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Myths and truths in functional MRI: a basic guide for practitioners
1Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, 1 Asahimachi, Niigata 951-8585, Japan. tnakada@bri.niigata-u.ac.jp
Summary
Functional MRI (fMRI) measures brain activity by tracking blood flow changes, similar to PET scans. However, fMRI data validity is questioned due to issues in raw image acquisition and analysis.
Area of Science:
- Neuroscience
- Medical Imaging
Background:
- Activation studies using regional blood flow alterations are a gold standard in neuroscientific investigation.
- Positron Emission Tomography (PET) and functional MRI (fMRI) are key non-invasive imaging techniques for human application.
- fMRI relies on spontaneous MRI signal alterations linked to cerebral blood flow changes, mirroring PET principles.
Purpose of the Study:
- To provide essential knowledge for non-MR physicist fMRI investigators.
- To address growing criticism regarding the validity of fMRI data.
- To clarify the principles and limitations of fMRI in neuroimaging.
Main Methods:
- Review of the principles underlying fMRI based on blood flow alteration.
- Discussion of the relationship between fMRI and H(2)O(15)-PET methodology.
- Identification of validation issues in fMRI raw image acquisition and data processing.
Main Results:
- fMRI is based on the empirical observation of MRI signal changes correlating with blood flow.
- The underlying principle of fMRI is blood flow alteration, consistent with the Munro-Kellie doctrine.
- Significant validation challenges exist in fMRI, primarily stemming from raw data acquisition.
Conclusions:
- fMRI is an inherently qualitative method lacking quantitative flow alteration information.
- Criticism of fMRI validity is increasing due to issues in image acquisition and statistical analysis.
- Understanding these limitations is crucial for non-physicist researchers utilizing fMRI.