diff --git a/01-Image_Modalities.html b/01-Image_Modalities.html index 97a89d9..8d84904 100644 --- a/01-Image_Modalities.html +++ b/01-Image_Modalities.html @@ -290,10 +290,10 @@

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See all in one page +
See all in one page
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Objectives

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You Are Here! -

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course_flow

Image acquisition -

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You Are Here!

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course_flow

Image acquisition


  1. The acquisition starts with application of strong magnetic field B0 (e.g. 1.5 or 3.0 Tesla > 10000x earth’s magnetic field) which forces the hydrogen nuclei of the abundant water molecules in soft @@ -410,8 +408,7 @@

    Objectives

    parameter: echo time (TE)) and how fast you repeat the tilt-relax process i.e. RF pulse frequency (design parameter: repetition time (TR)).

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T1 and T2 relaxation -

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T1 and T2 relaxation


Here we see signal from two different tissues as the nuclei are tilted and realigned. The figure on the left shows a single nucleus (i.e. tiny magnet) being tilted away and then precessing back to the the @@ -419,13 +416,11 @@

Objectives

corresponding registered T1 and T2 signal profiles for two different “tissues”. The difference in their signal intensities results in the image contrast.

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MR_relax

Brain tissue comparison -

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MR_relax

Brain tissue comparison


The dotted-black line represents the epoch when you “listen” to the signal (i.e. echo time or TE).

relax_tissue_contrast)

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T1w, T2w, and PD acquisition -

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T1w, T2w, and PD acquisition


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Objectives

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pulse sequence parameters and image contrast -

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pulse sequence parameters and image contrast

What are the two basic pulse sequence parameters that impact T1w and T2w image contrasts? Which one is larger?

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T1 and T2 relaxation tim

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Tissue type and image contrast -

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Tissue type and image contrast

In the T1w image, which one is brighter: White matter, Grey Matter, or CSF?

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Applications per modalitySimilar to T2 with the CSF signal suppressed

TE short TE long (~ T2 of tissue of interest) Identify demyelination
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Image acquisition process and parameters -

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Drawing

What do we want? -

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Image acquisition process and parameters

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Drawing

What do we want?


  • High image contrast
  • High spatial resolution
  • Low scan time!
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What can we control?


Magnetic strengths 1.5T vs 3T vs 7T


PYTHON

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PYTHON