Echogenicity

Echogenicity of a structure (acoustic interface) refers to the amount of sound it reflects back to the probe, which is dependent on the amplitude of incident sound, how much of the sound is absorbed, how much is reflected, and the angle of reflection.
These same properties also dictate tissue echogenicity, which is the collective back-scatter from numerous microscopic interfaces and is determined by the micro-architecture.
Increased echogenicity lacks specificity and in histologic studies has correlated with interstitial fibrosis, tubular atrophy, inflammation, and glomerulosclerosis .
Decreased echogenicity usually results from edema. Cortical echogenicity can only be evaluated qualitatively and should be less than the liver or spleen .
The medulla should have less echogenicity than the cortex, but the ability to discern this is dependent on scanning parameters and overlying structures.
Although the lack of cortico-medullary differentiation is frequently mentioned in ultrasound reports, the inability to see the medullae is common and not abnormal.
Rather, prominence of the medullae is usually abnormal, generally indicating increased echogenicity of the cortex

Ultrasound

Ultrasound with Doppler examination of intrarenal vessels is usually performed in patients with CKD, and it is common to have a normal exam.

findings of a severe CKD (especially stage 5) are :

reduced renal cortical thickness <6 mm 6 more reliable than length 7

reduced renal length

increased renal cortical echogenicity

poor visibility of the renal pyramids and the renal sinus

marginal irregularities

papillary calcifications

cysts

Abnormal Doppler findings in these patients are 2:

reduced renal vascularity

increased resistance index (RI) values (segmental and interlobular arteries)
Since renal cortical echogenicity has the advantage of being irreversible in comparison to serum creatinine levels, it can be used as a parameter of renal function.