Imaging panorama in postoperative complications after liver transplantation

Vascular complications after liver transplantation: contemporary approaches to detection and treatment. A literature review

Vascular complications (VCs) after liver transplantation (LT) are rare but are one of the most dreaded conditions that can potentially lead to graft loss and recipient death. This paper has analyzed the international experience in the early diagnosis of various VCs that can develop following LT, as well as the optimal timing and methods of treatment of these complications.

Intensive Doppler Ultrasonography for Early Detection of Hepatic Artery Thrombosis After Adult Living Donor Liver Transplantation

Background

Early hepatic artery thrombosis (eHAT) is a severe arterial complication leading to biliary complications and graft failure in living donor liver transplantation (LDLT). This study sought to early identify the abnormal waveforms of eHAT by using intensive Doppler ultrasonography (DUS) after LDLT and to assess the clinical outcome in these eHAT patients.

Material/Methods

DUS for 419 adult LDLT recipients was performed twice after vascular anastomosis during liver transplantation and once a day at the bedside for at least 2 weeks.

Results

Nine adult LDLT recipients with eHAT were identified by using bedside DUS with subsequent computed tomography angiography (CTA). All eHAT cases were noted in the first 2 weeks. Five patients with CTA findings of partial thrombus with the small visualized intrahepatic hepatic artery (HA) were treated with intravenous thrombolysis (IVT) (medical group). Another 4 patients with CTA findings of extrahepatic HA occlusion and nonvisualization of intrahepatic HAs were treated by arterial re-anastomosis (surgical group). The prevalence of long-term non-anastomotic biliary strictures was 33.3% in the surgical group. Intensive post-LDLT DUS is a convenient and sensitive tool for eHAT detection.

Conclusions

Subsequent CTA gives valid information on occluded arteries and associated findings, which impact decision-making and are correlated with patient outcome. Our protocol of DUS has high sensitivity and diagnostic accuracy for use in in eHAT patients with partial occlusion, and it can be applied for IVT treatment, avoiding the need for reoperation and preventing long-term biliary complications.

Indirect Doppler ultrasound abnormalities of significant portal vein stenosis after liver transplantation

PURPOSE

To determine indirect Doppler ultrasound (DUS) abnormalities associated with significant portal vein (PV) stenosis (PVS) in recipients of liver transplantation (LT).

METHODS

This retrospective study was approved by our institutional review board. Between February 2006 and May 2017, 41 LT recipients were diagnosed with significant PVS, defined as having more than 50% narrowing of PV diameter for any reason, including thrombosis or flow disturbance associated with prominent collateral vessels on portal venography. We reviewed the DUS findings of hepatic arteries (HAs) as well as PVs of them, before and after treatment of PVS, and in comparison, with a one-to-one case-matched control. Inter-group comparison of frequency in DUS abnormalities was performed using Chi square (χ²) with Fisher's exact test and McNemar's test. Diagnostic values of each abnormal DUS finding and combinations were also evaluated.

RESULTS

DUS of significant PVS showed "no demonstrable color flow," either at recipient PVs or anastomoses (26.7%), and showed turbulence (66.7%) and hepatofugal portal flow (HFPF; 20.0%) at the graft PVs. HFPF was more frequently observed in those with "no demonstrable color flow" at recipient PVs or anastomoses (p = 0.006). DUS of graft HAs revealed tardus-parvus waveforms (20.9%) and prolonged systolic acceleration times (16.3%), more commonly in the "no demonstrable color flow" group (p = 0.012). These indirect DUS abnormalities disappeared and resolved on follow-up DUS after treatment. In the control group, such Doppler abnormalities were less frequently shown than in the PVS group (p ≤ 0.01, respectively). When one of the portal-blood flow velocity (PFV)-related index abnormalities (such as increased time average velocity [TAV] at anastomosis and TAV ratio between recipient PV and anastomosis) or "no demonstrable color flow" were shown in DUS as well as one of the indirect DUS abnormalities, sensitivity, and specificity was 71.11 and 97.78%, respectively.

CONCLUSION

In addition to PFV-related abnormalities, DUS occasionally shows "no demonstrable color flow" either at recipient PVs or anastomoses, and indirect Doppler abnormalities such as turbulence, HFPF at graft PVs, and abnormal waveforms at graft HAs in LT recipients with significant PVS. The combination of PFV-related abnormalities and indirect DUS abnormalities would be helpful for diagnosis of PVS.

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.

Depicting surgical anatomy of the porta hepatis in living donor liver transplantation

Visualizing the complex anatomy of vascular and biliary structures of the liver on a case-by-case basis has been challenging. A living donor liver transplant (LDLT) right hepatectomy case, with focus on the porta hepatis, was used to demonstrate an innovative method to visualize anatomy with the purpose of refining preoperative planning and teaching of complex surgical procedures. The production of an animation-enhanced video consisted of many stages including the integration of pre-surgical planning; case-specific footage and 3D models of the liver and associated vasculature, reconstructed from contrast-enhanced CTs. Reconstructions of the biliary system were modeled from intraoperative cholangiograms. The distribution of the donor portal veins, hepatic arteries and bile ducts was defined from the porta hepatis intrahepatically to the point of surgical division. Each step of the surgery was enhanced with 3D animation to provide sequential and seamless visualization from pre-surgical planning to outcome. Use of visualization techniques such as transparency and overlays allows viewers not only to see the operative field, but also the origin and course of segmental branches and their spatial relationships. This novel educational approach enables integrating case-based operative footage with advanced editing techniques for visualizing not only the surgical procedure, but also complex anatomy such as vascular and biliary structures. The surgical team has found this approach to be beneficial for preoperative planning and clinical teaching, especially for complex cases. Each animation-enhanced video case is posted to the open-access Toronto Video Atlas of Surgery (TVASurg), an education resource with a global clinical and patient user base. The novel educational system described in this paper enables integrating operative footage with 3D animation and cinematic editing techniques for seamless sequential organization from pre-surgical planning to outcome.

Imaging of liver transplantation

Liver transplantation (LT) is the treatment of choice for end-stage chronic liver disease, fulminant liver failure and early stage hepatocellular carcinoma. As discussed in this review, state-of-the-art imaging modalities including ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) play a pivotal role in the selection of patients and donors, as well as in early detection of those complications at risk of impairing graft function and/or survival. We also illustrate main imaging findings related to the wide spectrum of clinical problems raised by LT.