Dr. Paolo Marra
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Biliary interventions are among the most common non-vascular procedures every interventional radiologist should be familiar with. While they are mainly performed in the adult population to manage hepatobiliopancreatic malignancies, in paediatric patients the indications to perform transhepatic biliary procedures are usually related to benign conditions that can be subdivided into two main categories: strictures and leakages. Biliary strictures are the most common source of morbidity after liver transplantation, as they may occur in up to 45% of patients and hamper graft survival [1]. Other relatively rare diseases that may require percutaneous biliary interventions in the paediatric population include obstructive neonatal cholestasis, congenital bile duct malformations, intrahepatic lithiasis, post-surgical complications and liver tumours [2]. Autoimmune cholangitis could be considered a rare indication only in case of failure of medical therapy and presence of dominant stenosis. It is worth remarking that biliary interventions rely on a multidisciplinary approach.
Before performing a percutaneous transhepatic biliary intervention, the operating IR should be aware of the exact anatomy of the biliary tract and liver vascular system, taking into account anatomic variants to choose the best approach and minimize the risks of complications. Moreover, the possibility of accessing the biliary tract though the endoscopic route must be previously considered: rendez-vous strategies could significantly improve the benefit-risk balance.
Imaging is crucial both for diagnosis and preoperative planning, as it should provide the following information:
Ultrasound (US)-based techniques, including B-mode and Color-Doppler, are the key tools for the assessment of the paediatric liver and biliary tract. They are widely available, radiation-free and provide the highest spatial and temporal resolution. However, US imaging is hampered by a limited panoramic view. When US findings are not conclusive or doubtful, magnetic resonance cholangiopancreatography (MRCP) should be performed. Besides providing high-resolution and panoramic images, MR is supported by the use of hepatocyte specific contrast agents (HSCA) which add functional information to the morphological assessment of MRCP [3]. Cholestasis is associated with reduced HSCA uptake that, in case of intrahepatic strictures, may show up as sectorial or segmental liver parenchyma hypointensity. The diagnosis of biliary leaks may rely on the hepatobiliary excretion phase of HSCAs to exactly localize the source of the bile extravasation with MRCP [4]. This is crucial to guide the treatment, since anastomotic leaks should be managed by percutaneous biliary drainage, while biliary leaks from the cut liver surface may heal spontaneously or require surgery.
To properly perform PTC, the paediatric interventional radiologist should operate in accordance with standard of practice recommendations [5] aimed to minimize the risk of periprocedural complications such as bleeding and infections. Different protocols in terms of the duration of biliary stenting have been reported, varying from 3 to 24 months, depending on the type and aetiology of the stenosis and the need for repeat balloon angioplasty [2]. However, in babies and children, the tolerance of external biliary drainages could be very limited, requiring the development of new strategies, such as stenting without external drainage catheters.
The most important and recent developments in this field are represented by the increasing clinical adoption of biodegradable biliary stents [6, 7]. Currently, there are three different devices on the market, one self-expandable, one balloon-expandable, and one non-expandable. They may provide a twofold advantage: they can be used to replace internal-external biliary drainages, reducing the infectious risk and discomfort, and prolong the effects of the bilioplasty [8].
While the treatment of benign biliary strictures may rely on effective strategies, refractory non anastomotic strictures could be challenging, finally leading to biliary cirrhosis. Although it has not been shown to prolong graft survival, the use of metal stents in case of advanced biliary cirrhosis may be considered as a bridge to retransplantation, to palliate cholestatic symptoms avoiding the use of poorly tolerated external drainage catheters.
Paolo Marra
ASST Papa Giovanni XXIII Hospital, Bergamo/IT
Dr. Marra completed his radiology training at San Raffaele Hospital, Milan, focusing on hepatobiliary and pancreatic diagnostic and interventional radiology and experimental preclinical imaging. His work has included advanced clinical and preclinical liver and pancreatic imaging and interventions, with independent research projects. Since October 2019, he has been employed as a general consultant radiologist at ASST Papa Giovanni XXIII Hospital where he has been the contact person for ultrasound and interventional radiology since 2020. Dr. Marra is a tutor at the School of Medicine and Surgery of the University of Milano-Bicocca, giving lectures on several topics regarding interventional radiology in adults and paediatric patients.
Besides general responsibilities in multimodality imaging, including thoraco-abdominal CT and MR examinations, Dr. Marra is dedicated to interventional radiology in adults and paediatric patients, covering all thoraco-abdominal pathologies, including peri-surgical assessment, trauma, oncology, vascular, and chronic diseases. His main activities involve the diagnosis and interventional management of complications of liver transplantations, dealing with more than 400 paediatric transplants in the last twenty years. Dr. Marra regularly runs multidisciplinary meetings for lung cancer, liver and biliary tract cancers, and adult and paediatric hepatology and liver transplantations. His professional goal is to improve the quality of IR work, optimizing organizational aspects, and defining operational standards. Dr. Marra does his best work in a team with a multidisciplinary perspective and is involved in various international research projects dedicated to paediatric liver diseases, such as the PORTAL registry, the HEPATIC registry, and the IRCPSS registry. Dr. Marra is committed to professional development, research, and teaching colleagues in training.
