Fundamental principles and techniques of Diffusion Tensor Imaging(DTI). Simplifiedbasis of DTI metrics such as Fractional Anisotropy (FA), Mean Diffusivity(MD), Axial Diffusivity(Da) and Radial Diffusivity(Dr). Application of DTI and DTI metrics in neuropathology such as tumors, ischemia, demyelination, axonal loss and trauma. Technique and applications of fiber tractography. Limitations and pitfalls of DTI.

Diffusion Tensor Imaging (DTI) is a novel method which has various applications in clinical neuroimaging and research Within the CNS, water diffusion is more anisotropic in white matter and isotropic in gray matter and CSF This property can be exploited to highlight white matter changes in various pathological processes DTI is a powerful tool for assessment of microstructural integrity of the white matter qualitatively as well as quantitatively Principle of Diffusion Imaging Water molecules in biological tissues are in constant movement, governed by two major...

DTI Metrics Mean Diffusivity (MD) = (λ1+λ2+λ3)/3 Axial Diffusivity (Da) = λ1 Radial Diffusivity (Dr) = (λ2+λ3)/2 (Fig 5) Fractional Anisotropy –FA Measures the degree of anisotropic (unequal) diffusion in a voxel Reflects the degree of alignment of tissue microstructure Ranges from 0 to 1 (no units) 0 – isotropic (sphere-like) 1 – Purely anisotropic (straight line) Can characterize demyelinating lesions, eg., breakdown of myelin and axonal loss can reduce FA and remyelination can increase FA FA value of CSF is 0 Mean Diffusivity –MD...

DTI is a powerful tool to investigate microstructural white matter changes and brain connectivity The major clinical application of DTI with fiber tractography in current clinical practice is preoperative surgical planning. DTI metrics used in conjunction with other routine and advanced imaging techniques can improve the specificity of detection of tissue changes in disease and can be used for prognostication and assessing treatment response It is critical for the radiologist to be aware of the fundamental principles, applications and pitfalls of this technique so as...

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