Dear Ramesh,

some first thoughts about your analysis:
1. By using an initial peak threshold of P<0.001 there survives one large cluster the cluster-level threshold FWE-corrected of P<0.05. Please check the SPM mail list for previous discussions about the use of cluster-level thresholds. In short: the initial peak-level threshold of P<0.001 allows the application of an additional (FWE-corrected) cluster-level threshold.
2. You can give the TFCE toolbox a try that combines peak- and cluster-levels
3. The estimated smoothness of about 18mm is surprisingly large for a Gaussian filtering with FWHM of 10mm. Have you used in the stat. model an absolute threshold of at least 0.1 to ensure that you only analyze gray matter?

Best,

Christian

---

Christian Gaser, Ph.D.
Professor of Computational Neuroscience/Neuroimaging
Biomagnetic Center
Structural Brain Mapping Group
Department of Neurology
Jena University Hospital
Am Klinikum 1, D-07747 Jena, Germany
Tel: ++49-3641-9325778 Fax: ++49-3641-9325772
e-mail: [log in to unmask]
http://www.neuro.uni-jena.de

On 12 Dec 2017, at 17:54, Ramesh Babu wrote:

Dear Expert,

I did VBM analysis on two groups with n=40 in each by using CAT12 tool in
SPM. Please see the attached VBM result. Initially I kept p value as 0.001
uncorrected and got significant finding in some regions. In the VBM result
table at cluster level I found p value <0.05 for first cluster. But when I
change the significance level to 0.05 FWE corrected in SPM result window, I
am not getting any output (empty glass brain result).
Could you please give me your suggestions to interpret and report the
result?

Additional details;
Smooth = 10mm
Nuisance co-variate - tiv, age, & sex
K=175

Thanks
RB