Kategorier: Alle - mri - gradient - acquisition - resolution

av Sanjay Gupta 15 år siden

889

CMR

Magnetic Resonance Imaging (MRI) involves balancing various parameters to optimize image quality and acquisition speed. Spatial resolution and Field of View (FOV) are inversely related; a smaller FOV yields higher resolution images.

CMR

CMR

Acquisition time

1/ETL
NPE
NAcqs
Echo duration for sampling time

increase sampling freq to reduce

higher receiver bandwidths

Stronger gradients

TE

asymmetric/partial Echos with zero filling

Stronger gradient

Faster slew rates

RF duration

Shorten RF duratin by

Assymetric RF pulses

Stronger slice select gradients

Shorter gradients

Higher transmitter bandwidths

Thickness of slice desired

constrained by max gradient strength

In spin echo TR affects image contrast hence dont change
only reduce TR for GRE for faster imaging
Higher receiver bandwidth reduces..

but also reduces SNR

Signal to noise ratio

1/noise
Signal
square root of time to acquire data
Magnetization
Volume of voxel
intrinsic characteristics of magnetization
Way in which RF pulses/gradients applied
C
receiver coil sensitivity to signal
constant

Temporal resolution

only relevant in Cine imaging
No of views/segment
TR

Spatial resolution

- for higher spatial res, use smaller FOV the higher the number the lower the sptial resolution
1/ no of voxels in the image

Inverse relationship between SNR and spatial resolution!

FOV