In vivo chlorine and sodium MRI of rat brain at 21.1 T

摘要

Object MR imaging of low-gamma nuclei at the ultrahigh magnetic field of 21.1 T provides a new opportunity for understanding a variety of biological processes. Among these, chlorine and sodium are attracting attention for their involvement in brain function and cancer development. Materials and methods MRI of ~(35)Cl and ~(23)Na were performed and relaxation times were measured in vivo in normal rat (n = 3) and in rat with glioma (n = 3) at 21.1 T. The concentrations of both nuclei were evaluated using the center-out back-projection method. esults T_1 relaxation curve of chlorine in normal rat head was fitted by bi-exponential function (T_(1a) = 4.8 ms (0.7) T_(1b) = 24.4 ± 7 ms (0.3) and compared with sodium (T_1 = 41.4 ms). Free induction decays (FID) of chlorine and sodium in vivo were bi-exponential with similar rapidly decaying components of T_(2a)~* 0:4 ms and T_2a~* 0:53 ms, respectively. Effects of small acquisition matrix and bi-exponential FIDs were assessed for quantification of chlorine (33.2 mM) and sodium (44.4 mM) in rat brain. Conclusion The study modeled a dramatic effect of the bi-exponential decay on MRI results. The revealed increased chlorine concentration in glioma (*1.5 times) relative to a normal brain correlates with the hypothesis asserting the importance of chlorine for tumor progression.