Applying a random projection algorithm to optimize machine learning model for breast lesion classification

TL;DR

This study demonstrates that applying a random projection algorithm to reduce feature dimensionality significantly improves machine learning model performance in classifying breast lesions from mammograms.

Contribution

The paper introduces the use of a random projection algorithm for feature reduction, enhancing SVM-based classification of breast lesions in medical imaging.

Findings

Random projection outperforms PCA, NMF, and Chi-squared methods in classification accuracy.

The SVM model with random projection achieved an AUC of 0.84 in lesion classification.

Random projection effectively generates optimal feature vectors for medical image analysis.

Abstract

Machine learning is widely used in developing computer-aided diagnosis (CAD) schemes of medical images. However, CAD usually computes large number of image features from the targeted regions, which creates a challenge of how to identify a small and optimal feature vector to build robust machine learning models. In this study, we investigate feasibility of applying a random projection algorithm to build an optimal feature vector from the initially CAD-generated large feature pool and improve performance of machine learning model. We assemble a retrospective dataset involving 1,487 cases of mammograms in which 644 cases have confirmed malignant mass lesions and 843 have benign lesions. A CAD scheme is first applied to segment mass regions and initially compute 181 features. Then, support vector machine (SVM) models embedded with several feature dimensionality reduction methods are built to predict likelihood of lesions being malignant. All SVM models are trained and tested using a leave-one-case-out cross-validation method. SVM generates a likelihood score of each segmented mass region depicting on one-view mammogram. By fusion of two scores of the same mass depicting on two-view mammograms, a case-based likelihood score is also evaluated. Comparing with the principle component analyses, nonnegative matrix factorization, and Chi-squared methods, SVM embedded with the random projection algorithm yielded a significantly higher case-based lesion classification performance with the area under ROC curve of 0.84+0.01 (p<0.02). The study demonstrates that the random project algorithm is a promising method to generate optimal feature vectors to help improve performance of machine learning models of medical images.