Abstract:
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Purpose: To perform an observer evaluation of the accuracy of a proposed
segmentation method for microcalcifications in mammograms and to demonstrate
the improvement in performance of our computerized classification scheme for
malignant versus benign microcalcifications when using the proposed
segmentation technique.
Methods and Materials: We have implemented a radial gradient-based segmentation
method for microcalcifications. It is difficult task for radiologists to
manually outline the contours of each microcalcification. Therefore, we have
conducted two observer studies to evaluate the proposed segmentation method.
Two observers participated in each study, reviewing a database of 50 digitized
mammograms with clustered microcalcifications. No observer participated in both
studies. The first observer study (A) required each observer to rate the
accuracies (0-100 scale) of both the proposed segmentation method and the one
currently used in our computerized classification scheme. In the second
observer study (B), each observer was asked to select their preferred method
from three displayed segmentation methods: the proposed segmentation method,
the watershed method and the current method. In these two studies, the original
mammograms with no segmentation were also displayed. In addition, the 50 cases
were randomly reviewed 2 to 3 times to analyze observers' consistencies. The
effect of the proposed segmentation method on the performance of our
computerized classification scheme was also investigated. ROC analysis was
performed and the Az value was used as a performance index.
Results: For study (A), the first observer gave accuracy ratings of 83 and 31
for the proposed and current segmentation methods respectively. The second
observer also preferred the proposed method, with accuracy ratings of 92 versus
68 for the current method. For study (B), the observers selected the proposed
method among the three displayed methods 56% and 62% of the time. Their other
selections were equally distributed between the other two segmentation methods.
The performance of the classification scheme improved when using the proposed
segmentation method. The Az values for case-based performance were 0.84 with
the proposed method versus 0.78 with the current method.
Conclusion: Two separate observer studies demonstrated that our proposed radial
gradient-based segmentation technique for mammographic microcalcifications was
preferred over other methods. The proposed method also improved the performance
of our CAD classification scheme. (R.M.N., J.P. are shareholders in R2
Technology.)
Questions about this event email: paquerau@uchicago.edu
Paquerault PhD, S,
Observer Evaluation and CAD Performance of a Radial Gradient-based Segmentation Method for Mammographic Microcalcifications. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3103077.html
