Our purpose was to test the feasibility and optimization of contrast-enhanced gray-scale harmonic sonography for the evaluation of focal renal perfusion defects in an animal model.

We performed arteriography and contrast-enhanced harmonic sonography on six anesthetized piglets after embolization of each kidney with an autologous clot through the main renal artery. Harmonic images were obtained with continuous (30 Hz) and ECG-triggered acquisition. The two harmonic sonography strategies were compared with respect to the number and conspicuity of devascularized areas, and correlation was made with arteriographic findings.

Contrast-enhanced harmonic sonography showed focal areas of absent or diminished vascularity that corresponded closely with perfusion defects seen on angiography. Enhancement ratios to perfused cortex were significantly higher than to devascularized cortex in both continuous (mean +/- SD, 469 +/- 5% versus 102 +/- 8%, p < .0005 by t test) and triggered (673 +/- 7% versus 198 +/- 7%, p < .0001) modes. Triggered acquisition increased the conspicuity of perfusion defects over that obtained with continuous imaging (p < .002 by t test).

Contrast-enhanced harmonic sonography is an effective method of depicting focal renal perfusion defects. Triggered acquisition further improves lesion conspicuity.