Multiband

Overview sequences

All h 10% gap, fat suppression SPIR offset 175Hz

3.0mm, TR=0550ms, MB4 S1.5, FOV 240x240x118mm, WFS 14.2pix (42.6mm), PNS moderate. Gradient Mode Maximum, Dyn stabilization Regular, Max dyns 1820
2.7mm, TR=0700ms, MB4 S1.5, FOV 240x240x130mm, WFS 14.4pix (38.9mm), PNS moderate, Gradient Mode Maximum, Dyn stabilization Regular, Max dyns 1489
2.0mm, TR=1600ms, MB4 S1.5, FOV=224x224x125mm, WFS 23.7pix (47.4mm), PNS moderate, Gradient Mode Maximum, Dyn stabilization Regular, Max dyns 1170

Shimming
- Shimbox: inside brain? Is bottomline shimbox wrt OFC/air transition most important?
- What is a good shim? Check LINEWIDTH before start EPI? 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 or less
- 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 not phase: not important as fat signal is already dispersed at this TE. TE30-32, 27 to short.
Slice gap optional for voxel sizes <3mm, set to sefault (10%)
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 (enhanced optional for longer runs, ~100ms penalty. May give distortion)
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: angulate in parallel to OFC. Change read-out direction? (AP-->PA?)
Equidistant dynamic sampling

Create second GE-EPI with opposite fatshift direction, set preparation to auto (so it won't perform a second B0 shim) and group the sequences
Alternatively create two SE-EPIs for distortion correction (better unwarping around regions with dropout)
Perhaps not include dummies and use one of the pre-saturation scans for registration as it has better grey/white matter contrast (see Multiband data registration)