Harmonization of cortical thickness measurements across scanners and sites

• Published in: NeuroImage (Orlando, Fla.) Vol. 167; pp. 104 - 120
• Main Authors: Fortin, Jean-Philippe, Cullen, Nicholas, Sheline, Yvette I., Taylor, Warren D., Aselcioglu, Irem, Cook, Philip A., Adams, Phil, Cooper, Crystal, Fava, Maurizio, McGrath, Patrick J., McInnis, Melvin, Phillips, Mary L., Trivedi, Madhukar H., Weissman, Myrna M., Shinohara, Russell T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.02.2018; Elsevier Limited
• Subjects: Adolescent; Adult; Age; Aged; Aged, 80 and over; Anxiety; Cerebral Cortex - anatomy & histology; Cerebral Cortex - diagnostic imaging; ComBat; Cortex; Cortical thickness; Data Interpretation, Statistical; Datasets; Datasets as Topic - standards; Female; Genomics; Harmonization; Humans; Inter-scanner; Magnetic resonance imaging; Magnetic Resonance Imaging - instrumentation; Magnetic Resonance Imaging - methods; Magnetic Resonance Imaging - standards; Male; Medical imaging; Mental depression; Middle Aged; Models, Theoretical; Multi-site; Multicenter Studies as Topic - instrumentation; Multicenter Studies as Topic - standards; Neuroimaging; Questionnaires; Scanners; Statistical analysis; Studies; Young Adult; United States > US; Texas; Massachusetts; Michigan; Cortical thickness; Inter-scanner; Multi-site; ComBat; Harmonization
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2017.11.024

With the proliferation of multi-site neuroimaging studies, there is a greater need for handling non-biological variance introduced by differences in MRI scanners and acquisition protocols. Such unwanted sources of variation, which we refer to as “scanner effects”, can hinder the detection of imaging features associated with clinical covariates of interest and cause spurious findings. In this paper, we investigate scanner effects in two large multi-site studies on cortical thickness measurements across a total of 11 scanners. We propose a set of tools for visualizing and identifying scanner effects that are generalizable to other modalities. We then propose to use ComBat, a technique adopted from the genomics literature and recently applied to diffusion tensor imaging data, to combine and harmonize cortical thickness values across scanners. We show that ComBat removes unwanted sources of scan variability while simultaneously increasing the power and reproducibility of subsequent statistical analyses. We also show that ComBat is useful for combining imaging data with the goal of studying life-span trajectories in the brain. •Cortical thickness (CT) measurements are highly scanner specific.•Identifying scanner effects is crucial for inference and biomarker development.•We propose to use ComBat to harmonize cortical thickness values across scanners.