Krombach Gabriele A, Higgins Charles B, Chujo Mitsuaki, Saeed Maythem
Department of Radiology, University of California, San Francisco, 505 Parnassus Ave, HSW 207B, San Francisco, CA 94143-0628, USA.
Radiology. 2005 Aug;236(2):510-8. doi: 10.1148/radiol.2362030847.
To evaluate Gadomer-enhanced magnetic resonance (MR) imaging in the quantification of small microvascular obstruction regions and determine if nicroandil alleviates the formation of microvascular obstruction.
Approval of the institutional committee on animal research was obtained, and this study complied with guidelines for care and use of animals. Rats underwent coronary artery occlusion and reperfusion. After 24 hours, Gadomer-enhanced T1-weighted spin-echo MR imaging was used to define microvascular obstruction in animals in control and nicorandil groups. Sequential MR images obtained at two midventricular levels were acquired to measure microvascular obstruction and ischemically injured regions and monitor diffusive and/or convective transport of Gadomer in microvascular obstruction regions. Two investigators working in consensus and using threshold signal intensity measured differentially enhanced regions. Left-ventricular (LV) end-systolic and end-diastolic MR images obtained at the same two midventricular levels were used to measure regional wall thickening and systolic reduction in LV relative volumes. Agreement and correlation between MR imaging and postmortem data were determined with Bland-Altman and linear regression analyses. Animals were sacrificed 3 minutes after intravenous injection of blue dye.
On Gadomer-enhanced MR images, two differentially enhanced regions were observed in ischemically injured myocardium, namely, the hypoenhanced region and the surrounding hyperenhanced region. Hypoenhanced regions at MR imaging and unstained regions at blue dye administration were identical 3 minutes after administration (17% +/- 1 and 17% +/- 2; P = .6; r = 0.98). In the control group, Gadomer provided a prolonged imaging window (eg, 6 minutes) for accurately quantifying small microvascular obstruction regions. Microvascular obstruction was observed in all animals in the control group and 27% of animals in the nicorandil group. Microvascular obstruction regions were smaller in the nicorandil group (eg, 3% +/- 1) than in the control group (eg, 17% +/- 2) (P < .001). Hyper- and hypoenhanced regions were also smaller (eg, 20% +/- 2) in rats in the nicorandil group than in those in the control group (37% +/- 4, P < .001). Improvement in LV function in the nicorandil group is likely related to alleviation and reduction in infarct size.
Gadomer-enhanced MR imaging can be used to quantify small microvascular obstruction regions 24 hours after reperfusion. Intravenous therapy with nicorandil reduces formation of microvascular obstruction regions.
评估钆喷酸葡胺增强磁共振成像在量化微小微血管阻塞区域中的应用，并确定尼可地尔是否能减轻微血管阻塞的形成。
获得了机构动物研究委员会的批准，本研究符合动物护理和使用指南。对大鼠进行冠状动脉闭塞和再灌注。24小时后，使用钆喷酸葡胺增强的T1加权自旋回波磁共振成像来定义对照组和尼可地尔组动物的微血管阻塞情况。在两个心室中部水平获取连续的磁共振图像，以测量微血管阻塞和缺血损伤区域，并监测钆喷酸葡胺在微血管阻塞区域的扩散和/或对流运输。两名研究人员达成共识，使用阈值信号强度测量差异增强区域。在相同的两个心室中部水平获得的左心室（LV）收缩末期和舒张末期磁共振图像用于测量区域壁增厚和左心室相对容积的收缩期减少。通过Bland-Altman和线性回归分析确定磁共振成像与尸检数据之间的一致性和相关性。在静脉注射蓝色染料3分钟后处死动物。
在钆喷酸葡胺增强的磁共振图像上，在缺血损伤心肌中观察到两个差异增强区域，即低增强区域和周围的高增强区域。给药3分钟后，磁共振成像上的低增强区域与蓝色染料给药时的未染色区域相同（分别为17%±1和17%±2；P = 0.6；r = 0.98）。在对照组中，钆喷酸葡胺提供了一个延长的成像窗口（例如6分钟），用于准确量化微小微血管阻塞区域。在对照组的所有动物和尼可地尔组的27%动物中观察到微血管阻塞。尼可地尔组的微血管阻塞区域（例如3%±1）比对照组（例如17%±2）小（P < 0.001）。尼可地尔组大鼠的高增强和低增强区域（例如20%±2）也比对照组（37%±4）小（P < 0.001）。尼可地尔组左心室功能的改善可能与梗死面积的减轻和缩小有关。
钆喷酸葡胺增强磁共振成像可用于量化再灌注24小时后的微小微血管阻塞区域。尼可地尔静脉治疗可减少微血管阻塞区域的形成。
