Dear all,

I have 2 groups (patients and controls), and I want to analysis the subfields of the hippocampus. Some of the subjects have 2 scans (before treatment and post treatment) and some subjects only have one scan(before treatment). aim 1: I want to compare the subfied volume of the hippocampus between patients and control using the before treatment data. aim 2: I also want to calculate the treatment effects on the subfield volume of the hippocampus.

Do I need to use longitudinal analysis ? or cross-sectional analysis is fine? If use longitudinal analysis, for the aim 1, only part of the subjects have 2 scans. I still need to use the cross-sectional data to calculate the groups' difference in order to include all subjects.

What your suggestions?

Thank you so much!

Best

Jinsong