Cardiology Research
One of the most important diagnostic challenges in medical imaging is assessment of cardiac mechanical function. High frame rates and regional measurements are needed to capture the rapid motion of cardiac tissues and assess local muscle performance.
Epsilon Imaging's technology may offer a new approach to tissue velocity, strain and strain rate imaging, providing regional 2-dimensional assessment of wall mechanics through processing of the fundamental, radio-frequency ultrasound data with a technique known as speckle tracking.
Speckle tracking technology has been shown to be useful in a number of specific cardiovascular clinical conditions, including the following areas:
- Coronary Artery Disease
- Cardiac Dyssynchrony
- Heart Failure
Coronary Artery Disease – also known as coronary heart disease or ischemic heart disease – an acute or chronic narrowing of the small blood vessels that supply blood and oxygen to the heart. Reduction of blood flow to the heart muscle is called ischemia and, over time, results in tissue damage. When heart muscle dies and scarring occurs, the heart’s pumping ability is permanently impaired. Detecting ischemia via accurately pinpointing areas of myocardial dysfunction can lead to identification of the associated arterial blockage(s) and is key to preventing permanent or further tissue damage. If damage has already occurred, identifying the extent of damage to heart tissue is necessary to predict viability and revascularization success. Myocardial tissue motion assessment plays an important role in diagnosing ischemia.
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Assessment of regional systolic function
Left panel: B-mode image loop acquired from the apical four chamber view showing the left ventricle of a subject with known coronary artery disease. Regional longitudinal strain is shown by color encoding of the myocardium, with the brown and green shades indicating contraction and relaxation, respectively. A region of low strain and little movement appears near the apical septum.
Right panel: Quantification of regional contractility described by longitudinal strain plots for each segment through the cardiac cycle. The ECG is shown in the lower plot panel. The longitudinal strain of the apical septum segment is described by the yellow line and shows relatively reduced mechanical activity.
Heart Failure – also known as congestive heart failure - a chronic, progressive cardiac condition in which a structural problem or functional impairment limits the heart’s ability to pump effectively and provide adequate blood flow to the body and organs. Sensitive, reliable, quantitative information on myocardial motion would be ideal to accurately identify and assess global and regional heart function, including the currently problematic diagnostic area of diastolic dysfunction.
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Assessment of diastolic function
Left panel: B-mode image loop acquired from the apical four chamber view showing the left ventricle of a subject with end stage renal disease and history of hypertension. The colorization of the left ventricle wall represents longitudinal strain rate which describes instantaneous contraction and relaxation. This display visualizes regional variation in systolic and diastolic contraction (brown) and relaxation (green) rates. For example, propagation of myocardium relaxation at early diastole can be clearly visualized in the septum as a travelling green wave.
Right panel: Quantification of global relaxation and contraction rates described by the average strain rate plot. The ECG is shown in the lower plot panel. The plot quantifies the peak systolic contraction and diastolic relaxation rates. The early diastolic period shows a lengthened relaxation time and normal, bi-phasic diastolic behavior appears significantly reduced.
Cardiac Dyssynchrony– unsynchronized contractions of opposite walls of the heart, causing poor heart pumping performance. One of the most common treatments for dyssynchrony is cardiac resynchronization therapy (CRT), involving the implantation of a medical device which uses electrical impulses to regulate heart contraction. New methods of measurement of the relative timing of regional myocardial tissue motions may deliver value for CRT through better classification of patients well-suited for CRT therapy, as well as more accurate identification of viable tissue for optimizing CRT lead placement.