Quantification and Differentiation of CK and ATPase Fluxes Between Human GM and WM Using 3D 31P CSI and Saturation Transfer

Xiao-Hong Zhu¹, Fei Du¹, Qiang Xiong¹, Hongyan Qiao¹, Xiao Liu¹, Jianyi Zhang², Xiaoliang Zhang³, Kamil Ugurbil¹, Wei Chen¹

In vivo ³¹P MRS in combine with saturation transfer provides a useful tool for noninvasively measuring the cerebral metabolic fluxes of creatine kinase (CK) and ATPase reactions. However, 3D imaging of these metabolic fluxes in human brain is challenging owing to limited sensitivity and complicated quantification model when a short (desired) repetition time is used. In this study, we demonstrate that with advanced ³¹P MRS imaging approach and a newly developed quantification method, it is possible to image the CK and ATPase reaction rate constants and fluxes in human brain at 7T. We found that these fluxes were several folds higher in the grey matter than white matter. This study demonstrates not only the superior sensitivity achievable at high/ultrahigh field, but also the great potential of ³¹P approach for studying cerebral HEP metabolism and neuroenergetics associated with brain function and dysfunction.