Contrast-enhanced ultrasonography with Sonazoid for evaluation of renal microcirculation

The renal medullary microcirculation plays an important role in regulating sodium and water excretion, and its impairment is closely associated with various renal diseases. Contrast-enhanced ultrasonography (CEUS) using Sonazoid has not yet been reported as a method for evaluating the renal microcirculation; consequently, this study was carried out to reveal the characteristics of renal microcirculation using CEUS with Sonazoid.

CEUS was performed on three healthy volunteers after they had fasted for at least 6 h. A GE LOGIQ7 ultrasound unit was used with a 2.0- to 5.5-MHz convex probe. Within approximately 1 min of intravenous injection of 0.0050 ml/kg Sonazoid, contrast images of the right kidney were acquired using a coded phase-inversion mode. Time-intensity curves were calculated for the cortex and medulla.

Peak contrast intensity was significantly higher in the cortex (-56.4 ± 1.9 dB) than in the medulla (-66.7 ± 1.7 dB; P < 0.005). Peak times were significantly earlier in the cortex (17.4 ± 3.7 ms) than in the medulla (28.8 ± 6.3 ms; P < 0.05).

CEUS using Sonazoid enables differentiation between the cortical and medullary microcirculation and is useful in clarifying renal pathophysiology and pharmacology.