**5. Conclusions**

The data sugges<sup>t</sup> that a serum medetomidine concentration of 14.4 ± 3.0 ng/mL is suitable for rats undergoing brain fMRI with 0.5% (vapouriser setting) isoflurane.

**Author Contributions:** Conceptualization, G.C.M., K.W.F. and J.R.; methodology, G.C.M., T.H.H., K.W.F. and J.R.; data collection, L.T.K., B.J.S. and G.C.M.; pharmacokinetic analysis, T.H.H. and S.H.E.; medetomidine quantification, M.W.C.; data curation, L.T.K., B.J.S. and G.C.M.; writing—original draft preparation, L.T.K., G.C.M. and B.J.S.; writing—review and editing, all authors. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the University of Western Australia internal research funds held by K.W.F.; K.W.F. is an Australian National Imaging Facility Fellow, a facility funded by the University, State and Commonwealth Governments. L.T.K. is supported by a University of Western Australia Winthrop Scholarship. B.J.S. is supported by a Forrest Research Foundation Scholarship, an International Postgraduate Research Scholarship, and a University Postgraduate Award. J.R. is supported by a Senior Research Fellowship from Multiple Sclerosis Western Australia and the Perron Institute for Neurological and Translational Science.

**Acknowledgments:** The authors thank Andrea Holme for her assistance with the serum collection process, Sandy Goodin and the team at M Block Animal Care Services for their assistance with animal care and pre-procedural monitoring. The authors acknowledge the facilities, scientific assistance and technical assistance of the National Imaging Facility, a National Collaborative Research Infrastructure Strategy (NCRIS) capability, at the Centre for Microscopy, Characterisation and Analysis, University of Western Australia.

**Conflicts of Interest:** The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
