Technical Development of Diagnostic Cardiovascular MRI

国家心肺血液研究所(NHLBI)/郊区医院心血管MRI研究项目的总体目标是开发利用MRI技术评估心血管疾病患者的新方法。 1)MRI对急性冠脉综合征的诊断和定性。除了我们最初的诊断非ST段抬高急性冠脉综合征的敏感性和特异性的临床研究(Kuong Rry等人。循环2003；107：538-544)我们重点关注对心肌水肿敏感的MRI方法在评估危险心肌区域中的作用。这项工作已经导致了明亮血液T2加权方法的技术发展，这些方法提高了诊断的确定性，超过了商业成像方法。 2)MRI显示心肌梗死及存活情况。我们继续使用成像心肌梗死的相敏重建方法(Kellman P等人。医学中的磁共振，2002年；47：372-383和Kellman等人。Magn Reson Med 2004；51：408-12)和用于量化这些图像和类似图像的计算机算法的变体(Hsu，L等。J Magn Reson成像。2006年；23(3)：309-14；L等人。J Magn Reson成像2006；23：315-22)在我们几乎所有的临床和临床前研究中)。非刚性运动校正成像方法已经推广到许多其他应用，包括T2加权成像和灌注成像。我们最近在接近细胞水平的分辨率上证实了基于Gd的造影剂与梗塞相关的纤维化相关(Schelbert E等人。中国心脏血管成像学会。2010年；3(6)：743-752)。 3)我们一直致力于通过仔细的定量分析来改进首过心肌灌注成像。除了我们最初的方法之外，我们已经在分析绝对心肌灌注方面取得了重大进展，这些方法在亚克大小的心肌切片中得到了验证(Christian，TF等人)。放射学2004；232：677-84)。最近，我们证明了MR首过血流灌注图像可以被量化到像素级别，从而在大约相当于32微升心肌的区域内(Hsu，L等人)。在新闻发布会上)。 4)心肌异常的特征。除梗塞和缺血外，许多疾病过程还会改变心肌的特性。我们已经开发了在心脏磁共振图像中分离水和脂肪的方法，以提高致心律失常性右室发育不良的诊断(Kellman P等人。Magn Reson Med.2009年；61：215-21)。这些技术具有广泛的临床应用(Kellman P等人。CURR心脏血管成像报告2010；3(2)：83-91)，并是明年由国际磁共振医学学会赞助的专门研讨会的主题。 5)心肌细胞外容积(ECV)显像。在过去的两年里，我们研究了大量患者的细胞外体积分数，发现远离梗死心肌的正常心肌有细微但有趣的异常。我们还发现ECV随着年龄的增加而增加，这与与年龄相关的心肌纤维化增加是一致的。由于心肌T1的测量是心肌ECV的基本决定因素，我们研究了不同T1标测方法的准确性和一致性(Nacif MS等人。J Magn Reson成像。电子版，2011年9月23日)。

The overall 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. 1) Detection and characterization of acute coronary syndrome with MRI. Beyond our initial clinical studies of sensitivity and specificity for diagnosing non-ST elevation acute coronary syndrome (Kwong RY et al. Circulation 2003; 107:538-544) we have focused attention on the role of MRI methods sensitive to myocardial edema in evaluating the myocardial area at risk. This work has resulted in technical developments of bright blood T2-weighted methods that improve diagnostic certainty beyond those of commercially imaging methods. 2) Characterizing myocardial infarction and viability with MRI. We have continued to use the phase sensitive reconstruction method of imaging myocardial infarction (Kellman P et al. Magnetic Resonance in Medicine 2002;47:372-383 and Kellman et al. Magn Reson Med 2004;51:408-12) and variants of the computer algorithm used to quantify these and similar images (Hsu L et al. J Magn Reson Imaging. 2006; 23(3):309-14; Hsu L et al. J Magn Reson Imaging 2006;23:315-22) in almost all of our clinical and preclinical studies. The non-rigid motion corrected imaging methods have propagated to many other applications including T2 weighted imaging and perfusion imaging. We recently validated that gadolinium based contrast agents correlate with infarct-related fibrosis at resolutions approaching a cellular level (Schelbert E et al. Circ Cardiovasc Imaging. 2010; 3(6): 743-752). 3) We have been working on improving first pass myocardial perfusion imaging through careful quantitative analysis. We have made a major advance in the analysis of absolute myocardial perfusion beyond our initial methods which were validated in sub-gram sized pieces of myocardium (Christian TF et al. Radiology 2004; 232:677-84). Most recently, we demonstrated that MR first pass perfusion images can be quantified down to a pixel level and thus in regions equivalent to about 32 microliters of myocardium (Hsu L et al. in press). 4) Characterization of myocardial abnormalities. Beyond infarction and ischemia, many disease processes alter the characteristics of myocardium. We have developed methods for separating water and fat in cardiac MR images to improve the diagnosis of arrhythmogenic right ventricular dysplasia (Kellman P et al. Magn Reson Med. 2009;61:215-21). These techniques have a wide range of clinical applications (Kellman P et al. Curr Cardiovasc Imaging Rep. 2010; 3(2):83-91) and are the subject of a dedicated workshop sponsored by the International Society of Magnetic Resonance in Medicine next year. 5) Myocardial Extracellular Volume (ECV) Imaging. We have studied the extracellular volume fraction in a large number of patients over the past two years and found subtle but intriguing abnormalities in normal myocardium remote from infarcted myocardium. We have also found the ECV increases with age consistent with an age-related increase in myocardial fibrosis. Since measurements of myocardial T1 is an fundamental determinant of myocardial ECV, we have studied the accuracy and agreement of different T1 mapping methods (Nacif MS et al. J Magn Reson Imaging. Electronically published 2011 Sep 23).