Ok, thanks Martin for your advice. Is good to have it in mind for long designs.
Best Daniel --- Daniel Ferreira NVS Department, Div of Clinical Geriatrics (Karolinska Institute, Sweden) Department of Clinical Neuroscience (Karolinska Institute, Sweden) danif...@gmail.com | daniel.ferreira.padi...@ki.se El 31/01/2014 13:18, Martin Reuter escribió: > Hi Daniel, > I'd also include 24 month into both the processing and analysis. It is > not really that we are trying to improve a registration here. We are > trying to improve segmentation and surface placement of each time > point. > I'd aways use all data, except there are good reasons to drop (eg > strong motion artifacts). > Best Martin > > Sent via my smartphone, please excuse brevity. > > -------- Original message -------- > From: Daniel Ferreira > Date:01/31/2014 3:41 AM (GMT-05:00) > To: freesurfer@nmr.mgh.harvard.edu,mreu...@nmr.mgh.harvard.edu > Subject: Re: [Freesurfer] longitudinal processing, template and flags > > Thanks Martin for your reply, > > I am agree with you on point 1. What would you say in the case that we > are interested in rates of decline from baseline to 12 months, but > besides 6 months follow-up we also have 24 months?. Here I see more > conceptual problems. In an hypothetical context of severe atrophy from > 12 to 24 months, adding the 24 mo follow-up perhaps difficult > registration more than improves it. What do you think? > > Thanks a lot > > Best > > Daniel > > Hi Daniel, > > 1. yes. But why not include 6 month in your study if you have those > scans??? You will get much more reliable slope estimates with 3 time > points compared to 2, so including that time point will not only help > for the image processing part, but also in your statistics (you gain > power). > > 2. I am not familiar with the mprage flag and think it mainly affects > the normalization. If you are sure you need it, then also add it to > the -base and -long runs, just to be safe. > > best, Martin > > On 01/29/2014 09:08 AM, Daniel Ferreira wrote: > >> Dear experts, >> >> I have two questions regarding the longitudinal stream: >> >> - I am including Baseline and 12 months follow-up in my study. >> However, I also have 6 months follow-up. I wonder if it is >> conceptually right to include these 6 months scans in template >> creation with the idea of increasing registration. >> >> - I am applying the -mprage flag in the crossectional first step. >> Should I use it in the -base and -longs steps too? >> >> Thanks very much >> >> Daniel Ferreira > > 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. _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
