Background phase correction for quantitative cardiovascular MRI

定量心血管 MRI 的背景相位校正

• 批准号: 9297307
• 负责人: Rizwan Ahmad
• 金额: $ 22.15万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9297307
• 关键词: Abdomen; Acoustics; Address; Affect; Anatomy; Aneurysm; Area; Atherosclerosis; Blood Vessels; Blood flow; Cardiac; Cardiac Output; Cardiovascular system; Clinical; Coupled; Data; Development; Diagnosis; Doppler Ultrasound; Error Sources; Evaluation; Functional disorder; Health; Heart; Heart Diseases; Image; Imaging Device; Imaging Phantoms; Imaging Techniques; Intracranial Aneurysm; Intracranial Arterial Stenosis; Kidney; Lead; Least-Squares Analysis; Link; Liver Cirrhosis; Location; Lung; Magnetic Resonance Imaging; Manufacturer Name; Maps; Measurement; Measures; Mechanics; Medical Imaging; Methodology; Methods; Morphology; Patients; Pelvis; Performance; Peripheral arterial disease; Phase; Physiologic pulse; Physiology; Polynomial Models; Portal Hypertension; Positioning Attribute; Process; Protocols documentation; Pulsatile Flow; Reporting; Research Personnel; Scanning; Scheme; Shunt Device; Slice; Specific qualifier value; Stenosis; Stroke Volume; Time; Tissues; Uncertainty; Validation; Vascular Diseases; Work; base; computerized data processing; congenital heart disorder; cost; data acquisition; healthy volunteer; heart imaging; hemodynamics; human subject; improved; in vivo; interest; non-invasive imaging; tool

Project Summary/Abstract Alterations in hemodynamics have been linked to wide-ranging cardiac and vascular conditions, including congenital heart disease, valvular abnormalities, aortic atherosclerosis and aneurysm, renal stenosis, portal hypertension due to liver cirrhosis, intracranial aneurysm and stenosis, and peripheral arterial disease. Phase- contrast MRI (PC-MRI) is a noninvasive imaging technique that can potentially provide a comprehensive evaluation of hemodynamics, which can be coupled with other important MRI-derived information on cardiovascular anatomy, function, and tissue characterization. However, the credibility of PC-MRI as a quantitative tool is challenged by the inaccuracies introduced by background phase. Studies have shown that this background phase can introduce significant errors in the quantification of flow. One method that has been proposed to quantify and correct for the background phase is to perform a separate scan using a static phantom. This method, despite being robust, is impractical because of the significant extra time required to perform phantom imaging for each clinical sequence performed. Another widely reported method to correct background phase is based on performing polynomial fitting to the pixels that belong to the static tissue. The accuracy of this method heavily relies on the availability of static tissue in the close vicinity of the region of interest–a requirement that is often not met when imaging the heart or great vessels. To address the issue of background phase that invariably impacts every PC-MRI measurement, we propose a new correction scheme called multi-slice acquisition and processing (mSAP). In mSAP, in addition to the slice of interest, at least one extra slice is collected using the same slice orientation and gradient waveforms but with a different table position. By jointly processing the background phase information from multiple slices, mSAP circumvents the shortcomings associated with existing methods at the cost of slightly prolonged acquisition. In Specific Aim 1, we will develop a data acquisition and processing method for mSAP. We will modify and streamline our current PC-MRI acquisition protocol to minimize the overhead associated with mSAP. To jointly process the multi-slice data, we will develop and implement polynomial regression based on generalized least squares with an ℓ1-norm penalty imposed on the coefficients of the polynomial. This fitting method is completely automated and does not require tuning parameters. In Specific Aim 2, we will validate mSAP using a pulsatile flow phantom and healthy volunteers. By using just one additional slice, we anticipate mSAP to reduce the background phase errors to the level where miscalculation of flow volume is reduced to below 5%. Our preliminary data demonstrate the validity of the primary assumption made in mSAP, i.e., background phase maps collected using the same gradient waveforms but different table positions are identical. We believe the methods developed in this work can be readily utilized in clinical settings to improve the accuracy of an otherwise potent imaging tool.

项目概要/摘要 血流动力学的改变与广泛的心脏和血管疾病有关，包括 先天性心脏病、瓣膜异常、主动脉粥样硬化和动脉瘤、肾狭窄、门静脉 肝硬化、颅内动脉瘤和狭窄以及周围动脉疾病引起的高血压。阶段- 对比 MRI (PC-MRI) 是一种无创成像技术，有可能提供全面的 血流动力学评估，可以与其他重要的 MRI 衍生信息相结合 心血管解剖、功能和组织特征。然而，PC-MRI 作为一种方法的可信度 定量工具受到背景阶段引入的不准确性的挑战。研究表明 该背景阶段可能会在流量量化中引入重大误差。已经有过的一种方法 建议对背景相位进行量化和校正，方法是使用静态扫描仪执行单独的扫描 幻影。该方法尽管很稳健，但并不实用，因为需要大量的额外时间 对每个临床序列进行幻影成像。另一种广泛报道的纠正方法 背景相位基于对属于静态组织的像素执行多项式拟合。这 该方法的准确性在很大程度上取决于该区域附近静态组织的可用性 兴趣——在对心脏或大血管进行成像时通常无法满足这一要求。 为了解决总是影响每个 PC-MRI 测量的背景相位问题，我们提出了一种 新的校正方案称为多切片采集和处理（mSAP）。在mSAP中，除了切片 有趣的是，使用相同的切片方向和梯度波形但使用相同的切片方向和梯度波形收集至少一个额外的切片 不同的桌子位置。通过联合处理来自多个切片的背景相位信息，mSAP 以略微延长采集时间为代价，规避了与现有方法相关的缺点。在 具体目标1，我们将开发一种mSAP的数据采集和处理方法。我们将修改并 简化我们当前的 PC-MRI 采集协议，以最大限度地减少与 mSAP 相关的开销。共同 处理多切片数据，我们将开发并实现基于广义最小二乘的多项式回归 对多项式的系数施加 ℓ1-范数惩罚的平方。这种拟合方法是 完全自动化，不需要调整参数。在具体目标 2 中，我们将使用以下方法验证 mSAP 脉动流模型和健康志愿者。通过仅使用一个额外的切片，我们预计 mSAP 将背景相位误差降低到流量误算降低到 5% 以下的水平。 我们的初步数据证明了 mSAP 中主要假设的有效性，即背景 使用相同梯度波形但不同表位置收集的相位图是相同的。我们 相信这项工作中开发的方法可以很容易地在临床环境中使用，以提高诊断的准确性 一种其他有效的成像工具。