Pooling morphometric estimates: a statistical equivalence approach
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Abstract
Changes in hardware or image processing settings are a common issue for large multi-center studies. In order to pool MRI data acquired under these changed conditions, it is necessary to demonstrate that the changes do not affect MRI-based measurements. In these circumstances classical inference testing is inappropriate because it is designed to detect differences, not prove similarity. We used a method known as statistical equivalence testing to address this limitation.
Equivalence testing was carried out on three datasets: (i) cortical thickness and automated hippocampal volume estimates obtained from 16 healthy individuals imaged different multi-channel head coils; (ii) manual hippocampal volumetry obtained using two readers; and (iii) corpus callosum area estimates obtained using an automated method with manual cleanup carried out by two readers. Equivalence testing was carried out using the “two one-sided tests” approach.
Cortical thickness values were found to be equivalent over 78% of the cortex when different head coils were used (p = 0.024). Automated hippocampal volume estimates obtained using the same two coils were statistically equivalent (p = 4.28 × 10-15). Manual hippocampal volume estimates obtained using two readers were not statistically equivalent (p = 0.97). The use of different readers to carry out limited correction of automated corpus callosum segmentations yielded equivalent area estimates (1.28 × 10-14).
We have presented a statistical method for determining if morphometric measures obtained under variable conditions can be pooled. The equivalence testing technique is applicable for analyses in which experimental conditions vary over the course of the study.
Cite this as
2015. Pooling morphometric estimates: a statistical equivalence approach. PeerJ PrePrints 3:e808v1 https://doi.org/10.7287/peerj.preprints.808v1Author comment
This is Version 1 of a submission to Human Brain Mapping.
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Competing Interests
The authors declare they have no competing interests.
Author Contributions
Heath R Pardoe conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.
Gary Cutter conceived and designed the experiments, wrote the paper, reviewed drafts of the paper.
Rachel A Alter performed the experiments, analyzed the data, reviewed drafts of the paper.
Rebecca Kucharsky Hiess performed the experiments, analyzed the data, reviewed drafts of the paper.
Mira Semmelroch performed the experiments, analyzed the data, reviewed drafts of the paper.
Donna Parker performed the experiments, analyzed the data, reviewed drafts of the paper.
Shawna Farquharson performed the experiments, reviewed drafts of the paper.
Graeme Jackson contributed reagents/materials/analysis tools, reviewed drafts of the paper.
Ruben Kuzniecky conceived and designed the experiments, reviewed drafts of the paper.
Data Deposition
The following information was supplied regarding the deposition of related data:
https://sites.google.com/site/hpardoe/equivalence
Funding
The work is supported by Amazon Web Services Education in Research grants. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
