Purdy P D, Horowitz M B, Mathews D, Walker B S, Carstens G J, Devous M D, White C L, Kulkarni P, Constantinescu A, Batjer H H
Department of Radiology, University of Texas Southwestern Medical Center, Dallas 75235-8896, USA.
AJNR Am J Neuroradiol. 1996 Jun-Jul;17(6):1161-70.
To determine whether transient ischemia can be separated from permanent ischemia via calcium 45 autoradiography and to assess the applicability of dual isotope single-photon emission CT (SPECT) in the evaluation of cerebral blood flow.
We examined calcium influx in 12 dogs (group A) by using whole-brain calcium 45 autoradiography: Animals received 250 microCi/kg 24 hours after 30-minute (n = 6) or permanent (n = 6) middle cerebral artery (MCA) occlusion. Forty-eight hours after MCA occlusion, 5-mm coronal brain sections were fixed for either autoradiography or pathologic examination. In a separate study, 9 mongrel dogs (group B) were given 250 microCi/kg calcium 45 and a mean dose of 700 microCi/kg technetium Tc 99m hexamethylpropyleneamine oxime intravenously. A silicone plug was then injected into the internal carotid artery and angiography was performed to verify MCA occlusion. A 10th (control) animal did not undergo occlusion. In an 11th animal, placement of the plug could not be achieved and a slurry of microfibrillar collagen was injected into the carotid artery. No angiography was performed in animals 10 and 11. After occlusion, each animal was injected with a mean dose of 126 microCi/kg simultaneous acquisition for technetium 99m and 123I-iodoamphetamine.
In group A, all animals who had permanent MCA occlusion showed infarction and increased calcium 45 uptake in infarcted territories. None of the animals who had 30-minute occlusion had either increased calcium 45 uptake or infarction at 48 hours. In group B, 7 or 10 dogs had SPECT findings that were consistent with the calcium autoradiographic marker for ischemia. One animal died during the procedure and 1 dog served as a control.
Calcium 45 autoradiography allowed distinction between areas of temporary and permanent occlusion. Iodoamphetamine imaging was not consistently sensitive to that level of ischemia. Timing of calcium influx may lead to insight that could impact timing of pharmacologic or endovascular intervention.
通过钙45放射自显影法确定短暂性缺血是否可与永久性缺血区分开来，并评估双同位素单光子发射计算机断层扫描（SPECT）在评估脑血流中的适用性。
我们通过全脑钙45放射自显影法检查了12只狗（A组）的钙内流情况：动物在大脑中动脉（MCA）闭塞30分钟（n = 6）或永久性闭塞（n = 6）24小时后接受250微居里/千克的剂量。MCA闭塞48小时后，将5毫米厚的冠状脑切片固定用于放射自显影或病理检查。在另一项研究中，9只杂种狗（B组）静脉注射250微居里/千克的钙45和平均剂量为700微居里/千克的锝Tc 99m六甲基丙烯胺肟。然后将硅胶栓塞注入颈内动脉，并进行血管造影以确认MCA闭塞。第10只（对照）动物未进行闭塞操作。在第11只动物中，无法放置栓塞，于是将微纤维胶原浆注入颈动脉。第10只和第11只动物未进行血管造影。闭塞后，给每只动物注射平均剂量为126微居里/千克的锝99m和123I - 碘安非他明进行同步采集。
在A组中，所有永久性MCA闭塞的动物均出现梗死，梗死区域钙45摄取增加。在30分钟闭塞的动物中，48小时时均未出现钙45摄取增加或梗死。在B组中，7只或10只狗的SPECT结果与缺血的钙放射自显影标记一致。1只动物在手术过程中死亡，1只狗作为对照。
钙45放射自显影法能够区分暂时性和永久性闭塞区域。碘安非他明成像对该缺血水平的敏感性并不一致。钙内流的时间可能会为影响药物或血管内介入时机的见解提供线索。
