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Proceedings Paper

Nodule polarity effects on detection and localization performance in liver CT images
Author(s): Richard G. Swensson; Philip F. Judy; Christine Wester; Steven E. Seltzer
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Paper Abstract

Performance accuracy for detecting and localizing small nodules on liver CT images depends on whether an observer is required to find dark nodules or bright nodules on those images. We investigated these asymmetric polarity effects using simulated nodules of varying sizes placed on spiral CT scans of clinical patients acquired with intravenous contrast material, which made blood vessels appear brighter than liver background on the displayed CT images. A concurrent analysis of each observer's detection-rating and scored-localization data estimated separate perceptual effects for the nodules of different sizes, and for locations of the dark or bright hepatic findings that observers regarded as most suspicious on the CT images. The results were consistent with equal visibility for dark and bright nodules of identical size and CT-contrast, and a linear increase in visibility with nodule signal-to-noise ratio for a non-prewhitening matched-filter calculation (NPW-SNR). The substantial lower accuracy for detecting and localizing the bright nodules, compared to the dark nodules, was a polarity effect apparently produced by the non- stationary liver CT backgrounds -- i.e., the presence of stronger confusing signals from the bright hepatic findings on these (contrast-enhanced) CT images than from the dark hepatic findings.

Paper Details

Date Published: 16 April 1997
PDF: 9 pages
Proc. SPIE 3036, Medical Imaging 1997: Image Perception, (16 April 1997); doi: 10.1117/12.271281
Show Author Affiliations
Richard G. Swensson, Brigham and Women's Hospital/Harvard Medical School (United States)
Philip F. Judy, Brigham and Women's Hospital/Harvard Medical School (United States)
Christine Wester, Brigham and Women's Hospital/Harvard Medical School (United States)
Steven E. Seltzer, Brigham and Women's Hospital/Harvard Medical School (United States)

Published in SPIE Proceedings Vol. 3036:
Medical Imaging 1997: Image Perception
Harold L. Kundel, Editor(s)

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