The Impact of Vendor-Specific Ultrasound Beam-Forming and Processing Techniques on the Visualization of In Vitro Experimental “Scar”: Implications for Myocardial Scar Imaging Using Two-Dimensional and Three-Dimensional Echocardiography

Power Modulation Echocardiography to Detect and Quantify Myocardial Scar

“…Power modulation echocardiography has been used to diagnose myocardial scar in patients with previous myocardial infarction [8,16]. Power modulation is a beam forming and post-processing ultrasound technique, which was originally developed to be used in combination with ultrasound contrast agents [17,18].…”

“…We hypothesized that power modulation echocardiography would enhance the nonlinear signal from disarrayed myocardial scar, whilst suppressing the linear signal from normal myocardium. In an experimental in-vitro and in-vivo study we previously explored several ultrasound pulse characteristics and beam-forming techniques to detect and quantify myocardial scar [16]. Power modulation with harmonic imaging at low frequency and no contrast enhancement was able to discriminate and quantify tissues with different acoustic properties.…”

“…LGE CMR technique is based on the magnetic properties and kinetics of a paramagnetic element, namely gadolinium, which is distributed in the extracellular space [26]. In contrast, echocardiography detects the backscattered ultrasound signal from the disarrayed scarred myocardium which is higher compared to the normal myocardial signal [6][7][8]16]. In addition, the LGE volume has been shown to vary substantially depending on the J o u r n a l P r e -p r o o f 18 quantification method used in CMR images, and we tested only the FWHM technique [20].…”

“…ultrasound machine and an X5-1 xMATRIX array transducer (Philips Healthcare, Andover, MA). The images were acquired using power modulation modality (Left Ventricular Opacification -LVO vendor specific pre-set) with second harmonic imaging (1.3/2.6MHz) and the mechanical index was set at 0.8-1.0 in line with previously published data [16]. The gain was adjusted above the noise floor and below saturation level, according to each patient's ultrasound reflectivity.…”

“…The slices were 3-5 mm apart. Special attention was applied to exclude the high intensity signal from the pericardium and the bright septal areas [7,16]. The sagittal and longitudinal axes were used to confirm the presence of hyperenhanced areas, and they were not used for tracing.…”