Correction of instrumental and physiological artefacts to enable advanced diffusion-weighted magnetic resonance imaging in the brain

• Applicant: Dr. Siawoosh Mohammadi
• Subject Area: Human Cognitive and Systems Neuroscience
• Term: from 2012 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 211423574

Magnetic resonance imaging (MRI) non-invasively can generate images with multiple different contrasts of the human brain and body. A special but important case is diffusion weighted imaging and diffusion tensor imaging (DTI) that display water diffusion in tissue within few minutes. Since water diffusion depends on the microstructure of the tissue, diffusion imaging has become an essential tool in clinical diagnosis and neuroscience research. It can detect the changes due to stroke or neurodegenerative disease and can be used to measure the directionality of white matter fiber tracts. To achieve the diffusion sensitivity strong imaging gradients need to be switched, which make the imaging technique prone to artefacts caused by the MRI scanner and the human physiology. These artefacts can reduce the image quality significantly and thus limit the use of diffusion imaging. This project focuses on prominent motion-induced artefacts that are caused by cardiac pulsation and mechanical vibration in the MRI scanner. Artefacts due to mechanical vibration limit the use of fast and strong gradients which are currently developed to accelerate diffusion imaging and allow for higher diffusion weightings. This proposal employs a two pronged approach to correct artefacts due to motion by (1) developing a retrospective correction using the phase of the MRI signal and (2) developing a novel DTI acquisition method. Both approaches will be combined to further reduce artifacts. In the final step, this novel combination will be compared to established DTI acquisition techniques. The assessment will consider motion artefacts but also other artefacts such as eddy current induced distortion and important imaging parameters such as acquisition time. The new development will facilitate emerging applications of diffusion imaging including measuring tissue characteristics at the cellular level such as axonal diameters, high-resolution DTI, and DTI at ultra high fields (7 Tesla).

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Professor Dr. Nikolaus Weiskopf