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: 9557023
• 负责人: Bruno Madore
• 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 2020-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9557023
• 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; Institutional Review Boards; 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; clinical practice; cost; data acquisition; diet and exercise; electric field; heart electrical activity; heart function; heart imaging; 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.

项目摘要 为了使心脏MRI脉冲序列正常运行，通常必须获得信号或触发器以帮助 将采集过程与心脏运动同步。由于这种同步，重建 图像代表给定的心脏相，主要没有心脏相关运动。不当检测 触发器会导致来自不同心脏相的数据混合成同一图像，从而导致运动伪像 和图像质量的丢失。最常见的是，使用心电图（ECG）引线来检测 心脏的电活动并产生此类触发器，允许MRI采集和心脏运动 保持同步。除了烧伤皮肤的小风险外，使用ECG铅的主要挑战之一是 心脏MRI来自磁流失动力学（MHD）效应，该效应倾向于扭曲ECG信号。 由于洛伦兹的力，并且以类似于霍尔效应的方式，血液中的阳性和负离子 倾向于在磁场中移动时弯曲不同的方向，形成电荷分离和一个 电场往往会破坏ECG信号。因为主动脉携带大量快速移动 血液，它往往是破坏电场的主要来源，问题变得更加重要 在较高的场强。扫描仪操作，尤其是梯度切换，也可能会进一步损坏ECG信号。 与心脏门控成像相反，实时心脏成像不一定需要可靠 触发器，但通常遭受较低的空间和时间分辨率。大概是由于这个原因，心脏 - 封闭的成像代表了临床心脏MR（CMR）扫描中大部分的压倒性成像。 ECG的替代方案 CMR门控的导线包括脉搏血氧饱和度，通常采用夹在手指上的传感器的形式。 虽然它具有对MHD效应不敏感的优势，但脉搏血氧仪和其他形式的外周 门控以延迟检测心跳，压力波到达检测点的时间 更直接和直接的ECG检测。有一个完全常规的心脏，这种延迟将很少 丝毫没有后果，但是心脏病患者经常心跳不规则，立即发现 收缩允许MRI获取以更明显的方式做出反应，并在图像质量上取得更好的结果。 本项目介绍了心脏门控MRI的ECG监测的替代方法，该MRI检测到 心脏运动直接。提出了一个基于超声的传感器，以及3D打印的胶囊以快速 应用于皮肤和现实的临床工作流程。在患者桌子滑入扫描仪之前， 磁场很弱，MHD效应很小，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，ECG痕迹将被降解，但我们的MR- 兼容传感器将不受影响。对于扫描仪中的患者，我们将证明有所改善 与使用ECG导线相比，使用传感器检测心脏触发器和改进的图像质量。