Final answer:
The echogenic appearance of the pericardium in ultrasound images is due to specular reflection, which occurs at the boundary of media with different acoustic impedances.
Step-by-step explanation:
The acoustic property that causes the echogenic appearance of the pericardium related to surrounding structures is specular reflection. Specular reflection occurs when a sound wave encounters a boundary between two media that have different acoustic impedances, such as the heart tissue and the pericardium. The greater the difference in acoustic impedance, the more sound wave energy is reflected back, thus making the pericardium appear echogenic on an ultrasound. This is outlined in TABLE 17.5 The Ultrasound Properties of Various Media, Including Soft Tissue Found in the Body.