 |
 |
This is one piece of published evidence... A Quantitative Evaluation of Cross-Participant Registration Techniques for MRI Studies of the Medial Temporal lobe Michael A. Yassa, Craig E.L. Stark PII: S1053-8119(08)01022-7 DOI: doi: 10.1016/j.neuroimage.2008.09.016 Reference: YNIMG 5703 To appear in: NeuroImage There will be more to come - eventually. Best regards, -John On Monday 13 October 2008 14:51, John Ashburner wrote: > So far, the evidence that I've seen seems to suggest that inter-subject > registration using Dartel tends to be more accurate than the registration > obtained with Unified Segmentation. Certainly, for the comparisons that > we've done here in the FIL, the Dartel results have made more sense than > those using the older spatial normalisation approaches in SPM. I would be > pretty surprised if other people's data did not follow a similar trend. > > I would suggest looking at the contrast images obtained using the different > registration approaches. These will show you the general trends in the > data. Then take a look at the ResSS image to see how the variance appears. > Maybe there is an outlier somewhere among your data. For example, if the > segmentation is given poor starting estimates for the positions of the head > in the field of view, then it will mess up. > > Best regards, > -John > > On Monday 13 October 2008 13:53, Marie-José van Tol wrote: > > Dear list, > > > > Recently, at our lab we switched from optimised VBM to DARTEL to perform > > spatial preprocessing in voxel-based morphometric studies, as it should > > give cleaner results. However, we have noticed that replicability of > > Dartel vs. optimised VBM is not too good in several data sets in which we > > compared samples of psychiatric patients to healthy controls (there was a > > previous post > > http://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind0806&L=SPM&P=R15164 for > > Parkinson patients vs. controls). Specifically, we have two fairly large, > > independent samples of n=105 (55 patients vs. 50 healthy controls) and > > n=142 (99 vs. 43); in the first we found robust results (at a corrected > > threshold, in expected brain regions) for optimised VBM, which we were > > unable to replicate when using Dartel (with either 8 or 12 mm FWHM > > smoothing). In the second, highly significant results obtained when using > > Dartel could not be replicated - not even remotely - with VBM. In both > > studies, analytical models for VBM and Dartel were identical. The > > templates created by DARTEL (template_6 (both grey and white matter)) > > look fine, as did the normalized grey and white matter images per subject > > (mwrc1xxxx.nii/mwrc2xxx.nii). > > > > Do others have similar experiences? Any thoughts? > > > > Best, > > > > Odile van den Heuvel, Marie-José van Tol & Dick Veltman. > > > > Department of psychiatry, VUmc, Amsterdam, the Netherlands.