Hierarchical K-means clustering method for accelerated Lorentzian estimation (KALE) in chemical exchange saturation transfer-magnetic resonance imaging quantification.

Background: Quantification of chemical exchange saturation transfer (CEST) magnetic resonance signals is challenging due to contamination from coexisting effects, including the direct water effect and asymmetric magnetization transfer. Fitting-based analysis allows the calculation of multiple types of signals from the line shape of Z-spectra. However, the conventional voxelwise method has several drawbacks, including its long computation time and its susceptibility to image noise and Z-spectra oscillations, and it is difficult to determine the initial fitting parameters.

Reassembled saturation transfer (REST) MR images at 2 B values for in vivo exchange-dependent imaging of amide and nuclear Overhauser enhancement.

Purpose: Design an efficient CEST scheme for exchange-dependent images with high contrast-to-noise ratio.

Theory: Reassembled saturation transfer (REST) signals were defined as r.Z = r.