EARLY DISEASE OF CORONARIES EVALUATED WITH FAST X RAY CT

这项为期三年的提案的目标是开发和评估一个新的 早期动脉粥样硬化的检测和定量技术 在发生明显的、离散的、管腔狭窄之前的冠状动脉。我们 建议使用多层快速X射线CT提供直接测量 冠状动脉管腔横截面积需要建立 存在弥漫性管腔狭窄。这项提议的新奇之处在于 是个性化的基线生理动脉管腔交叉- 截面面积(相对于测量的病理弥漫性管腔 可以进行比较)将从最近演示的 冠状动脉腔内横截面积与冠状动脉狭窄程度的关系 冠脉树上游和下游的分支几何结构。 此分支几何将以累积分段为特征 动脉的长度，从主动脉起点到动脉段的交叉处 感兴趣的部分，以及由动脉灌流的心肌质量 顺流而下至感兴趣的横截面。首先，我们建议 确定生理学评估的精确度和可重复性 冠状动脉管腔横截面积可以在以下范围内计算 有或无心肌疾病的患者类型。这将是 在目标I中使用身体心脏和使用身体测量实现 作为对基于CT的测量进行比较的标准。 其次，为了确定这种方法是否可以在临床上应用 我们将在AIM II中(通过软件和/或准直)修改一个电子- 射束CT扫描仪，可提供所需的3D成像分辨率 一个6秒的呼吸期，以实现我们的临床方面 研究目标。最后，在AIM III中，我们将使用99mMIBI 扫描数据，在符合以下条件的急性动脉阻塞患者中进行 随后用腺苷和溶栓治疗，以提供一种 对心肌灌注量的独立、有效的估计 暂时闭塞的血管段。我们将比较基于CT的 根据基于~(99)m-MIBI的值估计灌注质量。如果 成功地，这方面的基于CT的冠状动脉分析 树将为正常血管的独立估计提供基础 横截面面积。这一成功结果的意义 建议有冠心病高危因素的患者 动脉粥样硬化可以在出现症状之前进行定量评估 冠脉狭窄是可能发生的。这将通过CT来实现 单次静脉注射后单次呼气时的扫描 造影剂。

The goal of this three-year proposal is to develop and evaluate a new technique for detection and quantitation of early atherosclerosis of coronary arteries before obvious, discrete, lumenal stenoses occur. We propose to use multislice fast x-ray CT to provide the direct measurement of coronary artery lumen cross-sectional area needed to establish the presence of diffuse lumenal narrowing. The novel aspect of this proposal is that the individualized baseline physiological arterial lumen cross- sectional area (against which the measured pathological diffuse lumenal narrowing can be compared) will be derived from the recently demonstrated relationship between coronary artery lumenal cross-sectional area and the branching geometry of the upstream and downstream coronary arterial tree. This branching geometry will be characterized by cumulative segment length of the artery, from aortic origin to the arterial segment's cross section of interest, and by the mass of myocardium perfused by the artery downstream to the cross section of interest. First we propose to establish how precise and reproducible an estimate of physiological coronary arterial lumen cross-sectional areas can be made in a range of patient types with or without diseases of the myocardium. This will be achieved in Aim I using cadaver hearts with postmortem measurements used as the standard against which the CT based measurements will be compared. Second, in order to determine if this approach can be applied clinically we will modify in Aim II (via software and/or collimation) an electron- beam CT scanner to provide the 3D imaging resolution necessary, within one 6 second breathold period, to achieve the clinical aspect of our study objectives. Finally, in Aim III we will use Technetium 99m MIBI scan data, performed in patients with acute arterial occlusion who are subsequently treated with adenosine and thrombolysis, to provide an independent, validated estimate of that myocardial mass perfused by the temporarily occluded vessel segment. We will compare the CT-based estimate of the perfused mass against the Tc-99m MIBI-based value. If successful, this aspect of the CT-based analysis of the coronary arterial tree will provide the basis for an independent estimate of normal vessel cross-sectional area. The significance of a successful outcome of this proposal is that patients with high risk factors for coronary atherosclerosis could be quantitatively evaluated before symptoms of coronary stenosis are likely to occur. This would be achieved by a CT scan during a single breathold following a single intravenous injection of contrast agent.