Novel Cost Function Definition for Minimum-Cost Tractography in MR Diffusion Tensor Imaging

The orientation of MRI-measured diffusion tensor in the myocardium has been directly correlated to the tissue fiber direction and widely characterized. However, the scalar anisotropy indexes have mostly been assumed to be uniform throughout the myocardial wall. The present study examines the fractional anisotropy (FA) as a function of transmural depth and circumferential and longitudinal locations in the normal sheep cardiac left ventricle. Results indicate that FA remains relatively constant from the epicardium to the midwall and then decreases (25.7%) steadily toward the endocardium. The decrease of FA corresponds to 7.9% and 12.9% increases in the secondary and tertiary diffusion tensor diffusivities, respectively. The transmural location of the FA transition coincides with the location where myocardial fibers run exactly circumferentially. There is also a significant difference in the midwall-endocardium FA slope between the septum and the posterior or lateral left ventricular free wall. These findings are consistent with the cellular microstructure from histological studies of the myocardium and suggest a role for MR diffusion tensor imaging in characterization of not only fiber orientation but, also, other tissue parameters, such as the extracellular volume fraction.

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MR diffusion tensor imaging of the spinal cord: can it help in early detection of cervical spondylotic myelopathy and assessment of its severity?

Egyptian Journal of Radiology and Nuclear Medicine ◽

10.1186/s43055-019-0072-1 ◽

2019 ◽

Vol 50 (1) ◽

Author(s):

Talaat Ahmed Abd El Hameed Hassan ◽

Ramy Edward Assad ◽

Shaimaa Atef Belal

Keyword(s):

Spinal Cord ◽

Diffusion Tensor Imaging ◽

Early Detection ◽

Cervical Spondylotic Myelopathy ◽

Diffusion Tensor ◽

Cervical Spinal Cord ◽

Cervical Cord ◽

Mr Diffusion ◽

Compressive Myelopathy ◽

Mr Diffusion Tensor Imaging

Abstract Background The aim of this study is to evaluate the potential application of MR diffusion tensor imaging (with calculation of fractional anisotropy (FA) values) in assessment of the spondylotic cervical spinal canal compromise and comparison with the information issued from conventional MR sequences for early detection of cervical spondylotic myelopathy (CSM). Thirty patients (11 males and 19 females) were included in this study; age ranged from 22 to 70 years (mean age = 44). All patients had conventional and diffusion tensor imaging (DTI) examinations of the cervical spine for detection and assessment of degree of cervical cord myelopathy. FA values of the whole cord circumference and at 3, 6, 9, 12 o’clock positions of the normal cord (opposite to C2), opposite to the most affected disc, and below the level of the most affected disc were measured. Results High statistically significant P values were obtained when comparing the FA values of the normal cord with the cord opposite to the most affected disc, the normal cord with the cord below the affected disc and the cord at the level of the most affected disc with the cord below the level of the most affected disc. Conclusions DTI of the cervical spinal cord with FA measurement in patients with cervical spondylosis helps in early detection of cervical cord compressive myelopathy prior to appearance of changes in conventional MRI, which can improve the clinical outcome and help in treatment plans.

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