Archived Talks

University of Pittsburgh Department of Biomedical Informatics Colloquium

Speaker: Dev Chakraborty, PhD
Imaging Research, Department of Radiology

Friday, March 30, 2007
2:00 pm - 3:00 pm
Room M-184 VALE [?]
200 Meyran Avenue

Title: “Free-response observer performance methodology - recent advances and applications to imaging system assessment”

Abstract: In the FROC paradigm the data-unit is a variable number of mark-rating pairs per image. A mark is the indicated location of a suspicious region. The rating is the corresponding degree of suspicion. Prior to analysis the data is classified or “scored” into lesion and non-lesion localizations. The scoring is done by choosing an acceptance-radius and classifying marks within the acceptance-radius of lesion centers as lesion localizations, and all other marks are classified as non-lesion localizations. The scored data is plotted as a free-response receiver operating characteristic (FROC) curve, essentially a plot of appropriately normalized numbers of lesion localizations vs. non-lesion localizations. Scored FROC curves are frequently used to compare imaging systems and computer aided detection (CAD) algorithms. A recent search-model for free-response data will be described. The search model can be used to infer a figure of merit of observer performance and to predict ROC and FROC curves. An approach to estimating search model parameters for CAD algorithms and human observers is described. Also described is a method of analysis that does not require the specification of an arbitrary acceptance-radius. The method allows one to plot a “perceptual FROC curve”. Unlike a scored FROC curve, a perceptual curve is independent of the choice of acceptance-radius.

For more information: jcumm@cbmi.pitt.edu or 412.647.7113