Fieldmaps and distortion Using fieldmaps to correct distortion

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Fieldmaps and distortion • Using fieldmaps to correct distortion • Using fieldmaps to predict

Fieldmaps and distortion • Using fieldmaps to correct distortion • Using fieldmaps to predict through-slice dephasing Psy 8960, Fall ‘ 06 Fieldmaps 1

Scaled phase data: phase evolution during d. TE TE = 7. 65 ms TE

Scaled phase data: phase evolution during d. TE TE = 7. 65 ms TE = 5. 19 ms Transverse plane Psy 8960, Fall ‘ 06 Fieldmaps 2

Functional imaging experiment Anatomical reference EPI data Psy 8960, Fall ‘ 06 Field map

Functional imaging experiment Anatomical reference EPI data Psy 8960, Fall ‘ 06 Field map Fieldmaps 3

Alignment b/w EPI and T 1 anatomy • Option 1: Assume they’re in the

Alignment b/w EPI and T 1 anatomy • Option 1: Assume they’re in the right place • Option 2: Use intensity-based or mutual information algorithm to find rigid-body transformation of EPI to anat. Psy 8960, Fall ‘ 06 Fieldmaps 4

Perfectly aligned EPI still doesn’t match Psy 8960, Fall ‘ 06 Fieldmaps 5

Perfectly aligned EPI still doesn’t match Psy 8960, Fall ‘ 06 Fieldmaps 5

Distortion prediction Field map EPI slice Psy 8960, Fall ‘ 06 Fieldmaps 6

Distortion prediction Field map EPI slice Psy 8960, Fall ‘ 06 Fieldmaps 6

Distortion prediction Field map EPI slice Psy 8960, Fall ‘ 06 Fieldmaps 7

Distortion prediction Field map EPI slice Psy 8960, Fall ‘ 06 Fieldmaps 7

Distortion prediction EPI slice Psy 8960, Fall ‘ 06 Voxel displacement map (Hz map

Distortion prediction EPI slice Psy 8960, Fall ‘ 06 Voxel displacement map (Hz map divided by pixel BW) Fieldmaps 8

Distortion prediction EPI slice Psy 8960, Fall ‘ 06 Voxel displacement map (Hz map

Distortion prediction EPI slice Psy 8960, Fall ‘ 06 Voxel displacement map (Hz map divided by pixel BW) Fieldmaps 9

Distortion correction + Psy 8960, Fall ‘ 06 = Fieldmaps 10

Distortion correction + Psy 8960, Fall ‘ 06 = Fieldmaps 10

Unwarping Ground truth Psy 8960, Fall ‘ 06 Warped overlay Fieldmaps Unwarped overlay 11

Unwarping Ground truth Psy 8960, Fall ‘ 06 Warped overlay Fieldmaps Unwarped overlay 11

Before Psy 8960, Fall ‘ 06 After Fieldmaps 12

Before Psy 8960, Fall ‘ 06 After Fieldmaps 12

Before Psy 8960, Fall ‘ 06 After Fieldmaps 13

Before Psy 8960, Fall ‘ 06 After Fieldmaps 13

Predicting through-slice dephasing Psy 8960, Fall ‘ 06 Fieldmaps 14

Predicting through-slice dephasing Psy 8960, Fall ‘ 06 Fieldmaps 14

Field map and gradients, inferior slice Psy 8960, Fall ‘ 06 Fieldmaps 15

Field map and gradients, inferior slice Psy 8960, Fall ‘ 06 Fieldmaps 15

Field map and gradients, middle slice Psy 8960, Fall ‘ 06 Fieldmaps 16

Field map and gradients, middle slice Psy 8960, Fall ‘ 06 Fieldmaps 16

Field map and gradients: artifacts Psy 8960, Fall ‘ 06 Fieldmaps 17

Field map and gradients: artifacts Psy 8960, Fall ‘ 06 Fieldmaps 17

Field map and gradients: artifacts Psy 8960, Fall ‘ 06 Fieldmaps 18

Field map and gradients: artifacts Psy 8960, Fall ‘ 06 Fieldmaps 18

Predicting drop-out • Need to know: – (Linear) field gradient in through-slice direction –

Predicting drop-out • Need to know: – (Linear) field gradient in through-slice direction – Echo time Psy 8960, Fall ‘ 06 Fieldmaps 19

Psy 8960, Fall ‘ 06 Fieldmaps 20

Psy 8960, Fall ‘ 06 Fieldmaps 20

History Game Correct Correct Correct Correct Correct IncorrectHistory Game Correct Correct Correct Correct Correct Incorrect
Ensuring correct patient correct procedure and correct sitesideEnsuring correct patient correct procedure and correct siteside
Correct Site Correct Patient Correct Procedure Verification DocumentationCorrect Site Correct Patient Correct Procedure Verification Documentation
Correct longcomplete version Correct version or Correct pictureCorrect longcomplete version Correct version or Correct picture
Correct Site Correct Patient Correct Procedure Documentation AuditCorrect Site Correct Patient Correct Procedure Documentation Audit
Residual Stresses and Distortion Residual Stresses and DistortionResidual Stresses and Distortion Residual Stresses and Distortion
Distortion All maps have distortion What type ofDistortion All maps have distortion What type of
DATA COMMUNICATION PRINCIPLES Delay Distortion Delay Distortion ADATA COMMUNICATION PRINCIPLES Delay Distortion Delay Distortion A
Performance of Correct Procedure at Correct Body SitePerformance of Correct Procedure at Correct Body Site
What to correct How to correct Why toWhat to correct How to correct Why to
ircle the correct 1 Min Circle the correctircle the correct 1 Min Circle the correct
Politically Correct OR Biblically Correct MIKE MAZZALONGO AngeloPolitically Correct OR Biblically Correct MIKE MAZZALONGO Angelo
Monday Warm Up If correct write correct IfMonday Warm Up If correct write correct If
Click on the correct answer Correct Next questionClick on the correct answer Correct Next question
MATCH THE CORRECT NUMBER TO THE CORRECT WORDMATCH THE CORRECT NUMBER TO THE CORRECT WORD
ircle the correct 1 Min Circle the correctircle the correct 1 Min Circle the correct
Click on the correct answer Correct Next questionClick on the correct answer Correct Next question
d have a correct answer concise grammatically correctd have a correct answer concise grammatically correct
Methods of Proof correct complete A correct wellreasonedMethods of Proof correct complete A correct wellreasoned