Published
Journal of Medical Imaging, 2023, 10.6: 061103-061103
Authors
Hyeongseok Kim1, Seoyoung Lee2, Woo Jung Shim3, Min-Seong Choi3, Seungryong Cho1
Affiliations
1Institute for Artificial Intelligence, Korea Advanced Institute of Science and Technology (Republic of Korea)
2Korea Advanced Institute of Science and Technology (Republic of Korea)
3Radisen Co., Ltd. (Republic of Korea)
Purpose
Although there are several options for improving the generalizability of learned models, a data instance-based approach is desirable when stable data acquisition conditions cannot be guaranteed. Despite the wide use of data transformation methods to reduce data discrepancies between different data domains, detailed analysis for explaining the performance of data transformation methods is lacking.
Approach
This study compares several data transformation methods in the tuberculosis detection task with multi-institutional chest x-ray (CXR) data. Five different data transformations, including normalization, standardization with and without lung masking, and multi-frequency-based (MFB) standardization with and without lung masking were implemented. A tuberculosis detection network was trained using a reference dataset, and the data from six other sites were used for the network performance comparison. To analyze data harmonization performance, we extracted radiomic features and calculated the Mahalanobis distance. We visualized the features with a dimensionality reduction technique. Through similar methods, deep features of the trained networks were also analyzed to examine the models’ responses to the data from various sites.
Results
From various numerical assessments, the MFB standardization with lung masking provided the highest network performance for the non-reference datasets. From the radiomic and deep feature analyses, the features of the multi-site CXRs after MFB with lung masking were found to be well homogenized to the reference data, whereas the others showed limited performance.
Conclusions
Conventional normalization and standardization showed suboptimal performance in minimizing feature differences among various sites. Our study emphasizes the strengths of MFB standardization with lung masking in terms of network performance and feature homogenization.