MRI: The Basics by unknow

Author:unknow
Language: eng
Format: epub
Tags: Referencia, Tecnología
Publisher: ePubLibre
Published: 2009-12-31T16:00:00+00:00

In summary, SNR can be increased by doing the following:

Increasing TR

Decreasing TE

Using a lower BW

Using volume (i.e., 3D) imaging

Increasing NEX

Increasing Ny

Increasing Nx

Increasing the voxel size

Resolution. Spatial resolution (or pixel size) is the minimum distance that we can distinguish between two points on an image. It is determined by Pixel size = FOV/number of pixels ↑ Ny → better resolution If we increase the number of phase-encoding steps, what happens to SNR? Obviously, better resolution usually means poorer SNR. However, if we look at Equation 17-2, it appears that by increasing Ny, the SNR should increase! What's the catch? The catch is, we are keeping the FOV constant while increasing Ny. Take, for example, Pixel size along y-axis = Δy = FOVy/Ny By increasing Ny, we are making the pixel size smaller. Now, recall that Voxel volume = Δx · Δy · Δz = FOVx · FOVy · Δz/(Nx · Ny) Incorporating this information into Equation 17-2 gives us another way of expressing SNR:

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