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Dear Jay, I agree with John that it sounds like you probably want to do a "standard" SPM analysis on "standard" PET data - just acquired with microPET, so with smaller animals. For this kind of analysis, you wouldn't need to segment your PET data into tissue classes at all. SPM has been used for the analysis of ligand PET data (i.e. one scan/subject - I guess that's what you are talking about) for a long time; as far as I know the first applications were: Koepp MJ et al. Cerebral benzodiazepine receptors in hippocampal sclerosis. An objective in vivo analysis. Brain. 1996 Oct;119 ( Pt 5):1677-87. Frey KA et al. Stereotaxic summation analysis of human cerebral benzodiazepine binding maps. J Cereb Blood Flow Metab. 1996 May;16(3):409-17 These principles can easily be extended to longitudinal (e.g. paired, tripled) scans; a recent example from our group would be: Hammers A et al. Upregulation of opioid receptor binding following spontaneous epileptic seizures. Brain. 2007 Apr;130(Pt 4):1009-16 and there are plenty of others. The problem is not tissue class segmentation, but in your case getting appropriate templates (average image datasets in a suitable standard space) for spatial normalisation - I can't help you there but there should be people on the list who can. It would be helpful for them if you said which PET tracer you are working with, and maybe you'll have to re-post your query as "SPM and microPET with .....[ligand name]" to get the right attention. Hope this helps a little, Alexander -----Original Message----- From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of John Ashburner Sent: 19 February 2008 12:39 To: [log in to unmask] Subject: Re: [SPM] VBM and microPET If you apply the technique to anything other than maps of tissue volume, then it is really an "SPM" analysis, rather than a "VBM". In my own personal view, such analyses of FA maps etc are also just SPM analyses, but I guess people can call them what they like. You could do an analysis of the original PET data (after spatially normalising and smoothing), but it is extremely unlikely that you would be able to segment out grey and white matter. Best regards, -John > How are you ? Our lab is doing microPET imaging research. > During lab meeting, someone asked ' Is it possible to apply VBM > technique for microPET image analysis ?'. Most people in our lab said > no. The main concern is it is very difficult to segment GM, WM and > CSF out from microPET image. In my heart I think there must have way > out of this, even though I don't know how. I appreciate your > suggestions and comments.