Runge V M, Kirsch J E, Wells J W, Dunworth J N, Woolfolk C E
Magnetic Resonance Imaging and Spectroscopy Center, University of Kentucky, Lexington 40536-0098.
AJR Am J Roentgenol. 1994 Feb;162(2):431-5. doi: 10.2214/ajr.162.2.8310940.
The detection of blood-brain barrier disruption in patients with cerebral infarction by means of contrast-enhanced MR images improves the specificity of diagnosis, enables lesion dating, and on occasion improves lesion detection. Accordingly, we performed a study to determine the extent of visualization of disruption of the blood-brain barrier on contrast-enhanced MR images, with specific attention to contrast dose, in a cat model of acute cerebral infarction. We used doses of 0.1 and 0.3 mmol/kg of a gadolinium chelate, gadoteridol, which is characterized by extracellular distribution and renal excretion, and was approved by the Food and Drug Administration for clinical use at these doses.
Blood flow in the middle cerebral artery was occluded unilaterally in seven cats for 1 hr, followed by 4 hr of reperfusion. T2- and T1-weighted MR images were obtained before the injection of contrast material. After injection, the time course of enhancement was observed for 1 hr by repeated sequential acquisition of T1-weighted images. Five cats received an initial injection of 0.1 mmol/kg of contrast material, supplemented 33 min later by 0.2 mmol/kg (cumulative dose, 0.3 mmol/kg). Two cats received a single injection of contrast material, either 0.1 or 0.3 mmol/kg. The images were reviewed in a prospective fashion by a single observer, who was blinded to the dose of contrast material and the timing of image acquisition, in order to detect abnormal contrast enhancement. Changes in single intensity were quantified by region-of-interest measurements.
Enhancement at 4 and 13 min, respectively, after injection of contrast material was 25 +/- 10% and 38 +/- 7% with 0.1 mmol/kg, vs 80 +/- 12% and 100 +/- 15% with 0.3 mmol/kg (n = 5). The difference between doses was statistically significant (p < .002) for all time points. Abnormal contrast enhancement was visible in three of six cats that received 0.1 mmol/kg and in all cats that received 0.3 mmol/kg. By 13 min after injection, enhancement had peaked with a dose of 0.1 mmol/kg and was within 20% of maximum with a dose of 0.3 mmol/kg.
Detection of disruption of the blood-brain barrier in acute cerebral infarction in cats is improved when high doses (0.3 mmol/kg) of contrast material are used. Disruption may not be visualized when 0.1 mmol/kg, the currently accepted standard dose, is used.
通过对比增强磁共振成像检测脑梗死患者的血脑屏障破坏情况，可提高诊断的特异性，有助于确定病变时间，有时还能改善病变的检测。因此，我们进行了一项研究，以确定在急性脑梗死猫模型中，对比增强磁共振成像上血脑屏障破坏的显示程度，特别关注对比剂剂量。我们使用了剂量为0.1和0.3 mmol/kg的钆螯合物钆特醇，其特点是细胞外分布和经肾排泄，并且已获美国食品药品监督管理局批准可按这些剂量用于临床。
对7只猫单侧大脑中动脉血流阻断1小时，然后再灌注4小时。在注射对比剂之前获取T2加权和T1加权磁共振图像。注射后，通过重复连续采集T1加权图像观察增强的时间进程1小时。5只猫最初注射0.1 mmol/kg的对比剂，33分钟后补充注射0.2 mmol/kg（累积剂量为0.3 mmol/kg）。2只猫单次注射对比剂，剂量为0.1或0.3 mmol/kg。由一名观察者以前瞻性方式对图像进行评估，观察者对对比剂剂量和图像采集时间不知情，以检测异常对比增强。通过感兴趣区测量对单个强度变化进行量化。
注射对比剂后4分钟和13分钟时，0.1 mmol/kg剂量组的增强分别为25±10%和38±7%，而0.3 mmol/kg剂量组分别为80±12%和100±15%（n = 5）。所有时间点剂量之间的差异均具有统计学意义（p <.002）。接受0.1 mmol/kg剂量的6只猫中有3只可见异常对比增强，而接受0.3 mmol/kg剂量的所有猫均可见。注射后13分钟时，0.1 mmol/kg剂量组增强达到峰值，0.3 mmol/kg剂量组增强在最大值的20%以内。
在猫急性脑梗死中，使用高剂量（0.3 mmol/kg）对比剂时，血脑屏障破坏的检测得到改善。使用目前公认的标准剂量0.1 mmol/kg时，可能无法显示血脑屏障破坏情况。
