Liability of performing CT screening for coronary artery disease and lung cancer

Missed lung cancer: when, where, and why?

Missed lung cancer is a source of concern among radiologists and an important medicolegal challenge. In 90% of the cases, errors in diagnosis of lung cancer occur on chest radiographs. It may be challenging for radiologists to distinguish a lung lesion from bones, pulmonary vessels, mediastinal structures, and other complex anatomical structures on chest radiographs. Nevertheless, lung cancer can also be overlooked on computed tomography (CT) scans, regardless of the context, either if a clinical or radiologic suspect exists or for other reasons. Awareness of the possible causes of overlooking a pulmonary lesion can give radiologists a chance to reduce the occurrence of this eventuality. Various factors contribute to a misdiagnosis of lung cancer on chest radiographs and on CT, often very similar in nature to each other. Observer error is the most significant one and comprises scanning error, recognition error, decision-making error, and satisfaction of search. Tumor characteristics such as lesion size, conspicuity, and location are also crucial in this context. Even technical aspects can contribute to the probability of skipping lung cancer, including image quality and patient positioning and movement. Albeit it is hard to remove missed lung cancer completely, strategies to reduce observer error and methods to improve technique and automated detection may be valuable in reducing its likelihood.

Establishing a computed tomography screening clinic

Since the publication of the National Lung Screening Trial results, there has been increasing interest among radiologists to establish computed tomography (CT) screening centers. During the past 10 years, we have operated a CT screening center in suburban Boston, MA. The purpose of this paper is to describe our process for performing self-referred CT lung screening exams, including our organizational structure, marketing, patient selection process, and standardized workflow. Direct communication between the patient and radiologist, both before and after the CT scan, in our opinion, is critical to a successful screening program. In many ways, CT screening offers radiologists a wonderful opportunity to interact directly with patients. Showing abnormal lung findings to patients on their CT scans may help create a unique "teachable" moment for current smokers and may help motivate patients to quit smoking.

Missed lung cancer on chest radiography and computed tomography

Missed lung cancer raises an important medicolegal issue and contributes to one of the most common causes for malpractice actions against radiologists. Lung cancer may be missed on either chest radiography or computed tomography. Although most malpractice cases involve lesions overlooked on the former, a small and increasing portion of cases are related to chest computed tomography scan. Factors contributing to overlooked lung cancer can be attributed to observer performance, lesion characteristics, and technical considerations.

Potential of computer-aided diagnosis to improve CT lung cancer screening

The development of low-dose spiral computed tomography (CT) has rekindled hope that effective lung cancer screening might yet be found. Screening is justified when there is evidence that it will extend lives at reasonable cost and acceptable levels of risk. A screening test should detect all extant cancers while avoiding unnecessary workups. Thus optimal screening modalities have both high sensitivity and specificity. Due to the present state of technology, radiologists must opt to increase sensitivity and rely on follow-up diagnostic procedures to rule out the incurred false positives. There is evidence in published reports that computer-aided diagnosis technology may help radiologists alter the benefit-cost calculus of CT sensitivity and specificity in lung cancer screening protocols. This review will provide insight into the current discussion of the effectiveness of lung cancer screening and assesses the potential of state-of-the-art computer-aided design developments.

Whole-body CT screening: spectrum of findings and recommendations in 1192 patients

PURPOSE

To retrospectively determine the frequency and spectrum of findings and recommendations reported with whole-body computed tomographic (CT) screening at a community screening center.

MATERIALS AND METHODS

This HIPAA-compliant study received institutional review board approval, with waiver of informed consent. The radiologic reports of 1192 consecutive patients who underwent whole-body CT screening of the chest, abdomen, and pelvis at an outpatient imaging center from January to June 2000 were reviewed. Scans were obtained with electron-beam CT without oral or intravenous contrast material. Reported imaging findings and recommendations were retrospectively tabulated and assigned scores. Descriptive statistics were used (means, standard deviations, and percentages); comparisons between subgroups were performed with univariate analysis of variance and chi(2) or Fisher exact tests.

RESULTS

Screening was performed in 1192 patients (mean age, 54 years). Sixty-five percent (774 of 1192) were men and 35% (418 of 1192) were women. Nine hundred three (76%) of 1192 patients were self referred, and 1030 (86%) of 1192 subjects had at least one abnormal finding described in the whole-body CT screening report. There were a total of 3361 findings, with a mean of 2.8 per patient. Findings were described most frequently in the spine (1065 [32%] of 3361), abdominal blood vessels (561 [17%] of 3361), lungs (461 [14%] of 3361), kidneys (353 [11%] of 3361), and liver (183 [5%] of 3361). Four hundred forty-five (37%) patients received at least one recommendation for further evaluation. The most common recommendations were for additional imaging of the lungs or the kidneys.

CONCLUSION

With whole-body CT screening, findings were detected in a large number of subjects, and most findings were benign by description and required no further evaluation. Thirty-seven percent of patients had findings that elicited recommendations for additional evaluation, but further research is required to determine the clinical importance of these findings and the effect on patient care.

The imaging manifestations of lung cancer

Imaging plays an integral role in diagnosing, staging, and following patients with lung cancer. Many lung neoplasms are detected on chest radiographs, but the majority of patients have advanced stage disease at the time of presentation. There is a wide spectrum of radiologic manifestations of lung cancer, and recognition of these findings is essential for patient management. As we continue to understand more about tumor biology, new imaging techniques likely will emerge. Nevertheless, the chest radiograph and CT remain important tools in establishing the diagnosis of lung cancer.

Lung cancer screening with low-dose chest CT: current issues

Computed tomography offers many advantages over routine radiographs in screening for lung cancer, and it is clear that low-dose spiral CT screening can more frequently find considerably smaller lung cancers than previous detection tools. Recently, investigators have performed low-dose spiral CT scanning for screening of lung cancer, and have suggested that CT screening can depict lung cancers at smaller sizes and at earlier stages. With technological advances in spiral CT scanners, the detection rate of small noncalcified pulmonary nodules has markedly increased, with higher rates noted with thinner collimation of CT scanning. Unfortunately, the majority of these have proved to be benign, i.e. false positive results. If, even in part, CT features could be found to predict benign nodules without follow-up, the false-positive rate would be reduced, and consequently, the cost, emotional stress, radiation dose, morbidity and mortality associated with interventional procedures would also be reduced. There have been several studies trying to establish reliable CT features for benign lesions in small pulmonary nodules and to determine their outcome. Although these efforts have not completely resolved the issue of false positive results, it is expected that lessons will be learnt on how to manage these small nodules through experience with screening in the near future. Because pulmonary nodules on CT are much more common in Korea than in western countries, the management algorithm for screening CT-detected nodules should be modified according to different circumstances, with consensus among related physicians and radiologists. In addition, to enhance patient care and avoid misunderstanding of inherent limitation of CT screening by the screening subjects, physicians, hospital managers as well as radiologists should provide proper information regarding CT screening to the screenees.

Screening for lung cancer

PURPOSE OF REVIEW

With the development of newer forms of technology such as low-dose spiral computed tomography, there has been a resurgent interest in screening for lung cancer. The purpose of this review is to highlight recent advances in screening for lung cancer. Articles published since September 2002 are reviewed here.

RECENT FINDINGS

More frequent screenings (every 4 or 6 months) showed increased mortality from lung cancer, compared with annual screening. A mass screening conducted in 1990 was effective in a case-control study. The results of lung cancer screening by low-dose spiral computed tomography were reported from the Milan group and the Mayo Clinic. Computed tomography depicted peripheral early lung cancer, especially adenocarcinoma. These results are consistent with previous reports from other groups. Screening with imaging becomes more sensitive with automated computerized methods.

SUMMARY

A high percentage of stage IA lung cancers were detected by screening with low-dose helical computed tomography. The characteristics of the nodules detected by low-dose spiral computed tomography have been clarified. There have been many controversial discussions about cost effectiveness and overdiagnosis. There is still no evidence that screening tests reduce the rate of cancer-specific mortality. Several studies of screening for lung cancer are under way.