L5-contrast

L5-contrast - Contrast & Signaltonoise ratio contrast =...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
2 ) ( ) ( 2 2 2 2 2 2 2 2 = βκγ στδ σιγναλ μεαν σνρ 2 1 signal signal contrast - =
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Contrast types Static contrast T1-weighted T2-weighted T2*-weighted   fMRI (BOLD) Dynamic contrast Time of flight (TOF)   MRA Velocity-encoded phase contrast (VENC-PC)   MRA Perfusion-weighted contrast    fMRI (cerebral blood flow) Diffusion-weighted Contrast
Background image of page 2
Relaxation time and image contrast T1-weighted T2-weighted T2*-weighted
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
What determines contrast type? Main pulse-sequence parameters Sequence family (Spin-echo, gradient echo, EPI, etc.) TR TE Flip angle (mainly for gradient-echo related sequences) Preparation-module parameters Spoiler TI (inversion time) Fat saturation Water excitation
Background image of page 4
TR=1.5 s, TE=3.05 ms, Flip angle = 10, TI = 0.8 s Water excitation: ON TR=1.61 s, TE=2.54 ms, Flip angle = 15, TI = 1.1 s MPRAGE: 3D gradient echo on Siemens Trio (3T)
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
A simple approximation MR signal: Contrast: 2 1 / / 0 ) 1 ( ) ( T TE T TR xy e e M TE M S - - - = = B B A A T TE T
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/31/2009 for the course PSYC 425 taught by Professor Lu during the Spring '08 term at USC.

Page1 / 41

L5-contrast - Contrast & Signaltonoise ratio contrast =...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online