Stroke Imaging Based on Amine-Water Proton Exchange (APEX): Correlations with ADC and Metabolite Concentrations

Xiaopeng Zong¹, Tao Jin¹, Ping Wang¹, Seong-Gi Kim¹

The amine-proton is present in abundant free amino acids, as well as in amino-acid residues of protein and peptide side chains. Recently, the amine-water proton exchange (APEX) effect has been proposed as a sensitive molecular imaging contrast at high magnetic field. In this work, we performed multi-parametric MRI and spectroscopic experiments in a rat MCAO model to investigate its potential applications in stroke. Our results show that the APEX signals are sensitive to rapid tissue pH changes following stroke and are also correlated with more gradual metabolite concentration (e.g. Glu) changes, and thus is a promising technique for stroke applications.