Hi Michael, This is one of the reasons we have moved away from using the T1w/T2w computed bias field on fMRI data (the other being that it isn't accurate enough anyway). The current version of the HCP Pipelines computes the fMRI bias field using the spin echo field map and the SBRef image. You definitely will want to acquire a new spin echo field map for each session because distortions and bias fields will change with each session.
Peace, Matt. From: <[email protected]<mailto:[email protected]>> on behalf of "Stevens, Michael" <[email protected]<mailto:[email protected]>> Date: Thursday, December 22, 2016 at 3:16 PM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: [HCP-Users] Question about multi-session HCP data setup Hi folks, We're about to start MRI data collection on a NIDA-funded project in which each participant will undergo 9 separate fMRI sessions. We'd like to use our HCP MR sequences for this project, as we've done for several other current studies. But the multi-session design of this one brings up a question that I need some guidance on. >From what I recall, the T1 and T2 is used to create a bias field that is then >registered to the fMRI data and used in the final intensity normalization step >in the fMRIVolume processing procedures, right? So if we DON'T collect a >brand new T1 and T2 at each and every one of these 9 sessions, but instead >refer the HCP scripts back to a T1 and T2 from collected at a baseline scan, >will we be messing up something crucial and unfixable? Our study design is >such that 3 of these MRI sessions happen each day... The packed protocol >follows a highly rigid and moment-by-moment schedule, so that we unfortunately >can't add an extra 15-16 minutes 3x a day for new T1/T2s each session and >still get everything else done. If we can collect the structural data only >once at the beginning, we can use HCP sequences and processing on this project. Just want to make sure I fully understand the issues and consequences, whether they be large or teeny... Thanks, Mike Michael C. Stevens, Ph.D. Director, Clinical Neuroscience & Development Laboratory, Olin Neuropsychiatry Research Center Director, Child & Adolescent Research, The Institute of Living / Hartford Hospital Adjunct Associate Professor of Psychiatry, Yale University School of Medicine This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, or an employee or agent responsible for delivering the message to the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message, including any attachments. _______________________________________________ HCP-Users mailing list [email protected]<mailto:[email protected]> http://lists.humanconnectome.org/mailman/listinfo/hcp-users ________________________________ The materials in this message are private and may contain Protected Healthcare Information or other information of a sensitive nature. If you are not the intended recipient, be advised that any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this email in error, please immediately notify the sender via telephone or return mail. _______________________________________________ HCP-Users mailing list [email protected] http://lists.humanconnectome.org/mailman/listinfo/hcp-users
