ObjectiveTo investigate the main influence factors of microbubble-enhanced sono-thrombolysis by an orthogonal array experimental design (OAD) and to confirm the optimal parameters of microbubble-enhanced sono-thrombolysis in vitro. Methods The peripheral blood was collected from 50 female Sprague Dawley rats to prepare the standard plasma, and then 100 μL standard plasma and 25 μL thrombin (0.15 U/μL) were mixed and incubated in 37℃ water bath for 3, 6, 12, and 24 hours respectively to prepare corresponding standardized thrombus. The physical parameters for the designed experiments included transmit powers of ultrasound (factor A: 5%, 25%, 50%, and 100%), microbubble volume (factor B: 50, 100, 200, and 400 μL), urokinase (UK) concentration (factor C: 100, 200, 400, and 800 U/mL), and thrombolysis time (factor D: 10, 20, 30, and 40 minutes), respectively. Then an OAD based on four parameters and four levels [L16(45)] was employed to optimize the thrombolysis conditions. The ultrasound frequency was 1.82 MHz. HE staining and scanning electron microscope (SEM) were used to observe the clots before and after thrombolysis. The thrombolysis rate was measured. ResultsHE staining and SEM observation showed that the fibrin was dissolved after thrombolysis. According to the OAD, the optimal parameter combination was C4-D4-A1-B4, indicating UK concentration 800 U/mL, thrombolysis time 40 minutes, transmit power of ultrasound 5%, and microbubble volume 400 μL, respectively. The four factors above had significant influence on thrombolysis (P lt; 0.05), and UK concentration was the most significant. There were significant differences in thrombolysis between different thrombolysis time (P lt; 0.05). ConclusionUnder the condition of fixed ultrasound frequency, microbubble-enhanced sono-thrombolysis efficiency is better in lower transmit power of ultrasound, higher UK concentration, longer thrombolysis time, higher microbubble volume, and shorter thrombolysis time
ObjectiveTo explore the possibility of intrahepatic biliary perfusion by contrast enhanced ultrasonography via bile duct. MethodsSixteen rabbits weighing 2 000-2 500 g were studied. A 22 gauge catheter was inserted in the common bile duct by surgery. The rabbits were divided into 4 groups according to the concentration of contrast agent, including group A:1/100 of standard concentration; group B:1/200 of standard concentration; group C:1/400 of standard concentration; and group D:1/800 of standard concentration. We observed the filling status, presence of outflow of contrast enhanced signal and satisfactory enhanced time after the injection of contrast agent via the catheter in common bile duct. ResultsFive milliliter of contrast agent was injected in each rabbit. The number of homogeneous filling in group A, B, C and D was 4, 4, 3 and 0 respectively. The number of presence of outflow of contrast enhanced signal in group A, B, C and D was 4, 1, 0 and 0 respectively. The satisfactory enhanced time in group A, B, C and D was (340±29) s, (284±37) s, (82±8) s and 0 s respectively. There was no statistical difference in the satisfactory enhanced time between group A and B (P=0.06) while significant difference in the satisfactory enhanced time between group A and C (P < 0.01), and between group B and C (P < 0.01) was found. ConclusionIt is possible to perfuse the intrahepatic biliary system by sonographic contrast agents via bile duct, and 1/200 of standard concentration is a proper concentration of contrast agent to achieve satisfactory imaging.