Computer-aided detection (CAD) of lung nodules in CT scans: Radiologist performance and reading time with incremental CAD assistance

Justus E. Roos, David Paik, David Olsen, Emily G. Liu, Lawrence C. Chow, Ann N. Leung, Robert Mindelzun, Kingshuk R. Choudhury, David P. Naidich, Sandy Napel, Geoffrey D. Rubin

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


Objective: The diagnostic performance of radiologists using incremental CAD assistance for lung nodule detection on CT and their temporal variation in performance during CAD evaluation was assessed. Methods: CADwas applied to 20 chest multidetector-row computed tomography (MDCT) scans containing 190 noncalcified ≥3-mm nodules. After free search, three radiologists independently evaluated a maximum of up to 50 CAD detections/patient. Multiple freeresponse ROC curves were generated for free search and successive CAD evaluation, by incrementally adding CAD detections one at a time to the radiologists' performance. Results: The sensitivity for free search was 53% (range, 44%-59%) at 1.15 false positives (FP)/patient and increased with CAD to 69% (range, 59-82%) at 1.45 FP/patient. CAD evaluation initially resulted in a sharp rise in sensitivity of 14%with a minimal increase in FP over a time period of 100 s, followed by flattening of the sensitivity increase to only 2%. This transition resulted from a greater prevalence of true positive (TP) versus FP detections at early CAD evaluation and not by a temporal change in readers' performance. The time spent for TP (9.5 s±4.5 s) and false negative (FN) (8.4 s±6.7 s) detections was similar; FP decisions took two- to threetimes longer (14.4 s±8.7 s) than true negative (TN) decisions (4.7 s±1.3 s). Conclusions: When CAD output is ordered by CAD score, an initial period of rapid performance improvement slows significantly over time because of non-uniformity in the distribution of TP CAD output and not to a changing reader performance over time.

Original languageEnglish (US)
Pages (from-to)549-557
Number of pages9
JournalEuropean Radiology
Issue number3
StatePublished - Mar 2010
Externally publishedYes


  • CAD
  • Computer-aided detection
  • Diagnostic performance
  • MDCT
  • Multidetector-row computed tomography
  • Pulmonary nodules

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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