Revision as of 09:26, 24 January 2018

Multiband

All h 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.

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?)
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
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)

@@ Line 2: / Line 2: @@
 == Overview sequences ==
-All have 10% gap, fat suppression SPIR offset 175Hz
+All h 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 ???
@@ Line 27: / Line 27: @@
 * 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).
-* Planning: angulate in parallel to OFC. Change read-out direction? (AP-->PA?
+* Planning: angulate in parallel to OFC. Change read-out direction? (AP-->PA?)
+* Perhaps not include dummies and use one of the pre-saturation scans for registration as it has better grey/white matter contrast (see [https://fsl.fmrib.ox.ac.uk/fslcourse/lectures/practicals/registration/index.html#multiband Multiband data registration]
 * Equidistant dynamic sampling