Heat-activated liposomal MR contrast agent: Initial in vivo results in rabbit liver and kidney
Heat-activated liposomal MR contrast agent: Initial in vivo results in rabbit liver and kidney
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DOI：
10.1148/radiol.2303021713
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发表时间：
2004-03-01
期刊：
影响因子：
19.7
通讯作者：
Hynynen, K
中科院分区：
文献类型：
--
作者：
McDannold, N;Fossheim, SL;Hynynen, K
目的：利用体内磁共振成像技术评价脂质体顺磁性造影剂的功能，该造影剂具有T1弛豫度，在高于脂质体膜的凝胶-液晶相变温度(T-c)时，其功能迅速显著增加。材料和方法：在聚焦超声应用前不久，分别以每公斤体重0.4或1.2mL(分别含有10或30摩尔的Gd)的脂质体Gd(二乙三氨基五乙酸)对肝脏(7只)或肾脏(3只)进行注射。其中4只兔肝内种植了VX2肿瘤。超声检查肝脏18个部位(正常组织13个，肿瘤5个)，肾脏12个部位。在超声检查过程中进行磁共振测温。在组织冷却后获得的T1加权图像上评估信号强度增强，并通过Bland-Altman分析将增强区域与脂体膜T-c处(约57℃)的等温线进行比较。在肝脏中，强化区也与组织学证实的热损伤区域进行了比较。通过监测10次不同功率的超声在正常肝组织两个部位的信号强度增加，验证T1加权成像的增强阈值温度。结果：所有超声肝脏部位的T1加权像均可观察到持续强化。在肝脏，T1加权图像上的强化带与组织学证实的坏死区(7个测量值；平均差值+/-SD，0.1 mm+/-0.9)是连续的，C等温线为57度(25个测量值；平均差值+/-SD，0.4 mm+/-1.2)。正常肝脏T1加权成像的增强阈值温度为53℃-57℃。在肾脏，T1加权像上的强化带与等温线不匹配。结论：脂质体造影剂对肝脏的体内MR测温有效，而对肾脏则无效。(C)RSNA，2004年。
PURPOSE: To evaluate by using in vivo magnetic resonance (MR) imaging the functionality of a liposomal paramagnetic contrast agent with T1 relaxivity that rapidly and markedly increases at temperatures above the gel-to-liquid crystalline phase transition temperature (T-c) of the liposome membrane.MATERIALS AND METHODS: Liposomal gadolinium diethylenetriaminepentaacetic acid bis(methylamide) was injected intravenously at a dose of 0.4 or 1.2 mL (containing 10 or 30 mumol of gadolinium, respectively) per kilogram of body weight shortly before the application of focused ultrasound in liver (seven rabbits) or kidney (three rabbits). VX2 tumors had been implanted in liver in four of the rabbits. Eighteen locations in liver (13 in normal tissue, five in tumor) and 12 locations in kidney were sonicated. MR thermometry was performed during sonications. Signal intensity enhancement was evaluated on T1-weighted images acquired after the tissue cooled, and enhanced zones were compared with isotherms at T-c of the liposome membrane (approximately 57degreesC) by using Bland-Altman analysis. In liver, enhanced zones also were compared with areas of histologically verified thermal damage. The threshold temperature of enhancement at T1-weighted imaging was verified by monitoring the signal intensity increase after 10 sonications at varied powers in two locations in normal liver tissue.RESULTS: Persistent enhancement was observed on T1-weighted images at all sonicated liver locations. In liver, enhanced zones on T1-weighted images were contiguous both with 57degreesC isotherms (25 measurements; mean difference +/- SD, 0.4 mm +/- 1.2) and with histologically verified areas of necrosis (seven measurements; mean difference +/- SD, 0.1 mm +/- 0.9). The threshold temperature of enhancement at T1-weighted imaging in normal liver was 53degrees-57degreesC. In kidney, enhanced zones on T1-weighted images did not match the isotherms.CONCLUSION: The liposomal contrast agent was effective at in vivo MR thermometry in liver but not in kidney. (C) RSNA, 2004.