Title
On evaluating brain tissue classifiers without a ground truth.
Abstract
In this paper, we present a set of techniques for the evaluation of brain tissue classifiers on a large data set of MR images of the head. Due to the difficulty of establishing a gold standard for this type of data, we focus our attention on methods which do not require a ground truth, but instead rely on a common agreement principle. Three different techniques are presented: the Williams’ index, a measure of common agreement; STAPLE, an Expectation Maximization algorithm which simultaneously estimates performance parameters and constructs an estimated reference standard; and Multidimensional Scaling, a visualization technique to explore similarity data. We apply these different evaluation methodologies to a set of eleven different segmentation algorithms on forty MR images. We then validate our evaluation pipeline by building a ground truth based on human expert tracings. The evaluations with and without a ground truth are compared. Our findings show that comparing classifiers without a gold standard can provide a lot of interesting information. In particular, outliers can be easily detected, strongly consistent or highly variable techniques can be readily discriminated, and the overall similarity between different techniques can be assessed. On the other hand, we also find that some information present in the expert segmentations is not captured by the automatic classifiers, suggesting that common agreement alone may not be sufficient for a precise performance evaluation of brain tissue classifiers.
Year
DOI
Venue
2007
10.1016/j.neuroimage.2007.04.031
NeuroImage
Keywords
Field
DocType
Evaluation,Validation,Image segmentation,Agreement,Gold standard
Data mining,Multidimensional scaling,Computer science,Cognitive psychology,Image segmentation,Software,Artificial intelligence,Pattern recognition,Segmentation,Expectation–maximization algorithm,Visualization,Outlier,Ground truth
Journal
Volume
Issue
ISSN
36
4
1053-8119
Citations 
PageRank 
References 
32
1.87
23
Authors
7
Name
Order
Citations
PageRank
Sylvain Bouix187755.88
Marcos Martin-Fernandez2545.62
Lida Ungar3433.39
Motoaki Nakamura4653.93
Min-Seong Koo5693.46
Robert W. McCarley631939.01
Martha E. Shenton739441.14