Biliary atresia (BA) is a rare and severe congenital disorder with a significant challenge for prenatal diagnosis. This study, registered at the Chinese Clinical Trial Registry (ChiCTR2200059705), aimed to develop an intelligent model to aid in the prenatal diagnosis of BA. To develop and evaluate this model, fetuses from 20 hospitals across China and infants sourced from public database were collected. The transfer-learning model (TLM) demonstrated superior diagnostic performance compared to the basic deep-learning model, with higher area under the curves of 0.906 (95%CI: 0.872-0.940) vs 0.793 (0.743-0.843), 0.914 (0.875-0.953) vs 0.790 (0.727-0.853), and 0.907 (0.869-0.945) vs 0.880 (0.838-0.922) for the three independent test cohorts. Furthermore, when aided by the TLM, diagnostic accuracy surpassed that of individual sonologists alone. The TLM achieved satisfactory performance in predicting fetal BA, providing a low-cost, easily accessible, and accurate diagnostic tool for this condition, making it an effective aid in clinical practice.

Early diagnosis of biliary atresia (BA) is crucial for improving patient outcomes, yet remains a significant global challenge. This challenge may be ameliorated through the application of artificial intelligence (AI). Despite the promise of AI in medical diagnostics, its application to multimodal BA data has not yet achieved substantial breakthroughs. This study aims to leverage diverse data sources and formats to develop an intelligent diagnostic system for BA.

We constructed the largest known multimodal BA dataset, comprising ultrasound images, clinical data, and laboratory results. Using this dataset, we developed a novel deep learning model and simplified it using easily obtainable data, eliminating the need for blood samples. The models were externally validated in a prospective study. We compared the performance of our model with human experts of varying expertise levels and evaluated the AI system's potential to enhance its diagnostic accuracy.

The retrospective study included 1579 participants. The multimodal model achieved an AUC of 0.9870 on the internal test set, outperforming human experts. The simplified model yielded an AUC of 0.9799. In the prospective study's external test set of 171 cases, the multimodal model achieved an AUC of 0.9740, comparable to that of a radiologist with over 10 years of experience (AUC = 0.9766). For less experienced radiologists, the AI-assisted diagnostic AUC improved from 0.6667 to 0.9006.

This AI-based screening application effectively facilitates early diagnosis of BA and serves as a valuable reference for addressing common challenges in rare diseases. The model's high accuracy and its ability to enhance the diagnostic performance of human experts underscore its potential for significant clinical impact.

Biliary atresia can be a challenging diagnosis to make as there is no single definitive diagnostic laboratory or imaging study available and no single agreed upon diagnostic algorithm. The purpose of this article is to review the complex puzzle of clinical, laboratory, and imaging studies that aid in the evaluation of infants suspected of having biliary atresia. We have reviewed historical and current manuscripts and society guidelines, added our own experience in evaluating infants for biliary atresia, and then summarized the findings to provide a concise review of what we feel is the modern approach to diagnosis of biliary atresia.

Prenatally diagnosed hepatic hilar cysts are a challenging finding for the clinician. They can either be a sign of cystic biliary atresia (BA) or a choledochal cyst (CC), two diagnoses with different postnatal management and prognosis. Based on a case report of four patients, we aim to propose a management algorithm for prenatally diagnosed "hepatic hilar cysts".

A hepatic hilar cyst, ranging from 5 to 25 mm, was detected prenatally in all four girls confirmed postnatally along with the presence of a gallbladder. Stool color was normal until two weeks of life at which time the stool color became lighter, and the patients developed cholestasis. All were operated before seven weeks of life: Case 1 had a CC with patent but irregular intrahepatic bile ducts at intraoperative cholangiogram, and no communication with the duodenum. A Roux-en-Y bilioenteric anastomosis was performed. The cyst showed complete epithelial lining loss, and liver pathology showed BA features. Case 2 had the final diagnosis of cystic BA with patent but abnormal intrahepatic bile ducts. She underwent two operations: the first operation at four weeks as described for case 1, since intraoperative findings were similar, as was histology. As cholestasis increased postoperatively, she underwent a Kasai hepato-porto-enterostomy six weeks later, where distinct BA findings were found with complete scarring of the hilar plate. Case 3 had a cystic BA with the cyst located within the common bile duct and atretic bile ducts proximal to the porta hepatis. It exhibited no communication with the liver or duodenum. A Kasai operation was performed, with histology showing complete epithelial loss within the cyst wall and scarring of the hilar plate. Case 4 had a cystic BA presenting a completely obliterated hepatic duct with the cyst lying within the common bile duct. A Kasai procedure was performed. Histology showed a common bile duct with a residual lumen of 0.1 mm.

The spectrum of disease from CC to BA in the setting of a prenatally discovered hepatic hilar cyst is emphasized. Even if cholangiogram differentiates most patients with BA from those with CC, caution is advised for transitional types.

Biliary atresia (BA) is a congenital disease that occurs when extrahepatic bile ducts are either absent or deficient, resulting in liver fibrosis, portal hypertension, and eventually cirrhosis. It is the most common cause of persistent obstructive jaundice in newborns lasting more than two weeks is this condition. Abdominal ultrasound (US) is the primary imaging technique used to diagnose BA, while computed tomography (CT) is reserved for more complex cases. The gold standard for diagnosing BA is still intraoperative cholangiogram with liver biopsy. Treatment for BA usually involves Kasai hepatoportoenterostomy, but some patients still require liver transplantation due to diagnostic delays and advanced disease. In this study, the authors present the case of a 3-month-old infant with biliary atresia and its ultrasound characteristics, who underwent liver transplantation due to advanced disease. The primary objective of imaging is to provide a prompt diagnosis, given the crucial significance of timely surgical intervention.

The workup of jaundiced infants may be variable and protracted, thereby delaying the diagnosis and timely intervention for biliary atresia (BA). This potentially leads to inferior outcomes. We developed a practical score to stratify infantile cholestasis according to the risk of having BA.

The score (0-7) [gallbladder length ≤ 15 mm (+ 1), common bile duct (CBD) diameter < 0.5 mm(+ 1), pre-portal vein (PV) echogenicity(+ 1), direct-to-total bilirubin ratio (D/T) ≥ 0.7(+ 2), and gamma-glutamyl transferase (GGT) ≥ 200 IU/L(+ 2)] are derived from logistic regression of data from a retrospective cohort of cholestatic infants (n = 58, 41 BA) in our institution. It was then validated with a separate retrospective cohort (n = 28, 17 BA) from another institution. Final diagnoses were as per intraoperative cholangiogram (IOC) and liver histopathology.

A cutoff score of ≥ 3 diagnosed BA with 100% and 94% sensitivity in the derivative cohort (area under receiver operating characteristic curve, AUROC 0.869) and validation cohort (AUROC 0.807), respectively. D/T ratio was the most sensitive (93%) and CBD diameter was the most specific (88%) parameter. The score accurately predicted non-BA in 11(65%) and 7(63%) infants in the derivative and validation cohorts, respectively, with one missed BA in the latter.

We propose a validated, simple, yet sensitive diagnostic score to risk-stratify cholestatic infants, aiming to expedite definitive management of BA.

Cholestasis, characterized by the obstruction of bile flow, poses a significant concern in neonates and infants. It can result in jaundice, inadequate weight gain, and liver dysfunction. However, distinguishing between biliary atresia (BA) and non-biliary atresia in these young patients presenting with cholestasis poses a formidable challenge, given the similarity in their clinical manifestations. To this end, our study endeavors to construct a screening model aimed at prognosticating outcomes in cases of BA. Within this study, we introduce a wrapper feature selection model denoted as bWFMVO-SVM-FS, which amalgamates the water flow-based multi-verse optimizer (WFMVO) and support vector machine (SVM) technology. Initially, WFMVO is benchmarked against eleven state-of-the-art algorithms, with its efficiency in searching for optimized feature subsets within the model validated on IEEE CEC 2017 and IEEE CEC 2022 benchmark functions. Subsequently, the developed bWFMVO-SVM-FS model is employed to analyze a cohort of 870 consecutively registered cases of neonates and infants with cholestasis (diagnosed as either BA or non-BA) from Xinhua Hospital and Shanghai Children's Hospital, both affiliated with Shanghai Jiao Tong University. The results underscore the remarkable predictive capacity of the model, achieving an accuracy of 92.639 % and specificity of 88.865 %. Gamma-glutamyl transferase, triangular cord sign, weight, abnormal gallbladder, and stool color emerge as highly correlated with early symptoms in BA infants. Furthermore, leveraging these five significant features enhances the interpretability of the machine learning model's performance outcomes for medical professionals, thereby facilitating more effective clinical decision-making.

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 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.

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.

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.

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.

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.

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.

The gallbladder is not part of the standard survey of a fetus during obstetrical ultrasound. Yet, some anomalies can be detected. Most are clinically benign, but some are features of or associated with more serious complications. Biliary atresia constitutes the diagnosis with the worst prognosis. Its in utero diagnosis is difficult. Still, markers do exist and should be searched for. Knowledge of the normal appearances, variants and abnormalities of the gallbladder contributes to proper management. Any suspicion should lead to meticulous postnatal workup. Pre- or postnatal magnetic resonance imaging can provide additional information in select cases.

Liver cirrhosis in children is a rare disease with multifactorial causes that are distinct from those in adults. Underlying reasons include cholestatic, viral, autoimmune, hereditary, metabolic and cardiac disorders. Early detection of fibrosis is important as clinical stabilization or even reversal of fibrosis can be achieved in some disorders with adequate treatment. This article focuses on the longitudinal evaluation of children with chronic liver disease with noninvasive imaging tools, which play an important role in detecting cirrhosis, defining underlying causes, grading fibrosis and monitoring patients during follow-up. Ultrasound is the primary imaging modality and it is used in a multiparametric fashion. Magnetic resonance imaging and computed tomography are usually applied second line for refined tissue characterization, clarification of nodular lesions and full delineation of abdominal vessels, including portosystemic communications.

Biliary Atresia (BA), an obstructive cholangiopathy, is the most common cause of end-stage liver disease and liver transplantation in children. Timely differentiation of BA from other causes of neonatal jaundice remains a challenge, yet is critical to improving outcomes.

Clinical characteristics including demographics, age at jaundice presentation, age at hepatobiliary scintigraphy, age at surgery, severity of liver fibrosis, and native-liver survival were reviewed in infants with hyperbilirubinemia and suspected BA for this single center retrospective cohort study. We investigated the accuracy of hepatobiliary scintigraphy as well as elapsed time from jaundice presentation to diagnostic intervention.

BA was suspected in 234 infants. BA was identified in 17% of infants with hepatobiliary scintigraphy and 72% of infants who underwent operative exploration without hepatobiliary scintigraphy. Elapsed time from jaundice presentation to Kasai Portoenterostomy (KPE) for BA patients was 2.1x longer if hepatobiliary scintigraphy was obtained (p = 0.084). The mean age at KPE for this cohort was 66.8 days (n = 54), with a significantly higher mean age at KPE (75.2 days) for infants who were later listed or underwent liver transplantation (p = 0.038). Histologically, the lowest liver fibrosis scores were seen in infants undergoing KPE <30 days old and worsened significantly with increased age (p < 0.001).

Hepatobiliary scintigraphy compared to operative exploration for the diagnostic evaluation of infants with suspected BA introduces significant time delays to KPE but enables avoidance of surgery in some infants. The temporal pattern of worsening cholestatic liver injury from BA with each day of increased age highlights the importance of intervening as early as possible for the best prognosis.

Retrospective study, Level of evidence: III.

To evaluate the feasibility of ultrasound shear wave elastography (SWE) for predicting hepatic fibrosis and native liver outcomes in patients with biliary atresia.

This prospective study included 33 consecutive patients with biliary atresia (median age, 8 weeks [interquartile range, 6-10 weeks]; male:female ratio, 15:18) from Severance Children's Hospital between May 2019 and February 2022. Preoperative (within 1 week from surgery) and immediate postoperative (on postoperative days [PODs] 3, 5, and 7) ultrasonographic findings were obtained and analyzed, including the SWE of the liver and spleen. Hepatic fibrosis, according to the METAVIR score at the time of Kasai portoenterostomy and native liver outcomes during postsurgical follow-up, were compared and correlated with imaging and laboratory findings. Poor outcomes were defined as intractable cholangitis or liver transplantation. The diagnostic performance of SWE in predicting METAVIR F3-F4 and poor hepatic outcomes was analyzed using receiver operating characteristic (ROC) analyses.

All patients were analyzed without exclusion. Perioperative advanced hepatic fibrosis (F3-F4) was associated with older age and higher preoperative direct bilirubin and SWE values in the liver and spleen. Preoperative liver SWE showed a ROC area of 0.806 and 63.6% (7/11) sensitivity and 86.4% (19/22) specificity at a cutoff of 17.5 kPa for diagnosing F3-F4. The poor outcome group included five patients with intractable cholangitis and three undergoing liver transplantation who showed high postoperative liver SWE values. Liver SWE on PODs 3-7 showed ROC areas of 0.783-0.891 for predicting poor outcomes, and a cutoff value of 10.3 kPa for SWE on POD 3 had 100% (8/8) sensitivity and 73.9% (17/23) specificity.

Preoperative liver SWE can predict advanced hepatic fibrosis, and immediate postoperative liver SWE can predict poor native liver outcomes in patients with biliary atresia.

Cholestatic jaundice characterized by elevated conjugated bilirubin can be due to multitude of factors in neonates and childhood. Extrahepatic biliary atresia (EHBA), choledochal cyst, neonatal hepatitis, cytomegalovirus (CMV), and biliary plug are some of the common causes in neonate and early infancy. Causes in late infancy and childhood comprises viral hepatitis, choledochal cyst, cholelithiasis, worm infestation, and biliary compression secondary to extrinsic causes (node, collection, tumor). Some serious disorders like biliary atresia must be considered with the emphasis on early diagnosis of treatable causes. In the modern era, with multiple diagnostic modalities available including high-resolution ultrasonography, magnetic resonance imaging (MRI), CT scan, and nuclear imaging [hepatobiliary iminodiacetic acid (HIDA) scan], rapid diagnosis can be made in many surgically treatable cases. The authors will discuss the imaging modality available with advantages, disadvantages, and common indications of each modality, and overview of obstructive jaundice discussing the wide spectrum of causes in neonates and late childhood. Combining available knowledge with careful and meticulous search can help narrow down the diagnosis and initiate prompt treatment.

Biliary atresia is a rare but significant cause of neonatal cholestasis. An early and accurate diagnosis is important for proper management and prognosis. To diagnose biliary atresia, various imaging studies using ultrasonography, MRI, hepatobiliary scans, and cholangiography can be performed, although ultrasonography is more important for initial imaging studies. In this article, we review the findings of biliary atresia from various imaging modalities, including ultrasonography, MRI, hepatobiliary scans, and cholangiography. The known key imaging features include abnormal gallbladder size and shape, periportal thickening visible as a 'triangular cord' sign, invisible common bile duct, increased hepatic arterial flow, and combined anomalies. Aside from the imaging findings of biliary atresia, we also reviewed the diagnostic difficulty in the early neonatal period and the role of imaging in predicting hepatic fibrosis. We hope that this review will aid in the diagnosis of biliary atresia.

Biliary atresia is an unknown etiology of extrahepatic bile duct obstruction with a 'fibrous ductal remnant,' which represents the obliterated ductal remnant in the porta hepatis. The sonographic'triangular cord' (TC) sign has been reported to indicate a fibrous ductal remnant in the porta hepatis. In this review, we discuss the correlations among surgicopathological and sonographic findings of the porta hepatis and the definition, objective criteria, diagnostic accuracy, and differential diagnosis of the TC sign in biliary atresia.

Biliary atresia is a progressive, idiopathic, obliterative disease of the extrahepatic biliary tree that presents with biliary obstruction in the neonatal period. It is the most common indication for liver transplantation in children. If untreated, progressive liver cirrhosis leads to death by two years of age. Nowadays, more than 90% of biliary atresia patients survive into adulthood with the development of Kasai portoenterostomy and liver transplantation technology. Early diagnosis is critical since the success rate of the Kasai portoenterostomy decreases with time. This study comprehensively reviews the recent advances in the etiology, classification, prevalence, clinical manifestations, treatment, and prognosis of biliary atresia.

When a pediatric hepatic cystic lesion is identified at imaging, the differential diagnosis may be broad, including developmental, infectious, neoplastic, and posttraumatic or iatrogenic causes. The location of a cystic lesion and its number, size, composition, and relationship to the biliary system are features that help in narrowing the differential diagnosis. An incidentally detected simple hepatic cyst is the most commonly encountered. Ciliated foregut cysts are typically located in hepatic segment IVa. The presence of multiple cysts should raise suspicion for fibropolycystic liver disease, a group of related lesions-including biliary hamartoma and choledochal cyst-caused by abnormal embryologic development of the ductal plate. Communication of the cystic lesion with the biliary tree can confirm the diagnosis of choledochal cyst. In a neonate with jaundice, a cystic lesion at the porta hepatis should raise suspicion for choledochal cyst versus cystic biliary atresia. Hepatic abscess can appear cystlike, though typically with internal contents. In an immunocompromised child, multiple cystlike lesions should raise concern for fungal microabscesses. A complex cystic mass in a young child should raise suspicion for mesenchymal hamartoma, which can evolve into undifferentiated embryonal sarcoma if untreated. Hepatic hematoma and biloma can appear cystlike in children with a history of trauma or recent intervention. In neonates with an umbilical vein catheter (UVC), an intrahepatic cyst along the course of the UVC should raise concern for infusate extravasation. Familiarity with imaging findings and clinical features is essential for achieving accurate diagnosis of pediatric hepatic cystic lesions, which in turn can guide appropriate clinical management. Online supplemental material is available for this article. ^©RSNA, 2022.

Biliary atresia is challenging to diagnose because many of the clinical and imaging features of this condition overlap with those of other causes of cholestasis in newborns. When jaundice persists beyond 2 weeks of age, the neonate should be evaluated for cholestasis, and biliary atresia - the most common cause of neonatal cholestasis - should be considered. It is critical to diagnose biliary atresia early because failure to treat can result in hepatic fibrosis and death in less than 1 year. In this paper, we review the current diagnostic imaging methods, differential considerations and treatment options for biliary atresia.

The objectives of this study is to compare the prognostic differences between cystic biliary atresia (CBA) and non-CBA, analyze the clinical and liver pathological differences between the two groups, and explore the possible factors that affect the native liver survival of infants with CBA after Kasai portoenterostomy (KPE).

From 2013 to 2020, 131 infants with BA were admitted to Tianjin Children's Hospital. A total of 108 infants with BA were included after excluding those who did not undergo surgery after diagnosis (n = 23), including 12 cases of CBA and 96 cases of non-CBA. The clinical data, native liver survival and liver pathology, including liver fibrosis, bile ductular proliferation (BDP), bile plug, and portal area inflammation infiltration of the two study groups were compared.

CBA accounts for 9.16% (12/131) and type I CBA accounts for 6.87% (9/131) of all types of BA. 16.7% (2/12) of CBA were detected prenatally with diagnosis of choledochal cyst (CC). The age at KPE, total bilirubin, direct bilirubin, and total bile acid levels of CBA were significantly lower than those of non-CBA (P = 0.047, P = 0.013, P = 0.009, P = 0.010, respectively). The long and wide diameters of the gallbladder were significantly larger than those of non-CBA (both P < 0.001). The 1-, 3-, and 5-year survival rates of CBA were 83.3%, 71.4%, and 71.4%, respectively, and 56.5%, 32.5%, and 29.8%, respectively, in non-CBA. The difference between the two groups was statistically significant (P = 0.031). The degree of liver fibrosis and bile plug in non-CBA was higher than that of CBA (P = 0.004, P < 0.001, respectively). There was no difference of BDP and inflammation infiltration between the two groups (P = 0.285, P = 0.243, respectively).

CBA is a distinct type different from non-CBA, with different pathological processes, pathological manifestations, and clinical prognosis. The favorable prognosis of CBA may be derived from the early diagnosis, early operation, and mild pathological changes.

Biliary atresia (BA) is the leading cause of chronic liver disease and the most common indication for pediatric liver transplantation. The use of ultrasound (US) and related techniques continues to evolve to help diagnose BA as well as potentially to help predict outcomes after treatment with the Kasai portoenterostomy (KP).

There are no US findings that are definitive for BA; however, signs which are consistent with BA include gallbladder abnormalities, the triangular cord sign, presence of hepatic subcapsular flow, and hilar lymphadenopathy. Elastography techniques to measure liver stiffness may also increase the diagnostic accuracy of detecting BA, particularly in older infants or without other US findings. In addition, both US and elastography are still being studied as potential methods to predict outcomes after KP such as the development of portal hypertension and the need for liver transplant.

US findings in the diagnosis of BA are well characterized. Future studies will help determine the utility of elastography in diagnosing BA, as well as both US and elastography in monitoring and predicting disease outcomes after KP.

We aim to present a practical approach to imaging in suspected biliary atresia, an inflammatory cholangiopathy of infancy resulting in progressive fibrosis and obliteration of extrahepatic and intrahepatic bile ducts. Left untreated or with failure of the Kasai procedure, biliary atresia progresses to biliary cirrhosis, end-stage liver failure and death within the first years of life. Differentiating biliary atresia from other nonsurgical causes of neonatal cholestasis is difficult as there is no single method for diagnosing biliary atresia and clinical, laboratory and imaging features of this disease overlap with those of other causes of neonatal cholestasis. In this second part, we discuss the roles of magnetic resonance (MR) cholecystopancreatography, hepatobiliary scintigraphy, percutaneous biopsy and percutaneous cholecysto-cholangiography. Among imaging techniques, ultrasound (US) signs have a high specificity, although a normal US examination does not rule out biliary atresia. Other imaging techniques with direct opacification of the biliary tree combined with percutaneous liver biopsy have roles in equivocal cases. MR cholecystopancreatography and hepatobiliary scintigraphy are not useful for the diagnosis of biliary atresia. We propose a decisional flowchart for biliary atresia diagnosis based on US signs, including elastography, percutaneous cholecysto-cholangiography or endoscopic retrograde cholangiopancreatography and liver biopsy.