Cheung Jerry S, Chow April M, Guo Hua, Wu Ed X
Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.
Neuroimage. 2009 Jul 1;46(3):658-64. doi: 10.1016/j.neuroimage.2009.02.037. Epub 2009 Mar 6.
Gas-filled microbubbles have the potential to become a unique MR contrast agent due to their magnetic susceptibility effect, biocompatibility and localized manipulation via ultrasound cavitation. In this study, two types of microbubbles, custom-made albumin-coated microbubbles (A-MB) and a commercially available lipid-based clinical ultrasound contrast agent (SonoVue), were investigated with in vivo dynamic brain MRI in Sprague-Dawley rats at 7 T. Microbubble suspensions (A-MB: 0.2 mL of approximately 4% volume fraction; SonoVue: 0.2 mL of approximately 3.5% volume fraction) were injected intravenously. Transverse relaxation rate enhancements (DeltaR(2)()) of 2.49+/-1.00 s(-1) for A-MB and 2.41+/-1.18 s(-1) for SonoVue were observed in the brain (N=5). Brain DeltaR(2)() maps were computed, yielding results similar to the cerebral blood volume maps obtained with a common MR blood pool contrast agent. Microbubble suspension DeltaR(2)(*) was measured for different volume fractions. These results indicate that gas-filled microbubbles can serve as an intravascular contrast agent for brain MRI at high field. Such capability has the potential to lead to real-time MRI guidance in various microbubble-based drug delivery and therapeutic applications in the central nervous system.
由于其磁化率效应、生物相容性以及通过超声空化进行局部操纵的特性，充气微泡有潜力成为一种独特的磁共振成像（MR）造影剂。在本研究中，使用7T的磁共振成像对Sprague-Dawley大鼠进行活体动态脑成像，研究了两种类型的微泡：定制的白蛋白包被微泡（A-MB）和市售的基于脂质的临床超声造影剂（声诺维）。静脉注射微泡悬液（A-MB：0.2 mL，体积分数约为4%；声诺维：0.2 mL，体积分数约为3.5%）。在大脑中观察到A-MB的横向弛豫率增强（DeltaR(2)()）为2.49±1.00 s(-1)，声诺维为2.41±1.18 s(-1)（N = 5）。计算了脑DeltaR(2)()图，得到的结果与使用常见MR血池造影剂获得的脑血容量图相似。测量了不同体积分数下微泡悬液的DeltaR(2)(*)。这些结果表明，充气微泡可作为高场脑MRI的血管内造影剂。这种能力有可能在中枢神经系统中基于微泡的各种药物递送和治疗应用中实现实时MRI引导。
