Value Of Advanced Ultrasonographic Technology In Assessing The Hemodynamics Of Transplanted Liver And Hepatic Vascular Complications

Part One:Hemodynamics of Occlusive Disease of Dogs' Hepatic Artery on UltrasonographyChapter One:Study of Occlusive Disease of Dogs' Hepatic Artery with Color Doppler Flow ImagingHepatic arterial stenosis(HAS) models were made by surgery in 6 healthy dogs and were divided into 4 types according to stenosis grade:0,＜50%,＞50%and 100%. All examinations were performed using PHILIPS-iU22 ultrasound system.Studies included direct detection of stenosis in common hepatic artery(CHA) and analysis of Doppler waveform obtained from intrahepatic artery branches indirectly.In the study,hepatic artery was visualized satisfactorily in 11 of 24 models evaluated by color Doppler flow imaging(CDFI).In identifing the degree of stenosis of CHA, CDFI revealed a coincidence rate of only 43.70%compared with models.Dogs that had an significant stenosis(stenosis greater than 50%) in CHA had prolonged acceleration time(AT) and reduced resistance index(RI),the acceleration index(AC) in intrahepatic artery(P＜0.05).An acceleration index(AC) value below 1.81m/s~2 or a resistance index(RI) lower than 0.58 produced both the sensitivity of 100%and specificities of 66.7%and 83.3%respectively,for the diagnosis of significant stenosis in CHA.Besides visualization of HA and evaluation of stenosis in CHA directly,CDFI can detect significant stenosis in CHA by analyzing the Doppler waveform obtained from intrahepatic artery branches of dogs.Chapter Two:Study of Occlusive Disease of Dogs' Hepatic Artery with Contrast Enhanced UltrasonographySix dogs were operated to make stenotic models at hepatic artery(HA)(same to chapter one).Contrast agent was SonoVue and low mechanical index harmonic contrast-enhanced ultrasonography(CEUS) was performed.After contrast agent injection,hepatic artery visualization was improved from 45.8%(11/24) to 95.8% (23/24).Mean contrast material arrival time and peak time of hepatic artery was (12.1±2.6) s and(15.7±3.9) s respectively.The time needed for technologist to identify HA was(1～2) min with CEUS,shorter than that(10～15) min with CDFI.In diagnosis of occlusive disease in dogs' HA,the correlations for CDFI and CEUS relative to model were 0.516 and 0.947 respectively.In the study,CEUS can improve hepatic artery visualization and assess the degree of stenoses accurately,which is superior to CDFI. Part Two:Hemodynamic Changes in Normal Transplanted Liver:Study with Color Doppler UltrasonographyOne hundred forty-four patients with transplanted livers were included in the study.The hemodynamic changes in the hepatic vessels were analyzed with color Doppler flow imaging(CDFI) after orthotopic liver transplantation(OLT) during a long observation period(4 years).All patients were examined with ultrasound equipments including Technos Megas GPX,Technos Du8 and PHILIPS-iU22. Hepatic morphology and parenchyma was investigated with B-mode ultrasound,and the patency of hepatic blood vessels and anastomosis were assessed with CDFI.The hemodynamic changes were measured and compared in 8 studied time points, including 1-day,1-month,6-month,12-month,18-month,2-year,3-year,4-year after OLT.After liver transplantation,hepatic hemodynamics changed as follows:peak systolic velocity of portal vein(PV-PSV)was high in the first day after operation,and decreased dramatically in 6-month after OLT,then a slowly decrease of PV-PSV from 6-month to 18-month,reached a lower value(0.26±0.11) m/s at 18-month time point. We also detected a slowly decrease of arterial velocities over a long time period after OLT.At 3-year time point,the peak systolic velocity of hepatic artery(HA-PSV) was (0.48±0.20) m/s,which was lower than that measured in any other time point.The resistance index of hepatic artery(HA-RI) decreased between the intervals 1-day and 1-month after OLT,the lowest value was(0.69±0.10) measured at 1-month(P＜0.05). And then it was stabilized at a level of(0.71±0.09) at many following studied time points.The ratio of abnormal HA-RI showed no significant difference among the 8 studied time points after liver transplantation(P＞0.05).All three hepatic veins showed monophasic,biphasic and triphasic wave form morphology in Doppler ultrasonography,but triphasic waveform occupied dominantly.The composition of three waveform morphology showed no significant difference among three hepatic veins(P＜0.05).Part Three:Study of Hepatic Vascular Complications in Transplanted Liver with UltrasonographyChapter one:Study of Hepatic Artery Complications in Transplanted Liver with UltrasonographyThirty-seven patients suspected of hepatic artery complications were examined by CDFI and CEUS.All examinations were performed by using a PHILIPS-iU22 scanner with a 2-5MHz convex probe.Contrast agent was SonoVue and low mechanical index harmonic contrast-enhanced ultrasonography was performed.After contrast agent injection,Flow visualization in hepatic artery was improved significantly,reaching 100%.Mean contrast material arrival time was(16.1±5.5) s in hepatic artery and(19.3±4.6) s in portal vein.The diagnostic accuracy of hepatic artery thrombosis(HAT) was improved from 86%(30/35) to 100%(35/35) with CEUS.In the HAT group,contrast material arrival time in portal vein was(13.6±4.6)s, shorter to that in group without HAT(P＜0.05).One hepatic artery pseudo-aneurysm and one hepatic artery stenosis were clearly revealed with CEUS after liver transplantation.In our study,CEUS is a useful technique in improving the visualization of hepatic artery,which is helpful in the diagnosis of hepatic artery complications after liver transplantation.Respective sensitivity and specificity and accuracy for detection HAT were 72.2%(13/18),100%(17/17) and 86%(30/35) for CDFI,and all 100%for CEUS.Chapter Two:Study of Portal Vein Complications in Transplanted Liver with ultrasonographyTwenty-two patients suspected of portal vein complications(PVC) after liver transplantation were examined with CDFI and CEUS.All examinations were performed by using a PHILIPS-iU22 scanner with a 2-5MHz convex probe.Contrast agent was SonoVue and low mechanical index harmonic contrast-enhanced ultrasonography was performed.A total of 9 portal vein complications were identified. In patients with portal vein stenosis(PVS),a narrowing portal vein and diffuse low velocities(between 0.06m/s to 0.14m/s) or focally elevated velocities(reaching 1.16m/s) at the stenostic site could be revealed with CDFI.Portal vein thrombosis (PVT) appears moderately hypoechoic or isoechoic on ultrasound,with no flow or partial flow showed on CDFI.In PVC group,peak systolic velocity in hepatic artery was(0.76±0.10) m/s,faster than that(0.47±0.16) m/s in group without PVC(P＜0.05). Doppler ultrasound failed to detect portal vein flow signal in 2 patients,but narrowing flow signal was visualized in the main portal vein after contrast agent adminstration, and the inner diameter of stenostic portal vein were 3.1 mm and 3.4mm respectively. Another portal vein was not identified clearly with CDFI because of ultrasound beam attenuation,then CEUS was performed and showed portal vein obstruction(PVO), and follow-up results confirmed CEUS findings.CDFI can assess the patency of portal vein and provide information about the direction and velocity of portal vein blood flow,but CEUS can improve portal vein visualization and measure stenotic site precisely,which is a better imaging modality for detecting portal vein complications in transplanted liver.In diagnosis of portal vein complications of transplanted liver, respective sensitivity and specificity and accuracy were 81.8%(9/11),100%(11/11) and 90.1%(20/22) for CDFI,and they were all 100%for CEUS.Chapter Three:Study of Outflow Obstruction in Transplanted Liver with ultrasonographyTwenty-three patients suspected of hepatic outflow complications after liver transplantation were examined with CDFI and CEUS.All examinations were performed by using a PHILIPS-iU22 scanner with a 2-5MHz convex probe.Contrast agent was SonoVue and low mechanical index harmonic contrast-enhanced ultrasonography was performed.Twelve patients with hepatic venous(HV) or inferior vein cava(IVC) complications were demonstrated by hepatic venograms or CTA.In the group with hepatic outflow block,six(50%,6/12) patients had monophasic wave pattern in hepatic veins and two(2/12,16.7%) patients had bidirectional or reversal portal flow examined with CDFI.In hepatic outflow obstruction group,peak systolic velocity in portal vein was(0.26±0.11)m/s,lower than that(0.38±0.18)m/s in group without hepatic outflow complications(P＜0.05).Seventeen patients suspected of hepatic outflow obstruction with CDFI,but CEUS showed 6 patients with hepatic outflow complications and 11 patients with patent hepatic outflow after contrast agent injection,and follow-up results confirmed CEUS findings.In the diagnosis of hepatic outflow obstruction in transplanted liver,respective sensitivity and specificity and accuracy were 64.7%(11/17) and 83.3%(5/6) and 69.9%(16/23) with CDFI,but that were 100%(11/11) and 91.7%(11/12) and 95.7(22/23) with CEUS.In addition to assessing the patency of HV and IVC,CDFI can provides information about the direction of blood flow and the Doppler waveform patterns of hepatic vessels.CEUS can improve hepatic veins and IVC visualization and can measure stenotic site precisely,which is a dominant imaging modality for the diagnosis of outflow obstruction of transplanted liver.Part Four:Three-dimensional Reconstruction of Contrast-enhanced Ultrasonography in Evaluating Hepatic Vessels in Transplanted LiverThirty-two patients suspected of vascular complications after liver transplantation were examined by two-dimensional contrast-enhanced ultrasonographic(2D-CEUS) and three-dimensional contrast-enhanced ultrasonography(3D-CEUS).All patients were examined with ultrasound equipment PHILIPS-iU22(probe V6-2,2～6MHz). Contrast agent was SonoVue and low mechanical index(0.06～0.08) harmonic contrast-enhanced ultrasonography was performed.The visualization of branching orders and imaging quanlity were assessed between 2D-CEUS and 3D-CEUS.The diagnostic value of vascular complications after liver transplantation with 3D-CEUS was also evaluated.Then 3D-CEUS were performed and showed twenty patients with patent hepatic vessels,and follow-up results confirmed 3D-CEUS findings.The three dimensional hepatic artery tree structures were visualized in all the patent arteries by 3D-CEUS.The hepatic artery were visualized(2.61±0.50) order branch averagely by 3D-CEUS,superior to the(3.61±0.50) order by 2D-CEUS(P=0.000).And the image quality scored(2.83±0.51) by 3D-CEUS,which was superior to(3.50±0.62) scored by 2D-CEUS(P=0.001).Twelve hepatic vascular complications in transplanted liver were diagnosed with 3D-CEUS,such as tortuous hepatic artery in 3 patients,tortuous hepatic veins without stenosis in 2 patients,hepatic artery stenosis in 2 patients,portal vein stenosis in 3 patients,and inferior vein cava stenosis in 2 patients,following CTA or DSA demonstrated the results.In conclusion,3D-CEUS is a useful technique to visualize the hepatic vessels and can provide more diagnostic information than 2D-CEUS.3D-CEUS is a beneficial complement of 2D-CEUS in the diagnosis of hepatic vascular complications after liver transplantation.