Dear Anderson and FSL users,

I am trying to run an analysis to relate changes in DTI with BOLD (BOLD and DTI images arein the same space and have the same spatial resolution). Thus, I have used the BOLD image as voxelwise EV in PALM. I have tried two options and both present problems:

1)  Use BOLD as voxelwise EV for DWI changes with FWE correction across contrasts and modalities and NPC across modalities
palm -i DTI_4D_S1-S2.nii -i DTI_4D_S3-S2.nii -evperdat 4d_BOLD.nii -npc -npcmod -corrcon -corrmod -n 500 -T -Tnpc -logp -accel tail -concordant  -nouncorrected -o $output -m $mask

In this case, I am getting the following warning:

Rank deficient = 0

I have tried adding -pmethodr Ridgway as partition method used in the regression to solve the rank deficiency, as I had seen suggested in a thread in this forum, but it didn't work for me.

2) Use BOLD as voxelwise EV for DWI changes with FWE correction across contrasts and modalities and design. The design I used is all ones in EV1 for the mean and all ones in EV2 for the voxelwise EV. The contrasts I used are [0 1] and [0 -1] to test for positive and negative associations.

palm -i DTI_4D_S1-S2.nii -i DTI_4D_S3-S2.nii -evperdat 4d_BOLD.nii 2 -d Design_voxelwiseEV.mat -t Design_voxelwiseEV.con -npc -npcmod -corrcon -corrmod -n 500 -T -Tnpc -logp -accel tail -nouncorrected -o $output -m $mask

In this case, I am getting a warning saying Matrix is singular to working precision.

What could be the problem here?

Thanks for any advice you can give me to solve this.

Regards,

Florencia.

--

Ing. Florencia Jacobacci.

PhD student / Becaria doctoral

Instituto de Fisiología y Biofísica (IFIBIO) - Bernardo Houssay

Laboratorio de Fisiología de la Acción, Facultad de Medicina

Universidad de Buenos Aires

Paraguay 2155, C.A.B.A.(C1121ABG), Argentina

☎ (+5411) 5285-3304

http://www.physiologyofactionlab.info/en/about-the-lab/
https://ar.linkedin.com/in/florenciajacobacci/en

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