Rationale and Objectives
The aim of this study was to evaluate the usefulness of computer-aided diagnosis (CAD) software for the detection of lung nodules on multidetector-row computed tomography (MDCT) in terms of improvement in radiologists’ diagnostic accuracy in detecting lung nodules, using jackknife free-response receiver-operating characteristic (JAFROC) analysis.
Materials and Methods
Twenty-one patients (6 without and 15 with lung nodules) were selected randomly from 120 consecutive thoracic computed tomographic examinations. The gold standard for the presence or absence of nodules in the observer study was determined by consensus of two radiologists. Six expert radiologists participated in a free-response receiver operating characteristic study for the detection of lung nodules on MDCT, in which cases were interpreted first without and then with the output of CAD software. Radiologists were asked to indicate the locations of lung nodule candidates on the monitor with their confidence ratings for the presence of lung nodules.
Results
The performance of the CAD software indicated that the sensitivity in detecting lung nodules was 71.4%, with 0.95 false-positive results per case. When radiologists used the CAD software, the average sensitivity improved from 39.5% to 81.0%, with an increase in the average number of false-positive results from 0.14 to 0.89 per case. The average figure-of-merit values for the six radiologists were 0.390 without and 0.845 with the output of the CAD software, and there was a statistically significant difference ( P < .0001) using the JAFROC analysis.
Conclusion
The CAD software for the detection of lung nodules on MDCT has the potential to assist radiologists by increasing their accuracy.
Because some evidence suggests that the early detection of lung cancer may allow timely therapeutic intervention and thus favorable prognoses for patients ( ), lung cancer screening using low-dose computed tomography has been proposed ( ). For example, in a 2006 report by the International Early Lung Cancer Action Program ( ), computed tomographic (CT) lung cancer screening resulted in diagnoses of lung cancer in 484 of 31,567 participants. Of these 484 participants, 412 (85%) had clinical stage I lung cancer, and the estimated 10-year survival rate was 88% in this subgroup. Among the 484 participants, 302 had clinical stage I cancer and underwent surgical resection within 1 month after diagnosis. Their survival rate was 92%.
The development of multidetector-row computed tomography (MDCT) has made it easier to cover the whole lung with thin-section images. In addition, it has become possible to obtain isotropic voxel data, which can be useful in the observation of lesions and/or vessels from multiple directions. As a result, more than 300 images with thin-section thickness in millimeters per thoracic CT examination are reconstructed for radiologists’ routine work.
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Materials and methods
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Image Database
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CAD Software
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Observer Study
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Results
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Table 1
FOM Values Obtained from JAFROC Analysis (Method 2) without and with Output of the CAD Software for the Six Radiologists
Reader Without CAD With CAD Sensitivity FP Results/Case FOM Sensitivity FP Results/Case FOM 1 24.5% 0.10 0.236 75.5% 0.90 0.808 2 30.6% 0.14 0.312 75.5% 1.00 0.792 3 59.2% 0.24 0.563 85.7% 1.10 0.870 4 40.8% 0.19 0.433 79.6% 0.52 0.819 5 38.8% 0.05 0.364 85.7% 0.95 0.881 6 42.9% 0.14 0.434 83.7% 0.86 0.901 Average 39.5% 0.14 0.390 ⁎ 81.0% 0.89 0.845 ⁎
CAD, computer-aided diagnosis; FOM, figure-of-merit; FP, false-positive; JAFROC, jackknife free-response receiver operating characteristic.
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Discussion
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Acknowledgment
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