[show abstract][hide abstract] ABSTRACT: The purpose of this study was to describe the effect of implementing an imaging quality assurance program on CT image quality in the Lung Screening Study component of the National Lung Screening Trial.
The National Lung Screening Trial is a multicenter study in which 53,457 subjects at increased risk of lung cancer were randomized to undergo three annual chest CT or radiographic screenings for lung cancer to determine the relative effect of use of the two screening tests on lung cancer mortality. Of the 26,724 subjects randomized to the CT screening arm of the National Lung Screening Trial, the Lung Screening Study randomized 17,309 through 10 screening centers. The others were randomized through the American College of Radiology Imaging Network. Quality assurance procedures were implemented that included centralized review of a random sample of 1,504 Lung Screening Study CT examinations. Quality defect rates were tabulated.
Quality defect rates ranged from 0% (section reconstruction interval) to 7.1% (reconstructed field of view), and most errors were sporadic. However, a recurrently high effective tube current-time product setting at one center, excessive streak artifact at one center, and excessive section thickness at one center were detected and corrected through the quality assurance process. Field-of-view and scan length errors were less frequent over the second half of the screening period (p < 0.01 for both parameters, two-tailed, paired Student's t test). Error rates varied among the screening centers and reviewers for most parameters evaluated.
Our experience suggested that centralized monitoring of image quality is helpful for reducing quality defects in multicenter trials.
American Journal of Roentgenology 09/2009; 193(2):419-24. · 2.90 Impact Factor
[show abstract][hide abstract] ABSTRACT: To evaluate agreement among radiologists on the interpretation of pulmonary findings at low-dose computed tomographic (CT) screening examinations for lung cancer.
Institutional review board approval and informed consent were obtained. HIPAA guidelines were followed. Sixteen radiologists from the 10 National Lung Screening Trial screening centers of the National Cancer Institute's Lung Screening Study network reviewed image subsets from 135 baseline low-dose screening CT examinations in 135 trial participants (89 men, 46 women; mean age, 62.7 years +/- 5.4 [standard deviation]). Interpretations were classified into one of four of the following categories: noncalcified nodule 4 mm or larger in greatest transverse dimension (positive screening result); noncalcified nodule smaller than 4 mm in greatest transverse dimension (negative screening result); calcified, benign nodule (negative screening result); or no nodule (negative screening result). A recommendation for follow-up evaluation was obtained for each case. Interobserver agreement was evaluated by using the multirater kappa statistic and by using response frequencies and descriptive statistics.
Multirater kappa values ranged from 0.58 (for agreement among all four classifications; 95% confidence interval: 0.55, 0.61) to 0.64 (for agreement on classification as a positive or negative screening result; 95% confidence interval: 0.62, 0.65). The average percentage of reader pairs in agreement on the screening result per case (percentage agreement) was 82%. There was wide variation in the total number of abnormalities detected and classified as pulmonary nodules, with differences of up to more than twofold among radiologists. For cases classified as positive, multirater kappa for follow-up recommendations was 0.35.
Interobserver agreement was moderate to substantial; potential for considerable improvement exists. Clinical trial registration no. NCT00047385.
[show abstract][hide abstract] ABSTRACT: The Lung Screening Study (LSS) was a pilot study designed to assess the feasibility of conducting a large scale randomized controlled trial (RCT) of low radiation dose spiral computed tomography (LDCT) versus chest X-ray (CXR) for lung cancer screening. Baseline results of LSS have been previously reported. Here, we report on the findings at the year one screen and on the final results of the LSS study. A total of 1660 subjects were randomized to the LDCT arm and 1658 to the CXR arm. Compliance with screening declined from 96% at baseline to 86% at year one in the LDCT arm and declined from 93% at baseline to 80% at year one in the CXR arm. Positivity rates for the year one screen were 25.8% for LDCT and 8.7% for CXR. Cancer yield was significantly less at year one for LDCT, 0.57%, than at baseline, 1.9%; cancer yield for CXR increased from 0.45% at baseline to 0.68% at year one. Forty lung cancers in the LDCT arm and 20 in the CXR arm were diagnosed over the study period. Stage I cancers comprised 48% of cases in the LDCT arm and 40% in the CXR arm. A total of 16 stage III-IV cancers were observed in the LDCT arm versus nine in the CXR arm. The LSS has established the feasibility of a RCT comparing annual spiral CT to chest X-ray for lung cancer screening.
Lung Cancer 02/2005; 47(1):9-15. · 3.39 Impact Factor
[show abstract][hide abstract] ABSTRACT: Low-radiation dose spiral computed tomography (LDCT) currently is being evaluated as a screening modality for lung carcinoma in a randomized trial. Although several diagnostic algorithms for the workup of positive LDCT screens have been proposed, to the authors' knowledge there is no widely accepted standard to date and there are few nationwide data concerning how such diagnostic workups are actually being performed outside a research protocol setting.
The Lung Screening Study (LSS) was a multicenter feasibility trial that randomized 1660 subjects to undergo LDCT and an equivalent number to undergo chest X-ray. Subjects with positive screens were referred to their own health care providers for diagnostic follow-up; LSS did not specify a diagnostic algorithm. LSS collected and abstracted medical records regarding procedures employed in the diagnostic workup of positive screens.
Of the 522 subjects with a positive LDCT screen at baseline or at Year One, 12% underwent biopsy. Biopsy was less likely to be performed in subjects with 4-9-mm nodules (5%) than in subjects with nodules measuring 10+ mm (25%) or in subjects with no nodules but other suspicious findings (15%). Among 63% of the subjects who underwent chest CT on follow-up, the median time between screening and first follow-up chest CT was 82 days. Only a minority of subjects received diagnostic workups that were consistent with published algorithms.
The data from the current study represent the experience of subjects followed by their health care providers in five different U.S. metropolitan areas and one rural area. As such, they provide some indication of practices in the U.S. with regard to the diagnostic workup of patients with positive spiral CT screens.
Cancer 02/2005; 103(1):157-63. · 5.20 Impact Factor