Hi Donald,
Many thanks for the prompt response. Below is the 1) scan parameters for the DTI scan, and 2) the analysis process. Please note unfortunately we did not acquire a blip scan, hence distortion correction process was skipped .
Many thanks,
Sally
1) scan Parameters
Scan Proto enable = "no";
Patient weight [kg] = 55;
SmartSelect = "yes";
Coil 1 (exclude) = "None";
Uniformity = "CLEAR";
FOV RL (mm) = 224;
AP (mm) = 224;
FH (mm) = 105.600006;
ACQ voxel size RL (mm) = 2.20000005;
AP (mm) = 2.20000005;
Slice thickness (mm) = 2.20000005;
Recon voxel size RL (mm) = 1.55555558;
AP (mm) = 1.55555558;
Fold-over suppression = "no";
Reconstruction matrix = 144;
SENSE = "yes";
P reduction (AP) = 1.29999995;
MB SENSE = "yes";
MB Factor = 3;
MB Shift = "default";
RF Phase opt = "default";
CS-SENSE = "no";
k-t Acceleration = "no";
Stacks = 1;
type = "parallel";
slices = 48;
slice gap = "user defined";
gap (mm) = 0;
slice orientation = "transverse";
fold-over direction = "AP";
fat shift direction = "P";
Stack Offc. AP (P=+mm) = -11.3460064;
RL (L=+mm) = -2.79287601;
FH (H=+mm) = 58.6840401;
Ang. AP (deg) = 0;
RL (deg) = -0;
FH (deg) = -0;
Free rotatable = "no";
Minimum number of packages = 1;
Slice scan order = "default";
Add offset = "no";
Large table movement = "no";
PlanAlign = "no";
REST slabs = 0;
Interactive positioning = "no";
Patient position = "head first";
Patient body position = "head first";
Patient orientation = "supine";
Patient body orientation = "supine";
Scan type = "Imaging";
Scan mode = "MS";
technique = "SE";
Modified SE = "no";
Acquisition mode = "cartesian";
Fast Imaging mode = "EPI";
shot mode = "single-shot";
Echoes = 1;
partial echo = "no";
TE = "shortest";
Flip angle (deg) = 90;
TR = "shortest";
Halfscan = "yes";
factor = 0.600000024;
Water-fat shift = "minimum";
RF Shims = "fixed";
Shim = "auto";
mDIXON = "no";
Fat suppression = "SPIR";
strength = "strong";
frequency offset = "default";
Grad Rev Fat suppr = "no";
Water suppression = "no";
BB pulse = "no";
MTC = "no";
Research prepulse = "no";
MDME = "no";
Diffusion mode = "DTI";
sequence = "SE";
gradient overplus = "no";
directional resolution = "opt 64";
nr of b-factors = 2;
b-factor order = "ascending";
max b-factor = 1000;
average high b = "user defined";
+ allow phase to be saved = "no";
b-factor averages = "(0) 1",
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T1 mapping = "no";
Transmit channels = "both";
SAR mode = "high";
B1 mode = "default";
SAR allow first level = "yes";
Patient pregnancy = "no";
Patient WB SAR [W/kg] = 0;
Patient Head SAR [W/kg] = 0;
Patient max. dB/dt [T/s] = 0;
Max slewrate [T/m/s] = 0;
Max. B1+rms [uT] = 0;
PNS mode = "high";
Gradient mode = "maximum";
SofTone mode = "no";
Cardiac synchronization = "no";
Heart rate > 250 bpm = "no";
Respiratory compensation = "no";
Navigator respiratory comp = "no";
Flow compensation = "no";
Temporal slice spacing = "default";
NSA = 1;
MRE enable = "no";
Manual start = "no";
Dynamic study = "no";
dyn stabilization = "regular";
Arterial Spin labeling = "no";
Preparation phases = "auto";
Interactive F0 = "no";
Quick Survey = "default";
SmartPlan survey = "no";
B0 field map = "no";
B1 field map = "no";
MIP/MPR = "no";
Images = "M", (3) "no";
Autoview image = "M";
Calculated images = (4) "no";
Reference tissue = "White matter";
Recon compression = "No";
Preset window contrast = "soft";
Reconstruction mode = "immediate";
Save raw data = "no";
Hardcopy protocol = "no";
Image filter = "system default";
Uniformity correction = "no";
Geometry correction = "default";
IF_info_seperator = 2000;
Research Options used = "51";
Total scan duration = "02:14.4";
Rel. SNR = 0.0646339282;
Act. TR (ms) = "1993";
Act. TE (ms) = "84";
ACQ matrix M x P = "104 x 100";
ACQ voxel MPS (mm) = "2.15 / 2.24 / 2.20";
REC voxel MPS (mm) = "1.56 / 1.56 / 2.20";
Scan percentage (%) = 96.25;
Packages = 1;
Min. slice gap (mm) = -0;
EPI factor = 77;
WFS (pix) / BW (Hz) = "21.415 / 20.3";
BW in EPI freq. dir. (Hz) = "2034.6";
Local torso SAR = "< 64 %";
Whole body SAR / level = "< 2.1 W/kg / 1st level";
SED = "< 0.3 kJ/kg";
Coil Power = "61 %";
Max B1+rms = "1.84 uT";
PNS / level = "84 % / 1st level";
dB/dt = "124.8 T/s";
Sound Pressure Level (dB) = 20.6376553;
Boil-off (hPa/h) = 11.2246542;
Max Boil-off (hPa/h) = 11.2247782;
Boil-off (hPa) = 0.418958157;
2) Analysis steps
#image conversion
mrconvert RAW_DWI.nii DWI_raw.mif -fslgrad bvec.bvec bval.bval
dwiextract DWI_raw.mif - -bzero | mrmath - mean mean_b0_PA.mif -axis 3
mrconvert -datatype uint32 aparc+aseg.mgz aparc+aseg_ut.mif
#preprocessing DWI images
#In this step, we will run denoising, removing gibbs artifacts, eddy correction, motion correction, and bias correction using MRTrix3, FSL
dwidenoise DWI_raw.mif dwi_den.mif -noise noise.mif
mrcalc DWI_raw.mif dwi_den.mif -subtract residual.mif
mrdegibbs dwi_den.mif dwi_den_unr.mif -axes 0,1
mrcalc dwi_den.mif dwi_den_unr.mif -subtract residualUnringed.mif
dwifslpreproc dwi_den_unr.mif dwi_den_unr_preproc.mif -pe_dir AP -rpe_none -eddy_options " --slm=linear" -topup_options " --estmov=0"
dwibiascorrect fsl dwi_den_unr_preproc.mif dwi_den_unr_preproc_unbiased.mif -bias bias.mif
#create a binary mask and extract mean b0 image using preprocessed DWI image
dwi2mask dwi_den_unr_preproc_unbiased.mif mask_dwi_den_unr_preproc_unb.mif
dwiextract dwi_den_unr_preproc_unbiased.mif - -bzero | mrmath - mean mean_b0_preprocessed.mif -axis 3
mrconvert mean_b0_preprocessed.mif mean_b0_preprocessed.nii.gz
#response function estimation for white matter, grey matter and CSF
#estimate fibre orientation distribution
dwi2response dhollander dwi_den_unr_preproc_unbiased.mif wm.txt gm.txt csf.txt -voxels voxels.mif
dwi2fod msmt_csd dwi_den_unr_preproc_unbiased.mif -mask mask_dwi_den_unr_preproc_unb.mif wm.txt wmfod.mif gm.txt gmfod.mif csf.txt csffod.mif
#normalisation
mtnormalise wmfod.mif wmfod_norm.mif gmfod.mif gmfod_norm.mif csffod.mif csffod_norm.mif -mask mask_dwi_den_unr_preproc_unb.mif