Ultrasound for the Diagnosis of Biliary Atresia: From Conventional Ultrasound to Artificial Intelligence

Biliary atresia

Biliary atresia (BA) is a progressive inflammatory fibrosclerosing disease of the biliary system and a major cause of neonatal cholestasis. It affects 1:5,000-20,000 live births, with the highest incidence in Asia. The pathogenesis is still unknown, but emerging research suggests a role for ciliary dysfunction, redox stress and hypoxia. The study of the underlying mechanisms can be conceptualized along the likely prenatal timing of an initial insult and the distinction between the injury and prenatal and postnatal responses to injury. Although still speculative, these emerging concepts, new diagnostic tools and early diagnosis might enable neoadjuvant therapy (possibly aimed at oxidative stress) before a Kasai portoenterostomy (KPE). This is particularly important, as timely KPE restores bile flow in only 50-75% of patients of whom many subsequently develop cholangitis, portal hypertension and progressive fibrosis; 60-75% of patients require liver transplantation by the age of 18 years. Early diagnosis, multidisciplinary management, centralization of surgery and optimized interventions for complications after KPE lead to better survival. Postoperative corticosteroid use has shown benefits, whereas the role of other adjuvant therapies remains to be evaluated. Continued research to better understand disease mechanisms is necessary to develop innovative treatments, including adjuvant therapies targeting the immune response, regenerative medicine approaches and new clinical tests to improve patient outcomes.

Impact of gallbladder hypoplasia on hilar hepatic ducts in biliary atresia

BACKGROUND

Biliary atresia (BA) is an intractable disease of unknown cause that develops in the neonatal period. It causes jaundice and liver damage due to the destruction of extrahepatic biliary tracts,. We have found that heterozygous knockout mice of the SRY related HMG-box 17 (Sox17) gene, a master regulator of stem/progenitor cells in the gallbladder wall, exhibit a condition like BA. However, the precise contribution of hypoplastic gallbladder wall to the pathogenesis of hepatobiliary disease in Sox17 heterozygous embryos and human BA remains unclear.

METHODS

We employed cholangiography and histological analyses in the mouse BA model. Furthermore, we conducted a retrospective analysis of human BA.

RESULTS

We show that gallbladder wall hypoplasia causes abnormal multiple connections between the hilar hepatic bile ducts and the gallbladder-cystic duct in Sox17 heterozygous embryos. These multiple hilar extrahepatic ducts fuse with the developing intrahepatic duct walls and pull them out of the liver parenchyma, resulting in abnormal intrahepatic duct network and severe cholestasis. In human BA with gallbladder wall hypoplasia (i.e., abnormally reduced expression of SOX17), we also identify a strong association between reduced gallbladder width (a morphometric parameter indicating gallbladder wall hypoplasia) and severe liver injury at the time of the Kasai surgery, like the Sox17-mutant mouse model.

CONCLUSIONS

Together with the close correlation between gallbladder wall hypoplasia and liver damage in both mouse and human cases, these findings provide an insight into the critical role of SOX17-positive gallbladder walls in establishing functional bile duct networks in the hepatic hilus of neonates.

Diseases of bile duct in children

Several diseases originate from bile duct pathology. Despite studies on these diseases, certain etiologies of some of them still cannot be concluded. The most common disease of the bile duct in newborns is biliary atresia, whose prognosis varies according to the age of surgical correction. Other diseases such as Alagille syndrome, inspissated bile duct syndrome, and choledochal cysts are also time-sensitive because they can cause severe liver damage due to obstruction. The majority of these diseases present with cholestatic jaundice in the newborn or infant period, which is quite difficult to differentiate regarding clinical acumen and initial investigations. Intraoperative cholangiography is potentially necessary to make an accurate diagnosis, and further treatment will be performed synchronously or planned as findings suggest. This article provides a concise review of bile duct diseases, with interesting cases.

Biliary Disorders, Anomalies, and Malignancies in Children

Biliary abnormalities in children are uncommon, and the spectrum of biliary disorders is broader than in adult patients. Unlike in adults, biliary disorders in children are rarely neoplastic and are more commonly rhabdomyosarcoma rather than cholangiocarcinoma. Pediatric biliary disorders may be embryologic or congenital, such as anatomic gallbladder anomalies, anomalous pancreaticobiliary tracts, various cholestatic processes, congenital cystic lesions, or genetic conditions. They may also be benign, such as biliary filling anomalies, biliary motility disorders, and biliary inflammatory and infectious disorders. Distinguishing these entities with a single imaging modality is challenging. US is the primary imaging modality for initial evaluation of biliary abnormalities in children, due to its wide availability, lack of ionizing radiation, and low cost and because it requires no sedation. Other examinations such as MRI, CT, and nuclear medicine examinations may provide anatomic and functional information to narrow the diagnosis further. Hepatobiliary-specific contrast material with MRI can provide better assessment of biliary anatomy on delayed images than can traditional MRI contrast material. MR cholangiopancreatography (MRCP) allows visualization of the intra- and extrahepatic biliary ducts, which may not be possible with endoscopic retrograde cholangiopancreatography (ERCP). Suspected biliary atresia requires multiple modalities for diagnosis and timely treatment. Determining the type of choledochal cyst calls for a combination of initial US and MRCP. Many benign and malignant biliary masses require biopsy for definitive diagnosis. Knowledge of the imaging appearances of different pediatric biliary abnormalities is necessary for appropriate imaging workup, providing a diagnosis or differential diagnosis, and guiding appropriate management. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Biliary atresia in children (analytical literature review and review of own observation)

OBJECTIVE

Aim: to review information resources and analysis of the own experience on this problem for the provision of modern knowledge in the pathogenesis of the pathology, the latest diagnostic and treatment technologies, with consideration of the need to adhere to a single strategy in the management of patients with BA.

PATIENTS AND METHODS

Materials and Methods: The analysis of the data regarding the results of existing studies evaluating the clinical benefit and safety of diagnostic and treatment methods in Biliary atresia.

CONCLUSION

Conclusions: BA is the leading cause of neonatal cholestasis development. Early diagnostics of BA, based on the complex evaluation of clinical-laboratory, instrumental and morphological signs of the pathology, has a significant meaning. Surgical correction during the first 2 months of life - the Kasai procedure, as well as dynamic post-surgery follow-up significantly prolong the life of children and allow postponing liver transplantation. The highest patient survival both at the first stage of treatment - conduction of the Kasai procedure and the stage of liver transplantation may be achieved by joined work of surgeons and pediatricians, which allows considering the whole row of possible problems.

Diagnostic Significance of Absence of Post-Feeding Contraction of the Gallbladder in Biliary Atresia: Two Case Reports

Ultrasonography is an essential part of the diagnostic process of biliary atresia (BA). The characteristic findings of BA include a hilar hyperechoic zone, the triangular cord sign (TCS), an absence of gallbladder contraction after feeding, and gallbladder atrophy. However, approximately 10% of patients with BA have a normal gallbladder. We herein present two cases of BA with normal morphology of the gallbladder as shown by ultrasonography. In the first case, the patient was positive for the TCS, negative for gallbladder atrophy, and positive for contraction of the gallbladder after feeding; the final diagnosis was hilar obstructive BA complicated by pancreaticobiliary maljunction. In the second case, the patient was positive for the TCS, negative for gallbladder atrophy, and negative for contraction of the gallbladder after feeding; the patient also had common bile duct obstruction and stenosis of the hepatic duct in the hilar region. Based on these two cases, we conclude that gallbladder findings are not diagnostic for BA because in some types, the gallbladder may be normal in morphology and even have the capacity for contraction after feeding.

Dysmorphic Gallbladder Found on Prenatal Ultrasound as a Hint for Biliary Atresia

Biliary atresia (BA) is a rare but devastating cholangiopathy. We report a case series of dysmorphic gallbladders detected during prenatal ultrasound, which were confirmed as BA after birth. We present the prenatal ultrasound findings as well as integral follow-up, with an aim to raise awareness regarding the association between BA and dysmorphic gallbladder. Although this dysmorphic gallbladder is a strong hint for BA, it is also important to search for other related sonographic features, such as the presence of microcysts at the hepatic hilum, dilated right hepatic artery, and seroperitoneum, which may provide more evidence for the diagnosis of BA.

Intraoperative hepatic subcapsular spider-like telangiectasia sign for the definitive diagnosis of biliary atresia

OBJECTIVE

To evaluate the accuracy of intraoperative hepatic subcapsular spider-like telangiectasia (HSST) sign for differentiating biliary atresia (BA) from other causes of hepatic cholestasis.

METHODS

The data of 69 patients with jaundice treated from January 2019 to December 2021 were retrospectively analyzed. Based on intraoperative cholangiography (IOC), the patients were divided into two groups: the BA group (n = 49) and the non-BA group (n = 20). The biochemistry tests, liver ultrasound, liver stiffness value and HSST sign of the two groups were compared.

RESULTS

The incidence of abnormal gallbladder, elevated γ-glutamyl transpeptidase (γ-GGT) > 182.0U/L and abnormal liver stiffness (> 6.4 kPa) in BA group were significantly higher than those in non-BA group (P < 0.001). The HSST sign was present in all BA patients and not found in non-BA group. The area under receiver operating curve of direct bilirubin(DBIL), γ-GGT, abnormal gallbladder, liver stiffness value and HSST sign were 0.53, 0.84, 0.78, 0.96, and 1.00, respectively. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value(NPV) of HSST sign in the diagnosis of BA were all 100%.

CONCLUSION

Presence of HSST sign on diagnostic laparoscopy is highly suggestive of BA.It can be used in the differential diagnosis of BA and non-BA.

LEVEL OF EVIDENCE

Level III.

[New advances in the diagnosis and treatment of biliary atresia]

The diagnosis of biliary atresia (BA) is mainly based on clinical manifestations, screening, and related biochemistry tests. In recent years, the development of blood biomarkers and the improvement in ultrasound examination have made it possible for BA to be diagnosed at a younger age. In particular, matrix metalloproteinase-7 shows high sensitivity and specificity and has a higher diagnostic efficiency than existing biochemical parameters, thereby holding a promise for clinical application. Sound touch elastography can increase the diagnostic efficiency for BA in terms of diagnosis and prognostic evaluation. Surgery is still the only method for the treatment of BA at present, with the preferred surgical treatment regimen of Kasai portoenterostomy combined with pharmacotherapies for alleviating infection and inflammation, and the patients who fail Kasai portoenterostomy or have liver dysfunction may require liver transplantation to save their lives. Therefore, the current research on BA should focus on the biomarkers for early diagnosis, specifically targeted drugs, and drugs for preventing progressive liver fibrosis. This article reviews the current diagnosis and treatment methods for BA and discusses the potential research directions.

The diagnostic performance of ultrasound elastography for biliary atresia: A meta-analysis

Background

Biliary atresia (BA) is a severe inflammatory obliterative cholangiopathy of infancy that requires early diagnosis and prompt surgical intervention. In this study, we aimed to obtain comprehensive evidence on the diagnostic performance of liver stiffness measurement by ultrasound elastography in the detection of BA through a meta-analysis.

Methods

The PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched for studies that investigated the diagnostic performance of ultrasound elastography in the detection of BA up to January 10, 2022. In this study, in order to summarize the diagnostic performance of ultrasound elastography, the summary receiver operating characteristic (SROC) modeling was constructed. Heterogeneity was estimated with the I ² statistic. Multiple subgroup analyses were also performed.

Results

Fourteen studies from eleven articles, including 774 BA patients, 850 non-BA patients, and 173 controls were included in the present meta-analysis. The summary sensitivity and specificity of ultrasound elastography for liver stiffness were 85% [95% confidence interval (CI): 79-89%] and 82% (95% CI: 73-88%) with the I ² value of 82.90 and 84.33%, respectively. The area under the SROC curve (AUROC) using ultrasound elastography for diagnosing BA was 0.90 (95% CI: 0.87-0.92). In addition, a subgroup analysis of 9 two-dimensional shear wave elastography studies was also performed. Subgroup analysis revealed that the summary sensitivity and specificity were 85% (95% CI: 77-91%) and 79% (95% CI: 71-86%), respectively, and the summary AUROC was 0.89 (95% CI: 0.86-0.92).

Conclusions

Ultrasound elastography exhibits good diagnostic accuracy for BA and can be served as a non-invasive tool to facilitate the differential diagnosis of BA.