CEST- or Z-spectrum is often obtained to characterize CEST agents and to quantify information related to molecule or microenvironment such as temperature and pH^1,2. It is conventionally acquired through multiple experiments with selective saturation at different frequency offsets of interest, leading to extreme long acquisition time³. Here, we employ gradient-encoding to substantially accelerate the acquisition of Z-spectrum4. The utilization of high resolution magic angle spinning (HRMAS) further increases the spectral resolution for better identification and analysis of the spectrum.Copper sulfate-doped (0.65 mM) phosphate-buffered saline with choline (10 mM) and varied concentrations of creatine (10, 20, 30 40 and 50 mM) in 1.5% agarose gel was used for phantom study. Middle cerebral artery occlusion (MCAO) was performed on six adult Wistar rats to induce ischemia stroke. 24 hours after MCAO, brain tissue samples from contralateral normal area or ipsilateral ischemia lesion were harvested, loaded into 4 mm Zirconia rotors with 1.0 μl of D₂O and introduced into the HRMAS probe. Spectroscopic measurements of ex vivo tissue were carried out at 37 °C and at a HRMAS spinning rate of 4800 Hz on a 14.1T Bruker AVANCE spectrometer (Bruker BioSpin, Billerica, Massachusetts, USA). Z-spectra were acquired using a spin-echo sequence without (B₁=0 µT) or with (B₁=1, 1.5, 2, 3 µT) RF saturation (Figure 1). By applying a constant magnetic field gradient during the saturation period, the off-resonant data points in the Z-spectrum are generated by a gradient-induced change of the Larmor frequencies of the nuclei in the sample, such that they experience saturation with different off-resonance conditions depending on their position⁵. Representative HRMAS Z-spectra and corresponding CEST asymmetry spectra from the phantom study showed strong CEST signal from creatine at the offset of 1.8 ppm for different B₁ power levels (Figure 2). The optimal B1 level can be found at 1.5 µT (Figure 3a). Figure 3b shows that the CESTR calculated from CEST asymmetry spectra at B₁=1.5 µT increases linearly with creatine concentration. Figure 4 illustrates HRMAS Z-spectra of tissue samples from normal area or ischemic lesion of stroke brains. CEST effects can be observed at multiple offsets such as -3.5, -2.5, 2, 3.5 and 4.5 ppm, etc. and significant differences between the normal and lesion tissue samples can be found (Figure 4). Compared to conventional approach, this new method substantially reduce acquisition time by encoding the frequency offsets along one spatial dimension. It does not require the sample to have a homogeneous shape as it can be compensated for by normalizing to the 1D projection of the sample acquired with saturation off. This speedup in combination with higher spectral resolution provided by HRMAS allows rapid quantification of chemical exchange rates of CEST agents, monitoring dynamic processes and fast tissue characterization.