True detection versus "accidental" detection of small lung cancer by a computer-aided detection (CAD) program on chest radiographs.
To evaluate the number of actual detections versus "accidental" detections by a computer-aided detection (CAD) system for small nodular lung cancers (<or=30 mm) on chest radiographs, using two different criteria for measuring performance. A Food-and-Drug-Administration-approved CAD program (version 1.0; Riverain Medical) was applied to 34 chest radiographs with a "radiologist-missed" nodular cancer and 36 radiographs with a radiologist-mentioned nodule (a newer version 3.0 was also applied to the 36-case database). The marks applied by this CAD system consisted of 5-cm-diameter circles. A strict "nodule-in-center" criterion and a generous "nodule-in-circle" criterion were compared as methods for the calculation of CAD sensitivity. The increased sensitivities by the nodule-in-circle criterion were considered as nodules detected by chance. The number of false-positive (FP) marks was also analyzed. For the 34 radiologist-missed cancers, the nodule-in-circle criterion caused eight more cancers (24%) to be detected by chance, as compared to the nodule-in-center criterion, when using the version 1.0 results. For the 36 radiologist-mentioned nodules, the nodule-in-circle criterion caused seven more lesions (19%) to be detected by chance, as compared to the nodule-in-center criterion, when using the version 1.0 results, and three more lesions (8%) to be detected by chance when using the version 3.0 results. Version 1.0 yielded a mean of six FP marks per image, while version 3.0 yielded only three FP marks per image. The specific criteria used to define true- and false-positive CAD detections can substantially influence the apparent accuracy of a CAD system.
Kurt Rossmann Laboratories for Radiologic Image Research, Department of Radiology, MC2026, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL 60637, USA. feng@uchicago.edu
Feng
F
Li
Roger
R
Engelmann
Kunio
K
Doi
Heber
H
Macmahon
D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003936:Diagnosis, Computer-Assisted; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D033162:Incidental Findings; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D013902:Radiography, Thoracic; D012680:Sensitivity and Specificity