Temporal changes in the stiffness of the remnant liver and spleen after donor hepatectomy as assessed by acoustic radiation force impulse: A preliminary study

Longitudinal ultrasound imaging and network modeling in rats reveal sex-dependent suppression of liver regeneration after resection in alcoholic liver disease

Liver resection is an important surgical technique in the treatment of cancers and transplantation. We used ultrasound imaging to study the dynamics of liver regeneration following two-thirds partial hepatectomy (PHx) in male and female rats fed via Lieber-deCarli liquid diet protocol of ethanol or isocaloric control or chow for 5–7 weeks. Ethanol-fed male rats did not recover liver volume to the pre-surgery levels over the course of 2 weeks after surgery. By contrast, ethanol-fed female rats as well as controls of both sexes showed normal volume recovery. Contrary to expectations, transient increases in both portal and hepatic artery blood flow rates were seen in most animals, with ethanol-fed males showing higher peak portal flow than any other experimental group. A computational model of liver regeneration was used to evaluate the contribution of physiological stimuli and estimate the animal-specific parameter intervals. The results implicate lower metabolic load, over a wide range of cell death sensitivity, in matching the model simulations to experimental data of ethanol-fed male rats. However, in the ethanol-fed female rats and controls of both sexes, metabolic load was higher and in combination with cell death sensitivity matched the observed volume recovery dynamics. We conclude that adaptation to chronic ethanol intake has a sex-dependent impact on liver volume recovery following liver resection, likely mediated by differences in the physiological stimuli or cell death responses that govern the regeneration process. Immunohistochemical analysis of pre- and post-resection liver tissue validated the results of computational modeling by associating lack of sensitivity to cell death with lower rates of cell death in ethanol-fed male rats. Our results illustrate the potential for non-invasive ultrasound imaging to assess liver volume recovery towards supporting development of clinically relevant computational models of liver regeneration.

Doppler ultrasound in the diagnosis of Budd-Chiari syndrome in children after split liver transplantation

PURPOSE

To assess the capabilities of a velocity ratio>3 for the diagnosis of Budd-Chiari syndrome (BCS) in children after split liver transplantation using Doppler ultrasonography (DUS).

MATERIALS AND METHODS

A total of 28 children who underwent liver transplantation using a split procedure were included. There were 11boys and 17girls with a mean age of 3.8years (range: 0.7-12years). Velocity ratio between blood velocity upstream of the anastomosis and that at the level of the inferior vena cava anastomosis was calculated. Sensitivity, specificity and accuracy of DUS for the diagnosis of BCS were estimated using a velocity ratio>3.

RESULTS

Eight children (8/28; 29%) had BCS and 20 (20/28; 71%) did not have BCS using the standard of reference. A velocity ratio>3 on DUS yielded 88% sensitivity (95% CI: 53-98%), 80% specificity (95% CI: 58-92%) and 82% accuracy (95% CI: 64-92%) for the diagnosis of BCS.

CONCLUSION

A velocity ratio>3 on DUS is a reliable finding for the diagnosis of BCS in children after split liver transplantation.

Perioperative liver and spleen elastography in patients without chronic liver disease

AIM

To investigate changes in hepatic and splenic stiffness in patients without chronic liver disease during liver resection for hepatic tumors.

METHODS

Patients scheduled for liver resection for hepatic tumors were considered for enrollment. Tissue stiffness measurements on liver and spleen were conducted before and two days after liver resection using point shear-wave elastography. Histological analysis of the resected liver specimen was conducted in all patients and patients with marked liver fibrosis were excluded from further study analysis. Patients were divided into groups depending on size of resection and whether they had received preoperative chemotherapy or not. The relation between tissue stiffness and postoperative biochemistry was investigated.

RESULTS

Results are presented as median (interquartile range). 35 patients were included. The liver stiffness increased in patients undergoing a major resection from 1.41 (1.24-1.63) m/s to 2.20 (1.72-2.44) m/s (P = 0.001). No change in liver stiffness in patients undergoing a minor resection was found [1.31 (1.15-1.52) m/s vs 1.37 (1.12-1.77) m/s, P = 0.438]. A major resection resulted in a 16% (7%-33%) increase in spleen stiffness, more (P = 0.047) than after a minor resection [2 (-1-13) %]. Patients who underwent preoperative chemotherapy (n = 20) did not differ from others in preoperative right liver lobe [1.31 (1.16-1.50) vs 1.38 (1.12-1.56) m/s, P = 0.569] or spleen [2.79 (2.33-3.11) vs 2.71 (2.37-2.86) m/s, P = 0.515] stiffness. Remnant liver stiffness on the second postoperative day did not show strong correlations with maximum postoperative increase in bilirubin (R² = 0.154, Pearson’s r = 0.392, P = 0.032) and international normalized ratio (R² = 0.285, Pearson’s r = 0.534, P = 0.003).

CONCLUSION

Liver and spleen stiffness increase after a major liver resection for hepatic tumors in patients without chronic liver disease.

Rapid change of liver stiffness after variceal ligation and TIPS implantation

Liver stiffness (LS) as measured by transient elastography is widely used to screen for liver fibrosis. However, LS also increases in response to pressure changes like congestion but no data on portal pressure are available. We study here the effect of rapid portal pressure changes on LS. Therefore, LS was assessed directly prior and after ligation of esophageal varices ( n = 11) as well as transjugular intrahepatic portosystemic shunt (TIPS) implantation in patients with established cirrhosis ( n = 14). Additionally, we retrospectively analyzed changes in LS and variceal size in patients with sequential gastroscopic monitoring and LS measurements ( n = 14). To study LS and portal pressure in healthy livers, LS (µFibroscan; Echosens, Paris, France) and invasive pressures (Powerlab, AD Instruments, New Zealand) were assessed in male Wistar rats after ligation of single liver lobes. Ligation of esophageal varices caused an immediate and significant increase of LS from 40.3 ± 19.0 to 56.1 ± 21.5 kPa. Likewise, LS decreased significantly from 53.1 ± 16.6 to 43.8 ± 17.3 kPa after TIPS placement, which correlated significantly with portal pressure ( r = 0.558). In the retrospective cohort, the significant LS decrease from 54.9 ± 23.5 to 47.9 ± 23.8 kPa over a mean observation interval of 4.3 ± 3 mo was significantly correlated with a concomitant increase of variceal size ( r = -0.605). In the animal model, LS and portal pressure increased significantly after single lobe ligation without changes of arterial or central venous pressure. In conclusion, rapid changes of portal pressure are a strong modulator of LS in healthy and cirrhotic organs. In patients with stable cirrhosis according to the model for end-stage liver disease (MELD), a decrease of LS may be indicative for enlarging varices. NEW & NOTEWORTHY Liver stiffness (LS) immediately increases after variceal ligation while it decreases after transjugular intrahepatic portosystemic shunt (TIPS) implantation due to portal pressure changes. LS and portal pressure rapidly increase after single lobe ligation in Wistar rats without changes of arterial or central venous pressure. Collateral formation may be one cause for a transient decrease in LS in the absence of other confounders. Such pressure changes should be considered when interpreting LS in clinical practice.

Hepatic Venous Outflow Stenosis After Auxiliary Left Hemiliver Transplantation Diagnosed by Ultrasonic Shear Wave Elastography Combined With Doppler Ultrasonography

Hepatic vein stenosis after liver transplantation is a relatively rare complication that could even result in graft loss. However, it is difficult to arrive at a definite diagnosis at the early stage of postoperation, and there are few researches on ultrasonic shear wave elastography in the diagnosis of hepatic vein stenosis. We report the case of an 11-year-old male patient with cirrhosis due to hepatolenticular degeneration who received an auxiliary left hemiliver graft from his uncle. Massive ascites developed in 4 days after the operation. Stenosis was suspected at the site of anastomosis by Doppler ultrasonography when elevating the velocity of the left hepatic vein. Meanwhile, increased stiffness of the graft was revealed by ultrasonic shear wave elastography. The stenosis was confirmed by subsequent digital subtraction angiography. Ascites decreased gradually after the stent implantation. Our case indicates that ultrasonic shear wave elastography combined with Doppler ultrasonography is a promising method for noninvasive diagnosis of hepatic venous outflow stenosis following liver transplantation.

Does apparent diffusion coefficient predict the degree of liver regeneration of donor and recipient after living donor liver transplantation?

OBJECTIVE

To elucidate the relationship between the ADCs of the liver graft and the remnant liver and the degree of liver regeneration in LDLT.

MATERIALS AND METHODS

15 recipients and 15 corresponding donors underwent magnetic resonance imaging and computed tomography 1-2 weeks after living donor liver transplantation (LDLT). For diffusion-weighted imaging (DWI), a single-shot echo-planar sequence with b-factors of 0, 500, and 1000s/mm² was scanned. ADCs of the liver parenchyma were calculated at b factors of 0 and 500 and 1000 (ADC 0-500-1000) or 0 and 500 (ADC 0-500) or 500 and 1000 (ADC 500-1000). The liver volume ratio at LDLT, the mean ADCs and the regeneration rate were compared between the graft and the remnant liver using paired-t tests.

RESULTS

The mean liver volume ratio of the recipients (41.3±9.8%) tended to be smaller than that of the donors (51.8±13.8%). The mean ADC 0-500 of the remnant liver (1.72±0.33) was significantly higher than that of the graft (1.43±0.32). The regeneration rate of the graft (2.07±0.41) was significantly higher than that of the remnant liver (1.53±0.49).

CONCLUSION

ADC 0-500 can describe differences in blood perfusion between liver grafts and the remnant liver according to the degree of liver regeneration.

Increased Stiffness of the Remnant Right Lobe Liver After Left Lobectomy or Lateral Segmentectomy in Donors of Living-Donor Liver Transplantation

BACKGROUND

Liver stiffness is associated with the degree of fibrosis along with other factors. Abrupt change of liver perfusion after hepatectomy is one such factor. In this study, we performed ultrasound elastography to explore the stiffness of the right lobe liver before and after hepatectomy in donors who underwent resection of left lobe or lateral segment of liver.

METHODS

A total of 32 left lobe liver donors (18 male and 14 female; age range, 21-55 years; mean age, 35.1 years; 19 left lobectomy with middle hepatic reserved for graft and 13 lateral segmentectomy with middle hepatic vein reserved in the remnant liver) were included in this study. Liver stiffness was measured by means of ultrasound elastography with the use of acoustic radiation force impulse imaging. Stiffness of the right lobe liver was obtained by means of right intercostal approach.

RESULTS

The stiffness of remnant right lobe liver significantly increased after hepatectomy (1.24 ± 0.18 vs 1.10 ± 0.13 m/s; P = .001). Donors of left lobe liver showed higher stiffness in the remnant right lobe liver compared with donors of lateral segment (1.30 ± 0.18 vs 1.15 ± 0.14 m/s; P = .027). There was no significant correlation between the remnant right lobe liver stiffness, postoperative liver function, and flow parameters of hepatic artery and portal vein.

CONCLUSIONS

The stiffness of remnant liver significantly increased after hepatectomy. Furthermore, the stiffness was higher in donors undergoing left lobectomy compared with those undergoing lateral segmentectomy.

A novel serum marker, glycosylated Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA(+)-M2BP), for assessing liver fibrosis

BACKGROUND

Recently, a novel marker, hyperglycosylated Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA(+)-M2BP), was developed for liver fibrosis using the glycan "sugar chain"-based immunoassay; however, the feasibility of WFA(+)-M2BP for assessing liver fibrosis has not been proven with clinical samples of hepatitis.

METHODS

Serum WFA(+)-M2BP values were evaluated in 200 patients with chronic liver disease who underwent histological examination of liver fibrosis. The diagnostic accuracy of WFA(+)-M2BP values was compared with various fibrosis markers, such as ultrasound based-virtual touch tissue quantification (VTTQ), magnetic resonance imaging based-liver-to-major psoas muscle intensity ratio (LMR), and serum markers, including hyaluronic acid, type 4 collagen, and aspartate transaminase to platelet ratio index (APRI).

RESULTS

Serum WFA(+)-M2BP levels in patients with fibrosis grades F0, F1, F2, F3, and F4 had cutoff indices 1.62, 1.82, 3.02, 3.32, and 3.67, respectively, and there were significant differences between fibrosis stages F1 and F2, and between F2 and F3 (P < 0.01). The area under the receiver operating characteristic curves for the diagnosis of fibrosis (F ≥ 3) using serum WFA(+)-M2BP values (0.812) was almost comparable to that using VTTQ examination (0.814), but was superior to the other surrogate markers, including LMR index (0.766), APRI (0.694), hyaluronic acid (0.683), and type 4 collagen (0.625) (P < 0.01 each).

CONCLUSIONS

Serum WFA(+)-M2BP values based on a glycan-based immunoassay is an accurate, reliable, and reproducible method for the assessment of liver fibrosis. This approach could be clinically feasible for evaluation of beneficial therapy through the quantification of liver fibrosis in hepatitis patients if this measurement application is commercially realized.

Mechanisms of splenic hypertrophy following hepatic resection

BACKGROUND

Following hepatic resection, liver regeneration has been associated with concurrent splenic hypertrophy. The mechanisms of this phenomenon are unknown, may be multiple and include: splanchnic sequestration caused by a reduction in the hepatic mass; hepatic growth factors that may indirectly act on the spleen, and the redistribution of the total reticuloendothelial system.

METHODS

Seventy-five patients (40 males; median age: 60 years) who underwent minor (16%) or major (84%) hepatectomy between September 2004 and October 2009 were included. Prospective measurements of liver and spleen volumes were obtained preoperatively and postoperatively 1 month after hepatectomy using computed tomography (CT). The future remnant liver volume (RLV) was calculated on preoperative CT and the extent of resection was expressed as the RLV divided by total liver volume (TLV). Liver and spleen hypertrophy were expressed according to the absolute gain or relative increase in the initial volumes (%).The presence of fibrosis >F1, associated extrahepatic resection (except minor resections), and previous hepatectomy (major or minor) within 3 months represented exclusion criteria.

RESULTS

Mean ± standard deviation (SD) liver volume at 1 month was higher than RLV (1187 ± 286 cm(3) versus 764 ± 421 cm(3) ; P < 0.001). Mean ± SD splenic volume increased from 252 ± 100 cm(3) preoperatively to 300 ± 111 cm(3) at 1 month (P < 0.001). Liver and splenic hypertrophy were significant after major hepatectomies (+100% and +26%, respectively; P < 0.001), but not after minor hepatectomies. Liver hypertrophy was inversely correlated to RLV/TLV (r = -0.687, P < 0.001). Splenic hypertrophy was not correlated to RLV/TLV. Liver and splenic hypertrophy were linearly correlated (r = 0.495, P < 0.001). Neoadjuvant chemotherapy (n = 37), preoperative portal vein embolization (n = 10) and postoperative complications (overall: n = 25; major: n = 10; infectious: n = 6) had no impact on hepatic or splenic hypertrophy.

CONCLUSIONS

Splenic hypertrophy occurred after major hepatectomy, but was not correlated to the extent of resection, by contrast with liver hypertrophy. Nevertheless, there was a linear correlation between splenic and liver hypertrophy. This correlation suggests the hypothesis of a splenic action of hepatic growth factors or a redistribution of the total reticuloendothelial system rather than an effect of reduction of the portal bed or hepatic outflow.

Hepatic venous congestion after living donor liver transplantation: quantitative assessment of liver stiffness using shear wave elastography--a case report

We report a 49-year-old right lobe liver transplant recipient, who developed a significant anastomotic stenosis of the right hepatic vein shortly thereafter. Shear wave elastography (SWE) was applied to investigate liver stiffness quantitatively. It showed increased stiffness in the anterior compared with the posterior segment of right lobe graft. The stenotic right hepatic venous anastomosis was then managed by angioplasty with stent placement. SWE after angioplasty showed a gradual decrease in stiffness of the anterior segment, which was almost equal to the posterior segment at 2 weeks thereafter. Our experience suggested that SWE may be a noninvasive tool to assess alterations in liver stiffness secondary to hepatic venous congestion after liver transplantation.