Complications of orthotopic liver transplantation: spectrum of findings with helical CT

Ultrasound innovations in abdominal radiology: multiparametic imaging in liver transplantation

PURPOSE

Ultrasound plays a central role in liver transplant evaluation. Acute, subacute, and chronic complications can be readily identified using grayscale and color Doppler ultrasound. Contrast-enhanced ultrasound adds a new dimension to liver transplant evaluation, depicting vascular and parenchymal processes with exquisite detail. In addition, emerging evidence suggests that contrast-enhanced ultrasound may allow for localization of biliary leak in select patients. We aimed to assess the use of multiparametric ultrasound-including grayscale, color and spectral Doppler, and contrast-enhanced ultrasound-in the setting of liver transplantation.

METHODS

A literature review was performed using the MEDLINE bibliographic database through the National Library of Medicine. The following terms were searched and relevant citations assessed: "abdominal ultrasound," "contrast-enhanced ultrasound," "liver transplant," and "ultrasound."

RESULTS

Grayscale and color Doppler ultrasound represent the mainstay imaging modalities for postoperative liver transplant evaluation. The addition of contrast enhancement plays a complementary role and can provide valuable information related to the allograft vasculature, parenchyma, and biliary tree. The appropriate implementation of grayscale, color Doppler, and contrast-enhanced ultrasound can optimize sensitivity, specificity, and accuracy for the detection of liver transplantation complications, including hepatic artery stenosis, biliary leakage, and infection.

CONCLUSION

Multimodal sonographic evaluation is essential to identify postoperative complications in liver transplant recipients. Contrast-enhanced ultrasound may be of value in challenging cases, providing excellent anatomic delineation and reducing the risk of false-positive and false-negative diagnoses. A broad familiarity with appropriate applications of both nonenhanced and contrast-enhanced ultrasound may help radiologists optimize allograft assessment and improve patient outcomes.

Perfusion Pressures and Weight Loss During Normothermic Machine Perfusion of Human Donor Livers

BACKGROUND

Normothermic machine perfusion (NMP) is increasingly used to preserve and assess donor livers prior to transplantation. Due to its success, it is expected that more centers will start using this technology. However, NMP may also cause adverse effects.

METHODS

In this retrospective, observational study, we investigated the effect of NMP pressures on donor liver weight, post-transplant outcomes, and hepatic perfusion characteristics. A total of 36 livers were transplanted after NMP. NMP perfusion pressure settings were lowered from a median (IQR) of 47 mmHg (42-54) to 34 mmHg (30-39) for the hepatic artery (HA), and from 8 mmHg (7-10) to 7 mmHg (6-8) for the portal vein (PV) to diminish potential edema formation inside the liver.

RESULTS

This change appeared to lead to a reduction of liver weight after NMP (-22 g to -143 g, p = 0.02), without affecting the PV flow velocity (35.5 to 48.0 cm/s, p = 0.54), or hepatocellular injury markers during NMP (AST 1511-1148 U/L, p = 0.44; ALT 318-849 U/L, p = 0.35), and post-transplantation outcomes. Changes in liver weight correlated significantly with the applied PV pressure during NMP (r = 0.52, p < 0.01) and the HA flow (r = 0.38, p < 0.05).

CONCLUSION

NMP can lead to a reduction in liver weight, which might be masked by edema when high perfusion pressures are used. We encourage applying the lowest perfusion pressures possible to reach adequate flows and oxygen supply during liver NMP.

Imaging of Ischemic Cholangiopathy Following Donation after Circulatory Death Liver Transplant

Ischemic cholangiopathy (IC) is the leading cause of inferior long-term outcomes following donation after circulatory death (DCD) liver transplant. Biliary strictures related to IC are nonanastomotic strictures (NASs) by definition and involve the donor hepatic ducts proximal to the anastomosis, compared with postsurgical anastomotic strictures that form due to fibrotic healing. IC-related NASs can be microangiopathic with patent hepatic artery or macroangiopathic with occluded or stenotic hepatic artery. Recently, IC with NASs have been described to have four distinct patterns at imaging: diffuse necrosis, multifocal progressive, confluence dominant, and minor form, which correlate clinically with graft prognosis. Severe IC can lead to ductal wall breakdown with subsequent bile leaks that can cause significant patient morbidity, with imaging playing a vital role in diagnosis and guiding intervention. IC also predisposes the transplanted liver to biliary stasis and subsequent formation of stones, casts, and sludge. Some cases of posttransplant biliary stricturing are not IC but are a sequela of reflux cholangitis seen with choledochojejunal anastomosis. Other biliary findings in the posttransplant liver can be explained by sphincter of Oddi dysfunction that results from denervation. The authors describe and comprehensively categorize the various IC types and their imaging patterns at MRI and MR cholangiopancreatography, review the prognostic significance of these imaging patterns, and discuss imaging features of additional biliary complications associated with IC after DCD liver transplant. ©RSNA, 2024 Supplemental material is available for this article.

The use of ferumoxytol for high-resolution vascular imaging and troubleshooting for abdominal allografts

Ferumoxytol is an ultrasmall superparamagnetic iron oxide which has been used as an off-label intravenous contrast agent for MRI. Unlike gadolinium-based contrast agents, ferumoxytol remains in the intravascular space with a long half-life of 14-21 h. During the first several hours, it acts as a blood-pool agent and has minimal parenchymal enhancement. Studies have shown adequate intravascular signal for up to 72 h after initial contrast bolus. Ferumoxytol has been shown to be safe, even in patients with renal failure. Ferumoxytol has shown promise in a variety of clinical settings. The exquisite resolution enabled by the long intravascular times and lack of background parenchymal enhancement is of particular interest in the vascular imaging of solid organ allografts. Ferumoxytol magnetic resonance angiography (MRA) may identify clinically actionable findings months before ultrasound, CT angiography, or Gadolinium-enhanced MRA. Ferumoxytol MRA is of particular benefit as a troubleshooting tool in the setting of equivocal ultrasound and CT imaging. In the following review, we highlight the use of ferumoxytol for high-resolution MR vascular imaging for abdominal solid organ allografts, with representative cases.

Diagnosis and Treatment of Hepatic Hematoma After Liver Transplantation in a Timely Manner

OBJECTIVE

Hematomas of the liver graft, that is, postintervention, subcapsular or intrahepatic are rare yet potentially fatal complications following liver transplantation (LT), necessitating immediate diagnosis and management to avert devastating outcomes. This study was aimed to introduce our approach to manage graft hematoma subsequent to LT.

METHODS

Among 131 orthotopic liver transplantations (OLT) conducted at our institution between January 2017 and May 2023, 3 cases of intrahepatic (n = 2) and extrahepatic (n = 1) hematoma were confirmed through computed tomography (CT) within 10 days after LT. The clinical outcomes of various treatment modalities for these three cases were analyzed.

RESULTS

Three out of 131 (2.3%) LT recipients developed graft hematoma. Patient 1 developed a spontaneous intrahepatic hematoma, without evident predisposing factors, while patient 2 developed an intrahepatic hematoma following endoscopic retrograde cholangiopancreatography (ERCP). The third case that is extrahepatic hematoma was speculated to be a result of minor hepatic parenchymal injury stemming from compressive and volume-reducing manipulation of a large graft, or secondary to focal ischemic necrosis of the liver. Our management protocol was summarized as follows: (1). Immediate ultrasound and CT, particularly enhanced CT; (2). Puncture and percutaneous drainage (PD) of the hematoma; (3). Arterial embolization if the origin could be identified as a ruptured vessel; (4). Surgical evacuation of the hematoma in the presence of bile leakage, to avoid a compartment respectably secondary infection. All three patients responded favorably to treatment and remained alive to date.

CONCLUSION

Prompt diagnosis and sequential individualized management can successfully deal with intra-/extrahepatic graft hematoma after LT. Our results underscored that an individualized management considering potential future complications into account.

Determinants of early surgical complications after pediatric liver transplantation: A single center/single surgeon experience over 20 years

BACKGROUND

The risk of early surgical complications of liver transplantation (LT) is higher in children when compared with adults. The aims of the present retrospective study from a single center cohort/single surgeon were to identify the predictive factors for surgical complications after pediatric LT.

METHODS

All children receiving a first LT from October 1990 to October 2010 in our center were included.

RESULTS

Included 151 children (boys 55.0%), with a mean age of 4.8 ± 4.8 years, and a mean weight of 17.9 ± 14.4 kg. Thirty-seven patients were transplanted within the first year, and 59 patients had a body weight below 10 kg. The main initial liver disease was biliary atresia (49.0%). Living donor LT was performed in 39 cases (25.8%), cadaveric whole liver LT in 50 cases (33.1%), and cadaveric partial liver LT in 62 cases (41.1%). Early surgical complications included reoperation (37.8%), vascular complications (8.6%), i.e. arterial (3.3%) or portal thrombosis/stenosis (7.3%) within the first month, and biliary complications in the first 90 days occurred in 22.5% of the cases. The main indications for surgical revision were abdominal bleeding, treatment of a biliary complication, and bowel perforation. Multivariate analysis disclosed that only graft type (split and moreover from a living donor) was significantly and independently associated with the occurrence of biliary complication, and that indication for LT, period, graft type, and operative time were significantly and independently associated with the necessity of surgical revision.

CONCLUSION

Our results emphasize that surgical complications are frequent and strongly depend on patient/graft characteristics.

Imaging and Intervention in the Management of Vascular Complications Following Liver Transplantation

Liver transplantation is the treatment of choice in majority of the patients with end stage liver disease. Vascular complication following liver transplantation is seen in around 7-13% of the patients and is associated with graft dysfunction and high morbidity and mortality. Early diagnosis and prompt treatment are crucial in management of these patients. Advances in interventional radiology have significantly improved the management of vascular complications using minimally invasive percutaneous approach. Endovascular management is preferred in patients with late hepatic artery thrombosis, or stenosis, whereas retransplantation, surgical revision, or endovascular management can be considered in patients with early hepatic artery thrombosis or stenosis. Hepatic artery pseudoaneurysm, arterioportal fistula, and splenic artery steal syndrome are often treated by endovascular means. Endovascular management is also preferred in patients with symptomatic portal vein stenosis, early portal vein thrombosis, and symptomatic late portal vein thrombosis, whereas surgical revision or retransplantation is preferred in patients with perioperative portal vein thrombosis occurring within 3 days of transplantation. Venoplasty with or without stent placement can be considered in patients with hepatic venous outflow tract or inferior vena cava obstruction. Transjugular intrahepatic portosystemic shunt (TIPS) may be required in transplant recipients who develop cirrhosis, often, secondary to disease recurrence, or chronic rejection. Indications for TIPS remain same in the transplant patients; however, major difference is altered vascular anatomy, for which adjunct techniques may be required to create TIPS.

Vascular Complications After Liver Transplantation

OBJECTIVES

Vascular complications after liver transplant can be lethal. High levels of suspicion and aggressive use of diagnostic tools may help with early diagnosis and treatment. Here, we share our experiences regarding this topic.

MATERIALS AND METHODS

Adult and pediatric patients who had liver transplant between February 1997 and June 2018 in our clinic were included in the study. Patients were grouped according to age (pediatric patients were those under 18 years old), male versus female, indication for transplant, type of liver transplant, type of vascular complication, treatment, and survival aftertreatment.We analyzed the statistical incidence of vascular complications according to age, male versus female, and type of liver transplant.

RESULTS

Our analyses included 607 liver transplant procedures, including 7 retransplants, with 349 (57.4%) from living donors and 258 (42.6%) from deceased donors. Of total patients, 539 were adults (89.8%) and 61 were children (10.2%). Vascular complications occurred in 25 patients (4.1%), with hepatic artery complications seen in 13 patients (2.1%) (10 adults [1.8%] and 3 children [4.9%]), portal vein complications seen in 9 patients (1.5%) (6 adults [1.1%] and 3 children [4.9%]), and hepatic vein complications seen in 3 patients (0.5%) (2 adults [0.36%] and 1 child [1.6%]). Rate of vascular complications was statistically higher in pediatric patients (11.4% vs 3.3%; P = .007) and higher but not statistically in recipients of livers from living donors (5.2% vs 2.7%; P = .19). Twelve patients (48.8%) were treated with endovascular approach, and 11 (0.44%)required surgicaltreatment. Two patients underwent immediate retransplant due to hepatic artery thrombosis.

CONCLUSIONS

Because vascular complications are the most severe complications afterlivertransplant,there must be close follow-up of vascular anastomoses, particularly early postoperatively, with radiologic methods. In cases of vascular complications, emergent treatment, including endovascular interventions, surgery, and retransplant, must be performed.

Inferior Vena Cava Stenosis Following Orthotopic Liver Transplantation: Differentiating Points from False Positives

Orthotopic liver transplantation has become the treatment of choice for patients with end-stage liver disease. Various early or delayed vascular complications, including arterial pseudoaneurysm, thrombosis, or stenosis, and venous stenosis or occlusion, may lead to graft failure. Early detection and prompt management of such complications are essential to achieve successful transplantation and prevent the need for retransplantation. This report presents differentiating points, using computed tomography and digital subtraction angiography findings and measurement of pressure gradient across the stenotic lesion, that require immediate intervention in patients with inferior vena cava stenosis after orthotopic liver transplantation.

Contrast-enhanced ultrasound of transplant organs - liver and kidney - in children

Ultrasound (US) is the first-line imaging tool for evaluating liver and kidney transplants during and after the surgical procedures. In most patients after organ transplantation, gray-scale US coupled with color/power and spectral Doppler techniques is used to evaluate the transplant organs, assess the patency of vascular structures, and identify potential complications. In technically difficult or inconclusive cases, however, contrast-enhanced ultrasound (CEUS) can provide prompt and accurate diagnostic information that is essential for management decisions. CEUS is indicated to evaluate for vascular complications including vascular stenosis or thrombosis, active bleeding, pseudoaneurysms and arteriovenous fistulas. Parenchymal indications for CEUS include evaluation for perfusion defects and focal inflammatory and non-inflammatory lesions. When transplant rejection is suspected, CEUS can assist with prompt intervention by excluding potential underlying causes for organ dysfunction. Intracavitary CEUS applications can evaluate the biliary tract of a liver transplant (e.g., for biliary strictures, bile leak or intraductal stones) or the urinary tract of a renal transplant (e.g., for urinary obstruction, urine leak or vesicoureteral reflux) as well as the position and patency of hepatic, biliary and renal drains and catheters. The aim of this review is to present current experience regarding the use of CEUS to evaluate liver and renal transplants, focusing on the examination technique and interpretation of the main imaging findings, predominantly those related to vascular complications.

Hyperspectral evaluation of hepatic oxygenation in a model of total vs. arterial liver ischaemia

Liver ischaemia reperfusion injury (IRI) is a dreaded pathophysiological complication which may lead to an impaired liver function. The level of oxygen hypoperfusion affects the level of cellular damage during the reperfusion phase. Consequently, intraoperative localisation and quantification of oxygen impairment would help in the early detection of liver ischaemia. To date, there is no real-time, non-invasive, and intraoperative tool which can compute an organ oxygenation map, quantify and discriminate different types of vascular occlusions intraoperatively. Hyperspectral imaging (HSI) is a non-invasive optical methodology which can quantify tissue oxygenation and which has recently been applied to the medical field. A hyperspectral camera detects the relative reflectance of a tissue in the range of 500 to 1000 nm, allowing the quantification of organic compounds such as oxygenated and deoxygenated haemoglobin at different depths. Here, we show the first comparative study of liver oxygenation by means of HSI quantification in a model of total vascular inflow occlusion (VIO) vs. hepatic artery occlusion (HAO), correlating optical properties with capillary lactate and histopathological evaluation. We found that liver HSI could discriminate between VIO and HAO. These results were confirmed via cross-validation of HSI which detected and quantified intestinal congestion in VIO. A significant correlation between the near-infrared spectra and capillary lactate was found (r = − 0.8645, p = 0.0003 VIO, r = − 0.7113, p = 0.0120 HAO). Finally, a statistically significant negative correlation was found between the histology score and the near-infrared parameter index (NIR) (r = − 0.88, p = 0.004). We infer that HSI, by predicting capillary lactates and the histopathological score, would be a suitable non-invasive tool for intraoperative liver perfusion assessment.

Imaging post liver transplantation part I: vascular complications

Liver transplantation continues to rise in frequency, with over 1,000 procedures performed in the UK in 2018. Complications are increasingly uncommon but when they occur, early recognition and intervention is vital to save grafts. Imaging after the perioperative period is often performed at patients' local hospitals meaning that all radiologists and sonographers need to have an understanding of how to assess a transplant liver. Part I of this series will focus on vascular complications, including the normal postoperative vascular anatomy following liver transplantation, normal post-transplantation vascular imaging findings and abnormal findings that may prompt further investigation. Vascular complications following liver transplantation will be illustrated using a collection of cases.

Role of contrast-enhanced ultrasound in the evaluation of post-liver transplant vasculature

Liver transplantation is a frequently used treatment for patients with end-stage liver disease and ultrasound is often the first-line imaging technique for detection of vascular complications after liver transplant. Although colour Doppler ultrasound is a good screening method for evaluation of post-liver transplant vasculature, it has limitations in evaluating small-calibre vessels and vessels in close proximity. Contrast-enhanced ultrasound (CEUS) has been proposed to overcome these limitations by improving visualisation of post-liver transplant vasculature and reducing the number of false-positive cases, which necessitate unnecessary additional investigations such as computed tomography or angiography. Liver transplant anatomy and the wide array of post-transplant imaging findings on colour Doppler have already been well described but literature on the use of CEUS and its image interpretation remain scarce. This review aims to discuss the indications for CEUS after liver transplant, to demonstrate CEUS technique and familiarise readers with the imaging appearances of post-transplant vascular complications on CEUS.

Radiological findings in ischaemic cholangiopathy

Ischaemic cholangiopathy occurs as a consequence of deficient arterial blood flow to the bile duct wall. Bile duct ischaemia can lead to full-thickness necrosis, bile leakage, biloma formation, and sepsis. It is an important cause of graft failure post-orthotopic liver transplantation. In the native liver, the causes of biliary ischaemia are diverse and include vasculitis or a complication of endovascular procedures. The present review describes the pathology and radiological findings of ischaemic cholangiopathy and outlines the role of interventional radiology in its management.

"Bright Band Sign" A Grayscale Ultrasound Finding in Hepatic Infarction

Hepatic infarction is infrequent due to the dual blood supply of the liver and the compensatory relationship between the hepatic artery and portal vein. Most cases occur in liver transplants due to vascular complications. Grayscale sonography combined with color and spectral wave Doppler can assess for vessel patency and parenchymal abnormalities. Liver infarctions appear as hypoechoic nonvascular regions on conventional and Doppler sonography. Here, we describe a grayscale ultrasound feature within liver infarctions in 2 liver transplants and in 1 native liver due to iatrogenic complication. This feature is similar to those described recently in the literature within splenic infarcts.

Role of imaging in the evaluation of vascular complications after liver transplantation

Clinical manifestations of liver transplantation complications can be subtle and non-specific. Medical imaging, mainly Doppler ultrasound, plays an important role to detect and grade these. Colour Doppler ultrasound exams are routinely performed at 24–48 h, on the 7th day, the first and third month after transplantation. MDCT and MR images are acquired based on the Doppler ultrasound (DUS) findings, even in the absence of abnormal liver function. As vascular complications appear early after surgery, DUS should be performed by experience personnel. Diagnostic angiography is seldom performed. This pictorial review illustrates the key imaging findings of vascular complications in patients with liver transplantation: hepatic artery complications (such as thrombosis, stenosis of the anastomosis and pseudoaneurysms), portal vein abnormalities (such as occlusion and stenosis) and hepatic veins and/or inferior vena cava flow changes (Budd-Chiari syndrome).

Very late hepatic arterial thrombosis manifesting as central biliary necrosis: A rare presentation

Hepatic artery thrombosis should always be considered on a liver graft recipient with mild and nonspecific symptoms, even after a decade of the transplantation.

Diagnostic Performance of Multidetector Computerized Tomography in the Detection of Abdominal Complications Early and Late After Liver Transplantation: A 10-Year Experience

BACKGROUND

Multidetector computerized tomography (MDCT) is considered to be a fast noninvasive diagnostic technique for the evaluation of postoperative complications in patients with liver transplantation (LT). However, its role has not been fully established in the diagnosis for detecting complications after liver transplantation. The aim of this work was to evaluate the diagnostic performance of MDCT for detecting abdominal complications in the early and late periods after LT.

METHODS

We retrospectively enrolled 75 patients who had undergone LT from March 2006 to January 2010, followed by MDCT from March 2006 to November 2017. Patients were divided into 2 groups according to the timing after LT: within the first 3 months (early period) or ≥3 months after LT (late period). We evaluated vascular, biliary, and other complications on MDCT. Angiography, endoscopic retrograde cholangiography, and percutaneous transhepatic cholangiography were used as reference standards.

RESULTS

We initially found 77 complications in 45 patients (60.0%) with the use of MDCT. After comparison with the reference standards, 83 complications were diagnosed in 49 patients (65.3%). Forty-seven complications (34 vascular, 10 biliary, 3 other complications) were diagnosed in 33 patients (44.0%) during the early period, and 36 complications (6 vascular, 20 biliary, 10 other complications) were detected in 27 patients (36.0%) in the late period. The sensitivity, specificity, and diagnostic accuracy of MDCT for diagnosing overall complications were, respectively, 93.6%, 90.2%, and 92.0% in the early period (for vascular complications: 97.1%, 92.6%, and 94.3%,; for biliary complications: 80.0%, 100%, and 97.7%) and 77.8%, 98.1%, and 89.8% in the late period (for vascular complications: 83.3%, 100%, and 98.9%; for biliary complications: 65.0%, 98.6%, and 90.9%).

CONCLUSIONS

Although MDCT in the late period should be interpreted with caution in patients with suspected biliary complication, MDCT is a reliable diagnostic technique for the identification of early and late abdominal complications after LT.

Pediatric Liver Transplant: Techniques and Complications

Liver transplant is considered to be the last-resort treatment approach for pediatric patients with end-stage liver disease. Despite the remarkable advance in survival rates, liver transplant remains an intricate surgery with significant morbidity and mortality. Early diagnosis of complications is crucial for patient survival but is challenging given the lack of specificity in clinical presentation. Knowledge of the liver and vascular anatomy of the donor and the recipient or recipients before surgery is also important to avoid complications. In this framework, radiologists play a pivotal role on the multidisciplinary team in both pre- and postoperative scenarios by providing a road map to guide the surgery and by assisting in diagnosis of complications. The most common complications after liver transplant are (a) vascular, including the hepatic artery, portal vein, hepatic veins, and inferior vena cava; (b) biliary; (c) parenchymal; (d) perihepatic; and (e) neoplastic. The authors review surgical techniques, the role of each imaging modality, normal posttransplant imaging features, types of complications after liver transplant, and information required in the radiology report that is critical to patient care. They present an algorithm for an imaging approach for pediatric patients after liver transplant and describe key points that should be included in radiologic reports in the pre- and postoperative settings. Online supplemental material is available for this article. ^©RSNA, 2017.

Computed tomography findings in ABO-incompatible living donor liver transplantation recipients with biliary strictures

OBJECTIVES

To evaluate CT findings of biliary strictures in ABO-incompatible living donor liver transplantation (LDLT) recipients, with emphasis on associated 1-month post-transplantation CT findings, and evaluate clinical outcomes.

METHODS

Of 351 ABO-incompatible recipients, we retrospectively evaluated CT scans in 65 recipients with biliary stricture. The biliary strictures on CT scans were classified as type A (perihilar) and type B (diffuse). Precedent CT abnormality patterns and the presence of a periportal halo sign at 1-month post-transplantation were evaluated. For each patient, clinical outcomes were evaluated.

RESULTS

Of 65 ABO-incompatible recipients with biliary strictures, 36.9% had type B strictures. Compared with biliary strictures at diagnosis, similar CT abnormality patterns were observed for 84.4% in type A and 86.4% in type B strictures at 1-month post-transplantation. Complex periportal halo signs on the 1-month post-transplantation CT were more frequently noted for type B than type A strictures (86.4% vs. 3.1%, P < 0.001). Progressive clinical outcomes were more frequently observed for type B than type A strictures (79.2% vs. 26.8%, P < 0.001), with a significantly shorter graft survival time (46.4 months vs. 90.8 months, P < 0.001).

CONCLUSION

CT abnormality patterns and complex periportal halo signs on 1-month post-transplantation CT may be clinically useful for managing biliary strictures in ABO-incompatible LDLT recipients. Key Points • Of ABO-incompatible LDLT recipients, type B biliary stricture incidence was 6.8%. • Of type B strictures, 86.4% exhibited similar CT abnormality patterns at 1-month post-transplantation. • Complex periportal halo at 1 month was significantly associated with type B strictures. • Progressive clinical outcomes were more frequently observed in type B strictures.

Outcomes of Percutaneous Portal Vein Intervention in a Single UK Paediatric Liver Transplantation Programme

Introduction

Percutaneous transluminal angioplasty (PTA), with or without stent placement, has become the treatment of choice for portal vein complications (PVC) following liver transplantation. We aimed to assess long-term outcomes of intervention in paediatric transplant recipients, in a single institution.

Materials and Methods

227 children received 255 transplants between November 2000 and September 2016. 30 patients developed PVC of whom 21 had percutaneous intervention. Retrospective clinical and procedural outcome data on these 21 patients were collected.

Results

21 patients, with median age 1.7 years (range 0.4–16.2), underwent 42 procedures with PTA with or without stenting. 36 procedures were for PV stenosis and 6 for PV thrombosis. Treatment was with primary PTA, with stenting reserved for suboptimal PTA result or restenosis within 3 months. 28 procedures were performed with PTA and 13 with stenting. Technical success (>50% reduction in mean pressure gradient, absolute pressure gradient ≤4 mmHg or venographic stenosis <30%) was achieved in 41 procedures. Failure to recanalise a thrombosed PV occurred in 1 procedure. There were no major procedural complications. Patients were followed-up with serial Doppler ultrasound surveillance. Kaplan–Meier estimated median primary patency was 9.9 months, with primary-assisted patency of 95% after median follow-up of 45.5 months (range 11.1–171.6).

Conclusion

With regular surveillance, excellent patency rates can be achieved following percutaneous intervention for PVC post-paediatric liver transplantation.

Tricky Findings in Liver Transplant Imaging: A Review of Pitfalls With Solutions

Orthotopic liver transplantation is the preferred treatment for end-stage liver disease. Imaging plays an important role in the follow-up of transplant recipients by identifying a variety of complications. Posttransplant liver imaging can be challenging with altered vascular and nonvascular postoperative findings closely mimicking pathologies. A thorough knowledge of these common imaging findings in a posttransplant liver is essential for the radiologist to avoid erroneous diagnoses and unnecessary workup. We focus on such imaging findings and provide tips to avoid misinterpretation.

Doppler Characteristics of Recurrent Hepatic Artery Stenosis

OBJECTIVES

We sought to assess midterm sonographic findings in patients after stenting for hepatic artery stenosis.

METHODS

Thirty-nine hepatic artery stent procedures were performed for hepatic artery stenosis after liver transplantation between September 2009 and December 2013. Thirty cases were technically successful and met the minimum follow-up time (76 days, defined by earliest diagnosed stenosis). Routine ultrasound surveillance was obtained on all patients, and statistical analysis of the findings in the patency and restenosis groups was performed.

RESULTS

Of the 30 cases, restenosis occurred 9 times in 6 patients. Mean follow-up was 677 days. Mean time to restenosis was 267 days. Five cases (56%) were identified within the first 6 months after stent placement. Four cases (44%) were recognized in the second year after stent placement. Prior to the sonographic diagnosis of restenosis, the mean resistive indices of the main (.64 versus .57, P < .0001), left (.63 versus .54, P < .0001), right anterior (.60 versus .52, P < .0001), and right posterior (.60 versus .53, P = .001) hepatic artery branches differed among patency and restenosis groups, respectively. The mean peak systolic velocity also differed significantly between the 2 groups: 254 cm/sec in patients with eventual restenosis versus 220 cm/sec in patients without restenosis (P = .02).

CONCLUSIONS

The sonographic evaluation of hepatic artery stenosis remains critical during the first 2 years after stent placement. While the vast majority of patients do not restenose, resistive index and peak systolic velocity differed significantly between the 2 groups and may be prognostic surveillance markers for the development of restenosis.

Imaging follow-up after liver transplantation

Liver transplantation (LT) represents the best treatment for end-stage chronic liver disease, acute liver failure and early stages of hepatocellular carcinoma. Radiologists should be aware of surgical techniques to distinguish a normal appearance from pathological findings. Imaging modalities, such as ultrasound, CT and MR, provide for rapid and reliable detection of vascular and biliary complications after LT. The role of imaging in the evaluation of rejection and primary graft dysfunction is less defined. This article illustrates the main surgical anastomoses during LT, the normal appearance and complications of the liver parenchyma and vascular and biliary structures.

Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation

Multidetector computed tomography angiography (MDCTA) has become a routine imaging tool to assess visceral vascular anatomy and abdominal parenchymal pathology. Enhanced temporal resolution and rapid acquisition allow for precise delineation of arterial and venous anatomy. The excellent spatial resolution permits assessment of small parenchyma lesions and vasculature. The ability of CT to rapidly acquire data and reconstruct with thinner slices allows robust 3D mapping using maximum intensity projection before definitive surgical or interventional therapy. Emerging novel techniques of image acquisition offer sensitive methods for detecting enhancement and allow for virtual imaging subtraction, all while limiting the total radiation burden.

Imaging panorama in postoperative complications after liver transplantation

The liver is the second most-often transplanted solid organ after the kidney, so it is clear that liver disease is a common and serious problem around the globe. With the advancements in surgical, oncological and imaging techniques, orthotopic liver transplantation has become the first-line treatment for many patients with end-stage liver disease. Ultrasound, and Doppler are the most economical and cost-effective imaging modalities for evaluating postoperative fluid collections and vascular complications. Computed tomography (CT) is used to confirm the findings of ultrasound and look for pulmonary complications. Magnetic resonance imaging (MRI) is used for the diagnosis of biliary complications, bile leaks and neurological complications. This article illustrates the imaging options for diagnosing the various complications that can be encountered in the postoperative period after liver transplantation.

Clinical utility of hepatic-perfusion computerized tomography in living-donor liver transplantation: a preliminary study

BACKGROUND

Vascular complications are a primary diagnostic consideration in liver transplant recipients, with an overall incidence of 9%. Cross-sectional imaging techniques provide information regarding vascular structure and luminal patency but can not quantitatively assess hepatocyte damage in the liver graft parenchyma. Perfusion computerized tomography (CT) is a recently developed method that allows for quantitative evaluation of hemodynamic changes in tissue. Our objective was to evaluate the clinical utility of perfusion CT in assessing vascular complications during living-donor liver transplantation (LDLT).

METHODS

The 33 recipients were divided into 3 groups according to Doppler ultrasonographic findings: hepatic arterial complication group, portal venous complication group, and hepatic venous complication group. Blood volume (BV), blood flow (BF), arterial liver perfusion (ALP), portal venous perfusion (PVP), and hepatic perfusion index (HPI) were calculated for the affected vascular territory regions.

RESULTS

Compared with normal liver parenchyma, BV, BF, ALP, and HPI were significantly lower in the hepatic arterial complication group. Although PVP and BV were significantly lower, ALP, HPI, and BF were higher in the affected vascular territory region than in normal liver parenchyma for the portal venous complication group. In the hepatic venous complication group, PVP was significantly higher and BF, ALP, and HPI significantly lower in the affected vascular territory regions than in normal liver parenchyma.

CONCLUSIONS

Perfusion CT imaging is a noninvasive technique that enables the quantitative evaluation of vascular complications in the graft parenchyma after LDLT and permits a quantitative evaluation of the treatment response.

Imaging of the porta hepatis: spectrum of disease

A wide array of pathologic conditions can arise within the porta hepatis, which encompasses the portal triad (the main portal vein, common hepatic artery, and common bile ducts), lymphatics, nerves, and connective tissue. Major vascular diseases of the portal triad include thrombosis, stenosis, and aneurysm. Portal vein thrombosis can complicate liver cirrhosis and hepatocellular carcinoma and has important therapeutic implications. Hepatic artery thrombosis and stenosis require immediate attention to reduce graft loss in liver transplant recipients. Congenital (eg, choledochal cyst) and acquired (benign and malignant) diseases of the biliary system can manifest as mass lesions in the porta hepatis. Lymphadenopathy can arise from neoplastic and nonneoplastic entities. Uncommon causes of mass lesions arise from nerves (eg, neurofibroma, neurofibrosarcoma) and connective tissue (sarcomas) and are rare. The hepatoduodenal ligament is a peritoneal reflection at the porta hepatis and is an important route for the spread of pancreatic and gastrointestinal cancers. Imaging plays a major role in diagnosis and enables appropriate management. Ultrasonography accurately demonstrates anatomic variations and pathologic conditions and is the initial modality of choice for detection of vascular and biliary lesions. Multidetector computed tomography and magnetic resonance imaging allow characterization and differentiation of various masses in the porta hepatis. Imaging-guided interventions, including embolization and stent placement, also play a key role in disease management.

Percutaneous Endovascular Treatment for Hepatic Artery Stenosis after Liver Transplantation: The Role of Percutaneous Endovascular Treatment

BACKGROUND

To retrospectively analyze the outcomes of interventional radiology treatment of patients with hepatic artery stenosis (HAS) after liver transplantation at our Institution.

MATERIAL/METHODS

Hepatic artery stenosis was diagnosed and treated by endovascular technique in 8 (2.8%) patients, who underwent liver transplantation between July 2007 and July 2011. Patients entered the follow-up period, during which we analyzed hepatic artery patency with Doppler ultrasound at 1, 3, 6, and 12 months after percutaneous endovascular treatment (PTA), and every six months thereafter.

RESULTS

During the 12-month follow-up period, 6 out of 8 patients (75%) were asymptomatic with patent hepatic artery, which was confirmed by multislice computed tomography (MSCT) angiography, or color Doppler (CD) ultrasound. One patient had a fatal outcome of unknown cause, and one patient underwent orthotopic liver retransplantation (re-OLT) procedure due to graft failure.

CONCLUSIONS

Our results suggest that HAS angioplasty and stenting are minimally invasive and safe endovascular procedures that represent a good alternative to open surgery, with good 12-month follow-up patency results comparable to surgery.

Role of multi-detector computed tomography for biliary complications after liver transplantation

AIM: To investigate the diagnostic performance of multi-detector computed tomography (MDCT) in detecting biliary complications after orthotopic liver transplantation (OLT).

METHODS: Eighty-three consecutive OLT recipients, who presented with clinical or biochemical signs of biliary complications, underwent MDCT examination. Two experienced radiologists assessed MDCT images in consensus to determine biliary complications. Final confirmation was based on percutaneous transhepatic cholangiography or endoscopic retrograde cholangiography in 58 patients, surgery in four patients, liver biopsy in 10, and clinical and sonography follow-up in 11 patients.

RESULTS: Biliary complications were eventually confirmed in 62 of 83 patients (74.7%), including anastomotic biliary strictures in 32, nonanastomotic biliary strictures in 21, biliary stones in nine (5 with biliary strictures), anastomotic bile leak in five, and biloma in six (all with nonanastomotic strictures, and 2 with biligenic hepatic abscess). Twenty-one patients had no detection of biliary complications. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of MDCT for detecting biliary strictures were 90.6%, 86.7%, 89.2%, 92.3% and 83.9%, respectively. For detecting biliary stones, anastomotic bile leak and biloma, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of MDCT were all 100%.

CONCLUSION: MDCT is a useful screening tool for detecting biliary complications after OLT.

Hepatic transplantation: postoperative complications

Advances in surgical techniques and immunosuppression have made orthotopic liver transplantation a first-line treatment for many patients with end-stage liver disease. The early detection and treatment of postoperative complications has contributed significantly to improved graft and patient survival with imaging playing a critical role in detection. Complications that can lead to graft failure or patient mortality include vascular abnormalities, biliary abnormalities, allograft rejection, and recurrent or post-transplant malignancy. Vascular abnormalities include stenosis and thrombosis of the hepatic artery, portal vein, and inferior vena cava, as well as hepatic artery pseudoaneurysm, arteriovenous fistula, and celiac stenosis. Biliary abnormalities include strictures, bile leak, obstruction, recurrent disease, and infection. While imaging is not used to diagnose allograft rejection, it plays an important role in identifying complications that can mimic rejection. Ultrasound is routinely performed as the initial imaging modality for the detection and follow-up of both early and delayed complications. Cholangiography and magnetic resonance cholangiopancreatography are used to characterize biliary complications and computed tomography is used to confirm abnormal findings on ultrasound or for the evaluation of postoperative collections. The purpose of this article is to describe and illustrate the imaging appearances and management of complications associated with liver transplantation.

Post-operative imaging in liver transplantation: State-of-the-art and future perspectives

Orthotopic liver transplantation (OLT) represents a major treatment for end-stage chronic liver disease, as well as selected cases of hepatocellular carcinoma and acute liver failure. The ever-increasing development of imaging modalities significantly contributed, over the last decades, to the management of recipients both in the pre-operative and post-operative period, thus impacting on graft and patients survival. When properly used, imaging modalities such as ultrasound, multidetector computed tomography, magnetic resonance imaging (MRI) and procedures of direct cholangiography are capable to provide rapid and reliable recognition and treatment of vascular and biliary complications occurring after OLT. Less defined is the role for imaging in assessing primary graft dysfunction (including rejection) or chronic allograft disease after OLT, e.g., hepatitis C virus (HCV) recurrence. This paper: (1) describes specific characteristic of the above imaging modalities and the rationale for their use in clinical practice; (2) illustrates main imaging findings related to post-OLT complications in adult patients; and (3) reviews future perspectives emerging in the surveillance of recipients with HCV recurrence, with special emphasis on MRI.

Hepatic venous outflow obstruction after transplantation: outcomes for treatment with self-expanding stents

OBJECTIVES

To evaluate the safety and patency of self-expanding stents to treat hepatic venous outflow obstruction after orthotopic liver transplantation. To evaluate differences in the response between patients with early obstruction and patients with late obstruction.

MATERIAL AND METHODS

This is a retrospective analysis of 16 patients with hepatic venous outflow obstruction after liver transplantation treated with stents (1996-2011). Follow-up included venography/manometry, ultrasonography, CT, and laboratory tests. We did a descriptive statistical analysis of the survival of patients and stents, technical and clinical success of the procedure, recurrence of obstruction, and complications of the procedure. We also did an inferential statistical analysis of the differences between patients with early and late obstruction.

RESULTS

The mean follow-up period was 3.34 years (21-5,331 days). The technical success rate was 93.7%, and the clinical success rate was 81.2%. The rate of complications was 25%. The survival rates were 87.5% for patients and 92.5% for stents. The rate of recurrence was 12.5%. The rate of primary patency was 0.96 (95% CI 0.91-1) at 3 months, 0.96 (95% CI 0.91-1) at 6 months, 0.87 (95% CI 0.73-1) at 12 months, and 0.87 (95% CI 0.73-1) at 60 months. There were no significant differences between patients with early and late obstruction, although there was a trend toward higher rates of primary patency in patients with early obstruction (P=.091).

CONCLUSIONS

Treating hepatic venous outflow obstruction after orthotopic transplantation with self-expanding stents is effective, durable, and effective. There are no significant differences between patients with early obstruction and those with late obstruction.

Imaging of vascular complications and their consequences following transplantation in the abdomen

Transplantation is the surgical treatment of choice for end-stage organ failure. Transplantation procedures performed in the abdomen include liver, renal, pancreas, islet, intestinal, and multivisceral transplantations. Imaging plays a pivotal role in the posttransplantation setting for monitoring the transplant allograft and screening for complications. Knowledge of the surgical techniques employed in abdominal transplantation is essential because it facilitates radiologic understanding and interpretation of the posttransplantation anatomy. This article includes a basic description of the standard surgical techniques performed in the abdomen, with emphasis on the relevant vascular anastomotic reconstructions used. Posttransplantation complications can be broadly classified as vascular or nonvascular in origin. Many of these complications can be accurately depicted and characterized at imaging and dealt with definitively by using interventional radiology techniques, which can be graft- and life-saving and can obviate further complex surgical intervention. The article discusses imaging appearances of vascular complications and their consequences after transplantation in the abdomen. These vascular complications include arterial thrombosis, arterial stenosis, venous thrombosis and stenosis, arteriovenous fistula formation, and pseudoaneurysm formation. The relevant predisposing factors, clinical features, imaging appearances, and potential treatment options for vascular complications of various types of transplantation are presented in a logical and integrated fashion. Knowledge and imaging recognition of the posttransplantation vascular complications discussed in this article will aid radiologists in accurate imaging characterization and thereby facilitate appropriate clinical management and therapy.

Therapeutic rather than prophylactic platelet transfusion policy for severe thrombocytopenia during liver transplantation

Platelet transfusion (PTx) has been identified as an important risk factor for morbidity and mortality after liver transplantation (LTx). Our aim was to evaluate the safety of therapeutic rather than prophylactic PTx policy in severe thrombocytopenic patients undergoing LTx. Recipients of LTx were divided into two groups: group I (GI) (n = 76) platelet count (PC) ≥ 50 × 10(9)/l and group II (GII) PC < 50 × 109/l (n = 76). Platelets were transfused following a thromboelastometry protocol and clinical signs of diffuse bleeding. Both groups were compared regarding hemoglobin (Hb), international normalized ratio (INR), fibrinogen level, blood loss (BL), blood products required, percentage of bloodless surgery, duration of mechanical ventilation, ICU stay, and vascular complications. Each group was further subdivided according to PTx into (GI NPTx and GII NPTx) with no platelet transfusion (NPTx) and (GI PTx and GII PTx) received PTx. These subgroups were further compared for some variables. Base line Hb was significantly higher while INR was significantly lower in GI.75% avoided PTx in GII. Comparisons of BL, packed red blood cells (PRBCs), and cryoprecipitate transfusion were insignificant. Fresh frozen plasma (FFP) transfusion was higher and the percentage of bloodless surgery was lower in GII. In GII, PC increased after start of surgery. Two cases of hepatic artery thrombosis in GI and one in GII were recorded. Recovery of platelets was quicker, and duration of mechanical ventilation and ICU stay was shorter in NPTx patients regardless the base line PC. Cut-off values of PC 30 × 10(9)/l (with sensitivity 73.7% and specificity 78.8%, p < 0.01), BL of 3750 ml in GI (sensitivity of 75% and specificity of 69%, p < 0.01) and of 3250 ml in GII (sensitivity of 84.2% and specificity of 87.7% (p < 0.01)) could indicate the need of PTx. With therapeutic approach, 75% of patients in GII could avoid unnecessary PTx with its hazards without excessive bleeding. PC in GII increased intraoperatively, PTx may lead to delayed recovery of platelets, increased duration of mechanical ventilation and ICU stay. The given cut-off values may help to guide PTx.

Perfusion defects detected after liver transplantation on multidetector computerized tomography: short- and long-term follow-up

BACKGROUND

Perfusion defects are sometimes found during the follow-up computerized tomography (CT) after liver transplantation (OLT). This study sought to determine the short- and long-term outcomes of perfusion defects observed after OLT with the use of multidetector CT.

METHODS

From February 4, 2004, to December 8, 2011, a total 46 LTs were performed in our hospital owing to end-stage liver cirrhosis (n = 43), liver cirrhosis with hepatocellular carcinoma (HCC; n = 1), combined HCC with cholangiocellular carcinoma (CCC; n = 1), or hepatic failure from acute hepatitis A (n = 1). The transplanted livers were procured from cadaveric (n = 24) or living related donors (n = 22). The average age of the recipient was 53.3 ± 10.4 years. The male-female ratio was 30:16. Postoperative multidetector CT was performed with a dynamic sequence in 203 examinations and with a portal phase in 46 examinations. The contrast media was Radisense. The rate of injection of 120 mL was 3 mL/s with a power injector; the iodine concentration was 300 or 370 mg/dL. Follow-up ranged from 3 months 3 days to 7 years 363 days. We classified perfusion defects as chronic segmental or subsegmental benign ischemia, transient focal perfusion defects, benign subcapsular ischemia, or fatal whole liver perfusion defects.

RESULTS

There were 3 cases of chronic segmental or subsegmental benign ischemia, 8 focal transient perfusion defects, 1 benign subcapsular ischemia, and 4 fatal whole liver perfusion defects. Except the fatal cases, all other perfusion defects occurred in the courses of benign conditions without resection or reoperation.

CONCLUSIONS

Most perfusion defects were benign and uneventful, requiring no treatment, with the exception of fatal whole liver perfusion defects, which resulted in death after detection.

Predictors of intra-abdominal coagulopathic hemorrhage after living donor liver transplantation

BACKGROUND

Results of preoperative conventional coagulation assays are a poor predictor of hemorrhage after liver transplantation. In this study, we evaluated the factors that are predictive of intra-abdominal coagulopathic hemorrhage after living donor liver transplantation surgery.

METHODS

During the period from January 2009 to December 2012, 118 adults underwent living donor liver transplantation (LDLT) in our institution. Of those patients, 18 (15.3%) developed intra-abdominal coagulopathic hemorrhage (n = 7) or hemorrhage due to non-coagulopathic causes (n = 11) that required emergency medical, radiological, or surgical intervention within the first month after LDLT. Possible predictors of postoperative coagulopathic hemorrhage included donor-related factors, age, body mass index, MELD score, INR value, intra-operative blood transfusion, graft/recipient weight ratio, anhepatic phase, cold ischemia time, operative time, APACHE II score, onset of re-bleeding, and hemoglobin levels during rebleeding episodes.

RESULTS

There were no differences in any of the variables between the two groups (coagulopathic and noncoagulopathic hemorrhage) except for cold ischemia time. We found that cold ischemia time was significantly longer in patients with postoperative coagulopathic hemorrhage (160.50 ± 45.02 min) than in patients with hemorrhage due to non-coagulopathic causes (113.55 ± 29.31 min; P = 0.027).

CONCLUSION

Prolonged cold ischemia time is associated with postoperative intra-abdominal coagulopathic hemorrhage in patients after LDLT. It is, therefore, necessary to shorten the cold ischemia time in order to reduce the risk of postoperative intra-abdominal hemorrhage due to coagulopathic causes.