Acute Outflow Obstruction of Hepatic Veins in Rabbits Quantitative Analysis of Hepatic Perfusion With Contrast-Enhanced Sonography

Objectives-To compare time-enhancement curve parameters of contrast-enhanced sonography in acute partial hepatic venous outflow obstruction with those of a baseline study. Methods-Contrast-enhanced sonography was performed in 11 rabbits with bolus administration of a sulfur hexafluoride contrast agent (0.1 mL/kg). After baseline scanning for 3 minutes, a 5.3F balloon catheter was placed into the left hepatic vein. Obstruction was artificially induced by 0.4-mL balloon inflation, and sonography was repeatedly performed thereafter. On images stored with 1-second intervals, 2 x 2-mm regions of interest were placed, and mean luminosity was measured. Time-enhancement curves were plotted, and contrast arrival times, peak enhancement values, peak enhancement times, 50% wash-out times, and 3-minute wash-out rates were obtained. Paired t tests were performed to evaluate the significance of differences in the parameters between baseline and obstruction. Results-On baseline sonography, the median contrast arrival time, peak enhancement value, peak enhancement time, 50% wash-out time, and 3-minute wash-out rate were 6 (range, 4-8; mean SD, 5.9 +/- 1.2) seconds, 188.5 (104.7-209.5; 178.4 +/- 33.1) arbitrary units, 19 (14-27; 19.8 +/- 4.1) seconds, 75 (60-101; 78.2 +/- 13.9) seconds, and 89.7% (81.3%-95.1%; 88.4% +/- 4.9%), respectively. With obstruction, those values were 7(5-12; 6.9 +/- 2.3) seconds, 202.8 (98.2-215.1; 186.0 +/- 39.3) arbitrary units, 31 (17-59; 32 +/- 11.6) seconds, 101 (47-136; 96.2 +/- 23.6) seconds, and 79.2% (66.2%-88.8%; 79.1% +/- 7.6%). Compared with baseline, the peak enhancement time was significantly delayed from 19 to 31 seconds (P = .0027), 50% wash-out time significantly delayed from 75 to 101 seconds (P = .0209), and 3-minute wash-out rate significantly decreased from 89.7% to 79.2% (P < .0001) with obstruction, but there were no significant differences in contrast arrival times and peak enhancement values (P = .0756 and .2179). Conclusions-Contrast-enhanced sonography can provide quantitative assessment of microbubble congestion in partial hepatic venous outflow obstruction. The peak enhancement time and 50% wash-out time are delayed and 3-minute wash-out rate is decreased in rabbits with artificially induced obstruction compared with a baseline study.