一种新型氟化物单体和聚合物19 F-MRI成像性能对比

Comparison of 19 F-MRI imaging performance between monomer and polymer of a new kind of fluoride

19 F磁共振成像(19 F magnetic resonance imaging,19 F-MRI)作为一种新兴的成像技术,在机体内无内源背景信号干扰,具有特异性好、无放射性和可定量检测等优点。高灵敏造影剂是19 F-MRI活体成像信噪比高的基础。基于此,本团队合成了一种新型氟化物N-(2-甲基丙烯酸乙酯)-N-(3,3,3-三氟丙基)-N-甲基甘氨酸分子(CBF 3),其具有分子量小,超亲水,代谢速度快等特点,但纵向弛豫率低,成像速度慢,成像时间窗较短,限制其作为19 F-MRI造影剂的活体成像性能。为了提升CBF 3的活体成像性能,我们利用可逆加成断裂链转移自由基聚合制备均聚物(PCBF 3)。然后利用19 F-MRI体外成像方法分别计算CBF 3和PCBF 3的纵向弛豫值(R1)、横向弛豫值(R2)、磁化矢量(M19F)。研究表明,相比CBF 3,PCBF 3的这3个参数均显著升高(p<0.01),R1值、R2值、M19F值分别升高了125.9%、1126.9%、32.3%。因此,在获得相同T1信号强度的情况下,PCBF 3的成像速度比CBF 3提高近2.26倍。进一步,利用19 F-MRS/MRI进行活体成像评价。结果表明,CBF 3注入小鼠体内约2小时后汇聚于膀胱,活体成像利用率(imaging availability in-vivo,IAIV)约为8%;PCBF 3的IAIV约为84%,可在主要器官、肌肉等区域以及腹主动脉中检测到明显的19 F-MRI信号。综上所述,PCBF 3纵向弛豫率高,成像速度快,成像时间窗长,活体成像利用率高,作为19 F-MRI造影剂的活体成像效果更好。

19 F magnetic resonance imaging(19 F-MRI)had the advantages of high specificity,no radioactivity and quantitative detection due to non-interference of endogenous background signals in-vivo.High sensitivity 19 F contrast agent was the basis of in-vivo imaging with high signal-to-noise ratio.To improve the imaging performance of CBF 3,the homopolymer(PCBF 3)was synthesized by the polymerization of reversible addition-fragmentation chain transfer(RAFT).Then,the longitudinal relaxation value(R1),transverse relaxation value(R2)and magnetization vector(M 19 F)of CBF 3 and PCBF 3 were calculated by 19 F-MRI.Compared with those three parameters of CBF 3,those of PCBF 3 were significantly increased(p<0.01),R1,R2 and M 19 F values of PCBF 3 increased respectively by 125.9%,1126.9%and 32.3%.The imaging speed of PCBF 3 was about 2.26 times faster than that of CBF 3 at the same T1 signal intensity.The imaging performance was evaluated by in-vivo 19 F-MRS/MRI.The results showed that,after being injected into mice for 2 hours later,CBF 3 excreted in bladder and the imaging availability in-vivo(IAIV)was about 8%.In contrast,PCBF 3 could be imaged in major organs,muscles and abdominal aorta,and the IAIV of PCBF 3 was about 84%.In conclusion,PCBF 3 has high longitudinal relaxation,fast imaging speed,long imaging time window and high imaging availability in-vivo,which has better in-vivo imaging performance as a contrast agent of 19 F-MRI.