Computational Fluid Dynamics-Based Blood Flow Assessment Facilitates Optimal Management of Portal Vein Stenosis After Liver Transplantation.

BACKGROUND: Portal vein stenosis develops in 3.4-14% of split liver transplantation1-3 and its early detection and treatment are essential to achieve long-term graft survival,2-5 although the diagnostic capability of conventional modalities such as Doppler ultrasound and computed tomography is limited.1,4,5 METHODS: This study used computational fluid dynamics to analyze portal vein hemodynamics in the management of post-transplant portal vein stenosis. To perform computational fluid dynamics analyses, three-dimensional portal vein model was created using computed tomographic DICOM data. The inlet flow condition was set according the flow velocity measured on Doppler ultrasonography. Finally, portal vein flow was simulated on a fluid analysis software (Software Cradle, Japan). RESULTS: An 18-month-old girl underwent liver transplantation using a left lateral graft for biliary atresia. At the post-transplant 1-week evaluation, the computational fluid dynamics streamline analysis visualized vortices and an accelerated flow with a velocity ratio < 2 around the anastomotic site. The wall shear stress analysis revealed a high wall shear stress area within the post-anastomotic portal vein. At the post-transplant 6-month evaluation, the streamline analysis illustrated the increased vortices and worsening flow acceleration to reach the proposed diagnostic criteria (velocity ratio > 3:1).3,5 The pressure analysis revealed a positive pressure gradient of 3.8 mmHg across the stenotic site. Based on the findings, the patient underwent percutaneous transhepatic portal venoplasty with balloon dilation. The post-treatment analyses confirmed the improvement of a jet flow, vortices, a high wall shear stress, and a pressure gradient. DISCUSSION: The computational fluid dynamics analyses are useful for prediction, early detection, and follow-up of post-transplant portal vein stenosis and would be a promising technology in post-transplant management.

Assessment of hepatic microvascular flow and density in patients undergoing preoperative portal vein embolization.

BACKGROUND: The microvascular effects occurring after unilateral preoperative portal vein embolization (PVE) are poorly understood. The aim of this study was to assess the microvascular changes in the embolized and the non-embolized lobes after right PVE. METHODS: Videos of the hepatic microcirculation in patients undergoing right hemihepatectomy following PVE were recorded using a handheld vital microscope (Cytocam) based on incident dark field imaging. Hepatic microcirculation was measured in the embolized and the non-embolized lobes at laparotomy, 3-6 weeks after PVE. The following microcirculatory parameters were assessed: total vessel density (TVD), microcirculatory flow index (MFI), proportion of perfused vessel (PPV), perfused vessel density (PVD), sinusoidal diameter (SinD) and the absolute red blood cell velocity (RBCv). RESULTS: 16 patients after major liver resection were included, 8 with and 8 without preoperative PVE. Microvascular density parameters were higher in the non-embolized lobes when compared to the embolized lobes (TVD: 40.3 ± 8.9 vs. 26.8 ± 4.6 mm/mm2 (p < 0.003), PVD: 40.3 ± 8.8 vs. 26.7 ± 4.7 mm/mm2 (p < 0.002), SinD: 9.2 ± 1.7 vs. 6.3 ± 0.8 µm (p < 0.040)). RBCv, PPV and the MFI were not significantly different. CONCLUSION: The non-embolized lobe has a significantly higher microvascular density, however without differences in microvascular flow. These findings indicate increased angiogenesis in the hypertrophic lobe.

Transjugular intrahepatic portosystemic shunt (TIPS) dysfunction: quantitative assessment of flow and perfusion changes using 2D-perfusion angiography following shunt revision.

PURPOSE: To analyze the feasibility of 2D-perfusion angiography (2D-PA) to quantify flow and perfusion changes pre- and post-transjugular intrahepatic portosystemic shunt (TIPS) revision. MATERIALS AND METHODS: Fifteen consecutive patients (54 ± 14 years, seven men and eight women) scheduled for TIPS revision were included in this study. To quantify flow and perfusion changes caused by TIPS revision, digital subtraction angiography (DSA) series acquired during the revision were post-processed using a dedicated software. Reference region-of-interest (ROI) in the main portal vein (input function) and target ROIs in the TIPS lumen, the liver parenchyma and in the right atrium were placed in corresponding areas on DSA pre- and post-TIPS revision. 2D-PA evaluation included time to peak (TTP), peak density (PD), and the area under the curve (AUC) assessment. The ratios of reference ROI to target ROIs pre- and post-TIPS revision were calculated (TTPparenchyma/TTPinflow, PDparenchyma/PDinflow, AUCparenchyma/AUCinflow, TTPTIPS/TTPinflow, PDTIPS/PDinflow, AUCTIPS/AUCinflow, TTPatrium/TTPinflow, PDatrium/PDinflow, and AUCatrium/AUCinflow). Pressure measurements pre- and post-TIPS revision were performed and correlated to the 2D-PA parameters. Reproducibility of 2D-PA was assessed by the intra-class correlation coefficient (ICC). RESULTS: The portosystemic pressure gradient was significantly reduced following TIPS revision (17.1 ± 6.3 vs. 8.9 ± 4.3 mmHg; p < 0.0001). PDTIPS/PDinflow (0.22 vs. 0.35; p = 0.0014) and AUCTIPS/AUCinflow (0.24 vs. 0.39; p = 0.0012) increased significantly. Likewise, PDatrium/PDinflow (0.32 vs. 0.78; p = 0.0004) and AUCatrium/AUCinflow (0.3 vs. 0.79; p < 0.0001) increased, whereas PDparenchyma/PDinflow decreased significantly (0.14 vs. 0.1; p = 0.0084). Pressure gradient changes correlated significantly with the increase in PDatrium/PDinflow (r = - 0.77, p = 0.0012) and AUCatrium/AUCinflow (r = - 0.76, p = 0.0018). ICC of the 2D-PA parameters was in the range of 0.88-0.99. CONCLUSION: 2D-PA offers a feasible approach to quantify flow and perfusion changes during TIPS revision. Therefore, 2D-PA may be a valuable amendment to mere pressure measurements.

Intrahepatic portal vein blood volume estimated by non-contrast magnetic resonance imaging for the assessment of portal hypertension.

PURPOSE: To investigate the feasibility of estimating the portal vein blood volume that flows into the intrahepatic volume (IHPVBV) in each cardiac cycle using non-contrast MR venography technique as a surrogate marker of portal hypertension (PH). MATERIALS AND METHODS: Ten patients with chronic liver disease and clinical symptoms of PH (40% males, median age: 54.0, range: 44-73 years old) and ten healthy volunteers (80% males, median age: 54.0, range: 44-66 years old) were included in this study. A non-contrast Triple-Inversion-Recovery Arterial-Spin-Labeling (TIR-ASL) technique was used to quantify the IHPVBV in one and two cardiac cycles. Liver (LV) and spleen volumes (SV) were measured by manual segmentation from anatomical MR images as morphological markers of PH. All images were acquired in a 1.5T Philips Achieva MR scanner. RESULTS: PH patients had larger SV (P=0.02) and lower liver-to-spleen ratio (P=0.02) compared with healthy volunteers. The median IHPVBV in healthy volunteers was 13.5cm(3) and 26.5cm(3) for one and two cardiac cycles respectively, whereas in PH patients a median volume of 3.1cm(3) and 9.0cm(3) was observed. When correcting by LV, the IHPVBV was significantly higher in healthy volunteers than PH patients for one and two cardiac cycles. The combination of morphological information (liver-to-spleen ratio) and functional information (IHPVBV/LV) can accurately identify the PH patients with a sensitivity of 90% and specificity of 100%. CONCLUSION: Results show that the portal vein blood volume that flows into the intrahepatic volume in one and two cardiac cycles is significantly lower in PH patients than in healthy volunteers and can be quantified with non-contrast MRI techniques.

Contrast-enhanced ultrasound for quantitative assessment of portal pressure in canine liver fibrosis.

AIM: To explore the feasibility of non-invasive quantitative estimation of portal venous pressure by contrast-enhanced ultrasound (CEUS) in a canine model. METHODS: Liver fibrosis was established in adult canines (Beagles; n = 14) by subcutaneous injection of carbon tetrachloride (CCl4). CEUS parameters, including the area under the time-intensity curve and intensity at portal/arterial phases (Qp/Qa and Ip/Ia, respectively), were used to quantitatively assess the blood flow ratio of the portal vein/hepatic artery at multiple time points. The free portal venous pressures (FPP) were measured by a multi-channel baroreceptor using a percutaneous approach at baseline and 8, 16, and 24 wk after CCl4 injections in each canine. Liver biopsies were obtained at the end of 8, 16, and 24 wk from each animal, and the stage of the fibrosis was assessed according to the Metavir scoring system. A Pearson correlation test was performed to compare the FPP with Qp/Qa and Ip/Ia. RESULTS: Pathologic examination of 42 biopsies from the 14 canines at weeks 8, 16, and 24 revealed that liver fibrosis was induced by CCl4 and represented various stages of liver fibrosis, including F0 (n = 3), F1 (n = 12), F2 (n = 14), F3 (n = 11), and F4 (n = 2). There were significant differences in the measurements of Qp/Qa (19.85 ± 3.30 vs 10.43 ± 1.21, 9.63 ± 1.03, and 8.77 ± 0.96) and Ip/Ia (1.77 ± 0.37 vs 1.03 ± 0.12, 0.83 ± 0.10, and 0.69 ± 0.13) between control and canine fibrosis at 8, 16, and 24 wk, respectively (all P < 0.001). There were statistically significant negative correlations between FPP and Qp/Qa (r = -0.707, P < 0.001), and between FPP and Ip/Ia (r = -0.759, P < 0.001) in the canine fibrosis model. Prediction of elevated FPP based on Qp/Qa and Ip/Ia was highly sensitive, as assessed by the area under the receiver operating curve (0.866 and 0.895, respectively). CONCLUSION: CEUS is a potential method to accurately, but non-invasively, estimate portal venous pressure through measurement of Qp/Qa and Ip/Ia parameters.

Quantitative assessment of hepatic blood flow in the diagnosis and management of necrotizing enterocolitis.

BACKGROUND: Necrotizing enterocolitis (NEC) is the most important gastrointestinal emergency in the neonatal period and early detection is very important for its management. Bowel ischemia-hypoperfusion is one of the main etiological factors. In the literature, a few studies have focused on arterial Doppler ultrasonography (DUS) features of splanchnic arteries; however, their clinical implications are not clear. OBJECTIVE: In this study, we aimed to quantitatively evaluate the blood flow features in the hepatic portal vein (PV) and hepatic veins (HVs) by using DUS in newborns with NEC. Patient-Method: Enrolled subjects were divided into two groups as patient (suspected/confirmed NEC, n = 24), and control group (n = 25). Daily serial DUS examinations were performed after the onset of the suspicion of NEC and continued until the initial day of the enteral feeding. Portal blood flow (PBF) and "hepatic blood flow ratio" (RHBF) were calculated manually by using DUS findings. Two groups were compared with respect to their PBF and RoHBF values. RESULTS: PBF and RHBF levels were significantly lower in patient group than those in control group. Clinical improvement in patients with NEC was associated with improvement in the PBF and RHBF. Cut-off level of the RHBF for the diagnosis of NEC was 0.66. CONCLUSION: DUS seems to be useful for the diagnosis and follow-up of NEC by providing quantitative information on liver blood flow. Daily measurements of the PBF and RoHBF in newborns with NEC may be beneficial to make the decision of starting enteral feeding.

Spleen stiffness and splenoportal venous flow: assessment before and after transjugular intrahepatic portosystemic shunt placement.

OBJECTIVES: To prospectively assess changes in spleen stiffness and splenoportal venous flow before and after transjugular intrahepatic portosystemic shunt (TIPS) placement. METHODS: We prospectively evaluated spleen stiffness measured by the mean shear wave velocity with acoustic radiation force impulse imaging and the splenoportal venous velocity with color Doppler sonography in 12 patients (mean age ± SD, 42.6 ± 11.0 years; range, 29-65 years) who underwent TIPS placement for portal hypertension and gastroesophageal bleeding. The mean shear wave velocity and angle-corrected splenoportal venous velocity at the main portal and splenic veins were measured 1 day before and 3 to 9 days after TIPS placement (mean interval, 6.0 ± 1.95 days; range, 4-10 days) and were compared with portal vein pressure measured during the procedure. RESULTS: There was a significant difference in portal vein pressure before and after TIPS (25.34 ± 6.21 versus 15.66 ± 6.07 mm Hg; P = .0005). After TIPS, the mean shear wave velocity decreased significantly in all 12 cases (3.50 ± 0.46 versus 3.15 ± 0.39 m/s before and after TIPS; P = .00015). The flow velocity at the main portal vein increased significantly after TIPS (22.21 ± 4.13 versus 47.25 ± 12.37 cm/s; P = .0000051). The splenic vein velocity and spleen index measured 25.57 ± 6.98 cm/s and 55.99 ± 21.27 cm(2), respectively, before TIPS and 35.72 ± 11.10 cm/s and 50.11 ± 21.12 cm(2) after TIPS (P = .0004 and .003). CONCLUSIONS: A significant decrease in the mean shear wave velocity and increase in the splenoportal venous velocity occurred with reduced portal vein pressure after TIPS placement. Hence, both parameters can be used as noninvasive quantitative markers for monitoring TIPS function after placement.

Deconvolution assessment of splenic and splanchnic contributions to portal venous blood flow in liver cirrhosis.

PURPOSE: To devise a noninvasive imaging method for resolving the relative contribution of splenic and splanchnic blood flow to portal venous flow and derive quantitative estimates for parameters pertaining to splenic and portal hemodynamics. METHODS: Tracer concentration-time curves of the aorta, portal vein, and spleen can be extracted from dynamic contrast-enhanced (DCE) CT or MR images. A combination of two tracer analysis approaches, namely arterial-venous sampling and residual tracer deconvolution, is proposed to model these concentration-time curves and derive hemodynamic parameters pertaining to splenic and portal circulation. Clinical feasibility of the proposed method was explored using DCE CT datasets of eight cirrhotic patients. Monte Carlo simulations were performed to evaluate the confidence of the parameter estimates. RESULTS: Portal blood flow was estimated to be 763.8 +/- 438.1 ml/min in cirrhotic patients and the splenic contribution was found to be elevated (0.75 +/- 0.22). Estimates of splenic blood flow (582 +/- 420 ml/min) and transit time (15.3 +/- 10.1 s) in cirrhotic patients were consistent with reported values obtained using duplex Doppler ultrasound and dynamic scintigraphy, respectively. CONCLUSIONS: This study shows the feasibility of noninvasive assessment of splenic and portal hemodynamic parameters by DCE imaging using a combination of tracer kinetics modeling techniques.

Encephalopathy assessment in children with extra-hepatic portal vein obstruction with MR, psychometry and critical flicker frequency.

BACKGROUND & AIMS: Mild cognitive and psychomotor deficit has been reported in patients with extra-hepatic portal vein obstruction. This prospective study was done to ascertain the presence of minimal hepatic encephalopathy by neuropsychological testing and its correlation with diffusion tensor imaging derived metrics, T1 signal intensity, brain metabolites in (1)H magnetic resonance spectroscopy, blood ammonia and critical flicker frequency in patients with extra-hepatic portal vein obstruction. METHODS: Neuropsychological tests, critical flicker frequency, blood ammonia, diffusion tensor imaging, T1 signal intensity and (1)H magnetic resonance spectroscopy were determined in 22 extra-hepatic portal vein obstruction and 17 healthy children. Bonferroni multiple comparison post hoc analysis was done to compare controls with patient groups. RESULTS: Based on neuropsychological tests, 7/22 patients had minimal hepatic encephalopathy, and significantly increased Glx/Cr ratio, blood ammonia, mean diffusivity and globus pallidus T1 signal intensity with decreased critical flicker frequency in comparison to controls and in those without minimal hepatic encephalopathy. Cho/Cr, mI/Cr ratio and fractional anisotropy were unchanged in patient groups compared to controls. A significant inverse correlation of neuropsychological test with mean diffusivity, Glx/Cr ratio and blood ammonia and a positive correlation among mean diffusivity, blood ammonia and Glx/Cr ratio was seen. CONCLUSIONS: Extra-hepatic portal vein obstruction is a true hyperammonia model with porto-systemic shunting and normal liver functions that results in minimal hepatic encephalopathy in one-third of these children. Hyperammonia results in generalized low grade cerebral edema and cognitive decline as evidenced by increased Glx/Cr ratio, mean diffusivity values and abnormal neuropsychological tests.

[Experimental models for assessment of pulmonary alterations in hepatopulmonary syndrome]. / Modelos experimentais para avaliação das alterações pulmonares na síndrome hepatopulmonar.

OBJECTIVE: The aim of this study was to identify the best experimental model in which to observe the pulmonary alterations characterizing hepatopulmonary syndrome (HPS). METHODS: Male Wistar rats, with mean weight of 250 g, were used in four experimental models: inhaled carbon tetrachloride; intraperitoneal carbon tetrachloride; partial portal vein ligation; and bile duct ligation (BDL). The animals in all groups were divided into control and experimental subgroups. The following variables were measured: transaminase levels; blood gases; lipoperoxidation, using thiobarbituric acid reactive substances (TBARS) and chemiluminescence; and levels of superoxide dismutase (SOD) anti-oxidant activity. Anatomopathological examination of the lung was also performed. RESULTS: There were statistically significant differences between the BDL control and BDL experimental groups: aspartate aminotransferase (105.3 +/- 43 vs. 500.5 +/- 90.3 IU/L); alanine aminotransferase (78.75 +/- 37.7 vs. 162.75 +/- 35.4 IU/L); alkaline phosphatase (160 +/- 20.45 vs. 373.25 +/- 45.44 IU/L); arterial oxygen tension (85.25 +/- 8.1 vs. 49.9 +/- 22.5 mmHg); and oxygen saturation (95 +/- 0.7 vs. 73.3 +/- 12.07%). Lipoperoxidation and antioxidant activity also differed significantly between the two BDL groups (control vs. experimental): TBARS (0.87 +/- 0.3 vs. 2.01 +/- 0.9 nmol/mg protein); chemiluminescence (16008.41 +/- 1171.45 vs. 20250.36 +/- 827.82 cps/mg protein); and SOD (6.66 +/- 1.34 vs. 16.06 +/- 2.67 IU/mg protein). The anatomopathological examination confirmed pulmonary vasodilatation in the BDL model. In the other models, there were no alterations that were characteristic of HPS. CONCLUSIONS: The data obtained suggest that the BDL model can be used in future studies involving hepatic alterations related to oxidative stress and HPS.

Modelos experimentais para avaliação das alterações pulmonares na síndrome hepatopulmonar / Experimental models for assessment of pulmonary alterations in hepatopulmonary syndrome

OBJETIVO: O objetivo deste trabalho foi avaliar o melhor modelo experimental para observar alterações pulmonares que caracterizam a síndrome hepatopulmonar (SHP). MÉTODOS: Ratos machos Wistar, com peso médio de 250 g foram usados em quatro modelos experimentais: tetracloreto de carbono inalatório; tetracloreto de carbono intraperitoneal; ligadura parcial de veia porta; e ligadura de ducto biliar (LDB). Em todos os grupos os animais foram divididos em controle e experimental. Foram avaliadas as seguintes variáveis: transaminases; gasometria; lipoperoxidação por substâncias que reagem ao ácido tiobarbitúrico (TBARS) e por quimiluminescência; e atividade antioxidante da enzima superóxido dismutase (SOD). Foi feito também o exame anatomopatológico do pulmão. RESULTADOS: Observou-se diferenças significativas entre os grupos LDB controle e experimental: aspartato amino transferase (105,3 ± 43 vs. 500,5 ± 90,3 UI/L); alanino aminotransferase (78,75 ± 37,7 vs. 162,75 ± 35,4 UI/L); fosfatase alcalina (160 ± 20,45 vs. 373,25 ± 45,44 UI/L); pressão parcial de oxigênio (85,25 ± 8,1 vs. 49,9 ± 22,5 mmHg); e saturação de hemoglobina (95 ± 0,7 vs. 73,3 ± 12,07 por cento). A lipoperoxidação e a atividade antioxidante também demonstrou diferenças entre os dois grupos LDB (controle vs. experimental): TBARS (0,87 ± 0,3 vs. 2,01 ± 0,9 nmol/mg proteína); quimiluminescência (16008,41 ± 1171,45 vs. 20250,36 ± 827,82 cps/mg proteína); e SOD (6,66 ± 1,34 vs. 16,06 ± 2,67 UI/mg proteína). No exame anatomopatológico observou-se vasodilatação pulmonar no modelo de LDB. CONCLUSÕES: Os dados sugerem que o modelo de LDB pode ser usado para outros estudos envolvendo alterações hepáticas e suas relações com o estresse oxidativo e a SHP.

OBJECTIVE: The aim of this study was to identify the best experimental model in which to observe the pulmonary alterations characterizing hepatopulmonary syndrome (HPS). METHODS: Male Wistar rats, with mean weight of 250 g, were used in four experimental models: inhaled carbon tetrachloride; intraperitoneal carbon tetrachloride; partial portal vein ligation; and bile duct ligation (BDL). The animals in all groups were divided into control and experimental subgroups. The following variables were measured: transaminase levels; blood gases; lipoperoxidation, using thiobarbituric acid reactive substances (TBARS) and chemiluminescence; and levels of superoxide dismutase (SOD) anti-oxidant activity. Anatomopathological examination of the lung was also performed. RESULTS: There were statistically significant differences between the BDL control and BDL experimental groups: aspartate aminotransferase (105.3 ± 43 vs. 500.5 ± 90.3 IU/L); alanine aminotransferase (78.75 ± 37.7 vs. 162.75 ± 35.4 IU/L); alkaline phosphatase (160 ± 20.45 vs. 373.25 ± 45.44 IU/L); arterial oxygen tension (85.25 ± 8.1 vs. 49.9 ± 22.5 mmHg); and oxygen saturation (95 ± 0.7 vs. 73.3 ± 12.07 percent). Lipoperoxidation and antioxidant activity also differed significantly between the two BDL groups (control vs. experimental): TBARS (0.87 ± 0.3 vs. 2.01 ± 0.9 nmol/mg protein); chemiluminescence (16008.41 ± 1171.45 vs. 20250.36 ± 827.82 cps/mg protein); and SOD (6.66 ± 1.34 vs. 16.06 ± 2.67 IU/mg protein). The anatomopathological examination confirmed pulmonary vasodilatation in the BDL model. In the other models, there were no alterations that were characteristic of HPS. CONCLUSIONS: The data obtained suggest that the BDL model can be used in future studies involving hepatic alterations related to oxidative stress and HPS.

[Assessment of hemodynamics in patients with Budd-Chiari syndrome after interventional treatment].

OBJECTIVE: To study the changes in morphology of liver and spleen and hemodynamics of the patients with Budd-Chiari syndrome (BCS) after interventional treatment. METHODS: The dimensions of liver and spleen were detected by routine ultrasonography in 30 normal control subjects and 256 BCS patients before and after inventional therapy. Color duplex sonography was employed to measure the hemodynamic changes. RESULTS: Compared with the control group, BCS patients before interventional therapy showed obvious liver and spleen enlargements (P<0.005), specially the caudate lobe of the liver (P<0.001), which were significantly reduced 7 days after interventional treatment (P<0.005), but the spleen was still larger than that of the control group (P<0.005) even till 6 months after the therapy. Color Doppler flow imaging (CDFI) revealed local high-speed blood flow in patients with stenosis of the inferior vena cave (IVC), but color flow was not detected in patients with IVC obstruction, who had hepatic vein dilation (P<0.005) with slowed blood flow and collateral formation of in the liver, as well as decreased velocity of blood flow in the portal vein. After interventional treatment, the diameter of the involved IVC increased with blood flow restoration and the size and shape of the stent were detected clearly. The velocity of blood flow was increased in both the hepatic and portal veins (P<0.005). CONCLUSION: Interventional therapy can relieve obstruction of blood flow in the liver and improve the hemodynamics of patients with BCS.

The assessment of pancreatic exocrine function by bentiromide test in patients with chronic portal vein thrombosis.

INTRODUCTION: It has been noted in the literature that cavernous transformation of the portal vein (CTPV) can cause pancreatic duct atrophy, probably by enhanced collateral formation, but the clinical significance of this has not been established. AIMS: To evaluate whether CTPV affects the pancreatic exocrine functions. METHODOLOGY: Eighteen patients with CTPV were identified and prospectively studied. In these cases, despite a full clinical, biochemical, radiologic, and hematological evaluation, we found no etiologic factor for thrombosis in the portal vein (PV). All patients underwent a detailed evaluation for pancreatic morphology and pancreatic exocrine functions. In all cases, abdominal Doppler ultrasonography (US), abdominal spiral computed tomography (CT), and endoscopic retrograde cholangiopancreatography (ERCP) were performed for evaluation of pancreatic morphology. For the purpose of this study, serial biochemical tests, including measurement of serum amylase, pancreatic amylase, lipase, glucose, calcium, and lipids, were performed every 3 months. All 18 patients also underwent a bentiromide test to determine whether there was any exocrine pancreatic insufficiency. The findings were compared with those for 20 healthy control subjects and reference controls. RESULTS: For all 18 patients with idiopathic CTPV and all controls, ERCP was performed successfully. The pancreatic duct was determined to be smaller than in control subjects and in a reference control group ( < 0.05). In this group serum pancreatic amylase, alkaline phosphatase, and direct bilirubin levels were found to be higher than in controls, and statistically important differences between the two groups ( < 0.05) were documented. In all 18 subjects the bentiromide test was well tolerated and was performed successfully. For 15 of them (83%), we found that urinary excretion of para-amino benzoic acid (PABA) was significantly less than in control subjects and the reference control group ( < 0.05). CONCLUSION: Pancreatic duct atrophy in patients with CTPV is clinically significant. When clinical signs are not manifest and routine biochemical tests are not useful for detecting exocrine pancreatic insufficiency, the bentiromide test is highly sensitive and specific for detecting probable pancreatic insufficiency in patients with CTPV.

Hepatic arterial blood flow in large hepatocellular carcinoma with or without portal vein thrombosis: assessment by transcutaneous duplex Doppler sonography.

BACKGROUND: As liver cirrhosis progresses, the portal venous blood (PVBF) flow decreases, accompanied by an increase in hepatic arterial blood flow. Large hepatocellular carcinoma is a hypervascular tumour with a rapid growth, which seems to require an increase of the tumoral arterial blood flow. Furthermore, hepatocellular carcinoma is frequently associated with portal vein thrombosis, which subsequently impedes portal blood supply. METHODS: The purpose of our study was to estimate alterations in the hepatic arterial blood flow in large hepatocellular carcinomas occurring in liver cirrhosis, in comparison with liver cirrhosis and controls. Liver blood flow measurements were determined by duplex Doppler sonography in 47 patients with large hepatocellular carcinomas (13 with portal vein thrombosis and 34 without this thrombosis), 42 liver cirrhosis patients and 30 controls. The Doppler perfusion index was calculated as the ratio of hepatic arterial blood flow to total hepatic blood flow. RESULTS: The patients with liver cirrhosis had a significant increase of hepatic arterial blood flow as compared to controls (P < 0.001), accompanied by a significant reduction in PVBF (P < 0.005). As a result, the Doppler perfusion index was increased in patients with liver cirrhosis as compared to controls (P < 0.001). The hepatic arterial blood flow was increased in patients with hepatocellular carcinoma but without portal vein thrombosis as compared to the cirrhotic patients (P < 0.001), with a significant reduction of PVBF (P < 0.001). Hepatic arterial blood flow was also increased in patients with both hepatocellular carcinoma and portal vein thrombosis as compared to the patients without this thrombosis (P < 0.001). CONCLUSION: These results suggest that in large hepatocellular carcinomas there is a decreased PVBF, accompanied by an increased hepatic arterial blood flow. The hepatic arterial buffer response seems to be active in hepatocellular carcinomas and maintains liver perfusion to adequate levels.

Pharmacologically stimulated portal flow measurement by magnetic resonance imaging for assessment of liver function.

PURPOSE: To evaluate pharmacologically stimulated portal flow measured by magnetic resonance (MR) imaging for assessment of liver function. MATERIALS AND METHODS: Pharmacologically stimulated portal flow was measured by phase contrast MR imaging in 27 patients when they were undergoing abdominal angiography for liver tumors or gall bladder cancer. The patients included 11 cases of liver cirrhosis and eight of chronic hepatitis. Pharmacological stimulation was done by infusion of 10 microg/Kg of nicardipine hydrochloride into the superior mesenteric artery through an angiographic catheter. We examined the correlation between stimulated or non-stimulated portal flow and biochemical liver function tests. RESULTS: Correlation coefficients and their corresponding p values between non-stimulated portal flow and the indocyanine green residual rate at 15 min after injection (ICG R15), serum albumin (ALB), total bilirubin (TB), cholinesterase (CHE), and hepaplastin test (HP) were--0.414 (0.056), 0.296 (0.134), -0.570 (0.002), 0.289 (0.153), and 0.321 (0.126), respectively, whereas those between stimulated portal flow and ICG R15, ALB, TB, CHE, and HP were--0.561 (0.007), 0.411 (0.033), -0.509 (0.007), 0.445 (0.023), and 0.494 (0.014), respectively. CONCLUSION: Stimulated portal flow showed better correlations with biochemical liver function tests than non-stimulated portal flow. It is suggested that stimulated portal flow measurement is more useful for the evaluation of liver function than non-stimulated portal flow measurement.

[Quantitative assessment of portal vein flow in subjects with active chronic hepatitis: comparison of magnetic resonance angiography with bolus tracking with color Doppler ultrasonography]. / Determinazione quantitativa del flusso nella vena porta nei soggetti con epatopatia cronica attiva: confronto tra angiografia con risonanza magnetica con bolo di protoni marcati ed eco color Doppler.

PURPOSE: To assess the accuracy of time-of-flight MR Angiography (MRA) with bolus tracking in evaluating mean blood velocity and flowrate in the portal vein in patients with chronic hepatitis versus healthy volunteers. MATERIAL AND METHODS: Fifteen patients with clinically-defined post-viral chronic hepatitis (viruses B and C) were examined with bolus tracking MRA and color Doppler US to evaluate portal blood flow. Both examinations were performed before and after a 1500 kcal meal. We evaluated mean blood flow velocity and flowrate in the portal vein. MRA results were compared with color Doppler findings; the results in chronic hepatitis patients were compared with those of healthy volunteers. RESULTS: The correlation between mean portal blood velocity, as measured with MRA and color Doppler US, was r = .82 before and r = .79 after the meal. There was no significant difference in mean velocity between the chronic hepatitis patients and the healthy volunteers. The correlation between portal flowrate, as measured with MRA and color Doppler US, was r = .87 before and r = .91 after the meal. There was no significant difference in mean flowrate between the chronic hepatitis patients and the healthy volunteers. In contrast, there were significant differences in mean velocity and portal flowrate, as measured with MRA before the meal, between the chronic hepatitis patients and the healthy volunteers. DISCUSSION AND CONCLUSIONS: Bolus tracking MRA is superior to color Doppler US in quantitating blood flow in the portal vein and evaluating changes after a meal. Decreased mean velocity and flowrate may indicate impaired function, as it happens in early chronic hepatitis.

Doppler ultrasound assessment of TIPS patency and function--the need for echo enhancers.

PURPOSE: The aim of this study was to illustrate the versatility of an i.v. administered echo enhancer for Doppler US assessment of TIPS patency and function. MATERIAL AND METHODS: A total of 22 Doppler US evaluations of TIPS patency and function were performed in 5 patients with alcoholic cirrhosis and recurrent oesophageal bleeding who had been treated with TIPS. TIPS patency was evaluated by means of colour or power Doppler US. The volume flow (VF) was assessed in the TIPS and in the portal vein by spectral Doppler. The ratio of the VF in the TIPS to the VF in the portal vein (T/P ratio) was used to express the functional status of the TIPS. If Doppler signals were inconclusive or absent, echo-enhanced US was performed. RESULTS: In 22 follow-up Doppler US examinations, echo-enhanced Doppler US was required in 7 cases (29%). The Doppler enhancement persisted in the range of 3-5 min. No adverse effects were observed. An apparently normal TIPS function reflected a T/P ratio in the range of 0.44-1.10, median 0.78 +/- 0.20 (2SD). CONCLUSION: The i.v. administration of echo enhancers would seem to be indicated in the assessment of the TIPS function if conventional Doppler US fails to prove normal TIPS patency and function. The T/P ratio may be a convenient monitoring parameter for reflecting the TIPS function.

Assessment of hepatic portal perfusion using T2 measurements of Gd-DTPA.

Recently, perfusion imaging has been of increasing interest in MRI. We applied this method for semiquantitative evaluation of hepatic parenchymal portal blood flow in patients with diffuse liver damage. Twenty patients with diffuse hepatic damage were divided according to the Child's Classification and studied. Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was administered into the superior mesenteric artery (SMA), and a dynamic series of T2*-weighted fast low angle shot (FLASH) images was obtained. We evaluated relative regional portal blood volume (rrPBV), mean transit time (MTT), and relative regional portal blood flow (rrPBF). The relationship between the rrPBV, rrPBF, and plasma indocyanine green retention rate test at 15 minutes (ICGR15 was also evaluated in 12 patients. Both rrPBF and rrPBV are significantly decreased in Child B & C patients compared with Child A patients. On the other hand, the MTT is significantly prolonged in Child B & C patients compared with Child A patients. Significant correlations were also noted between rrPBV and ICGR15 and between rrPBF and ICGR15. By means of selective catheterization into the SMA, we were able to estimate rrPBV, rrPBF, and MTT. This method may play a clinical role for assessment of regional portal perfusion in various diseases with diffuse liver damage.

Portal and splanchnic haemodynamics in patients with advanced post-hepatitic cirrhosis and in healthy adults. Assessment with duplex Doppler ultrasound.

PURPOSE: To assess portal and splanchnic haemodynamics, and splanchnic vascular resistance in patients with advanced post-hepatitic cirrhosis and in healthy volunteers, by means of duplex Doppler ultrasound (US). MATERIAL AND METHODS: The duplex Doppler US examination was performed in 16 patients with cirrhosis and in 24 healthy volunteers. We investigated vessel diameters, mean flow velocities, and mean blood flows in the portal vein, the superior mesenteric artery (SMA), and the splenic artery (SA), and measured the resistive index values of SMA and SA. RESULTS: The mean portal venous blood flow in patients with cirrhosis (829 +/- 264 ml/min) was not statistically different from those in the volunteers (734 +/- 194 ml/min). The ratio of the SMA and SA blood flows (621 ml/min) to the portal venous blood flow (734 ml/min) was 0.85 in the control subjects. The mean portal venous blood flow (1261 ml/min) and the portal venous velocity (14.6 cm/s) were higher in the patients with recanalized para-umbilical veins than in the volunteers and in the patients without recanalized para-umbilical veins. The SMA and SA blood flows were significantly increased in patients with cirrhosis compared with volunteers. Splanchnic inflow (the sum of the SMA and SA blood flows) was higher than the portal blood flow in patients with cirrhosis except in the subjects with recanalized para-umbilical veins. SMA and SA resistive index values were significantly higher in these patients than in the volunteers. CONCLUSION: Splanchnic blood flow and splanchnic vascular impedance increased significantly in patients with advanced post-hepatitic cirrhosis. Splanchnic inflow must not exceed portal venous blood flow in patients with recanalized para-umbilical veins. Portal vein velocity and portal venous blood flow measurements alone are not useful parameters for discriminating patients with cirrhosis from healthy subjects.