Ongoing MR methodological research

Index:

Diffusion Tensor Imaging (DTI)
Compressed Sensing (CS)
Advanced Phase-Contrast MRI
Elastography
MR Methods

Diffusion Tensor Imaging (DTI)

DTI allows us to quantify the degree and direction of water diffusion in tissue. The technique exploits diffusion encoding gradients in several directions so as to determine the degree of diffusion in 3D. This can be used to determine tissue properties such as myofiber architecture and extra-cellular volume (ECV). This is currently being performed ex-vivo, however the sequence is being adapted for future in-vivo use.




For more information about DTI:
Basser P.J., Jones, D.K., NMR Biomed., 15, 456-467, (2002)


Illustration: DTI image of myocardial fibers (IEMR)



Compressed Sensing (CS)

CS is used in MRI to accelerate image acquisition. The method relies on data redundancy, incoherent data sampling, and a non-linear reconstruction algorithm in order to reconstruct undersampled images. The image reconstruction process is performed in a manner analogous to restoring compressed data i.e. jpeg. This acceleration method is currently being used to accelerate PC-MRI and CINE acquisition by a factor of four. This allows us to increase experimental throughput, however could also lead to new MR imaging possibilities, such as in-vivo preclinical DTI.


For more information about compressed sensing:
Lustig M. et al., IEEE Sign. Proc. Magazine., 25(2), 72-82, (2008)


Illustration: PC-MRI velocity measurement;

fully sampled and 4x undersampled data (IEMR)


Advanced Phase-Contrast MRI


We are investigating novel applications of tissue phase mapping for assessment of the regional myocardial function.


Related publications from the core facility:
Espe E.K. et al., Circ. Cardiovasc. Imaging, 8(2), (2015)
Espe E.K. et al., J. Cardiovasc. Magn. Reson., 15, 82, (2013)



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Illustration: PC-MRI strain and strain rate measurement of the beating rat heart (IEMR)

Elastography


Elastography is a PC-MRI method of assessing stiffness in tissue, such as the liver or the myocardium. This is achieved by measuring the motional perturbation caused by the propogation of shear waves applied via an external device.


For more information about elastography: Mariappan Y. K. et al., Clin. Anat., 23(5), 497-511, (2011)



METHODS:

ONGOING RESEARCH:

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