Robust Cardiac-gated MRI using Ultrasound Sensors

使用超声波传感器的稳健心门控 MRI

• 批准号: 9436878
• 负责人: Frank Preiswerk
• 金额: $ 8.88万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-05 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9436878
• 关键词: 3D Print; Abdomen; Acoustics; Algorithms; American Heart Association; Angioplasty; Anticoagulants; Aorta; Arrhythmia; Automobile Driving; Award; Blood; Blood flow; Breathing; Burn injury; Bypass; Calcium; Cardiac; Cardiac health; Cardiovascular Diseases; Cessation of life; Charge; Cholesterol; Clinical; Clip; Contracts; Coupling; Custom; Data; Deposition; Detection; Devices; Diagnosis; Diagnostic; Diagnostic tests; Discipline of Nuclear Medicine; Electrocardiogram; Electrophysiology (science); Ensure; Evaluation; Fingers; Gel; Heart; Heart Atrium; Heart Diseases; Hybrids; Image; Intervention; Ions; Lead; Life Style; Magnetic Resonance Imaging; Malignant Neoplasms; Measures; Metabolism; Methods; Monitor; Morphologic artifacts; Morphology; Motion; Myocardial; Myocardial Contraction; Myocardium; Names; Organ; Outcome; Pacemakers; Paper; Patient Schedules; Patients; Performance; Perfusion; Peripheral; Pharmaceutical Preparations; Phase; Physiologic pulse; Play; Process; Protocols documentation; Published Comment; Pulse Oximetry; Pump; Reference Standards; Research Personnel; Resolution; Respiration; Risk; Role; Safety; Scanning; Severities; Side; Signal Transduction; Skin; Slide; Societies; Source; Systole; Temperature; Testing; Time; Transducers; Ultrasonography; Uncertainty; Vendor; Work; base; capsule; cardiovascular visualization; clinical practice; cost; data acquisition; diet and exercise; electric field; heart electrical activity; heart motion; imaging modality; improved; magnetic field; magnetohydrodynamic; meetings; novel; operation; pressure; prototype; sensor; software development; temporal measurement; tool; trend

Project summary For cardiac MRI pulse sequences to function properly, a signal or trigger must typically be obtained to help synchronize the acquisition process with the cardiac motion. As a result of such synchronization, reconstructed images represent a given cardiac phase, mostly free of cardiac-related motion. Improper detection of such triggers would cause data from different cardiac phases to mix into a same image, leading to motion artifacts and loss of image quality. Most commonly, electrocardiogram (ECG) leads are employed to detect the electrical activity of the heart and to generate such triggers, allowing the MRI acquisition and the heart motion to remain in sync. Besides a small risk for skin burns, one of the main challenges with using ECG leads for cardiac MRI comes from the magnetohydrodynamic (MHD) effect, which tends to distort the ECG signal. Because of the Lorenz force, and in a manner similar to the Hall effect, the positive and negative ions in blood tend to curve in different directions as they move through a magnetic field, creating a charge separation and an electric field that tends to corrupts the ECG signal. Because the aorta carries a large amount of fast-moving blood, it tends to be the main source of corrupting electrical fields, and the problem becomes more significant at higher field strength. Scanner operation, especially gradient switching, can also further corrupt ECG signals. Real-time cardiac imaging, as opposed to cardiac-gated imaging, does not necessarily require reliable triggers, but typically suffers from lower spatial and temporal resolution. Presumably for this reason, cardiac- gated imaging represents the overwhelming bulk of clinical cardiac MR (CMR) scans. Alternatives to ECG leads for CMR gating include pulse oximetry, which typically takes the form of a sensor clipped around a finger. While it has the advantage of being insensitive to the MHD effect, pulse oximetry and other forms of peripheral gating detect heartbeats with a delay, the time for the pressure wave to reach the detection point, as opposed to ECG detection that is more direct and immediate. With a perfectly regular heart, such delay would be of little to no consequence, but cardiac patients often have irregular heartbeats and immediate detection of a contraction allows the MRI acquisition to react in a more sensible way, with better outcomes on image quality. The present project introduces an alternative to ECG monitoring for cardiac-gated MRI which detects cardiac motion directly. An ultrasound-based sensor is proposed, along with 3D-printed capsule for quick application to the skin and realistic clinical workflow. Before the patient table slides into the scanner, as the magnetic field is weak and the MHD effect is minimal, we will validate our approach with ECG detection as the reference standard. As the patient goes into the scanner, the ECG trace will be degraded but our MR- compatible sensor will remain unaffected. With patients in the scanner, we will demonstrate an improved detection of cardiac triggers and improved image quality using our sensors as compared to using ECG leads.

项目概要 为了使心脏 MRI 脉冲序列正常工作，通常必须获得信号或触发器来帮助 将采集过程与心脏运动同步。作为这种同步的结果，重建 图像代表给定的心脏相位，大部分没有与心脏相关的运动。此类检测不当 触发器会导致来自不同心脏相位的数据混合到同一图像中，从而导致运动伪影 和图像质量的损失。最常见的是，使用心电图 (ECG) 导联来检测 心脏的电活动并产生此类触发器，从而允许 MRI 采集和心脏运动 保持同步。除了皮肤烧伤的小风险外，使用心电图导联的主要挑战之一是 心脏 MRI 来自磁流体动力学 (MHD) 效应，该效应往往会扭曲心电图信号。 由于洛伦兹力，并且以类似于霍尔效应的方式，血液中的正离子和负离子 当它们穿过磁场时，它们倾向于向不同方向弯曲，从而产生电荷分离和 电场往往会破坏心电图信号。因为主动脉携带大量快速移动的 血液，它往往是腐蚀电场的主要来源，问题变得更加严重 在较高的场强下。扫描仪操作，尤其是梯度切换，也会进一步破坏心电图信号。 与心门控成像相反，实时心脏成像不一定需要可靠的 触发器，但通常会受到较低的空间和时间分辨率的影响。大概是因为这个原因，心脏 门控成像占临床心脏 MR (CMR) 扫描的绝大多数。心电图的替代品 用于 CMR 门控的引线包括脉搏血氧测定法，其通常采用夹在手指上的传感器的形式。 它的优点是对 MHD 效应、脉搏血氧饱和度和其他形式的外周血氧饱和度不敏感。 门控检测心跳有延迟，即压力波到达检测点的时间，而不是 心电图检测更直接、即时。对于心脏完全正常的人来说，这样的延迟不会有什么影响。 没有什么后果，但心脏病患者通常会出现心律不齐，并立即检测到 收缩使 MRI 采集能够以更合理的方式做出反应，从而获得更好的图像质量结果。 目前的项目介绍了一种心电图监测的替代方案，可用于心门控 MRI 检测 心脏直接运动。提出了一种基于超声波的传感器以及 3D 打印的胶囊，用于快速 应用于皮肤和现实的临床工作流程。在患者台滑入扫描仪之前，随着 磁场较弱且 MHD 效应最小，我们将通过 ECG 检测来验证我们的方法 参考标准。当患者进入扫描仪时，心电图迹线将会退化，但我们的 MR- 兼容的传感器将不受影响。对于扫描仪中的患者，我们将展示改进的 与使用心电图导联相比，使用我们的传感器可以检测心脏触发因素并提高图像质量。