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

Comprehensive review of imaging in pancreas transplantation: a primer for radiologists

Pancreas transplantation is a complex surgical procedure performed to restore normoglycemia in patients with type 1 diabetes and includes whole/segmental organ transplant and islet cell transplantation (ICT). In the United States, simultaneous pancreas-kidney transplant (SPK) is most commonly performed due to the higher occurrence of end-stage renal disease in diabetic patients. Understanding the surgical technique and postoperative anatomy is imperative for effective and accurate surveillance following transplantation. Imaging plays an essential role in patients with pancreatic transplants and is often used to evaluate viability, vascular and parenchymal anatomy, and identify potential complications. Imaging techniques such as ultrasound, color and spectral Doppler, computed tomography (CT), magnetic resonance imaging (MRI), and angiography have a complementary role in the postoperative evaluation following a pancreas transplant. The common complications after a whole organ pancreas transplant include vascular thrombosis, graft rejection, pancreatitis, and infections. Complications can be classified into vascular (partial or complete venous thrombosis, arterial thrombosis, stenosis or pseudoaneurysm), parenchymal (pancreatitis, graft rejection), and bowel-related or miscellaneous causes (bowel obstruction, anastomotic leak, and peripancreatic fluid collections). Islet cell transplantation is an innovative therapy for patients with type 1 diabetes. It involves isolating insulin-producing islet cells from donor pancreas and transplanting into recipients, to provide long-term insulin independence or significantly reduce insulin requirements. In recent years, isolation techniques, immunosuppressive regimens, and post-transplant monitoring advancements have propelled ICT as a viable therapeutic option. This comprehensive review aims to provide insights into the current state-of-the-art imaging techniques discussing both normal and abnormal features following pancreas transplantation.

Pancreatic Transplantation: Surgical Anatomy and Complications

Pancreatic transplantation is a complex surgical procedure performed for patients with chronic severe diabetes, often performed in combination with renal transplantation. Vascular and exocrine drainage anatomy varies depending on the surgical technique. Radiology plays a critical role in the diagnosis of postoperative complications, requiring an understanding of grayscale/Doppler ultrasound as well as computed tomography and MR imaging. In this review, we detail usual surgical methods and normal postoperative imaging appearances. We then review the most common complications following pancreatic transplants, emphasizing diagnostic features of vascular (arterial/venous), surgical, and diffuse parenchymal pathologic conditions on multiple imaging modalities.

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.

A Study Protocol Exploring the Role of an Implantable Doppler Probe in Kidney Transplantation: A Feasibility Randomized Controlled Trial with an Embedded Qualitative Study

OBJECTIVES

Vascular complications in kidney transplant surgery constitute one-third of early graft loss, which can be prevented by timely diagnosis of vascular compromise. A blood flow monitoring device may have a beneficial role in the early identification of graft hypoperfusion critical to reducing graft loss. This research protocol aims to evaluate the potential of an implantable Doppler probe as a blood flow monitoring device in kidney transplant recipients.

MATERIALS AND METHODS

The potential study will be a mixed methodology, 2-arm feasibility randomized controlled trial with an embedded qualitative study. For the trial, we will compare demographic characteristics and outcome measures of kidney transplant patients receiving implantable Doppler probe monitoring (intervention group, n = 30) with those having standard clinical care (control group). For the qualitative study, we will conduct semi-structured interviews with stakeholders (n = 12) recruited by purposive sampling to explore experiences of participants. All interviews will be audio recorded with verbatim transcription.

RESULTS

Our results will use the summarized quantitative data and descriptive statistics to determine differences between the groups. We will use CONSORT guidelines to determine the suitability of the research processes, availability of research resources, and potential challenges faced during the feasibility randomized controlled trial. We will use thematic analysis and NVivo software to analyze the acceptability of the intervention in clinical practice. We will compile the results according to the consolidated criteria for reporting qualitative research checklist.

CONCLUSIONS

The goal of this protocol is to determine the feasibility of an implantable Doppler probe monitoring device in kidney transplant recipients. The feasibility study will collect preliminary information, fill gaps in evidence, and test research processes for the pragmatic future randomized controlled trial. The template of this study is transferable to other transplant centers across the United Kingdom.

Doppler evaluation of hepatic hemodynamics after living donor liver transplantation in infants

Objective: The aim of this study was to explore the hemodynamic changes of hepatic artery and portal vein detected by Doppler ultrasound (DU) in infants who underwent living donor liver transplantation (LDLT).

Methods: The data of 41 infant patients (22 Males, 19 Females, median age of 5 months) were collected in the Children’s Hospital affiliated to the Chongqing Medical University from May 2018 to December 2019. The patients underwent left lateral segment LDLT (LLS -LDLT) because of biliary atresia (BA). Hemodynamic parameters, including the peak systolic velocity (PSV), resistivity index (RI) of the hepatic artery (HA), portal vein velocity (PVV), and portal vein flow (PVF) were recorded from Doppler ultrasound on the day before the operation, and on the 1st, the 7th, the 14th and the 30th day after LDLT procedures. The changes of PSV_HA, RI_HA, PVV and PVF before and on the 1st day after transplantation were analyzed by paired t-test. The comparison of the data between different postoperative time points were assessed by ANOVA.

Results: Compared with the parameters measured before LDLT, PSV_HA, and RI_HA decreased, and PVV and PVF increased significantly (p < 0.001) on the 1st day after LLS-LDLT. As for PSV, there was no significant difference between the 7th day and the 1st day after transplantation (POD7 VS POD1, p = 0.167) while there was a substantial difference between the 14th, 30th and 1st day after LT (POD14 vs. POD1, p = 0.003) (POD30 vs. POD1, p ＜0.001). And there was a significant difference between the 14th, 30th, and 7th days after LT (POD14 vs. POD7, p = 0.014) (POD30 vs. POD7, p ＜0.001). There was no significant difference between 30th and 14th after transplantation (POD30 vs. POD14, p = 0.092). As for RI_HA and PVV, the decrease was slow within the first month after the operation, and there was no significant difference at different times.

Conclusion: We have identified major hepatic flow changes that occurred in 41 infants who underwent LLS -LDLT due to BA. The data could be used for future studies of LDLT in infants including hemodynamic modeling, liver regeneration and clinical management.

Utilization of dielectric properties for assessment of liver ischemia-reperfusion injury in vivo and during machine perfusion

There is a shortage of donor livers and patients consequently die on waiting lists worldwide. Livers are discarded if they are clinically judged to have a high risk of non-function following transplantation. With the aim of extending the pool of available donor livers, we assessed the condition of porcine livers by monitoring the microwave dielectric properties. A total of 21 livers were divided into three groups: control with no injury (CON), biliary injury by hepatic artery occlusion (AHEP), and overall hepatic injury by static cold storage (SCS). All were monitored for four hours in vivo, followed by ex vivo plurithermic machine perfusion (PMP). Permittivity data was modeled with a two-pole Cole–Cole equation, and dielectric properties from one-hour intervals were analyzed during in vivo and normothermic machine perfusion (NMP). A clear increasing trend in the conductivity was observed in vivo in the AHEP livers compared to the control livers. After four hours of NMP, separations in the conductivity were observed between the three groups. Our results indicate that dielectric relaxation spectroscopy (DRS) can be used to detect and differentiate liver injuries, opening for a standardized and reliable point of evaluation for livers prior to transplantation.

Ultrasonographic evaluation of patients with abnormal liver function tests in the emergency department

Ultrasonography is often the initial modality used to evaluate patients found to have abnormal liver function tests (LFTs) in the emergency department. While an assessment for biliary ductal dilatation and obstruction remains one of the main questions to answer, radiologists should also be aware of the ultrasonographic appearance of other conditions that can cause abnormal LFTs. This may be crucial for the management and disposition of patients in the emergency department. This article reviews the ultrasonographic features of diseases that may cause abnormal LFTs.

Imaging complications of liver transplantation: a multimodality pictorial review

Liver transplantation is one of the most commonly performed surgical procedures for the treatment of end-stage liver disease and hepatocellular carcinoma. Post-transplantation complications include vascular, nonvascular, and biliary. Common imaging techniques used to evaluate the hepatic graft are ultrasonography (US), CT, MR imaging, cholangiography, angiography, and scintigraphy. The purposes of this pictorial review are to review imaging findings of complications of liver transplantation and provide a framework for early detection of post-surgical complications.

Imaging in whole organ pancreatic transplants and a multimodality review of its complications

This pictorial review will describe the normal anatomy of whole organ pancreatic transplants and the common surgical variants with which the radiologist should be familiar. Complications may be divided into (1) vascular: arterial occlusion and stenosis, venous thrombosis, pseudoaneurysms and arteriovenous fistulae, (2) parenchymal complications such as pancreatitis and the variety of peripancreatic collections, and (3) enteric complications including leak and fistula formation. The radiologist plays a crucial role in the initial assessment of graft anatomy and perfusion, prompt diagnosis, and increasingly, in the management of complications.

Transplant renal artery and vein occlusion evaluated with ferumoxytol-enhanced magnetic resonance angiography

BACKGROUND

Compromise of the transplanted vasculature accompanying a kidney allograft can lead to graft failure if not diagnosed and treated expeditiously. Location of the vascular defect in the transplant renal artery or vein is difficult to anticipate, given the variety of etiologies. However, early diagnosis can anticipate further progression of kidney allograft dysfunction. Ferumoxytol-enhanced magnetic resonance angiography (FeMRA) can precisely localize lesions in both the transplant renal artery and vein and provide a comprehensive survey of the vascular conduits of concern. It avoids complications of kidney injury associated with intravenous iodinated contrast that may amplify a diagnosis of delayed graft function or further impair an allograft already compromised by donor-derived vascular disease.

METHODS

We report a case of concomitant and irreversible proximal transplant renal artery and vein stenosis diagnosed by FeMRA and treated with surgical intervention.

RESULTS AND CONCLUSIONS

FeMRA offers a rapid, non-invasive approach to simultaneously diagnose compromised blood flow through the transplant artery and or vein in preparation for definitive correction of the defect.

Pediatric living donor left lateral segment liver transplantation for biliary atresia: Doppler ultrasound findings in early postoperative period

PURPOSE

To analyze hepatic hemodynamic parameters detected by Doppler ultrasound (DU) of uncomplicated children with biliary atresia who underwent left lateral segment living donor liver transplantation (LLS-LDLT), explore its normal change trend over time and determine the normal reference interval.

METHODS

We retrospectively involved the data from 227 biliary atresia patients (100 Males,127 Females). Hemodynamic parameters include peak systolic velocity (PSV), end-diastolic velocity (EDV), resistivity index (RI), and pulsation index (PI) of the hepatic artery (HA), portal vein velocity (PVV), portal vein flow (PVF) and hepatic vein velocity (HVV) during intra-operative and on the 1st, 3rd, 5th and 7th day after operation were collected. Repeated measures analysis of the variance and Friedman test were used to analyze the changing trend of hemodynamic parameters over time in the first week after the operation.

RESULTS

PSV_HA and EDV_HA showed a similar changing tendency at one week after surgery, with an overall decrease-rise trend; RI_HA and PI_HA also changed similarly with an overall rise-decrease trend. The HVV and PVV at surgery were lower than at all time points after surgery. As for PVF, the value of POD5 was the highest and then decreased. Additionally, this study provided the normal reference interval of hemodynamic parameters for LLS-LDLT patients, which were PSV_HA: 18.4-98.3 cm/s, EDV_HA: 0-43.3 cm/s, RI_HA: 0.41-1.0, PI_HA: 0.51-2.0, PVV: 19.0-83.7 cm/s, HVV: 19.4-68.0 cm/s, and PVF:99.5-500.0 ml/min/100 g at intraoperation. Within the first postoperative week: PSV_HA: 21.0-97.7 cm/s, EDV_HA: 0-32.7 cm/s, RI_HA: 0.47-1.0, PI_HA: 0.62-2.0, PVV: 23.0-92.0 cm/s, HVV: 19.7-86.0 cm/s, and PVF: 100.0-513.0 ml/min/100 g.

CONCLUSION

The hepatic hemodynamic of post-transplanted children detected by DU had specific changing trends and normal ranges, which provides valuable reference values for ultrasonologists and pediatric transplant clinicians.

Multimodality imaging of pancreas-kidney transplants

Simultaneous pancreas-kidney transplant remains a treatment option for patients with insulin-dependent diabetes mellitus type 1, aimed at restoring normoglycemia, alleviating insulin dependency, avoiding diabetic nephropathy, and thereby improving the quality of life. Imaging remains critical in the assessment of these transplant grafts. Ultrasound with Doppler remains the primary imaging modality for establishing baseline assessment of the graft as well as for evaluating vascular, parenchymal, and perigraft complications. Noncontrast MR imaging is preferred over non-contrast CT for evaluation of parenchymal or perigraft complications in patients with decreased renal function, although contrast-enhanced CT/MR imaging may be obtained following multidisciplinary consultation in cases with high clinical and laboratory suspicion for graft dysfunction. Catheter angiography is reserved primarily for therapeutic intervention in suspected or confirmed vascular complications. An understanding of the surgical techniques and imaging appearance of a normal graft is crucial to identify potential complications and direct timely management. This article provides an overview of surgical techniques, normal imaging appearance, as well as the spectrum of imaging findings and potential complications in pancreas-kidney transplants.

Venous Thrombosis and Hypercoagulability in the Abdomen and Pelvis: Causes and Imaging Findings

Venous thromboembolism (VTE), which includes deep venous thrombosis and pulmonary embolism, is a significant cause of morbidity and mortality. In recent decades, US, CT, and MRI have surpassed catheter-based angiography as the imaging examinations of choice for evaluation of vascular structures and identification of thrombus owing to their ready availability, noninvasive nature, and, in the cases of US and MRI, lack of exposure to ionizing radiation. As a result, VTE and associated complications are commonly identified in day-to-day radiologic practice across a variety of clinical settings. A wide range of hereditary and acquired conditions can increase the risk for development of venous thrombosis, and many patients with these conditions may undergo imaging for unrelated reasons, leading to the incidental detection of VTE or one of the associated complications. Although the development of VTE may be an isolated occurrence, the imaging findings, in conjunction with the clinical history and vascular risk factors, may indicate a predisposing condition or underlying diagnosis. Furthermore, awareness of the many clinical conditions that result in an increased risk of venous thrombosis may aid in detection of thrombus and any concomitant complications. For these reasons, it is important that practicing radiologists be familiar with the multimodality imaging findings of thrombosis, understand the spectrum of diseases that contribute to the development of thrombosis, and recognize the potential complications of hypercoagulable states and venous thrombosis. Online DICOM image stacks and supplemental material are available for this article. ^©RSNA, 2020.

Management of vascular and nonvascular complications following pancreas transplantation with interventional radiology

Pancreas transplantation exposes to high rates of complications, either vascular (thrombosis, stenosis, pseudoaneurysm, arteriovenous fistula) or nonvascular (fluid collection, graft rejection). With advances in percutaneous and endovascular techniques, interventional radiologists are increasingly involved in the management of these complications. In this article, we review the anatomical considerations relevant to pancreas transplantation, the techniques used for image-guided interventions for vascular and nonvascular complications, and the expected outcomes of these interventions.

Pancreatic transplantation with duodenoduodenostomy drainage: technique, normal radiological appearance and complications

Pancreas transplantation is considered the curative treatment for severe type 1 diabetes mellitus in selected cases. Since the first procedure in 1966, surgical techniques have been improved. The current trend among most medical centers, as well as at our Institution, is enteric drainage and systemic venous or portal anastomosis. The aim of this pictorial essay is to describe the main imaging features of pancreatic transplantation with duodenoduodenostomy drainage.

Imaging of Abdominal Postoperative Complications

We present a case-based review of abdominal postoperative complications, organized by organ system affected, including wound/superficial, hepatobiliary, pancreatic, gastrointestinal, genitourinary, and vascular complications. Both general complications and specific considerations for certain types of operations are described, as well as potential pitfalls that can be confused with complications. Representative cases are shown using all relevant imaging modalities, including CT, fluoroscopy, ultrasound, MRI, and nuclear medicine. Management options are also described, highlighting those that require radiologist input or intervention.

Iatrogenic Vascular Injuries of the Abdomen and Pelvis: The Experience at a Hellenic University Hospital

Background:

The aim of this study is to present the experience of a Vascular Division at a Hellenic University hospital concerning the management of iatrogenic vascular injuries (IVIs) of the abdomen or pelvis.

Patients and Methods:

This is a retrospective study evaluating all IVIs reported during a 10-year period in our institution. Only injuries warranting a vascular surgeon consultation were included in the study. Non-iatrogenic injuries were not included. Mortality and major complications within 30 days were evaluated.

Results:

Overall, 70 cases were recorded, with 41% being venous and 59% being arterial injuries. Iliac arteries (51%) were the most common location and rupture/lacerations (73%) were the most common type of injury. General surgery (61.5%) and cardiology (30%) procedures were the most frequently involved procedures. A 30-day mortality was 5.7%, with 30% of cases treated conservatively. Synthetic bypass grafting (odds ratio [OR] = 65.0; 95% confidence interval [CI], 4.022-1050.358; P = .003) and male gender (OR = 83.77; 95% CI, 4.040-1736.738; P = .004) were associated with death.

Conclusions:

Iatrogenic vascular injuries of the abdomen or pelvis are usually associated with general surgery and endovascular procedures. When vascular consultation is requested early, mortality could remain low. However, a selected number of stable patients with retroperitoneal or pelvic hematomas could be treated conservatively, yielding satisfying results.

Intestinal transplants: review of normal imaging appearance and complications

Intestinal transplant (IT) is one of the least common forms of organ transplant but is increasing both in volume of cases and number of centers performing intestinal transplants, with the busiest centers in North America and Europe. IT can be performed in isolation or as part of a multivisceral transplant (MVT). Intestinal failure either in the form of short gut syndrome or functional bowel problems is the primary indication for IT. The normal post-surgical anatomy can be variable due to both recipient anatomy in regard to amount of residual bowel and status of native vasculature as well as whether the transplant is isolated or part of a multivisceral transplant. Complications of isolated IT and IT as part of an MVT include complications shared with other types of organ transplants such as infection, rejection, post-transplant lymphoproliferative disorder and graft versus host disease. Mechanical bowel complications of the graft include bowel obstruction, stricture, leak, perforation and enterocutaneous fistula. Lastly, vascular complications of both the venous and arterial anastomoses including stricture and pseudoaneurysm occur.

Imaging in pancreas transplantation complications: Temporal classification

Pancreatic transplantation is a therapeutic option for both poorly controlled cases of diabetes mellitus and patients with advanced diabetic nephropathy. It is important for radiologists to know the different surgical techniques as well as the typical radiological appearance after pancreatic transplantation, in order to accurately identify the complications. These complications can be classified according to the period of time after the transplantation in which they typically occur: immediate (first 24 hours), early (24-72 hours), intermediate (72 hours to weeks) and late (months). An accurate and early diagnosis of pancreas transplantation complications is essential to start the adequate treatment and increase the chances of graft survival.

Doppler Parameters of the Hepatic Artery as Predictors of Graft Status in Pediatric Liver Transplantation

OBJECTIVE

The purpose of this article is to determine whether hepatic artery (HA) Doppler parameters can be used to predict pediatric liver graft status in the immediate postoperative (< 10 days) period and in the first year after transplant.

MATERIALS AND METHODS

A retrospective review of the liver transplant database was performed to review operative, clinical, laboratory, histopathologic, and ultrasound findings at three time points after surgery: 3 days, 3 months, and 1 year. The association between HA velocity and resistive index (RI) with graft status was assessed.

RESULTS

Of 120 children (54 girls and 66 boys; mean age, 3 years 2 months) enrolled, 70 had satisfactory graft status at the 1-year follow-up examination. HA velocity of 50-200 cm/s at 3 days was associated with normal graft status during the immediate postoperative period (p = 0.003), at 3 months (p = 0.0653), and at the 1-year follow-up examination (p = 0.0268). Vascular and biliary complications in the immediate postoperative period were more frequent at an HA velocity of 201-300 cm/s (p = 0.0024). There was a significant association between RI at 3 days and graft status in the immediate postoperative period (p = 0.0308), with an RI less than 0.5 associated with vascular complications (p = 0.0116).

CONCLUSION

An RI less than 0.5 is associated with vascular complications. An HA velocity of 50-200 cm/s and an RI of 0.5-0.8 are associated with normal graft status in children within the first year after transplant. Values outside this range, or in this range along with a constellation of other ultrasound findings and clinical status, support the initiation of additional more-specific investigations that may help in early treatment to prevent complications.

The Sonographic Stenosis Index: A New Specific Quantitative Measure of Transplant Hepatic Arterial Stenosis

OBJECTIVES

This study evaluates the sensitivity and specificity of stenosis index (SI), which accounts for the entire spectral Doppler waveform, to detect significant transplant hepatic arterial stenosis.

MATERIALS AND METHODS

In this institutional review board-approved, HIPAA compliant study, we retrospectively analyzed 69 patients who had catheter angiography for suspected transplant hepatic arterial stenosis (THAS) between January 2006 and December 2010; all patients had Doppler ultrasound within 30 days before angiography. Patients with angiographic stenosis requiring intervention were considered positive for THAS. Stenosis index was calculated from each patient's spectral Doppler ultrasound images by obtaining the ratio of the area under the high-frequency signal to low-frequency signal in the spectral Doppler. Resistive index (RI) and pulsatility index (PI) were also calculated. Receiver operator curve analysis was performed and the area under the curve (AUC) was compared among the three metrics.

RESULTS

Forty-eight of 69 patients had THAS by angiography requiring intervention; 21patients had no angiographic evidence of THAS. SI was significantly different (P < .001) between patients with THAS (SI = 1.04 ± 0.20) and those without THAS (SI = 1.39 ± 0.30). Stenosis index had an AUC of 0.86 for detecting THAS, which was significantly higher than that from RI (AUC = 0.68, P = .038 for the comparison) and PI (AUC = 0.70, P = .029). For SI < 1.35, the sensitivity for THAS was 94% and specificity was 52%. For RI < 0.5, the sensitivity was 96% and the specificity was 29%.

CONCLUSIONS

Stenosis index is more accurate than the resistive index and the pulsatility index for detecting transplant hepatic artery stenosis.

New Dimensions in Renal Transplant Sonography: Applications of 3-Dimensional Ultrasound

BACKGROUND

The aim of this study is to demonstrate the usefulness of adding 3-dimensional (3D) ultrasound in evaluation of renal transplant vasculature compared to 2-dimensional (2D) Duplex ultrasound.

METHODS

One hundred thirteen consecutive renal transplant 2D and 3D ultrasound examinations were performed and retrospectively reviewed by 2 board-certified radiologists and a radiology resident individually; each reviewed 2D and then 3D images, including color and spectral Doppler. They recorded ability to visualize the surgical anastomosis and rated visualization on a subjective scale. Interobserver agreement was evaluated. Variant anastomosis anatomy was recorded. Tortuosity or stenosis was evaluated if localized Doppler velocity elevation was present.

RESULTS

The reviewers directly visualized the anastomosis more often with 3D ultrasound ((Equation is included in full-text article.)=97.5%) compared with 2D ((Equation is included in full-text article.)=54.5%) [difference in means (DM) = 43% (95% confidence interval (CI) = 36%-50%) (P < 0.001)]. The reviewers visualized the anastomosis more clearly with 3D ultrasound (P < 0.001) [difference in medians = 0.5, 1.0, and 1.0, (95% CI = 0.5-1.0, 0.5-1.0, and 1.0-1.5)]. Detection of variant anatomy improved with 3D ultrasound by 2 reviewers [DM = 7.1% and 8.9% (95% CI = 1%-13% and 4%-14%, respectively) (P < 0.05)]. There was high interobserver agreement [(Equation is included in full-text article.)= 95.3%, (95% CI = 91.9%-98.7%) regarding anastomosis visualization among reviewers with wide-ranging experience.

CONCLUSIONS

Direct visualization of the entire anastomosis was improved with 3D ultrasound. Three-dimensional evaluation improved detection of anatomic variants and identified tortuosity as the likely cause of borderline localized elevation in Doppler velocity. The data added by 3D ultrasound may obviate confirmatory testing with magnetic resonance angiography or computed tomographic angiography after equivocal 2D ultrasound results.

Imaging of Pancreas Transplantation and Its Complications

Whole pancreas transplantation is an effective treatment for obtaining euglycemic status in patients with insulin-dependent diabetes mellitus, and is usually performed concurrent with renal transplantation in the affected patient. This article discusses complex surgical anatomical details of pancreas transplantation including surgical options for endocrine and exocrine drainage pathways. It then describes several possible complications related to surgical factors in the immediate post operative period followed by other complications related to systemic issues, vasculature, and the pancreatic parenchyma.

Case report of hepatic artery dissection secondary to hepatic artery pseudoaneurysm after living donor liver transplantation

Background

Hepatic artery pseudoaneurysm (HAP) and Hepatic artery dissection are rare vascular complications after living donor liver transplantation (LDLT), which may lead to graft loss and death of the recipients. Conventional gray-scale and Doppler ultrasound, as well as contrast-enhanced ultrasound (CEUS), play important roles in identifying vascular complications in the early postoperative period and during follow-up. We report a case of hepatic artery dissection secondary to HAP after LDLT, which was diagnosed and followed for one year by ultrasound. To the best of our knowledge, few studies have reported similar cases after liver transplantation in the English literature.

Case presentation

A 43-year-old man underwent right-lobe LDLT for treatment of a severe acute hepatitis B infection and was followed up with ultrasound examinations for one year. Conventional gray-scale and Doppler ultrasound combined with contrast-enhanced ultrasound (CEUS) accurately revealed the occurrence of HA dissection secondary to HAP and accompanied by thrombosis and collateral circulation, as well as secondary biliary complications, which provided a prompt diagnosis and guidance for the treatment.

Conclusion

Our case suggests that ultrasound can help detect hepatic artery pseudoaneurysm and dissection, as well as secondary biliary lesions after LDLT in an accurate and timely manner and provide useful information for the treatment chosen. CEUS shows potential as an important complementary technique to gray-scale and Doppler ultrasound.

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

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

Regenerative liver surgeries: the alphabet soup of emerging techniques

New surgical procedures taking advantage of the regenerative abilities of the liver are being introduced as potential curative therapies to these patients either to provide auxiliary support while the native liver recovers or undergoes hypertrophy. For patients with hepatocellular carcinoma outside of the Milan criteria or bilobar colorectal metastases liver transplantation is not an option. Fulminant hepatic failure can be treated but requires life-long immunosuppression. These complex surgical procedures require high quality and directed imaging.

Nonvascular post-liver transplantation complications: from US screening to cross-sectional and interventional imaging

Orthotopic liver transplantation is becoming an increasingly routine procedure for a variety of benign and malignant diseases of the liver and biliary system. Continued improvements in surgical techniques and post-transplantation immunosuppression regimens have resulted in better graft and patient survival. A number of potentially treatable nonvascular complications of liver transplantation are visible at imaging, and accurate diagnosis of these complications allows patients to benefit from potential treatment options. Biliary complications include stricture (anastomotic and nonanastomotic), leak, biloma formation, and development of intraductal stones. Pathologic conditions, including hepatitis C infection, hepatocellular carcinoma, hepatic steatosis, and primary sclerosing cholangitis, may recur after liver transplantation. Transplant patients are at increased risk for developing de novo malignancy, including post-transplantation lymphoproliferative disorder, which results from immunosuppression. Patients are also at increased risk for systemic infection from immunosuppression, and patients with hepatic artery and biliary complications are at increased risk for liver abscess. Transplant recipients are typically followed with serial liver function testing; abnormal serum liver function test results may be the first indication that there is a problem with the transplanted liver. Ultrasonography is typically the first imaging test performed to try to identify the cause of abnormal liver function test results. Computed tomography, magnetic resonance imaging, angiography, and/or cholangiography may be necessary for further evaluation. Accurately diagnosing nonvascular complications of liver transplantation that are visible at imaging is critically important for patients to benefit from appropriate treatment.

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.

Pancreas transplant imaging: how I do it

Pancreas transplantation aims to restore physiologic normoglycemia in diabetic patients with glomerulopathy and avoid or delay the onset of diabetic retinopathy and arteriopathy. Simultaneous pancreas-kidney transplant is the most common approach, using a cadaveric pancreas donation in conjunction with either cadaveric or live donor renal transplant. Alternative techniques include pancreas after kidney transplant, in which the pancreas transplant is performed some years after renal transplant. Pancreas transplant alone is utilized rarely in diabetic patients with compensated renal function. Pancreas grafts have vascular and enteric connections that vary in their anatomic approach, and understanding of this is critical for imaging with ultrasonography, computed tomography, or magnetic resonance imaging. Imaging techniques are directed to display the pancreatic transplant arterial and venous vasculature, parenchyma, and intestinal drainage pathway. Critical vascular information includes venous thrombosis (partial or complete), arterial occlusion, or aneurysm. Parenchymal abnormalities are nonspecific and occur in pancreatitis, graft rejection, and subsequent graft ischemia. Peripancreatic fluid collections include hematoma/seroma, pseudocyst, and abscess. The latter two are related to pancreatitis, duct disruption, or leak from the duodenojejunostomy. An understanding of transplant anatomy and complications will lead to appropriate use of imaging techniques to diagnose or exclude important complications.

Pancreas transplantation: a treatment option for people with diabetes

Since the first pancreas transplants in the early 1960s, whole-organ pancreas transplantation, either alone or combined with kidney transplantation, has become commonplace in many countries around the world. Whole-organ pancreas transplantation is available in the UK, with ~200 transplants currently carried out per year. Patient survival and pancreas graft outcome rates are now similar to other solid organ transplant programmes, with high rates of long-term insulin independence. In the present review, we will discuss whole-pancreas transplantation as a treatment for diabetes, focusing on indications for transplantation, the nature of the procedure performed, graft survival rates and the consequences of pancreas transplantation on metabolic variables and the progression of diabetes-related complications.