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http://cds.ismrm.org/protected/13MPresentations/E225/

http://cds.ismrm.org/protected/13MPresentations/E225/. Go to 51:47-1:06 mark listen for 9 minutes. = γ. = γ. 2 π. 2 π. Diffusion of water used in Diffusion MRI Imaging and Diffusion Tensor Imaging ( DTI ) MRI. Spin echo signal strength. More Signal Loss when encoding for diffusion. y.

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http://cds.ismrm.org/protected/13MPresentations/E225/

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  1. http://cds.ismrm.org/protected/13MPresentations/E225/ • Go to 51:47-1:06 mark listen for 9 minutes

  2. = γ = γ 2π 2π

  3. Diffusion of water used inDiffusion MRI Imaging andDiffusion Tensor Imaging (DTI) MRI Spin echo signal strength More Signal Loss when encoding for diffusion

  4. y The rest of the sequence Time RF Gx - Gy Gz Area under the gradients is b x Don’t let protons move -NO DIFFUISION protons (Hydrogen) signalloss with DIFFUISION

  5. Time RF Gx - Gy DxxDxyDxz DyxDyy Dyz Dzx DzyDzz 1 0 0 1 0 0 Gz D = Dxx = Dxx Y X Z Every voxel has a diffusion tensor to describe diffusion

  6. Time RF Gx - Gy DxxDxyDxz DyxDyy Dyz Dzx DzyDzz 1 1 0 1 1 0 Gz (½) = ½(Dxx +Dyx +Dxy+Dyy) = ½(Dxx +2Dyx+Dyy) Y X Z

  7. Why diffusion another stroke example Dead Will Die Look for mismatch and find healthy tissue

  8. 2) Fiber tracking Information available through DTI Tract

  9. fMRI Functional Magnetic Resonance Imaging

  10. The BOLD Effect Karen Miller Frequency spread causes signal loss over time BOLD contrast: Amount of signal loss reflects [dHb] Deoxygenated hemoglobin – unpaired iron electrons Contrast increases with delay (TE = echo time)

  11. neuron HbO2 = oxyhemoglobin dHb = deoxyhemoglobin HbO2 HbO2 HbO2 HbO2 HbO2 dHb HbO2 HbO2 HbO2 dHb dHb dHb dHb HbO2 HbO2 HbO2 HbO2 HbO2 HbO2 HbO2 HbO2 dHb HbO2 dHb dHb HbO2 HbO2 dHb HbO2 HbO2 HbO2 HbO2 HbO2 HbO2 HbO2 O2 metabolism blood volume [dHb] blood flow Karen Miller Vascular Response to Activation capillary Decreased deoxygenated larger signal in metabolically active regions

  12. Language fMRI task Science Direct

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