3T Multiband: Difference between revisions
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= Multiband = | = Multiband = | ||
== Sequence- | == Overview sequences == | ||
All have 10% gap, fat suppression SPIR offset 175Hz | |||
* 3mm, TR=600ms, MB4 S1.8, FOV 240x240x132mm, WFS12pix (36mm), PNS moderate. Max dyns/time ??? | |||
* 2.5mm, TR=800ms, MB4 S1.8, FOV 240x240x140mm, WFS 14pix (35mm), PNS moderate. Max time ??? | |||
* 2mm, TR=1400ms, MB3 S2, FOV=224x224x125, (min TR=1337ms), WFS 21 pix (42mm), PNS low, Gradient Mode Maximum, Dyn stabilization Regular. Max ~1100 dyns, 26 min. | |||
== Sequence-parameter considerations == | |||
* Shimming | * Shimming | ||
** Shimbox: inside brain? Is bottomline shimbox wrt OFC / air transition most important? | ** Shimbox: inside brain? Is bottomline shimbox wrt OFC / air transition most important? | ||
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* Dynamic Stabilization: regular (niet enhanced, kost teveel tijd. Kan ook verstoring geven?) | * Dynamic Stabilization: regular (niet enhanced, kost teveel tijd. Kan ook verstoring geven?) | ||
* Offc/Ang: free rotatable Yes | * Offc/Ang: free rotatable Yes | ||
* PNS moderate | * PNS moderate or low | ||
* Flip angle --> [http://www.mritoolbox.com/ErnstAngle.html Ernst angle] A typical T1 value for gray matter @ 3T: 1330 ms (Kruger, et al, 2001). | * Flip angle --> [http://www.mritoolbox.com/ErnstAngle.html Ernst angle] A typical T1 value for gray matter @ 3T: 1330 ms (Kruger, et al, 2001). | ||
* Planning: stevig anguleren. Read-out richting omdraaien AP-->PA? | * Planning: stevig anguleren. Read-out richting omdraaien AP-->PA? | ||
Revision as of 18:17, 23 January 2018
Multiband
Overview sequences
All have 10% gap, fat suppression SPIR offset 175Hz
- 3mm, TR=600ms, MB4 S1.8, FOV 240x240x132mm, WFS12pix (36mm), PNS moderate. Max dyns/time ???
- 2.5mm, TR=800ms, MB4 S1.8, FOV 240x240x140mm, WFS 14pix (35mm), PNS moderate. Max time ???
- 2mm, TR=1400ms, MB3 S2, FOV=224x224x125, (min TR=1337ms), WFS 21 pix (42mm), PNS low, Gradient Mode Maximum, Dyn stabilization Regular. Max ~1100 dyns, 26 min.
Sequence-parameter considerations
- Shimming
- Shimbox: inside brain? Is bottomline shimbox wrt OFC / air transition most important?
- What is a good shim?LINEWIDTH checken voor scannen? Log values
- Acquire extra B0-scan as check to avoid large B0-gradient?
- Use Maarten's patch for image based shimming: this patch applies shim to B0-prescan
- TR:
- for physiological noise correction, aim for 750ms
- minimal TR: to be adjusted on-scanner (not realistic in VM)
- Gradient mode: Set to Enhanced if duty cycle is limiting factor (enormous difference on AMC-wide bore scanner)
- Water Fat Shift: minimal. Increase to reduce TR
- TE hoeft niet in phase: niet belangrijk voor vet want signaal is al dispersed met deze TE. TE~32.23, 27 is te kort.
- Geen slice gap (maar waarom?)
- Acquired/Reconstructed Matrix size should match
- Multiband factor * SENSE ~= 6
- Half scan: no. Unless minimal TR deviates more than 10% from shortest. But: see Gradient mode
- Dynamic Stabilization: regular (niet enhanced, kost teveel tijd. Kan ook verstoring geven?)
- Offc/Ang: free rotatable Yes
- PNS moderate or low
- Flip angle --> Ernst angle A typical T1 value for gray matter @ 3T: 1330 ms (Kruger, et al, 2001).
- Planning: stevig anguleren. Read-out richting omdraaien AP-->PA?
- Equidistant dynamic sampling
distortion correction
Create two SE-EPIs for distortion correction (better unwarping in regions with dropout)
Data-export
- enhanced dicom does not work for >16k images
- export nifti
- export PAR/REC or XML/REC to store sequence parameters