Burke Stephen J, Annapragada Ananth, Hoffman Eric A, Chen Emmanuel, Ghaghada Ketan B, Sieren Jered, van Beek Edwin J R
Department of Radiology, Carver College of Medicine, University of Iowa, 200 Hawkins Drive, Iowa City, IA, USA.
Acad Radiol. 2007 Mar;14(3):355-62. doi: 10.1016/j.acra.2006.12.014.
Polyethylene glycol-coated liposomal blood pool contrast agents maintain contrast enhancement over several hours. This study aimed to evaluate (long-term) imaging of pulmonary arteries, comparing conventional iodinated contrast with a liposomal blood pool contrast agent. Also, visualization of the (real-time) therapeutic effects of tissue plasminogen activator (t-PA) on pulmonary embolism (PE) was attempted.
Six rabbits (weight approximately 4 kg) had autologous blood clots injected through the superior vena cava. Imaging was performed using conventional contrast (iohexol, 350 mg I/ml; GE HealthCare, Princeton, NJ) at a dose of 1400 mg I per animal, and after wash-out, animals were imaged using an iodinated liposomal blood pool agent (88 mg I/mL, dose 900 mg I/animal). Subsequently, five animals were injected with 2 mg of t-PA and imaging continued for up to 4(1/2) hours.
Both contrast agents identified PE in the pulmonary trunk and main pulmonary arteries in all rabbits. Liposomal blood pool agent yielded uniform enhancement, which remained relatively constant throughout the experiments. Conventional agents exhibited nonuniform opacification and rapid clearance postinjection. Three of six rabbits had mistimed bolus injections, requiring repeat injections. Following t-PA, pulmonary embolus volume (central to segmental) decreased in four of five treated rabbits (range 10-57%, mean 42%). One animal showed no response to t-PA.
Liposomal blood pool agents effectively identified acute PE without need for reinjection. PE resolution following t-PA was quantifiable over several hours. Blood pool agents offer the potential for repeated imaging procedures without need for repeated (nephrotoxic) contrast injections.
聚乙二醇包被的脂质体血池造影剂可在数小时内维持对比增强效果。本研究旨在评估肺动脉的（长期）成像，将传统碘化造影剂与脂质体血池造影剂进行比较。此外，还尝试观察组织纤溶酶原激活剂（t-PA）对肺栓塞（PE）的（实时）治疗效果。
六只兔子（体重约4千克）通过上腔静脉注射自体血凝块。使用传统造影剂（碘海醇，350毫克碘/毫升；通用电气医疗集团，新泽西州普林斯顿）以每只动物1400毫克碘的剂量进行成像，冲洗后，使用碘化脂质体血池剂（88毫克碘/毫升，剂量900毫克碘/动物）对动物进行成像。随后，给五只动物注射2毫克t-PA，并持续成像长达4.5小时。
两种造影剂均在所有兔子的肺动脉主干和主要肺动脉中识别出PE。脂质体血池剂产生均匀增强，在整个实验过程中保持相对恒定。传统造影剂表现出不均匀的显影，注射后清除迅速。六只兔子中有三只推注时间不当，需要重复注射。注射t-PA后，五只接受治疗的兔子中有四只（范围为10%-57%，平均42%）的肺栓塞体积（中央至节段性）减小。一只动物对t-PA无反应。
脂质体血池剂无需再次注射即可有效识别急性PE。t-PA治疗后的PE溶解情况在数小时内可量化。血池剂为无需重复（肾毒性）造影剂注射的重复成像程序提供了可能性。
