Speckle tracking echocardiography

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In the fields of cardiology and medical imaging, Speckle Tracking Echocardiography (STE) is an echocardiographic imaging technique that analyzes the motion of tissues in the heart by using ultrasonic sound waves to generate interference patterns and natural acoustic reflections.[1] These reflections, also described as ‘‘speckles’’, ‘‘markers’’, ‘‘patterns’’, ‘‘features’’, or ‘‘fingerprints’’ are tracked consecutively frame to frame and ultimately resolved into angle-independent two-dimensional (2D) and three-dimensional strain-based sequences (3D) [2][3][4] These sequences provide both quantitative and qualitative information regarding tissue deformation and motion.

Strain[edit]

Strain is defined as the fractional or percentage change in an objects dimension in comparison to the object’s original dimension.[5] Similarly, strain rate can be defined as the speed at which deformation occurs. Mathematically, three components of normal strain (εx, εy, and εz) and three components of shear strain (εxy, εxz, and εyz) are recognized. Congruently, when applied to the left ventricle, left ventricular deformation is defined by the three normal strains (longitudinal, circumferential, and radial) and three shear strains (circumferential-longitudinal, circumferential-radial, and longitudinal-radial). The principal benefit of LV shear strains is amplification of the 15% shortening of myocytes into 40% radial LV wall thickening, which ultimately translates into a >60% change in LV ejection fraction. Left ventricular shearing increases towards the subendocardium, resulting in a subepicardial to subendocardial thickening strain gradient. Similar to MRI, STE utilizes “Lagrangian strain” which defines motion around a particular point in tissue as it revolves through time and space.[6] Throughout the cardiac cycle, the end-diastolic tissue dimension represents the unstressed initial material length.

Twist or torsional deformation define the base-to-apex gradient and is the result of myocardial shearing in the circumferential-longitudinal planes such that, when viewed from the apex, the base rotates in a counterclockwise direction. Likewise the LV apex concomitantly rotates in a clockwise direction. During ejection, LV torsion results in the storage of potential energy into the deformed myofibers. This stored energy is released with the onset of relaxation similar to a spring uncoiling and results in suction forces. These forces are then used for rapid early diastolic restoration.

Applications and Limitations[edit]

The utilities of STE are increasingly recognized. Strain results derived from STE have been validated using sonomicrometry and tagged MRI and results correlate significantly with tissue Doppler–derived measurements.[7][8][9] Tissue Doppler technology, the predecessor of speckle tracking technology, requires achieving parallel orientation between the direction of motion and the ultrasound beam. Its use has remained limited due to angle dependency, substantial intraobserver and interobserver variability and noise interference. Speckle tracking technology has overcome these limitations. Studies have proven greater both longitudinal and radial strain measurements with STE to have significantly greater area under the curve than DTI on receiver operating characteristic curve analysis in differentiating dysfunctional from normal segments.[10]

Clinical Applications of Speckle Tracking Technology
Coronary Artery Disease
Myocardial Infarctions
Stress Echocardiography
Revascularization
Valvular Disease
Left Ventricular Hypertrophy
Hypertensive Heart Disease
Hypertrophic Cardiomyopathy
Dilated Cardiomyopathy
Stress Cardiomyopathy
Pericardial Disease/Restrictive Cardiomyopathy
Diastolic Heart Disease
Left Ventricular dyssynchrony
Congenital Heart Disease
Drug-Induced Cardiotoxicity


References[edit]

  1. ^ Geyer, Holly; Caracciolo, Giuseppe; Abe, Haruhiko; Wilansky, Susan (2010), "Assessment of Myocardial Mechanics Using Speckle Tracking Echocardiography: Fundamentals and Clinical Applications", Journal of the American Society of Echocardiography (C.V. Mosby) 23 (4): 351, doi:10.1016/j.echo.2010.02.015, ISSN 0894-7317, OCLC 605144740 
  2. ^ Reisner, SA; Lysyansky, P; Agmon, Y; Mutlak, D (2004), "Global longitudinal strain: a novel index of left ventricular systolic function", Journal of the American Society of Echocardiography (Jun; 17(6)): 630–3, ISSN 0894-7317, OCLC 110737191 
  3. ^ Leitman M, Lysyansky P, Sidenko S, Shir V, Peleg E, Binenbaum M, et al. Two-dimensional strain-a novel software for real-time quantitative echocardiographic assessment of myocardial function. JAm Soc Echocardiogr 2004;17:1021-9.
  4. ^ Kaluzynski K, Chen X, Emelianov SY, Skovoroda AR, O’Donnell M. Strain rate imaging using two-dimensional speckle tracking. IEEE Trans Ultrason Ferroelectr Freq Control 2001;48:1111-23.
  5. ^ Abraham TP, Dimaano VL, Liang HY. Role of tissue Doppler and strain echocardiography in current clinical practice. Circulation 2007;116: 2597-609.
  6. ^ D’Hooge J, Heimdal A, Jamal F, Kukulski T, Bijnens B, Rademakers F, et al. Regional strain and strain rate measurements by cardiac ultrasound: principles, implementation and limitations. Eur J Echocardiogr 2000;1: 154-70.
  7. ^ Edvardsen T, Gerber BL, Garot J, Bluemke DA, Lima JA, Smiseth OA.Quantitative assessment of intrinsic regional myocardial deformation by Doppler strain rate echocardiography in humans: validation against three-dimensional tagged magnetic resonance imaging. Circulation 2002;106:50-6
  8. ^ Amundsen BH, Helle-Valle T, Edvardsen T, Torp H, Crosby J, Lyseggen E,et al. Noninvasive myocardial strain measurement by speckle tracking echocardiography: validation against sonomicrometry and tagged magnetic resonance imaging. J Am Coll Cardiol 2006;47:789-93
  9. ^ Roes SD, Mollema SA, Lamb HJ, van derWall EE, de Roos A, Bax JJ. Validation of echocardiographic two-dimensional speckle tracking longitudinal strain imaging for viability assessment in patients with chronic ischemic left ventricular dysfunction and comparison with contrastenhanced magnetic resonance imaging. Am J Cardiol 2009;104:312-7
  10. ^ Cho GY, Chan J, Leano R, Strudwick M, Marwick TH. Comparison of two-dimensional speckle and tissue velocity based strain and validation with harmonic phase magnetic resonance imaging. Am J Cardiol 2006; 97:1661-6

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