A Test Statistic Estimation-Based Approach for Establishing Self-Interpretable CNN-Based Binary Classifiers

Sourya Sengupta, Mark A. Anastasio

Research output: Contribution to journalArticlepeer-review

Abstract

Interpretability is highly desired for deep neural network-based classifiers, especially when addressing high-stake decisions in medical imaging. Commonly used post-hoc interpretability methods have the limitation that they can produce plausible but different interpretations of a given model, leading to ambiguity about which one to choose. To address this problem, a novel decision-theory-inspired approach is investigated to establish a self-interpretable model, given a pre-trained deep binary black-box medical image classifier. This approach involves utilizing a self-interpretable encoder-decoder model in conjunction with a single-layer fully connected network with unity weights. The model is trained to estimate the test statistic of the given trained black-box deep binary classifier to maintain a similar accuracy. The decoder output image, referred to as an equivalency map, is an image that represents a transformed version of the to-be-classified image that, when processed by the fixed fully connected layer, produces the same test statistic value as the original classifier. The equivalency map provides a visualization of the transformed image features that directly contribute to the test statistic value and, moreover, permits quantification of their relative contributions. Unlike the traditional post-hoc interpretability methods, the proposed method is self-interpretable, quantitative. Detailed quantitative and qualitative analyses have been performed with three different medical image binary classification tasks.

Original languageEnglish (US)
Pages (from-to)1753-1765
Number of pages13
JournalIEEE transactions on medical imaging
Volume43
Issue number5
DOIs
StatePublished - May 1 2024
Externally publishedYes

Keywords

  • Decision theory
  • classification
  • deep learning
  • interpretability
  • medical imaging

ASJC Scopus subject areas

  • Software
  • Radiological and Ultrasound Technology
  • Electrical and Electronic Engineering
  • Computer Science Applications

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