Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland; Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland; A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
J Magn Reson. 2018 Nov;296:79-84. doi: 10.1016/j.jmr.2018.09.001. Epub 2018 Sep 5.
The dynamics of spin system coupled by chemical exchange between two sites with different chemical shifts during periodic radiofrequency (RF) irradiation was here investigated. When the instantaneous π-flip of effective frequency during the course of frequency sweep was applied, a significant increase of exchange-induced relaxation rate constants was observed for small tip angle of magnetization in the laboratory frame of reference. This increase of the rate constants corresponds to the side bands generated by the periodic irradiation during the RF pulses. The exchange - induced relaxation rate constants depend on the exchange conditions, the RF power and the irradiation period. The described phenomenon promises applications for studying protein dynamics and for generating exchange specific relaxation contrasts in MRI.
本文研究了在周期性射频（RF）辐照期间，两个化学位移不同的位点之间通过化学交换耦合的自旋系统的动力学。当在频率扫描过程中应用有效频率的瞬时π翻转时，在实验室参考系中观察到磁化小尖端角度的交换诱导弛豫率常数显著增加。 这种速率常数的增加对应于在 RF 脉冲期间周期性辐照产生的边带。 交换诱导的弛豫率常数取决于交换条件、RF 功率和辐照周期。 所描述的现象有望用于研究蛋白质动力学以及在 MRI 中产生交换特异性弛豫对比。
