Title: Intensity warping for multisite MRI harmonization
Authors: Julia Wrobel - University of Colorado Denver (United States) [presenting]
Jeff Goldsmith - Columbia University (United States)
Russell Shinohara - University of Pennsylvania (United States)
Melissa Martin - University of Pennsylvania (United States)
Abstract: In multisite neuroimaging studies there is often unwanted technical variation across scanners and sites. These scanner effects can hinder detection of biological features of interest, produce inconsistent results, and lead to spurious associations. We assess scanner effects in two brain magnetic resonance imaging (MRI) studies where subjects were measured on multiple scanners within a short time frame, so that one could assume any differences between images were due to technical rather than biological effects. We propose mica (multisite image harmonization by CDF alignment), a tool to harmonize images taken on different scanners by identifying and removing within-subject scanner effects. The goals were to (1) establish a method that removes scanner effects by leveraging multiple scans collected on the same subject, and, building on this, (2) develop a technique to quantify scanner effects in large multisite trials so these can be reduced as a preprocessing step. We found that unharmonized images were highly variable across site and scanner type, and our method effectively removed this variability by warping intensity distributions. We further studied the ability to predict intensity harmonization results for a scan taken on an existing subject at a new site using cross-validation.