Focused sonography of the renal pyramids with linear array transducers may depict a wide variety of unique physiological and pathological changes in children. Transient hyperechogenicity of the pyramids may be seen in neonates as part of normal physiology but may also be seen in older infants with dehydration. In urinary tract obstruction two types of changes in echogenicity may be recognised in the pyramids.
Echogenic bands may reflect increase in acoustic interfaces due to mild collecting duct dilatation while a greater distension of these ducts may be appreciated as linear or rounded fluid filled spaces. Ischemic changes in neonates, such as medullary necrosis or renal vein thrombosis, may lead to changes that have not yet been well documented. Polycystic renal diseases may lead to a variety of changes in the pyramids and at times may be nonspecific. Metabolic diseases which cause nephrocalcinosis may affect the kidney in several ways and focused sonography reveals changes not previously clearly delineated. More work is required to attempt to offer more complete explanations for these various patterns of changed echogenicity in the pyramids.