being studied for the early detection of lung cancer. These strategies involve new methods of imaging (including low-dose computed tomography [CT] scanning), DNA analysis, and proteomic-based techniques. These strategies have not only improved our understanding of lung cancer but show promise in offering better survival to patients with this deadly disease. Of paramount importance in the search for methods of early detection is the need for the identification of the ideal population to screen, a multidisciplinary approach, and validation of promising techniques.

Characterization of the interstitial lung diseases via density-based and texture-based analysis of computed tomography images of lung structure and function1

RATIONALE AND OBJECTIVES

Efforts to establish a quantitative approach to the computed tomography (CT)-based character ization of the lung parenchyma in interstitial lung disease (including emphysema) has been sought. The accuracy of these tools must be site independent. Multi-detector row CT has remained the gold standard for imaging the lung, and it provides the ability to image both lung structure as well as lung function.

MATERIAL AND METHODS

Imaging is via multi-detector row CT and protocols include careful control of lung volume during scanning. Characterization includes not only anatomic-based measures but also functional measures including regional parameters derived from measures of pulmonary blood flow and ventilation. Image processing includes the automated detection of the lungs, lobes, and airways. The airways provide the road map to the lung parenchyma. Software automatically detects the airways, the airway centerlines, and the branch points, and then automatically labels the airway tree segments with a standardized set of labels, allowing for intersubject as well intrasubject comparisons across time. By warping all lungs to a common atlas, the atlas provides the range of normality for the various parameters provided by CT imaging.

RESULTS

Imaged density and textural changes mark underlying structural changes at the most peripheral regions of the lung. Additionally, texture-based alterations in the parameters of blood flow may provide early evidence of pathologic processes. Imaging of stable xenon gas provides a regional measure of ventilation which, when coupled with measures of flow, provide for a textural analysis regional of ventilation-perfusion matching.

CONCLUSION

With the improved resolution and speed of CT imaging, the patchy nature of regional parenchymal pathology can be imaged as texture of structure and function. With careful control of imaging protocols and the use of objective image analysis methods it is possible to provide site-independent tools for the assessment of interstitial lung disease. There remains a need to validate these methods, which requires interdisciplinary and cross-institutional efforts to gather appropriate data bases of images along with a consensus on appropriate ground truths associated with the images. Furthermore, there is the growing need for scanner manufacturers to focus on not just visually pleasing images, but on quantitatifiably accurate images.