Dynamic sonographic tissue perfusion measurement to evaluate renal cortical perfusion in healthy and insufficient kidneys

Objective: To prevent loss of renal function it is necessary to find very early noninvasive functional criteria of impending irreversible tissue damage. We used therefore the novel method of dynamic tissue perfusion measurement to prove its ability of monitoring a creeeping, subliminal loss of renal microvasculature.

Method: Renal cortical perfusion was measured under strictly standardized conditions in millimeter-thin slices with a specially designed software for dynamic (i.e. heart cycle synchronized) perfusion measurement: PixelFlux (www.chameleon-software.de) in 102 healthy probands (0,4–18, mean 6 years) and 37 patients with chronic renal failure (0,5–20, mean 11 years) in three cortical layers: proximal 20%, proximal 50% and distal 50% of the cortex above the outer edge of medullary pyramids.

Results: In renal insufficiency in all layers a highly significant decrease of perfusion intensity could be demonstrated (2,05 vs. 0,84cm/s in proximal 20%, 1,98 vs. 0,87cm/s in proximal 50% and 0,58 vs. 0,39cm/s in distal 50% p<0,001 for each comparison, values represent mean flow velocity of the whole region of interest including nonperfused parts). Ratios of perfusion between the layers also differed significantly. Moreover significant perfusion differences between different creatinine clearance classes even within highly normal ranges could be demonstrated.

Conclusion: The dynamic renal tissue perfusion measurement with PixelFlux is capable to monitor the creeping function loss already in highly normal functional states and can clearly differentiate healthy from threatened and insufficient kidneys.