Hi Ram,
I’m not sure what’s going on here, but it seems clear there’s something unusual about the data you’re providing. One possibility might be that your input DWI data includes one of those synthetic isotropic-weighted images that Philips tend to include as the last image in the series (not sure what it’s for). One way to check is to run:
mrinfo -dwgrad dwi.mif
and post the output here. If that’s the issue, I’m expecting to see an entry of the form “0 0 0 1000
” (where that last b-value is the actual b-value you used) somewhere in the gradient table (i.e. non-zero b-value with a zero direction vector). In which case you could try removing that volume from your DWI image, using a command like e.g.:
mrconvert dwi.mif -coord 3 0:58 dwi_clean.mif`
where that last number 59
is the index of the last volume you want included (indexed from zero). In the example above, that would remove the last volume assuming you have 60 volumes in the original dwi.mif
.