ABSTRACT
Assessment of renal anatomy is easily performed, and US is often used as image guidance for renal interventions by using B-mode imaging. In the longitudinal scan plane, the kidney has the characteristic oval bean-shape. The right kidney is often found more caudally and is slimmer than the left kidney, which may have a so-called dromedary hump due to its proximity to the spleen. Complex cysts can have membranes dividing the fluid-filled center with internal echoes, calcifications or irregular thickened walls. The complex cyst can be further evaluated with Doppler US, and for Bosniak classification and follow-up of complex cysts, either contrast-enhanced ultrasound or contrast-enhanced computed tomography are used. Hydronephrosis is seen as an anechoic fluid-filled interconnected space with enhancement within the renal sinus, and normally, the dilated pelvis can be differentiated from dilated calyces. Hydronephrosis can also be caused by non-obstructive conditions, such as brisk diuresis in patients treated with diuretics, in pregnant women and in children with vesicoureteral reflux.
