Wanted Dead or Alive? The Tradeoff between In-Vivo Versus Ex-Vivo MR Brain Imaging in the Mouse.

Jason Philipp Lerch¹, Jurgen Germann¹, John G. Sled¹, R. Mark Henkelman¹, Brian J. Nieman¹

Brain morphology in the mouse is a sensitive indicator of disease, treatment, and environmental effects on the brain. It is unclear, however, when to select an in-vivo longitudinal or an ex-vivo cross-sectional study design. Using multiple simulations based on existing data and assuming a linear change, we determined that 3-5 timepoints per subject in-vivo MRI equates to a single high-resolution ex-vivo experiment. The key for in-vivo imaging is to keep the within-subject variance low.