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For the pre-surgical patients I scan, I only do a single subject analysis. I think comparing to a group of controls, for the purposes of a pre-surgical evaluation, is risky business. How would you interpret the results? Or rather, what information would be added above and beyond the information you get from the single subject result? e.g. let's say your patient has a tumor near Broca's area, and you perform a verbal language fMRI task (in addition to DTI and other scans). If there is activation around Broca's area, the surgeon may be hesitant to resect. If there is no activation (perhaps language is RH dominant in this patient) at a "safe" statistical threshold, the surgeon may feel confident in resecting. I think bringing in a group of controls will complicate the matter. I understand this issue is probably not so simple with smaller tumors or other lesions. Any thoughts from others in the clinical world? Chris ________________________________________ From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of Laura Bled [[log in to unmask]] Sent: Tuesday, November 13, 2012 10:07 AM To: [log in to unmask] Subject: Re: [SPM] single subject clinical fMRI Sure the question about variance is omnipresent in such comparison. And yet I wish I could use fMRI as a powerful tool in presurgical evaluation - not only evaluation of single subject maps but in comparison with healthy controls "database". So for the sake of this comparison I still have to find the optimal nr of subjects (perhaps the more the better, and yet there are scanning costs, man power, volunteers search etc). Perhaps anyone is doing such examinations in your clinic? Marko, I am very grateful for your response Thank you Laura > Date: Mon, 12 Nov 2012 17:04:34 +0100 > From: [log in to unmask] > To: [log in to unmask] > CC: [log in to unmask] > Subject: Re: [SPM] single subject clinical fMRI > > Hi Laura, > > the issue you are facing is not necessarily the size of your control > population but the fact that you do not have variance in one of your > "groups" (as n=1). Consequently, there are strong reservations against > doing it this way. However, the need you see of course is there, and > some groups have tried circumventing direct comparisons by creating > z-score maps of "the usual" activation pattern (see Mbwana et al., > 2009). Also, VBM faces similar issues and a recent paper by Mühlau et > al., 2009 includes some discussions on this issue. Perhaps this gives > you some pointers on where to begin. > > Cheers, > Marko > > Laura Bled wrote: > > > > Dear experts > > > > We are trying to find out what would be the most appropriate nr of > > control subjects for our clinical fMRI experiment. We want to compare > > single patients data to controls (a semantic task experiment). There are > > 3 runs, block design. In already acquired data the activation per > > subject, in controls or in patients is quite large. Is it appropriate to > > compare 12 controls and 1 patients (a t-test) ? > > I checked Rik Henson syntax on single case, but it's not quit the > > response i was looking > > for http://www.mrc-cbu.cam.ac.uk/people/rik.henson/personal/Henson_Singlecase_06.pdf > > > > Would be very grateful for any suggestions > > > > Laura > > > > -- > ____________________________________________________ > PD Dr. med. Marko Wilke > Facharzt für Kinder- und Jugendmedizin > Leiter, Experimentelle Pädiatrische Neurobildgebung > Universitäts-Kinderklinik > Abt. III (Neuropädiatrie) > > > Marko Wilke, MD, PhD > Pediatrician > Head, Experimental Pediatric Neuroimaging > University Children's Hospital > Dept. III (Pediatric Neurology) > > > Hoppe-Seyler-Str. 1 > D - 72076 Tübingen, Germany > Tel. +49 7071 29-83416 > Fax +49 7071 29-5473 > [log in to unmask] > > http://www.medizin.uni-tuebingen.de/kinder/epn/ > ____________________________________________________