Revealing impaired blood supply to the bile ducts on contrast-enhanced ultrasound: a novel diagnosis method to ischemic-type biliary lesions after orthotropic liver transplantation

Evaluation value of contrast enhanced ultrasound quantitative parameters in ischemic-type biliary lesions after liver transplantation-a prospectively study

PURPOSE

To explore the evaluation value of contrast enhanced ultrasound (CEUS) quantitative parameters in ischemic-type biliary lesions after liver transplantation to assist its early-diagnosis.

METHODS

Patients who underwent liver transplantation and intravenous CEUS at Beijing Friendship Hospital, Capital Medical University from June 25, 2020 to December 28, 2022 and were diagnosed with Ischemic-type biliary lesions (ITBLs) by Magnetic Resonance Cholangiopancreatography (MRCP) or Endoscopic Retrograde Cholangiopancreatography (ERCP) or Percutaneous Transhepatic Cholangiography (PTC) were prospectively enrolled. SonoLiver software was used to quantitatively analyze the contrast images, transplanted livers with normal biliary tracts as the control group. SPSS 25.0 software was used to analyze the data.

RESULTS

There was a total of 35 patients enrolled in the study, and 15 ITBLs and 30 normal biliary tract of transplanted livers, respectively. The dynamic vascular patterns (DVP) curve of the ITBLs group was negative wave, while the DVP curve of the normal biliary tract group was positive wave. Compared with the patients with normal biliary tract, the Maximum intensity (IMAX), Rise slope 50% (Rs50), Area under curve (AUC), Area under curve in Wash-in phase (WinAUC), Wash in Rate (WinR), Rise slope 10-90% (Rs1090), and Wash out Rate (WouR) of the ITBLs group were lower, while the Fall slope (Fs50) was higher. There was no significant difference in Rise time (RT), Time to Peak (TTP), Fall half time (FHT), Mean transit time (mTT), Fall time (FT), WioAUC ((WioAUC = WinAUC + WouAUC)), and Area under curve in Wash-out phase (WouAUC) between the two groups (P > 0.05). The ROC curve results showed that Fs50 > -2.64 was the cutoff value for predicting ITBLs, with an area under the curve of 0.816 (95%CI: 0.683-0.949), and a sensitivity and specificity of 0.846 and 0.607; Rs50 < 7.08, AUC < 39761.7050, WinR < 101.7 and WouR < 474.52 were the cutoff values ​​for predicting ITBLs, with areas under the curve of 0.853 (95%CI: 0.728-0.979), 0.911 (95%CI: 0.783-1.000), 0.756 (95%CI: 0.615-0.896) and 0.700 (95%CI: 0.536-0.864).

CONCLUSION

The quantitative parameters of CEUS imaging, such as IMAX, Rs50, AUC, WinAUC, WinR, Rs1090, WouR, and Fs50, are helpful in predicting ITBLs and improving the reproducibility of diagnosis. The threshold of these quantitative parameters will aid in the early diagnosis of ischemic-type biliary lesions after liver transplantation.

Secondary sclerosing cholangitis and IgG4-sclerosing cholangitis - A review of cholangiographic and ultrasound imaging

Sclerosing cholangitis (SC) represents a spectrum of chronic progressive cholestatic diseases of the intrahepatic and/or extrahepatic biliary system characterized by patchy inflammation, fibrosis, and stricturing. Primary and secondary SC must be distinguished given the different treatment modalities, risks of malignancy, and progression to portal hypertension, cirrhosis, and hepatic failure. This review focuses on secondary SC and the pathogenic mechanisms, risk factors, clinical presentation, and novel imaging modalities that help to distinguish between these conditions. We explore the detailed use of cholangiography and ultrasound imaging techniques.

Liver Transplant Imaging prior to and during the COVID-19 Pandemic

BACKGROUND

The suspension of the surgical activity, the burden of the infection in immunosuppressed patients, and the comorbidities underlying end-stage organ disease have impacted transplant programs significantly, even life-saving procedures, such as liver transplantation.

METHODS

A review of the literature was conducted to explore the challenges faced by transplant programs and the adopted strategies to overcome them, with a focus on indications for imaging in liver transplant candidates.

RESULTS

Liver transplantation relies on an appropriate imaging method for its success. During the Coronavirus Disease 2019 (COVID-19) pandemic, chest CT showed an additional value to detect early signs of SARS-CoV-2 infection and other screening modalities are less accurate than radiology.

CONCLUSION

There is an emerging recognition of the chest CT value to recommend its use and help COVID-19 detection in patients. This examination appears highly sensitive for liver transplant candidates and recipients, who otherwise would have not undergone it, particularly when asymptomatic.

Contrast-Enhanced Ultrasound for Biliary Ischemia: A Possible New Clinical Indication

OBJECTIVES

Biliary perfusion is considered to contribute to biliary diseases, but routine imaging methods are insufficient to show it. This research investigated the ability of contrast-enhanced ultrasound (CEUS) for biliary perfusion in a biliary ischemia model.

METHODS

This research consisted of 2 parts. First, to determine whether CEUS enhancement of the tiny biliary wall represents biliary perfusion, a vascular tracer was used as a reference to evaluate the consistency with the enhancement of the biliary wall on CEUS and the staining by the vascular tracer under the conditions of occluded and recovered biliary perfusion. In the second part, the ability of CEUS for biliary ischemia was further evaluated with microvascular density measurement as a reference. The enhancement patterns were assigned CEUS scores, in which higher scores meant more decreased enhancement, and the diagnostic ability of CEUS was assessed by a receiver operating characteristic curve analysis.

RESULTS

The biliary wall was unstained by the vascular tracer and nonenhanced on CEUS when biliary perfusion was interrupted and was stained blue and enhanced after recovery. The biliary wall in the ischemia surgery group showed lower microvascular density measurements (P < .001), decreased enhancement levels (P < .001), and higher CEUS scores (P < .001). When a CEUS score of 3 or higher (obvious decrease of the biliary wall to hypoenhancement or nonenhancement in the arterial phase or rapid wash-out to nonenhancement in the portal venous phase) was applied, CEUS had sensitivity of 87.8%, specificity of 98.3%, accuracy of 93.8%, and an area under the receiver operating characteristic curve of 0.98.

CONCLUSIONS

Contrast enhancement of the biliary wall on CEUS represents biliary perfusion and has reasonably good diagnostic performance for biliary ischemia in an experimental animal setting.

A novel MSC-based immune induction strategy for ABO-incompatible liver transplantation: a phase I/II randomized, open-label, controlled trial

BACKGROUND

ABO-incompatible liver transplantation (ABO-i LT) has become a rescue therapeutic option for patients with severe hepatic failure. Although the use of rituximab greatly reduces the morbidity of antibody-mediated rejection (AMR), severe adverse effects, such as infection and biliary complications, still seriously threaten the survival of transplant recipients. The aim of this study was to evaluate the safety and feasibility of using mesenchymal stem cells (MSCs) to replace rituximab in ABO-i LT.

METHODS

Twenty-two patients with severe hepatic failure undergoing ABO-i LT were enrolled and randomly divided into two groups: the MSC group and the rituximab group. The safety of the application of MSCs and the incidence of allograft rejection, including antibody-mediated rejection (AMR) and acute cellular rejection (ACR), were evaluated in both groups at the 2-year follow-up period as primary endpoints. Recipients and graft survival and other postoperative complications were compared as secondary endpoints.

RESULTS

No severe MSC-related adverse events were observed during the trial. MSC treatment yielded comparable, if not better, results than rituximab at decreasing the incidence of acute rejection (9.1% vs 27.3%). Inspiringly, compared to those in the rituximab group, the rates of biliary complications (0% vs 45.5%) and infection (9.1% vs 81.8%) were significantly decreased in the MSC group. In addition, there were no significant differences in 2-year graft and recipient survival between the two groups (81.8% vs 72.7%).

CONCLUSIONS

Our data show that MSC transfusion is comparable to rituximab treatment for AMR prophylaxis following ABO-i LT. Additionally, the results indicate that MSCs are more beneficial to the prevention of infection and biliary complications and may be introduced as a novel immunosuppressive approach for ABO-i LT.

TRIAL REGISTRATION

Trial registration: chictr.org.cn , ChiCTR2000037732. Registered 31 August 2020- Retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=57074 .

Contrast-enhanced ultrasound applications in liver transplant imaging

Contrast-enhanced ultrasound (CEUS) is gaining ever-increasing acceptance in the preoperative and postoperative evaluation of liver-transplanted patients. While indications are still a matter of research, CEUS is used in tertiary centers to supplement ultrasound (US) and Color Doppler US examination, with the potential of providing a comprehensive first-line ultrasound-based diagnosis. Alternatively, CEUS is used as a problem-solving tool when previous cross-sectional or US imaging was inconclusive, especially in assessing hepatocellular carcinoma, parenchymal perfusion abnormalities, the vascular status, and even the biliary tree. This review describes the potential use for CEUS in the setting of orthotopic liver transplantation (OLT).

CEUS detection of biliary ischaemia during the first 4 weeks after liver transplantation predicts non-anastomotic biliary stricture

BACKGROUND

Biliary ischaemia is an important factor in the pathogenesis of non-anastomotic biliary stricture (NAS) after liver transplantation (LT). Contrast-enhanced ultrasound (CEUS) can be used to detect biliary ischaemia, but no study has examined the utility of CEUS in predicting NAS.

OBJECTIVE

To evaluate whether repeated CEUS as a non-invasive method of biliary ischaemia can identify NAS.

METHODS

Consecutive LT patients who underwent CEUS examinations at 1-4 weeks after LT from September 2012 to December 2015 at our institution were included. The CEUS images and clinical data were analysed.

RESULTS

Among 116 eligible LT patients, 39 (33.6%) were diagnosed with NAS within 1 year after LT. The patients with NAS had a significantly higher CEUS score at weeks 2-4 (all P < 0.05) and a higher slope of CEUS score progression (0.480 vs -0.044, P < 0.001). The accuracy of CEUS in identifying NAS improved over time after LT, reaching its maximum at week 4, with a sensitivity of 66.7%, a specificity of 87.9%, a positive predictive value (PPV) of 75.9%, a negative predictive value (NPV) of 82.3%, and an accuracy of 80.2%in the full cohort when a CEUS score≥3 was used as the cut-off. Multivariate analysis identified gamma-glutamyl transpeptidase (GGT), alanine transaminase (ALT) and the CEUS score at week 4 as independent predictors of NAS. In the task of identifying NAS, an NAS score combining the above 3 variables at week 4 showed areas under the receiver operating characteristic curve of 0.88 (95%CI, 0.78-0.99) in the estimation group (n = 60) and 0.82 (95%CI, 0.69-0.96) in the validation group (n = 56). An NAS score cut-off of 0.396 identified 87.2%of NAS cases in the estimation group, with a PPV of 93.3%; and 75.0%of NAS cases in the validation group, with a PPV of 58.8%.

CONCLUSIONS

CEUS examination during the first 4 weeks is useful in assessing the risk of NAS within 1 year after LT. In particular, an NAS score combining the CEUS score, GGT level, and ALT level at week 4 can be used to accurately predict the risk of NAS in LT patients.

Vascular complications after adult living donor liver transplantation: Evaluation with ultrasonography

Living donor liver transplantation (LDLT) has been widely used to treat end-stage liver disease with improvement in surgical technology and the application of new immunosuppressants. Vascular complications after liver transplantation remain a major threat to the survival of recipients. LDLT recipients are more likely to develop vascular complications because of their complex vascular reconstruction and the slender vessels. Early diagnosis and treatment are critical for the survival of graft and recipients. As a non-invasive, cost-effective and non-radioactive method with bedside availability, conventional gray-scale and Doppler ultrasonography play important roles in identifying vascular complications in the early postoperative period and during the follow-up. Recently, with the detailed vascular tracing and perfusion visualization, contrast-enhanced ultrasound (CEUS) has significantly improved the diagnosis of postoperative vascular complications. This review focuses on the role of conventional gray-scale ultrasound, Doppler ultrasound and CEUS for early diagnosis of vascular complications after adult LDLT.

Application of contrast-enhanced ultrasound after liver transplantation: Current status and perspectives

Liver transplantation is an effective treatment for patients with end-stage liver disease. Accurate imaging evaluation of the transplanted patient is critical for ensuring that the limited donor liver is functioning appropriately. Ultrasound contrast agents (UCAs), in combination with contrast-specific imaging techniques, are increasingly accepted in clinical use for the assessment of the hepatic vasculature, bile ducts and liver parenchyma in pre-, intra- and post-transplant patients. We describe UCAs, their technical requirements, the recommended clinical indications, image interpretation and the limitations for contrast-enhanced ultrasound applications in liver transplantation.

New diagnosis and therapy model for ischemic-type biliary lesions following liver transplantation--a retrospective cohort study

Ischemic-type biliary lesions (ITBLs) are a major cause of graft loss and mortality after orthotopic liver transplantation (OLT). Impaired blood supply to the bile ducts may cause focal or extensive damage, resulting in intra- or extrahepatic bile duct strictures or dilatations that can be detected by ultrasonography, computed tomography, magnetic resonance cholangiopancreatography, and cholangiography. However, the radiographic changes occur at an advanced stage, after the optimal period for therapeutic intervention. Endoscopic retrograde cholangio-pancreatography (ERCP) and percutaneous transhepatic cholangiodrainage (PTCD) are the gold standard methods of detecting ITBLs, but these procedures cannot be used for continuous monitoring. Traditional methods of follow-up and diagnosis result in delayed diagnosis and treatment of ITBLs. Our center has used the early diagnosis and intervention model (EDIM) for the diagnosis and treatment of ITBLs since February 2008. This model mainly involves preventive medication to protect the epithelial cellular membrane of the bile ducts, regular testing of liver function, and weekly monitor of contrast-enhanced ultrasonography (CEUS) to detect ischemic changes to the bile ducts. If the liver enzyme levels become abnormal or CEUS shows low or no enhancement of the wall of the hilar bile duct during the arterial phase, early ERCP and PTCD are performed to confirm the diagnosis and to maintain biliary drainage. Compared with patients treated by the traditional model used prior to February 2008, patients in the EDIM group had a lower incidence of biliary tract infection (28.6% vs. 48.6%, P = 0.04), longer survival time of liver grafts (24±9.6 months vs. 17±12.3 months, P = 0.02), and better outcomes after treatment of ITBLs.

Survival without biliary complications after liver transplant for primary sclerosing cholangitis

OBJECTIVES

Patients who have a liver transplant for primary sclerosing cholangitis may develop recurrent disease and biliary complications, organ loss necessitating revision liver transplant, or death. We evaluated long-term outcomes in patients who had liver transplant for primary sclerosing cholangitis.

MATERIALS AND METHODS

In 71 patients who had a liver transplant for end-stage liver disease because of primary sclerosing cholangitis, a retrospective review was done to evaluate biliary complication-free survival, transplanted organ survival, and death. Human leukocyte antigen typing and matching were reviewed.

RESULTS

There were 39 patients (55%) who had biliary complications, loss of the liver transplant, or death at a mean 12.1 years after transplant. The 5- and 10-year event-free survival reached 74.6% and 45% (53 patients after 5 years, and 32 patients after 10 years). Male sex of transplant recipients was a significant risk factor for biliary complications, revision liver transplant, or death. Most patients had inflammatory bowel disease, primarily ulcerative colitis. The human leukocyte antigen profile or number of mismatches had no effect on complication-free survival.

CONCLUSIONS

Biliary complications, revision liver transplant, and death are a useful combined primary endpoint for recurrent primary sclerosing cholangitis after liver transplant.

Effects of air embolism size and location on porcine hepatic microcirculation in machine perfusion

The handling of donor organs frequently introduces air into the microvasculature, but little is known about the extent of the damage caused as a function of the embolism size and distribution. Here we introduced embolisms of different sizes into the portal vein, the hepatic artery, or both during the flushing stage of porcine liver procurement. The outcomes were evaluated during 3 hours of machine perfusion and were compared to the outcomes of livers with no embolisms. Dynamic contrast-enhanced ultrasound (DCEUS) was used to assess the perfusion quality, and it demonstrated that embolisms tended to flow mostly into the left lobe, occasionally into the right lobe, and rarely into the caudate lobe. Major embolisms could disrupt the flow entirely, whereas minor embolisms resulted in reduced or heterogeneous flow. Embolisms occasionally migrated to different regions of the same lobe and, regardless of their size, caused a general deterioration in the flow over time. Histological damage resulted primarily when both vessels of the liver were compromised, whereas bile production was diminished in livers that had arterial embolisms. Air embolisms produced a dose-dependent increase in vascular resistance and a decline in oxygen consumption. This is the first article to quantify the impact of air embolisms on microcirculation in an experimental model, and it demonstrates that air embolisms have the capacity to degrade the integrity of donor organs. The extent of organ damage is strongly dependent on the size and distribution of air embolisms. The diagnosis of embolism severity can be safely and easily made with DCEUS.