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.
Sonography of the kidneys shows an echogenic mass in the kidney, caused by the high fat content. The fat content typically causes a hypodense mass in the kidney with -20 to -80 HU, this enables the differentiation to renal cell carcinoma [fig. CT of angiomyolipoma]. Calcifications are rare in renal angiomyolipoma.