MRI Evaluation Of Acute Cardiovascular Disease

国家心肺血液研究所(NHLBI)/郊区医院心血管MRI研究项目的主要目标是开发新的方法，利用MRI技术评估心血管疾病患者。到目前为止，我们的重点是四个具体目标。 1)MRI检查急性冠脉综合征。今年早些时候，我们发表了静息MRI扫描诊断非ST段抬高的急性冠脉综合征比心脏危险因素、心电图和肌钙蛋白更高的敏感性和特异性。MRI诊断急性冠脉综合征的敏感性和特异性分别为84%和85%，心电图异常分别为80%和61%，ST段压低和T波倒置分别为16%和95%，肌钙蛋白I峰值分别为40%和97%，TIMI风险评分分别为48%和85%。MRI诊断急性冠脉综合征的敏感性高于严格的心电图缺血标准(P&lt；0.001)、峰值肌钙蛋白I(P&lt；0.001)和TIMI风险评分(P=0.004)。核磁共振比异常心电图更具特异性(p&lt；0.001)。多因素Logistic回归分析显示，MRI异常是急性冠脉综合征的最强预测因子，其对临床参数的诊断价值具有统计学意义(p&lt；0.001)。我们认为，静息MRI扫描具有诊断性操作特征，适合急诊科胸痛患者的分诊。 我们在第二个方案中扩展了这项工作，使用腺苷负荷磁共振对141名肌钙蛋白阴性的急性冠脉综合征患者进行评估。诊断缺血性心脏病的总体灵敏度和特异度均大于90%。腺苷负荷MRI异常对1年预后有重要价值。 2)MRI评价存活心肌的能力。我们还开发了一种相位敏感的重建方法，该方法提高了心脏病发作图像的质量，并将用户选择的参数对心脏病发作的表观大小的影响降至最低。今年，我们完成了对相位敏感重建方法的组织病理学验证。这项验证研究进一步表明，计算机算法可以准确地测量体内和体外的梗塞面积图像。 3)首次通过心肌灌注成像。我们已经扩展了我们的第一道灌注法，以提供定量分析方法。我们已经证明，MRI可以像注射微球一样精确地测量心肌灌注(这是一种仅在动物模型中使用的金标准方法)。我们正在将这些方法转化为分析人类潘生丁压力测试的方法。 4)动脉粥样硬化斑块的MRI表现。我们已经扩展了我们先前的观察，即Gd几乎使区分动脉粥样硬化斑块不同部分的能力增加了一倍。我们研究了造影剂进入颈动脉粥样硬化的纤维帽和脂核的动力学。 5)我们已经确定了Gd延迟增强心血管磁共振与心肌梗死临床指标的相关性。。这项研究对急性心肌梗死患者心肌梗死后平均2天进行了成像。跨壁延迟强化程度预示局部心肌功能的恢复。 6)通过另一项研究扩展了相敏逆变恢复方法在心肌梗死成像中的有效性：B1加权相控阵组合相敏逆变恢复在心肌梗死成像中的伪影抑制。 7)我们减少了密集图像上的图像伪影，这是一种成像心肌应变的方法。

The major aim of the National Heart, Lung and Blood Institute (NHLBI)/Suburban Hospital Cardiovascular MRI Research Project is to develop new approaches in assessing patients with cardiovascular disease with MRI technology. To date, we have focused on four specific aims. 1) Detection of acute coronary syndrome with MRI. Earlier this year, we published that a rest MRI scan had higher sensitivity and specificity for diagnosing non-ST elevation acute coronary syndrome than cardiac risk factors, ECG, and troponin. The sensitivity and specificity for detecting acute coronary syndrome was 84% and 85% by MRI, 80% and 61% by an abnormal ECG, 16% and 95% for ST depression or T-wave inversion, 40% and 97% for peak troponin-I, and 48% and 85% for a TIMI risk score >3. The MRI was more sensitive than strict ECG criteria for ischemia (p<0.001), peak troponin-I (p<0.001), and the TIMI Risk Score (p=0.004). The MRI was more specific than an abnormal ECG (p<0.001). Multivariate logistic regression analysis showed an abnormal MRI was the strongest predictor of acute coronary syndrome and added statistically significant diagnostic value over clinical parameters (p<0.001). We concluded that the resting MRI scan exhibited diagnostic operating characteristics suitable for triage of patients with chest pain in the emergency department. We have extended this work in a second protocol that used adenosine stress MRI to evaluate 141 consecutive patients with troponin-negative acute coronary syndrome. The overall sensitivity and specificity for detecting ischemic heart disease were both greater than 90%. An abnormal adenosine stress MRI had significant 1 year prognostic value. 2) Characterizing myocardial viability with MRI. We also developed a phase sensitive reconstruction method which improves the quality of heart attack images and minimizes the influence of user selected parameters on the apparent size of the heart attack. This year we completed histopathological validation of the phase sensitive reconstruction method. This validation study further shows that a computer algorithm can accurately measure in vivo and ex vivo images of infarct size. 3) First pass myocardial perfusion imaging. We have extended our first pass perfusion methods to provide quantitative analysis methods. We have shown that the MRI can measure myocardial perfusion as accurately as microsphere injections (a gold standard method only usable in animal models). We are in the process of translating these methods to analyze human dipyridamole stress tests. 4) MRI characterization of atherosclerotic plaque. We have extended our prior observations that gadolinium nearly doubles the ability to discriminate different portions of the atherosclerotic plaque. We have studied the kinetics with which contrast enters the fibrous cap and lipid core of carotid atheroma. 5) We have determined that gadolinium delayed enhancement cardiovascular magnetic resonance corrrelateeees with clinical measures of myocardial infarction. . This study imaged patients with acute myocardial infarction an average of 2 days post-MI. The transmural extent of delayed enhancement predicted the recvery of regional myocardial function. 6) We have extended our validations of the phase sensitive inverson recovery methods for imaging myocardial infarction with another study: Artifact suppression in imaging of myocardial infarction using B1-weighted phased-array combined phase-sensitive inversion recovery. 7) We have reduced image artifacts on DENSE images, a method for imaging myocardial strain.