Dwidenoise multi-band, multi-shell noise.mif output

Hi All -

I’ve read another thread, that was a bit older, but I wasn’t able to glean the information I was hoping to acquire. I was hoping someone may help me resolve my concern.
I am using the BATMAN tutorial for our MRtrix DWI preprocessing/analyses. Our acquisition is: Hyperband sequence TR 4s, Minimum TE, 140x140, multiple b-values (0, 500, 1000, 2000, 3000), 102 directions.

For the dewidenoise script, we run

dwidenoise raw_dwi.mif dwif_den.mif -noise noise.mif

When reviewing the noise.mif output, there are some visible outlines of what looks like a brain (example attached). I am curious whether this level of non-randomness is normal/abnormal for this acquisition?

Any thoughts would be appreciated!

Hi Michael.
Your output looks fine. The noise is symmetrical and there is almost always more noise in the middle of the scan.
I assume by “hyperband” that you are using a GE scanner? What was your hyperband factor (I am assuming a factor of 3 based on your TR of 4)? Which head coil are you using?
Regards,
Jerome

Jerome, thank you very much for your reply. Yes, you are spot on! We are using a GE 750, with a multi-channel standard adult head coil. From my conversations with some folks, it seems with GE we’re getting a little bit more artifacts, but helpful to know that this type of noise is standard.

Hi Michael. When you say standard adult head coil, is that a GE coil? I always use a Nova 32 channel with MR750 and MR750w scanners and the artifacts are minimal. Using DV25 (or newer) also helps.