Modelling Magnetization Transfer Considering Spin-Locking Effects

Abstract

Purpose: Recently it was demonstrated that spin-locking (SL) effects can manifest as pseudo mag-netization transfer (MT). To our best knowledge the MT models proposed so far cannot distin-guish between saturation effects caused by the MT preparation pulses and SL phenomena. There-fore a new MT model is proposed. Materials and Methods: A binary spin-bath model for magneti-zation transfer was extended in that sense that SL effects are considered. The new modified spin bath model was tested for a phantom with different agar concentrates (2%, 4%, 8%) and a MnCl2 (0.3 mM) solution. Results: The mean fitting error is 3.2 times lower for the modified model com-pared to the original model. Especially the parameter F for the fractional part of the bounded pro-ton pool describes the situation for the MnCl2 (F = 0) better than the original model (F = 0.004). Conclusion: The proposed mathematical modifications of the binary spin-bath model considering SL seem to be a step in the right direction in that sense that the effects associated with SL are not interpreted as magnetization transfer.