Translating High-Frame-Rate Imaging into Clinical Practice: Where Do We Stand?

Aniela Popescu; Stéphanie Bézy; Jens-Uwe Voigt

doi:10.2478/rjc-2023-0008

Figure 1 -

Conventional versus high-frame-rate ultrasound. (A) Traditional echocardiography makes use of focused transmit beams. (A–C) High frame rate imaging either transmits several focused beams in parallel (two in the example in (B)); defocused or diverging waves (C). (From Voigt14 with permission.)

Figure 2 -

Shear wave imaging with intrinsic excitation. (A) Physiologic events, such as aortic or mitral valve closure can generate a shear wave that propagates along the myocardium. The propagation of the wave is then measured by high frame rate imaging. (B) Anatomic M-mode, derived from a straight line drawn along the anteroseptal wall (dotted line) from the base towards the apex in a parasternal long axis echo image. (C) The colors in the M-mode display code the radial acceleration of the myocardium. Note the pronounced waves (light blue) propagating from the anteroseptal base towards the apex immediately after aortic valve closure (AVC) with a velocity of 3.6 m/s. AVC = aortic valve closure; MVC = mitral valve closure; LV = left ventricle. (Adapted from Santos et al.[34] with permission.)

Figure 3 -

3D visualization of mechanical wave propagation along the left ventricle at atrial systole. The normalized tissue acceleration is mapped in 3D over time. The white arrow indicates the maximum acceleration. (From Salles et al.[40] with permission.)

Figure 4 -

Shear wave imaging with external excitation. (A) External excitation by a strong focused ultrasound impulse induces a translational wave (shear wave) that propagates along the myocardium and is then measured by high frame rate imaging. (B) The shear wave propagation can be visualized on B-mode acquisition with high-frame-rate imaging; example of pushing locations shown by 3 red dots. (C) The propagation velocity of a shear wave is directly related to the stiffness of the tissue, which varies within a cardiac cycle depending on the pushing time. LV = left ventricle. (Adapted from Pernot et al.[38] with permission.)

Figure 5 -

Myocardial stiffness in healthy volunteers of different ages and patients with HCM. Comparison of myocardial stiffness in healthy volunteers (HV, green bar) and heart failure patients with hypertrophic cardiomyopathy (HCM, red bar). Values denote the myocardial stiffness in kPa. Based on the ROC curve analysis, the optimal cut-off value of myocardial stiffness for detection of HCM-HFpEF was 8 kPa. (From Villemain et al.[44] with permission.)

Figure 6 -

Shear wave propagation velocities in patients after HTX. CMR T1 mapping of the mid left ventricular segment of the anteroseptal wall and acceleration M-mode map of the anteroseptal wall in three heart transplant recipients (HTx1-3). Note that shear wave velocities at mitral valve closure (MVC) increase with increasing native T1 value. The highlighted region of the ECG indicates the time interval covered by the M-mode map. HTx = heart transplant recipient; MVC = mitral valve closure. (From Petrescu et al.[32] with permission.)

Figure 7 -

2D ultrafast color Doppler imaging of intramural coronary vasculature. Flow in epicardial and intramyocardial vessels an open-chest swine experiment. Vessels below 100 µm remain below resolution. The scale bar represents 3 mm. A and B are longitudinal images, C and D are short axis images. Panels A and C: in a systole, venous blood flow moves upwards from the endocardium to the epicardium (red) and is collected in the epicardial veins. Panels B and D: in diastole, arterial blood from the epicardial vessels flows downwards (blue) in the myocardium. (From Maresca et al.[68] with permission.)

Figure 8 -

3D ultrafast Doppler coronary angiography. (1) Coronary blood flow at baseline (left) and during reactive hyperemia (right) after transient occlusion of the LAD artery. (2) Flow velocity mapping using 3D ultrafast Doppler coronary angiography at early diastole. (From Correia et al.[70] with permission.)

Figure 9 -

Cardiac blood speckle tracking imaging in a neonate with double-outlet right ventricle. The figure displays frames from the parasternal long-axis view at four different moments in the cardiac cycle. Ao, aorta; LV, left ventricle; RV, right ventricle. (From Nyrnes et al.[78] with permission.)

Figure 10 -

3D blood speckle tracking imaging. The figure shows a 3D representation of the flow path lines in three parts of the cardiac cycle corresponding to diastole, diastasis, and systole by using blood speckle tracking. Complex swirling flow patterns can be displayed throughout the cardiac cycle. Ao = aorta; LA = left atrium; LV = left ventricle. (From Wigen et al.[77] with permission.)

Figure 11 -

Myocardial fiber orientation assessed by Elastic Tensor Imaging. (A) The probe is placed at the surface of the myocardium and rotated around a single axis z, depth of the myocardial wall. (B) Shear waves were generated by using acoustic radiation force and were measured for different depths within the myocardium (in percentage) for each angle of rotation. (From Ngo et al.[82], modified after Lee et al.[73] with permission.)