Hi, Thanks, yes, we have this problem on our scans from the Allegra and 7 T scanners, where there's a local transmit coil (no body transmit coil) and therefore blood with non-inverted spins enters the head after the inversion pulse and appears bright in the images. With our Allegra scans this has indeed caused problems with FreeSurfer, where the vessels are included as part of some labelled structures. I did try to segment and label the vessels with only partial success (since the images are already collected). In your case, a sat band might help... is your inversion pulse non-selective? If you have an axial slab and axial slab-selective inversion, maybe just making the inversion pulse non-selective will help. If the coil has no coverage of the neck, I guess your sat band won't work and you'll have to address the issue in post-processing. Sorry, I don't have a specific solution, but we've also seen the problem. First thing perhaps is to verify whether you're using a local transmit coil.
Cheers, Andre. On 08/01/2014 12:50 PM, Bruce Fischl wrote: > Hi Kate > > I'll cc Andre and Dylan, but I would have thought some sat bands in the > neck would do it. I think vessels are usually bright in the mprage, but > don't usually case problems. Comments welcome.... > > cheers > > Bruce > > On Fri, 1 Aug 2014, McLaughlin, Katie wrote: > >> >> Hi Doug, Bruce, et al. >> We've used the MGH meMPRAGE protocol successfully with children and >> adolescents previously on a Siemens 3T. I've recently moved to a new >> institution and am using the protocol on a Philips 3T Achieva scanner and >> we've been having a lot of issues with high-intensity blood vessels >> (appearing bright white and interfering with segmentation in FreeSurfer). >> Screenshot of an example attached. >> >> We have added some rest slabs/sat bands to the protocol to address >> this, but >> it hasn't fully solved the problem. >> >> I'm wondering if you have any recommendations about adjusting things in >> FreeSurfer to help us get better segmentation? >> >> Thanks for your thoughts on this, >> Kate >> >> >> >> _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
