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.

Figure 2 B-mode and contrast enhanced-ultrasound images showing a focus of pyelonephritis. In the B-mode image, a non-homogeneous ovary image is highlighted at the cortical level. Upon completion of contrast enhanced-ultrasound, this area appears hypovascular compared to the surrounding parenchyma, especially 40 seconds after the infusion of the contrast medium.