Different sequences


We are working with a large number of acquired imaging and unfortunately, the pulse sequences that have been used are not the same. We have two different groups of pulse sequence: T1-3D-FFE and T1-MPRAGE. We are planning to use freesurfer to volumetric analysis.
Could we use all of these images in the same study?

Thank you in advance for your answer,

A. Alp Karakasli

Hitit University

Department of Psychiatry

Be aware that different manufacturers can use different acronyms for the same sequence.

Your question is under specified. Typically for Magnetization Prepared T1-weighted scans the most crucial variables include TI, TE, TR and flip angle. Therefore, two MPRAGE sequences might be very different from each other.

If you have a large study, with your dependent variable independent from the sequence used, you could always add the sequence as a nuisance regressor to your analysis. The variability may reduce your statistical power, but if you find results that survive thresholding, it suggests the effects are robust. So a null-effect with a study that combines this variance would be hard to interpret, but positive effects are still meaningful.

As an aside, for planning future work that will use FreeSurfer, you may want to consider multi-echo sequences where the multiple echo-times help distinguish meninges from gray matter.

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Thanks for your informative response!