Inverse Z-spectrum analysis for clean NOE and amide CEST-MRI – application to human glioma

Inverse Z-spectrum analysis for clean NOE and amide CEST-MRI – application to human glioma Moritz Zaiss, Johannes Windschuh, Jan-Eric Meissner, Daniel Paech, Alexander Radbruch, and Peter Bachert Dept. Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, Dept. of Neuroradiology, University of Heidelberg, Heidelberg, Germany, Section Neuro–oncologic Imaging, German Cancer Research Center (DKFZ), Heidelberg, Germany Purpose Endogenous chemical exchange saturation transfer (CEST) effects are always diluted by competing effects such as direct water saturation and semi-solid magnetization transfer (MT). This leads to unwanted T2 and MT signal contributions that dilute the observed CEST signal (spillover effect)1,2. Furthermore, all CEST effects appear also to be scaled by the T1 relaxation time of the mediating water pool2,3. As MT, T1 and T2 are also altered in tumor regions, a recently published correction algorithm yielding the apparent exchange-dependent relaxation AREX, is used to evaluate in vivo CEST effects2. This study focuses on CEST effects of amides (3.5 ppm) and Nuclear-Overhauser-mediated saturation transfer (NOE, -3.5 ppm) in human glioblastoma.