Dear SPMusers,
I am confused with some points on using SPM12-CAT12(DARTEL) for structural MRI data preprocessing (I have Parkinson's disease and control groups).
-How can I check the performance of each preprocessed smwp1 data (Is it logical to check values on report pdfs and say higher results of resolution/noise/bias/weighted average are well processed)?
-I used two sample t test. For masking, I only use implicit masking:yes (leave threshold masking none as default). Would using threshold absolute value 0.2 increase my classification result? Should i take it into account? (Since I have few clusters detected in the mask, i prefer not to take it).
I use age and TIV as two nuisance variables by taking them under covariates in the factorial design spec. Should I use TIV as global value as follows:
o Global Calculation → User <-X → Define here the TIV values
o Global Normalization
• Overall grand mean scaling → Yes (and value 50)
o Normalization → User → Proportional
-In result, I check t-contrast (FWE: none, p<0.001, k_threshold=0) to see the differences between two groups . I have few clusters and hence a few number of voxels (Around 6 clusters and 300 voxels). If I use FWE p<0.05, then I have no clusters detected. Is it normal in PD data (I have 40PD and 40 HC) or am i doing something wrong?
I would appreciate your help a lot.
Thank you in advance.
Best
--
Ozkan
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