1. When TR is not long enough (~ 5 x T1) to allow equilibrium, the contrast in MPRAGE sequence is not only determined by TI, but also influenced by TR. The optimal TI = 1000 ms is in the context of TR = 2400 ms from the HCP protocol. The Freesurfer recommended TI = 1100 ms should also be taken in the context of the TR of their recommended MPRAGE protocol.
Gordon On Aug 1, 2017, at 9:23 PM, Glasser, Matthew <glass...@wustl.edu<mailto:glass...@wustl.edu>> wrote: 1. TI=1000 actually separates the CSF/Grey/White peaks of the the histogram more evenly than TI=900ms (CSF and Grey too close) or TI=1100 (Grey and White too close). I don’t understand why the FreeSurfer group has recommended TI=1100 as it wouldn’t seem to make things easier for their software. 2. I don’t remember the rational for the BOLD TE decision, but perhaps someone else does. Peace, Matt. From: <hcp-users-boun...@humanconnectome.org<mailto:hcp-users-boun...@humanconnectome.org>> on behalf of HMZ <hmz...@163.com<mailto:hmz...@163.com>> Date: Tuesday, August 1, 2017 at 8:05 PM To: "hcp-users@humanconnectome.org<mailto:hcp-users@humanconnectome.org>" <hcp-users@humanconnectome.org<mailto:hcp-users@humanconnectome.org>> Subject: [HCP-Users] Questions about parameters in CCF protocols Dear HCP team, This is Meizhen Han at Center for MRI research in Peking University. I read CCF protocol carefully and have 2 questions in my mind. I would be very appreciate it if you could share some ideas with me. 1/ Why the TI in T1w was changed from 1060ms(LS in UMN/CMRR) to 1000ms(CCF)? Is there some significant difference between them? I find that TI can influence the contrast, and the TI recommended by freesurfer group is 1100ms, and the TI in HCP main project is 1000ms. From your experience, do you think TI=1000ms is better? 2/ TE in BOLD sequence(in CCF) is 37ms, while in common BOLD protocols TE is 30ms usually. I think the echo should come at 30ms, and will decay significantly at 37ms. In my opinion, losing the edge of the k-space will blur the image and reduce SNR slightly. So why you choose TE = 37ms without a 7/8 partial fourier to shorten it? I have tested similar protocol, and I find if I choose a 7/8 partial fourier, the TE can be around 30ms. Any information and idea would help a lot! Looking forward to your reply. Thank you very much! Best wishes! -- Meizhen Han PhD Candidate Center for MRI Research Peking University Beijing, China _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org<mailto:HCP-Users@humanconnectome.org> http://lists.humanconnectome.org/mailman/listinfo/hcp-users<https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.humanconnectome.org_mailman_listinfo_hcp-2Dusers&d=DwMF-g&c=shNJtf5dKgNcPZ6Yh64b-A&r=QJgqxaIpHmQUddDGZ_5g0PzQF9rcc9xrheyw6Wux7DQ&m=uBz7noSX5tvZYaIXg0HlKmySVc4B0d5SP8jrnsgqeFU&s=2OHvAqB5YOPBCpIrdOoL7m6w02uBxfYWEhUP7oz9euI&e=> _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org<mailto:HCP-Users@humanconnectome.org> http://lists.humanconnectome.org/mailman/listinfo/hcp-users<https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.humanconnectome.org_mailman_listinfo_hcp-2Dusers&d=DwQF-g&c=shNJtf5dKgNcPZ6Yh64b-A&r=QJgqxaIpHmQUddDGZ_5g0PzQF9rcc9xrheyw6Wux7DQ&m=uBz7noSX5tvZYaIXg0HlKmySVc4B0d5SP8jrnsgqeFU&s=2OHvAqB5YOPBCpIrdOoL7m6w02uBxfYWEhUP7oz9euI&e=> _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users
