Ultrasound, contrast-enhanced ultrasound and pyelonephritis: A narrative review

Figure 1 Following the ultrasound contrast agent injection. A: Enhancement in the central arteries becomes visible 10-15 seconds after contrast injection, followed by the renal cortex a few seconds later, while the pyramids remain echo-poor; B: The renal pyramids gradually fill in, becoming almost isoechoic with the cortex within 30 seconds to 40 seconds after injection. During early-phase scanning, the kidneys appear hyperechoic compared to the liver or spleen. Later, the kidneys turn rapidly hypoechoic relative to the adjacent parenchyma, particularly the spleen.