Detection and differentiation of early hepatocellular carcinoma from cirrhosis using CT perfusion in a rat liver model

BACKGROUND

Functional imaging such as CT perfusion can detect morphological and hemodynamic changes in hepatocellular carcinoma (HCC). Pre-carcinoma and early HCC nodules are difficult to differentiate by observing only their hemodynamics changes. The present study aimed to investigate hemodynamic parameters and evaluate their differential diagnostic cut-off between pre-carcinoma and early HCC nodules using CT perfusion and receiver operating characteristic (ROC) curves.

METHODS

Male Wistar rats were randomly divided into control (n=20) and experimental (n=70) groups. Diethylnitrosamine (DEN) was used to induce pre-carcinoma and early HCC nodules in the experimental group. Perfusion scanning was carried out on all survival rats discontinuously from 8 to 16 weeks. Hepatic portal perfusion (HPP), hepatic arterial fraction (HAF), hepatic arterial perfusion (HAP), hepatic blood volume (HBV), hepatic blood flow (HBF), mean transit time (MTT) and permeability of capillary vessel surface (PS) data were provided by mathematical deconvolution model. The perfusion parameters were compared among the three groups of rats (control, pre-carcinoma and early HCC groups) using the Kruskal-Wallis test and analyzed with ROC curves. Histological examination of the liver tissues with hematoxylin and eosin staining was performed after CT scan.

RESULTS

For HPP, HAF, HBV, HBF and MTT, there were significant differences among the three groups (P<0.05). HAF had the highest areas under the ROC curves: 0.80 (control vs pre-carcinoma groups) and 0.95 (control vs early HCC groups) with corresponding optimal cut-offs of 0.37 and 0.42, respectively. The areas under the ROC curves for HPP was 0.79 (control vs pre-carcinoma groups) and 0.92 (control vs early HCC groups) with corresponding optimal cut-offs of 136.60 mL/min/100 mg and 108.47 mL/min/100 mg, respectively.

CONCLUSIONS

CT perfusion combined with ROC curve analysis is a new diagnosis model for distinguishing between pre-carcinoma and early HCC nodules. HAF and HPP are the ideal reference indices.

Establishment of a hepatic cirrhosis and portal hypertension model by hepatic arterial perfusion with 80% alcohol

AIM: To determine the feasibility and safety of establishing a porcine hepatic cirrhosis and portal hypertension model by hepatic arterial perfusion with 80% alcohol.

METHODS: Twenty-one healthy Guizhou miniature pigs were randomly divided into three experimental groups and three control groups. The pigs in the three experimental groups were subjected to hepatic arterial perfusion with 7, 12 and 17 mL of 80% alcohol, respectively, while those in the three control groups underwent hepatic arterial perfusion with 7, 12 and 17 mL of saline, respectively. Hepatic arteriography and direct portal phlebography were performed on all animals before and after perfusion, and the portal venous pressure and diameter were measured before perfusion, immediately after perfusion, and at 2, 4 and 6 wk after perfusion. The following procedures were performed at different time points: routine blood sampling, blood biochemistry, blood coagulation and blood ammonia tests before surgery, and at 2, 4 and 6 wk after surgery; hepatic biopsy before surgery, within 6 h after surgery, and at 1, 2, 3, 4 and 5 wk after surgery; abdominal enhanced computed tomography examination before surgery and at 6 wk after surgery; autopsy and multi-point sampling of various liver lobes for histological examination at 6 wk after surgery.

RESULTS: In experimental group 1, different degrees of hepatic fibrosis were observed, and one pig developed hepatic cirrhosis. In experimental group 2, there were cases of hepatic cirrhosis, different degrees of increased portal venous pressure, and intrahepatic portal venous bypass, but neither extrahepatic portal-systemic bypass circulation nor death occurred. In experimental group 3, two animals died and three animals developed hepatic cirrhosis, and different degrees of increased portal venous pressure and intrahepatic portal venous bypass were also observed, but there was no extrahepatic portal-systemic bypass circulation.

CONCLUSION: It is feasible to establish an animal model of hepatic cirrhosis and portal hypertension by hepatic arterial perfusion with 80% alcohol, however, the safety of this model depends on a suitable perfusion dose.

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.

Contrast-enhanced ultrasonography for the evaluation of liver fibrosis after biliary obstruction

AIM: To investigate perfusion change in contrast-enhanced ultrasonography (CEUS) to evaluate liver fibrosis based on biliary obstruction using an animal model.

METHODS: New Zealand white rabbits (3-4 kg) underwent bile duct ligation to form a biliary obstruction model. We performed liver CEUS and laboratory tests on the day before the operation (day 0) and every 7 postoperative days until the rabbits were sacrificed. After CEUS, signal intensity of liver parenchyma with a time-intensity curve was analyzed. Perfusion parameters were automatically calculated from region-of-interests, including peak signal intensity, mean transit time, area under the curve and time to peak. Histological grades of liver fibrosis were assessed according to the Metavir score system immediately after sacrifice. Generalized estimating equations were used to analyze the association between liver fibrosis grades and perfusion parameters for statistical analysis. The perfusion parameters were measured on the last day and the difference between day 0 and the last day were evaluated.

RESULTS: From the nine rabbits, histological grades of liver fibrosis were grade 1 in one rabbit, grade 2 and 3 in three rabbits each, and grade 4 in two rabbits. Among the four CEUS parameters, only the peak signal intensity measured on the last day demonstrated a significant association with liver fibrosis grades (OR = 1.392, 95%CI: 1.114-1.741, P = 0.004). The difference in peak signal intensity between day 0 and the last day also demonstrated an association with liver fibrosis (OR = 1.191, 95%CI: 0.999-1.419, P = 0.051). The other parameters tested, including mean transit time, area under the curve, and time to peak, showed no significant correlation with liver fibrosis grades.

CONCLUSION: This animal study demonstrates that CEUS can be used to evaluate liver fibrosis from biliary obstruction using peak signal intensity as a parameter.

Window-modulated compounding Nakagami imaging for ultrasound tissue characterization

Ultrasound Nakagami parametric imaging is a useful tool for tissue characterization. Previous literature has suggested using a square with side lengths corresponding to 3 times the transducer pulse length as the minimum window for constructing the Nakagami image. This criterion does not produce sufficiently smooth images for the Nakagami image to characterize homogeneous tissues. To improve image smoothness, we proposed window-modulated compounding (WMC) Nakagami imaging based on summing and averaging the Nakagami images formed using sliding windows with varying window side lengths from 1 to N times the transducer pulse length in 1 pulse length step. Simulations (the number densities of scatterers: 2-16 scatterers/mm(2)) and experiments on fully developed speckle phantoms (the scatterer diameters: 20-106 μm) were conducted to suggest an appropriate number of frames N and to evaluate the image smoothness and resolution by analyzing the full width at half maximum (FWHM) of the parameter distribution and the widths of the image autocorrelation function (ACF), respectively. In vivo ultrasound measurements on rat livers without and with cirrhosis were performed to validate the practical performance of the WMC Nakagami image in tissue characterization. The simulation results showed that using a range of N from 7 to 10 as the number of frames for image compounding reduces the estimation error to less than 5%. Based on this criterion, the Nakagami parameter obtained from the WMC Nakagami image increased from 0.45 to 0.95 after increasing the number densities of scatterers from 2 to 16 scatterers/mm(2). The FWHM of the parameter distribution (bins=40) was 13.5±1.4 for the Nakagami image and 9.1±1.43 for the WMC Nakagami image, respectively (p-value<.05). The widths of the ACF for the Nakagami and WMC Nakagami images were 454±5.36 and 458±4.33, respectively (p-value>.05). In the phantom experiments, we also found that the FWHM of the parameter distribution for the WMC Nakagami image was smaller than that of the conventional Nakagami image (p-value<.05), and there was no significant difference of the ACF width between the Nakagami and WMC Nakagami images (p-value>.05). In the animal experiments, the Nakagami parameters obtained from the WMC Nakagami image for normal and cirrhotic rat livers were 0.62±0.08 and 0.92±0.07, respectively (p-value<.05). The results demonstrated that the WMC technique significantly improved the image smoothness of Nakagami imaging without resolution degradation, giving Nakagami model-based imaging the ability to visualize scatterer properties with enhanced image quality.

Fast and accurate X-ray fluorescence computed tomography imaging with the ordered-subsets expectation maximization algorithm

The ordered-subsets expectation maximization algorithm (OSEM) is introduced to X-ray fluorescence computed tomography (XFCT) and studied; here, simulations and experimental results are presented. The simulation results indicate that OSEM is more accurate than the filtered back-projection algorithm, and it can efficiently suppress the deterioration of image quality within a large range of angular sampling intervals. Experimental results of both an artificial phantom and cirrhotic liver show that with a satisfying image quality the angular sampling interval could be improved to save on the data-acquisition time when OSEM is employed. In addition, with an optimum number of subsets, the image reconstruction time of OSEM could be reduced to about half of the time required for one subset. Accordingly, it can be concluded that OSEM is a potential method for fast and accurate XFCT imaging.

Using ultrasound Nakagami imaging to assess liver fibrosis in rats

This study explored the feasibility of using the ultrasound Nakagami image to assess the degree of liver fibrosis in rats. The rat has been widely used as a model in investigations of liver fibrosis. Ultrasound grayscale imaging makes it possible to observe fibrotic rat livers in real time. Statistical analysis of the envelopes of signals backscattered from rat livers may provide useful clues about the degree of liver fibrosis. The Nakagami-model-based image has been shown to be useful for characterizing scatterers in tissues by reflecting the echo statistics, and hence the Nakagami image may serve as a functional imaging tool for quantifying rat liver fibrosis. To validate this idea, fibrosis was induced in each rat liver (n=21) by an intraperitoneal injection of 0.5% dimethylnitrosamine. Livers were excised from rats for in vitro ultrasound scanning using a single-element transducer. The backscattered-signal envelopes of the acquired raw ultrasound signals were used for Nakagami imaging. The Metavir score determined by a pathologist was used to histologically quantify the degree of liver fibrosis. It was found that the Nakagami image could be used to distinguish different degrees of liver fibrosis in rats, since the average Nakagami parameter increased from 0.55 to 0.83 as the fibrosis score increased from 0 (i.e., normal) to 4. This correlation may be due to liver fibrosis in rats involving an increase in the concentration of local scatterers and the appearance of the periodic structures or clustering of scatterers that would change the backscattering statistics. The current findings indicate that the ultrasound Nakagami image has great potential as a functional imaging tool to complement the use of the conventional B-scan in animal studies of liver fibrosis.

In vivo quantification of liver stiffness in a rat model of hepatic fibrosis with acoustic radiation force

Liver fibrosis is currently staged using needle biopsy, a highly invasive procedure with a number of disadvantages. Measurement of liver stiffness changes that accompany progression of the disease may provide a quantitative and noninvasive method to assess the health of the liver. The purpose of this study is to investigate the correlation between liver stiffness measured by radiation force induced shear waves and disease related changes in the liver. An additional aim is to present initial findings on the effects of liver viscosity on radiation force induced shear wave morphology. Liver fibrosis was induced in 10 rats using carbon tetrachloride (CCl(4)), while five rats acted as controls. Liver stiffness was measured in vivo in all rats after a treatment period of 8 weeks using a modified Siemens SONOLINE Antares scanner (Siemens Medical Solutions USA, Ultrasound Division, Issaquah, WA, USA). The spatial coherence of radiation force induced shear waves propagating in the viscoelastic rat liver decreased significantly with propagation distance, compared with shear waves in an elastic phantom and a finite element model of a purely elastic medium. Animals were sacrificed after imaging and liver samples were taken for histopathologic analysis and collagen quantification using picrosirius red staining and hydroxyproline assay. At the end of the treatment period, five rats had healthy livers (stage F0), while six had severe fibrosis (F3) and the rest had light to moderate fibrosis (F1 and F2). The measured liver stiffness for the F0 group was 1.5+/-0.1 kPa (mean+/-95% confidence interval) and for F3 livers was 1.8+/-0.2 kPa. In this study, liver stiffness was found to be linearly correlated with the amount of collagen in the liver measured by picrosirius red staining (r(2)=0.43, p=0.008). In addition, stiffness spatial heterogeneity was also linearly correlated with liver collagen content (r(2)=0.58, p=0.001) by picrosirius red staining. These results are consistent with those obtained by Salameh et al. (2007) and Yin et al. (2007b) using animal models of liver fibrosis and MR elastography. This suggests that stiffness measurement using acoustic radiation force can provide a quantitative assessment of the extent of fibrosis in the liver and can be potentially used for the diagnosis, management and study of liver fibrosis.

[Establishment of liver fibrosis in rabbit model and quantitative study on hepatic perfusion with dynamic whole-liver 3D MR imaging]

OBJECTIVE

To investigate the ideal approach in creating rabbit model of hepatic fibrosis and to evaluate the feasibility and value of dynamic whole-liver 3D magnetic resonance (MR) perfusion-weighted imaging (PWI) in the quantitative study on the staging of hepatic fibrosis.

METHODS

Rabbit model of hepatic fibrosis was created by intraperitoneal injection of 5% and 100% carbon tetrachloride (0.1 ml/kg, once a week) respectively. MR perfusion weighted imaging was performed at the 6th, 8th, 10th and 12th week since injection. The time of peak (TOP), the time to peak (TTP), the maximum slope of increase(MSI) and the maximal relative signal increase (MRSI) of portal vein and hepatic parenchyma were analyzed quantitatively, and were compared with pathological results. Comparison of different concentrations of CCl4 was analyzed using chi-square test. Inter-group comparison of perfusion parameters was analyzed using one-way ANOVA P less than 0.05 was regarded as statistically significant.

RESULTS

40% of the rabbits treated with 5% carbon tetrachloride developed hepatic fibrosis, while 75% of the rabbits treated with 100% carbon tetrachloride developed hepatic fibrosis; the mortality rate is significantly different between these two groups (X2=5.013, P less than 0.05). PWI examination was successfully achieved in 31 rabbits, liver perfusion baseline was stable, and good TIC curve was obtained. With the progress of hepatic fibrosis, TOP and TTP of portal vein and hepatic parenchyma were increased, and MSI and MRSI were decreased. There were significant differences among stage of S0-S2, S3 and S4.

CONCLUSIONS

The method (100% carbon tetrachloride intraperitoneal injection, 0.1 ml/kg, once a week) has high success rate of creating rabbit model of hepatic fibrosis. The stage of hepatic fibrosis could be evaluated quantitatively with dynamic whole-liver 3D MR perfusion-weighted imaging.

An ultrasound and histomorphological analysis of experimental liver cirrhosis in rats

We investigated whether liver injury by dual exposure to ethanol and carbon tetrachloride (EtOH + CCl4) for 15 weeks would persist after hepatotoxic agents were removed (EtOH + CCl4/8wR). After 15 weeks of hepatic injury with ethanol (5.5%, m/v) and carbon tetrachloride (0.05, mL/kg, ip), 5 of 11 female Wistar rats were sacrificed. The other 6 rats were maintained for an additional 8 weeks without hepatotoxic agents. Ultrasonography showed increased liver echogenicity and dilation of portal vein caliber in both groups (EtOH + CCl4: 0.22 +/- 0.01 cm, P < 0.001; EtOH + CCl4/8wR: 0.21 +/- 0.02 cm, P < 0.01) vs control (0.16 +/- 0.02 cm). Histopathology showed regenerative nodules in both experimental groups. Histomorphometry revealed increased fibrosis content in both groups (EtOH + CCl4: 12.6 +/- 2.64%, P < 0.001; EtOH + CCl4/8wR: 10.4 +/- 1.36%, P < 0.05) vs control (2.2 +/- 1.21%). Collagen types I and III were increased in groups EtOH + CCl4 (collagen I: 2.5 +/- 1.3%, P < 0.01; collagen III: 1.3 +/- 0.2%, P < 0.05) and EtOH + CCl4/8wR (collagen I: 1.8 +/- 0.06%, P < 0.05; collagen III: 1.5 +/- 0.8%, P < 0.01) vs control (collagen I: 0.38 +/- 0.11%; collagen III: 0.25 +/- 0.06%). Tissue transglutaminase increased in both groups (EtOH + CCl4: 66.4 +/- 8%, P < 0.01; EtOH + CCl4/8wR: 58.8 +/- 21%, P < 0.01) vs control (7.9 +/- 0.8%). Cirrhosis caused by the association of CCl4-EtOH remained for at least 8 weeks after removal of these hepatotoxic agents. Ultrasound images can be a useful tool to evaluate advanced hepatic alterations.

Experimental study on the relation between the noninvasive ultrasonography quantitative scoring system and the degree of the hepatic fibrosis

BACKGROUND/AIMS

The fibrosis models were constructed in the experimental rats which underwent complex fibrosis models methods, and the aim was to assess the value of noninvasive ultrasonography quantitative scoring system in the diagnosis of hepatic fibrosis using high-frequency ultrasonography unit.

METHODOLOGY

Thirty-five male rats were included in this study. The fibrosis models were constructed in the 35 experimental rats which underwent complex fibrosis models methods. Ultrasonography, serum fibrosis markers were submitted in week 0, week 2, week 4, and week 6, during the construction of fibrosis models, which were also detected with pathological diagnosis. Ultrasonography quantitative scoring system was used to discriminate the degree of hepatic fibrosis, and the results were compared with pathological diagnosis.

RESULTS

The complex fibrosis models methods can be used to construct hepatic fibrosis model. The ultrasonography quantitative scoring system had a higher relativity to pathological stage (r=0.86), when it was combined with serum fibrosis markers, the sensitivity (96.5%) and specificity (95.8%) were increased.

CONCLUSIONS

High-frequency ultrasonography appears to be an efficient tool allowing new possibilities to use this animal model, ultrasonography quantitative scoring system, especially when it was combined with CT, serum fibrosis markers, had a higher value in noninvasive quantitative diagnosis of hepatic fibrosis in longitudinal studies, which are much more powerful.

[Three-dimensional assessment of the remnant hepatic function following surgery using single photon emission computed tomography in an animal model]

OBJECTIVE

The predictive value of postoperative hepatic function evaluated by liver functional imaging combined with single photon emission computed tomography (SPECT) technique was appraised in the present study.

METHODS

Twenty New Zealand white rabbits were divided randomly into two groups, including the Hepatic Fibrosis with Carcinoma Group (FC-Group, n = 10) and the Control Group (C-Group, n = 10). All the rabbits underwent the resection of outer-right lobe of the liver. The whole hepatic function indexes, such as HCI(5), HLI(5) and Ex(15), and the hepatic function remnant indexes, including HCI(5P), HLI(5P) and Ex(15P), were calculated by 99mTc-EHIDA liver imaging.

RESULTS

Ex(15) of FC-Group was lower than that of C-Group (P < 0.05). HCI(5) and HLI(5) of FC-Group had the trends to increase compared with the C-Group. Ex(15) was positively correlated with ALB, and negatively correlated with TBil and GGT (P < 0.05). HCI(5) had a positive correlation with CHE (P < 0.05), while HLI(5) had a negative correlation with A/G (P < 0.05). HLI(5P) had the negative correlation with postoperative A/G (P < 0.05), and Ex(15P) had the negative correlation with postoperative TBil and GGT (P < 0.05).

CONCLUSIONS

This study has established a method of 3-D liver function evaluation system on an animal model. Among the indexes, Ex(15) can exactly represent the whole liver function while Ex(15P) and HLI(5P) can predict the liver function after the liver resection. The results may help the future clinical use of this technique to evaluate the risk of operation.

Neighborhood-pixels algorithm combined with Sono-CT in the diagnosis of cirrhosis: an experimental study

The goal was to investigate the role of neighborhood-pixels algorithm (NPA) in analyzing the echogram of experimental cirrhosis and the value of high frequency real-time compound imaging (Sono-CT) in improving texture analysis. A cirrhosis model was established by subcutaneously injecting CCl(4) in 80 rats. The total group of rats were divided into a control group and four treatment groups (treated for 6, 8, 10 and 12, weeks respectively). The texture of hepatic-echograms was analyzed using a "neighborhood-pixels" algorithm. Images were obtained under conventional imaging mode and Sono-CT, respectively. The second texture parameter (FP(2)) was estimated and compared in different groups and under different modes. FP(2) increased gradually with the time of treatment and group differences were significant (p < 0.01). In these groups, FP(2) was higher under Sono-CT than under conventional condition (p < 0.01) and group differences in FP(2) under both conditions were significant (p < 0.01). Thus, FP(2) measured by neighborhood-pixels algorithm can reflect the dynamic change of the texture of echogram of cirrhosis in rats and Sono-CT can improve texture analysis by neighborhood-pixels algorithm, thus facilitating the early diagnosis of cirrhosis.

Structural requirements for in vivo detection of cell death with 99mTc-annexin V

(99m)Tc-Annexin V is used to image cell death in vivo via high-affinity binding to exposed phosphatidylserine. We investigated how changes in membrane-binding affinity, molecular charge, and method of labeling affected its biodistribution in normal mice and its uptake in apoptotic tissues.

METHODS

An endogenous Tc chelation site (Ala-Gly-Gly-Cys-Gly-His) was added to the N-terminus of annexin V to create annexin V-128. The membrane-binding affinity of annexin V-128 was then progressively reduced by 1-4 mutations in calcium-binding sites. In addition, mutations were made in other residues that altered molecular charge without altering membrane-binding affinity. All mutant proteins were labeled with (99m)Tc at the same N-terminal endogenous chelation site. Wild-type annexin V was also labeled with (99m)Tc after derivatization with hydrazinonicotinamide (HYNIC). Radiolabeled proteins were tested for biodistribution in normal mice and in mice treated to induce apoptosis of the liver.

RESULTS

Comparison of (99m)Tc-annexin V-128 with (99m)Tc-HYNIC-annexin V showed that the protein labeled at the endogenous chelation site had the same or higher uptake in apoptotic tissues, while showing 88% lower renal uptake at 60 min after injection. The blood clearance of annexin V was unaffected by changes in either the membrane-binding affinity or the molecular charge. Kidney uptake was unaffected by changes in binding affinity. In marked contrast, uptake in normal liver and spleen decreased markedly as affinity decreased. The same pattern was observed in animals treated with cycloheximide to induce apoptosis. Control experiments with charge mutants showed that the effects seen with the affinity mutants were not due to the concomitant change in molecular charge that occurs in these mutants.

CONCLUSION

(a) All four domains of annexin V are required for optimal uptake in apoptotic tissues; molecules with only 1 or 2 active domains are unlikely to be suitable for imaging of cell death in vivo. (b) Uptake in normal liver and spleen is specific (dependent on phosphatidylserine-binding affinity), whereas renal uptake is nonspecific. (c) (99m)Tc-Annexin V-128 detects cell death as well as (99m)Tc-HYNIC-annexin V, while showing 88% less renal retention of radioactivity due to much more rapid urinary excretion of radioactivity.

Diagnostic evaluation of carbon tetrachloride-induced rat hepatic cirrhosis model

BACKGROUND

To find a non-invasive method of diagnosing hepatic fibrosis and cirrhosis, we evaluated the relationship of the hepatic cirrhosis grade between histopathology and mean grey level (MGL) in B-mode ultrasonography in CCl4-induced liver cirrhosis.

MATERIALS AND METHODS

Three groups of rats were treated with olive oil, CCl4, and CCl4 + silymarin. Rats were sacrificed at weeks 4, 8 and 12, after B-mode ultrasonography examination, and then analyzed histopathologically for fatty change and fibrosis.

RESULTS

On the grade of fibrosis, the CCl4 group showed higher value at 8 and 12 weeks than the silymarin group. However, the fatty change was enhanced in the silymarin group, compared with the CCl4 group. The B-mode histogram values were the highest in the silymarin group, but the collagen rate was highest in the CCl4-treated group, at week 12. These results suggest that the B-mode histogram can be more affected by infiltration of lipid than by intact accumulation of collagen fibers.

CONCLUSION

In the histogram of 8 and 12 weeks, there were significant differences between the CCl4-treated group and silymarin group in mean grey levels of B-mode ultrasonography. The histogram of B-mode mean grey level has a close correlation with fatty change and is useful for the diagnosis of liver fibrosis by histopathological analysis.

A novel method for determining hepatic sinusoidal oxygen permeability in the isolated perfused rat liver using [15O]O2

Measurement of hepatic sinusoidal permeability of oxygen and other substrates may help elucidate the mechanisms responsible for impaired liver function in cirrhosis. However studies of sinusoidal oxygen permeability in normal liver and various disease states have been limited due to the considerable technical difficulties involved in the use of standard techniques. We have developed a new method for measuring sinusoidal oxygen permeability in the isolated perfused rat liver that overcomes the difficulties of previous methods by using [(15)O]O(2) and an in-line fluid monitor. This method uses data obtained from impulse response curves of radiolabelled red cells, albumin and oxygen that are fitted mathematically using the axial dispersion model to yield rate constants that describe oxygen transit through the liver. We have demonstrated the utility and reproducibility of this method by comparing multiple injections and permeability determinations in the same preparation. This approach could be used in isolated perfused organs to study oxygen permeability in a range of disease states.

A canine model of multiple portosystemic shunting

The objective of this study was to develop and describe an experimental canine model of multiple acquired portosystemic shunts (PSS) similar in nature to spontaneously occurring PSS. Sixteen dogs were used and were divided into a control (n = 6) and a diseased group (n = 10). Dogs of the diseased group were administered dimethylnitrosamine (2 mg/kg of body weight, po) twice weekly, and clinicopathologic, ultrasonographic, and hepatic scintigraphic findings were recorded during the development of hepatic disease and PSS. Surgery was then performed to permit visual verification of multiple shunts, catheter placement for portography examination, and biopsy of the liver. All diseased dogs developed severe hepatic disease and multiple PSS as documented visually at surgery and on portography. Based on this study, dimethylnitrosamine-induced portosystemic shunting appears to be an appropriate model for spontaneously occurring multiple PSS secondary to portal hypertension.

The efficacy of FP 736-04 in experimental liver cirrhosis

PURPOSE

To determine whether the uptake of FP 736-04, a hepatocyte-specific CT contrast agent, is influenced by cirrhotic changes in the liver.

MATERIAL AND METHODS

Liver cirrhosis was induced by bile duct ligation (BDL) in Sprague-Dawley rats. Seventy-four animals were divided into three groups comprising: rats with acute BDL; rats with chronic BDL; and normal controls. CT was performed after i.v. infusion of FP 736-04 or saline at a dose of 2 ml/kg b.w., and the mean attenuation in the liver and spleen was measured. The livers from the chronic BDL group were taken for histopathological examination and the extent of the disease was graded according to an arbitrary scale.

RESULTS AND CONCLUSION

There was a significant reduction of the native liver attenuation in both chronic and acute BDL groups as compared with the normal controls. FP 736-04 was taken up by the liver parenchyma with a similar degree of enhancement in all three groups.

Experimental evaluation of hepatic functional reserve using 111In colloid for clinical application

We have postulated that reduced hepatic blood flow is the primary factor responsible for postoperative hepatic insufficiency, and have shown the usefulness of the hepatic blood flow index (KL) estimated by 198Au colloid. However, 198Au colloid has became unavailable due to its intense exposure activity. Therefore, we prepared 111In colloid as a substitute for 198Au colloid to evaluate hepatic functional reserve. In the present study, a 111In colloid was administered to rats to investigate the possibility of clinical application. First, liver cirrhosis was induced in rats using CCl4 Changes in KL and hepatic tissue blood flow were measured by hydrogen gas clearance (HL) after CCl4 injection, and was shown to correlates well with it. The correlation between KL and HL, together with normal and cirrhotic liver, was significant (r = 0.83, p < 0.01) Second, reticuloendothelial function was modulated with Zymosan A (stimulation) and Silica (suppression). The KL value remained unchanged in spite of the addition of an activator or suppressor to the reticuloendothelial system. Third, 30% and 70% hepatectomy models were studied according to the method of Higgins-Anderson. KL and HL was measured before and 1, 3 and 7 days after hepatectomy. KL and HL after 30% and 70% hepatectomy showed similar changes. These results indicate that the clearance of 111In colloid can be used clinically as an index of the hepatic blood flow.

Ultrasonography, biochemical and hematological profiles in liver disease caused by intravenous administration of dimethylnitrosamine in dogs

The results of liver function tests and ultrasonographical findings were analysed in 7 dogs that were intravenously injected dimethylnitrosamine (DMNA 2 mg/kg body weight) on 2 consecutive days each week for 10 weeks. Typical clinical signs and similar changes in liver enzyme concentrations that develop in dogs with natural cirrhosis were observed in this canine model. Severe anaemia and a significant reduction in the platelet numbers occurred in the dogs that died in the 5th week, while in all the other dogs these parameters decreased slightly. Serum total protein and the albumin/globulin ratio decreased gradually while the alkaline phosphatase, alanine amino transferase, aspartate amino transferase and gamma glutamyl transpeptidase activities increased significantly (p < 0.05) in all dogs after beginning the administration of DMNA. Ultrasound findings of a coarsened and heterogeneous echo pattern with increased echogenicity that are characteristic of canine cirrhosis were noticed at the same time when the changes in liver enzymes became evident. Present results suggest that ultrasonography in conjunction with liver function tests may be useful in the evaluation of experimentally induced liver cirrhosis.

Injection of ethanolamine oleate into a segmental portal branch for pharmacologic hepatic segmentectomy in dogs

RATIONALE AND OBJECTIVES

Currently available treatments for hepatocellular carcinoma are not satisfactory in terms of recurrence rates. In this study, we injected ethanolamine oleate (EO) into a portal branch in an attempt to cause necrosis of a liver segment in which hepatocellular carcinoma might be located.

METHODS

Nine dogs received EO injections via a balloon catheter into a segmental portal branch of the liver.

RESULTS

Immediately after injection, 80-100% of the liver cells in the EO-injected segment underwent coagulative necrosis. After 1 week, the EO-injected segment had become completely necrotic in two dogs. Only a few viable hepatocytes were still observed around the arteries and beneath the liver capsule in another dog. No pathologic changes were observed in the lungs, kidneys, or heart of any dog. There was a correlation between the EO dosages and the volume of the EO-injected liver tissue.

CONCLUSION

EO injection into a portal branch results in the pharmacologic destruction of the corresponding liver segment. This procedure may be beneficial in the treatment of hepatic malignancies.

Serologic and ultrasonographic parameters of praziquantel treatment of hepatic fibrosis in Schistosoma japonicum infection

We describe the parameters useful in evaluating the development of hepatic fibrosis in Schistosoma japonicum infection, as well as its improvement after treatment with praziquantel (PZQ). Various serologic parameters and ultrasonographic images were examined, and their changes were monitored using rabbits infected with 200 or 300 cercariae of S. japonicum. Infected rabbits were administered one oral treatment of PZQ at a dosage of 100 mg/kg at 6, 12, or 24 weeks after infection. Histopathologic examinations revealed that PZQ had a strong and rapid effect, even on damage that developed long after the infection. The improvement of moderate hepatic fibrosis that developed over 24 weeks after infection was also detected by histopathologic examinations. The serum level of total bile acid was the most sensitive parameter in evaluating the severity of hepatic fibrosis and its improvement after treatment with PZQ. The level of serum procollagen-III-peptide was also useful in evaluating the development of hepatic fibrosis, but not in its improvement. Ultrasonography revealed specific echogenic bands and nodules according to the progress of granuloma formation and fibrosis, and the reversal of these changes could also be observed after treatment with PZQ.

Biokinetics of 99mTc-labelled liver-imaging agents in an animal model of liver cirrhosis

Comparable degree of liver cirrhosis, as judged by liver function tests and histopathology, was induced in rats by carbon tetrachloride. Comparative organ distribution of 99mTc-sulphur colloid and 99mTc-phytate was studied in the liver, spleen and lungs of these cirrhotic rats. Compared to controls, the biodistribution of 99mTc-sulphur colloid was found to be affected more than that of 99mTc-phytate in cirrhotic rats, especially at early time intervals.

Assessment of Kupffer cell function in rats with chronic liver injury caused by CCl4

Kupffer cell function was assessed by using scintigraphy to evaluate the turnover of a metabolizable tracer (99mTc-millimicrosphered albumin). The organ uptake rate of the tracer, and new parameters concerned with the degradative functions of Kupffer cells obtained from analysis of the excretion phase of the hepatic time-uptake rate curve, were measured in rats with two different types of chronic liver damage induced by carbon tetrachloride (fatty liver group and liver cirrhosis group). The hepatic uptake rate in chronic liver injury decreased, while in contrast the splenic and pulmonary uptake rates increased. A particularly high uptake by the lungs was observed. The data demonstrated a reduced phagocytic activity of the Kupffer cells in rats with chronic liver injury. The new parameters concerned with Kupffer cell degradative function; i.e. the excretion rate (K) and the degradation rate in the first 60-min (D60), were markedly decreased even in the early stage of chronic liver injury. The data showed that the impairment of Kupffer cell degradative function occurred even earlier in liver damage than impairment of the phagocytic activity, so that the K value and the D60 value were the more sensitive indicators of Kupffer cell function.

The role of sinusoidal stenoses in portal hypertension of liver cirrhosis

To investigate the significance of sinusoidal stenoses in portal hypertension, liver cirrhosis was produced by feeding a choline-deficient diet for 6 months in rats, and hepatic haemodynamics were examined in the cirrhotic rats before and after feeding ordinary rat pellets for another 2 months. Feeding ordinary rat pellets led to the disappearance of fat droplets accumulated in the hepatocytes, normalization of the size of the swollen hepatocytes, and recovery from sinusoidal stenoses. As a result, increased sinusoidal vascular resistance and elevated portal vein pressure were reduced markedly, and clinical signs of portal hypertension, ascites and collateral blood circulation around the liver improved prominently. These facts suggest that sinusoidal stenoses lead to an increase in hepatic vascular resistance and portal hypertension.

Kupffer cell depletion associated with capillarization of liver sinusoids in carbon tetrachloride-induced rat liver cirrhosis

Rats were made cirrhotic by carbon tetrachloride inhalation associated with phenobarbital in the drinking water over 10 weeks. After a 1-week recovery period a 99mTc sulphur colloid radioisotope scan of the liver was carried out on each animal following bolus injection into the iliac vein. Kupffer cells were then histologically identified by one of three methods: colloidal carbon uptake, iron staining after ferritin-dextran, or endogenous peroxidase staining. The degree of liver injury was classified into four pathological groups and these were correlated with the phagocytic capacity of each liver as recorded on the isotope scan. All three histological markers demonstrated that in normal liver, Kupffer cells are more plentiful in periportal areas. In cirrhotic liver, there were very few Kupffer cells in nodular regenerative areas, where continuous capillaries are found, but Kupffer cells were present in the remaining more normal trabecular-sinusoidal areas. Morphometric counting of carbon- and ferritin-labelled Kupffer cells demonstrated a significant decrease in cirrhotic livers. A close correlation was also found between increasing degree of liver injury and diminished hepatic phagocytic capacity, as demonstrated by the radioisotope scan. The study demonstrates that where regenerative liver is capillarized, with replacement of fenestrated sinusoids, Kupffer cells are absent.

Prostaglandins in diagnostic and therapeutic superior mesenteric artery pharmacoangiography

The hemodynamic effects of prostaglandins PGA1, PGE1, PGE2, and PGF2 alpha on the splanchnic circulation were evaluated in five chronic dogs with portal hypertension, periportal fibrosis, and portosystemic venous shunting. The maximum effect was achieved with dosages of 2 micrograms/kg/min after bolus injection into the superior mesenteric artery. With this dosage a monophasic increase of portal blood flow and pressure was found with PGA1, PGE1, and PGE2, whereas PGF2 alpha caused a biphasic response: an initial decrease in portal blood flow and pressure was followed by an increase in these parameters. The average peak increase in portal blood flow and pressure was similar for PGE1 and PGF2 alpha, and significantly smaller for PGA1 and PGE2. Average peak iodine concentrations in the portal blood after superior mesenteric angiography were highest with PGF2 alpha, similar for PGE1 and tolazoline, and lowest in controls. The vasoconstrictor effect of PGF2 alpha is, overall, reduced and less reproducible when compared with vasopressin. This investigation suggests that both PGE1 and PGF2 alpha are effective for improved arterial portography, the latter agent appearing superior. On the other hand, PGF2 alpha cannot be recommended as a therapeutic agent for the treatment for gastrointestinal and particularly variceal bleeding.

Evaluation of portal circulation in rats by rectal administration of 201Tl followed by intrasplenic injection of 51Cr-labeled microspheres

The heart-to-liver (H/L) uptake ratio in rats was determined 8 min after the rectal administration of 201Tl. Apart from normal controls, three groups of rats were examined; these were composed of animals with induced (1) acute hepatic damage, (2) liver cirrhosis, and (3) partial portal-vein ligation. After the rectal administration of 201Tl, 51Cr-labeled microspheres were injected into the spleen. The radioactivity of the removed liver, lungs, and heart was determined in a gamma-well scintillation counter, and the radioactivity of 201Tl and the 51Cr-labeled microspheres was separately calculated using simultaneous equations derived from the results of a preliminary experiment. The H/L ratios (201Tl) in the normal controls and the animals with acute hepatic damage were not significantly different; however, there was a positive correlation (P less than 0.01) between the H/L ratio and the shunt index (51Cr microspheres) in three groups, i.e., normal controls, liver cirrhosis, and partial portal-vein ligation.

Angiographic, hemodynamic, and histologic evaluation of portal hypertension and periportal fibrosis induced in the dog by intraportal polyvinyl alcohol injections

Intrahepatic periportal fibrosis and portal hypertension were produced in the dog by repeated intraportal injection of a polyvinyl alcohol suspension over a two- to six-month period. Progressive hepatic fibrosis originating in the portal triads around occluded portal vein radicles occurred during the first year. Porto-systemic venous collaterals developed at the earliest three to four weeks after initial embolization. Angiographic changes included an increase in number and diameters of opacified hepatic arterial branches and a more dense arterial hepatogram than on the baseline studies, but these were only evident in advanced hepatic fibrosis. Decreases in portal and total hepatic blood flow of 53 +/- 15% and 17 +/- 7%, respectively, were observed after development of periportal fibrosis and stable portal hypertension, while the compensatory increase in hepatic arterial flow was a slowly evolving process resulting in an increase of 135 +/- 51% in the fibrotic stage. Animals with advanced hepatic fibrosis and portal hypertension remained in good general health, allowing extensive follow-up examinations at regular intervals over a prolonged period of time.

Complications and hazards with angiographic occlusion balloon catheters

Twenty angiographic procedures involving the superior mesenteric artery (SMA) were performed with balloon occlusion catheters in dogs with chronic liver cirrhosis and portal hypertension. The following complications were found: (a) rapid balloon inflation during angiography due to a leak between the two catheter lumens (two cases); (b) failure to deflate a balloon located in the SMA (two cases); (c) balloon detachment intravascularly and during catheter insertion (one case each); and (d) rupture of the SMA (one case). Balloon detachment occurred only with re-used catheters. The safety of angiographic occlusion balloon catheters for general use is questioned. Under no circumstances should catheters be re-used.