Gilad Assaf A, van Laarhoven Hanneke W M, McMahon Michael T, Walczak Piotr, Heerschap Arend, Neeman Michal, van Zijl Peter C M, Bulte Jeff W M
Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Neurosection, Baltimore, Maryland 21231, USA.
Magn Reson Med. 2009 Apr;61(4):970-4. doi: 10.1002/mrm.21928.
A major challenge for cellular and molecular MRI is to study interactions between two different cell populations or biological processes. We studied the possibility to simultaneously image contrast agents based on two different MRI contrast mechanisms: chemical exchange saturation transfer (CEST) and enhancement of T2 relaxation. Various amounts of superparamagnetic iron oxide (SPIO) nanoparticles were mixed with a fixed concentration (250 microM) of the CEST agent poly-L-lysine. T2 maps, CEST maps, and frequency-dependent saturation spectra were then measured. Color-coded overlay maps demonstrated the feasibility of concurrent dual contrast enhancement. We found that at concentrations lower than 5 microg(Fe)/mL both contrast agents can be imaged simultaneously. At higher concentrations, the iron-based agent can be used to "shut off" the signal arising from the CEST agent. These initial findings are a first step toward using dual CEST/T2 contrast imaging for studying multiple cellular or molecular targets simultaneously in vivo.
细胞和分子磁共振成像面临的一个主要挑战是研究两种不同细胞群体或生物过程之间的相互作用。我们研究了基于两种不同磁共振成像对比机制同时对造影剂进行成像的可能性：化学交换饱和转移（CEST）和T2弛豫增强。将不同量的超顺磁性氧化铁（SPIO）纳米颗粒与固定浓度（250微摩尔）的CEST剂聚-L-赖氨酸混合。然后测量T2图、CEST图和频率依赖性饱和光谱。彩色编码叠加图证明了同时进行双对比增强的可行性。我们发现，在浓度低于5微克（铁）/毫升时，两种造影剂可以同时成像。在较高浓度下，铁基造影剂可用于“关闭”CEST剂产生的信号。这些初步发现是朝着在体内同时使用双CEST/T2对比成像研究多个细胞或分子靶点迈出的第一步。
