In its classic definition, by FranÃ§ois-Louis Ganshof (1944), feudalism describes a set of reciprocal legal and military obligations among the warrior nobility revolving around the three key concepts of lords, vassals and fiefs.
The exact cause of intracardiac echogenic foci remains unclear; however, they appear to be caused by small deposits of calcium in the papillary muscle of the fetal heart.
Echogenic structures appear bright on ultrasound (the higher the amplitude of the reflected wave, the brighter the pixel). Echogenicity of Various Structures. 1  Bones: hyperechoic. 2  Tendons: hyperechoic.  Nerves: variable (hyperechoic in the upper extremity, hypoechoic in the lower extremity)