Dear SPM users,
I have two questions regarding how to do the partial correlation for a
ligand PET study.
I have 7 patients and each of them had one FLB-PET scan. I produced binding
potential maps (3D image) using some in-house software.
I have two covariates. One of the covariates is the behavioural score and
the other is age which should be controlled for (nuisance covariate).
So, I have design matrix of X = [behaviour, age, constant].
Of course, Those are column vectors.
And, I used C = [1 0 0].
My first question is...is this the right way to do partial correlation?
My second question is about extent threshold.
I put 0.001 for uncorrected height threshold, and put 10 for extent
threshold.
And, I think the SPM gives me some unrealistic values.
All of the p_corrected in cluster-level was less than 0.001.
And, in the left bottom of the result window, it gives:
Height threshold: T=7.17, p=0.001 (1.000) {p<0.001 (unc.)}
Extent threshold: k = 10 voxels, p=0.000 (0.000)
Expected voxels per cluster, <k>=0.156
Expected number of clusters, <c>=0.00
Expected false discovery rate, <=0.15
I think there is something wrong.
How can I have such "good" p_corrected values with only 7 scans?
Please help...
Best,
Ji Hyun
____________________________________
Ji Hyun Ko, PhD
Post-doctoral Fellow,
Centre for Addiction and Mental Health &
Toronto Western Research Institute,
University of Toronto
Physical Address:
455 Spadina Ave., Suite 402
Toronto, Ontario, M5S 2G8
CANADA
Mailing Address:
PET Centre, CAMH
250 College street
Toronto, Ontario, M5T 1R8
CANADA
Phone: +1-416-535-8501 ext. 7396
Fax: +1-416-979-3855
|