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

Early postoperative duplex ultrasound findings of the hepatic artery in postoperative vascular complications from paediatric liver transplantation

PURPOSE

To evaluate duplex US findings of the HA in all three postoperative vascular (HA, PV, HV and IVC) complications of paediatric LT for early detection and some helpful secondary signs to determine these vascular complications.

MATERIALS AND METHODS

We collected data from 44 post-LT paediatric patients who underwent daily duplex US for seven consecutive days and three months after LT during January 2017-June 2020. Four duplex US parameters of the HA (extrahepatic PSV, intrahepatic PSV, RI and AT) were compared in patients with and without complications.

RESULTS

The PSV of the extrahepatic HA in patients with HA complications was higher than that in patients without complications (P value = 0.019). The PSV at 107.7 cm/s is the optimal cut-off parameter associated with HA complications [a sensitivity of 88.9% and a specificity of 80.0% (ROC area is 0.84)]. The intrahepatic RI was higher on the first day than on the last day and gradually decreased in patients without vascular complications (P value = 0.000). The intrahepatic PSV significantly decreased with time when comparing the first and last days in patients without PV and HV-IVC complications (P value = 0.014 and 0.038). In contrast, patients with vascular complications showed no significant decrease.

CONCLUSION

The extrahepatic PSV relates to HA complications after paediatric LT but not PV and HV-IVC complications. Non-significantly decreased intrahepatic RI and PSV from the first day to the day of complication diagnosis may correlate with the occurrence of vascular complications.

Superb Microvascular Imaging (SMI) Compared with Color Doppler Ultrasound for the Assessment of Hepatic Artery in Pediatric Liver Transplants: A Feasibility Study

(1) Background: Despite progression in surgical techniques and immunological treatments, hepatic artery (HA) thrombosis and stenosis still develop as an early or late liver transplant (LT) complication. We aimed to compare superb microvascular imaging (SMI) with conventional Doppler imaging (CDI) in the assessment of HA in a cohort of pediatric patients undergoing follow-up ultrasound (US) for LT. (2) Methods: This prospective, observational study included 73 pediatric LT recipients (median age, 7 years; IQR, 5.8 years; 35 females) who underwent US during LT follow-up from March to December 2019. For each examination, CDI and SMI were separately assessed in terms of HA visibility and spectral waveform morphology (SWM). The former was scored based on HA discrimination from the blooming signal of the surrounding vessels, as follows: 0, not visible; 1, majority course hardly distinguishable; and 2, majority course clearly distinguishable. The latter was scored on a two-point scale: 0, combined venous and arterial SWM, and 1, pure arterial SWM. The patient’s overall score was finally calculated by adding the two individual scores. (3) Results: Both the absolute scores and frequency of overall scores equal to 3 (maximum global score) were higher using SMI compared with CDI. The median overall score was 3 for SMI and 2 for CDI (p = 0.011; IQR = 1). An overall score equal to 3 was obtained in 74% and 49.3% of the study population using SMI and CDI, respectively (p = 0.002). This was attributable to a better score in HA visibility (p = 0.007). (4) Conclusions: SMI has shown promise for assessing HA in pediatric LT recipients, possibly serving as a complementary non-invasive tool of CDI in everyday practice.

Initial experience with contrast-enhanced ultrasound in the first week after liver transplantation in children: a useful adjunct to Doppler ultrasound

BACKGROUND

Doppler US is the primary screening for post-liver transplant vascular complications, but indeterminate findings require further imaging.

OBJECTIVE

To evaluate whether contrast-enhanced US improves diagnostic assessment of vascular complications suspected by Doppler US.

MATERIALS AND METHODS

We retrospectively reviewed Doppler US and contrast-enhanced US studies obtained in the first week following liver transplant. Doppler US was performed twice daily for the first 5 postoperative days, and CEUS in the first postoperative day and when vascular complications were suspected. We correlated Doppler US and CEUS with surgical findings, and clinical and imaging follow-up. We evaluated Doppler US and CEUS quality in demonstrating the main hepatic artery (HA) at the porta hepatis as follows: Grade 0 = not seen, Grade 1 = only segments, Grade 2 = entire main HA, and Grade 3 = entire main HA to the intrahepatic branching. We used a Wilcoxon signed rank test to test the difference between Doppler US and CEUS methods.

RESULTS

Twenty-nine children (15 girls, 14 boys) were identified, with median age 2.2 years (range 0.5-17.6 years). The most common transplant indication was biliary atresia (n=13). There was significantly (P<0.0001) improved main HA visualization with CEUS. In five children, CEUS was performed to evaluate suspected vascular complications; CEUS confirmed normal vascularity in two. CEUS demonstrated portal vein thrombosis (n=2) and main HA thrombosis (n=1), confirmed at surgery. In one child the main HA thrombosis was missed; marked HA narrowing was seen retrospectively on CEUS.

CONCLUSION

Immediately following liver transplantation, CEUS improves main HA visualization and diagnostic assessment of vascular complications.

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.

Additional value of superb microvascular imaging for assessing hepatic arterial blood flow after pediatric liver transplantation

BACKGROUND

The aim of this study was to explore the value of SMI compared with conventional ultrasonography for assessing hepatic arterial blood flow after pediatric liver transplantation.

METHODS

From March 2018 to November 2018, a total of 105 pediatric recipients with biliary atresia underwent liver transplantation in our hospital. Ultrasound examinations were performed at the bedside in the intensive care unit to check the patency of the blood flow in the hepatic allograft. CDI, PDI, cSMI, and mSMI were performed to assess the display, orientation, and distribution of the graft hepatic artery. Ultrasound examinations were performed by one radiologist, and the images were judged by two observers.

RESULTS

The median age, weight, and height of the recipients were 6.97 (5.92, 9.58) months, 6.50 (6.00, 7.80) kg, and 64.00 (62.00, 68.00) cm, respectively. The measure of kappa agreement was 0.902, 0.889, 0.882, and 0.882 for CDI, PDI, cSMI, and mSMI, respectively. HAT occurred in 7 pediatric recipients and was confirmed by CTA (computed tomography angiography) and surgery. The diagnostic performance of sensitivity, specificity, PPV (positive predictive value), NPV (negative predictive value), and accuracy were 100%, 92.86%, 50%, 100%, and 93.33% for CDI and 100%, 98.98%, 87.50%, 100%, and 99.05% for SMI.

CONCLUSIONS

As an additional method to CDI, SMI can clearly show the distribution of hepatic arterial blood flow and provide more details, thereby markedly improving the diagnostic performance of postoperative HAT.

Doppler ultrasound values after liver transplantation in children and their association with graft outcomes: a protocol for a systematic review and meta-analysis

INTRODUCTION

Liver graft and patient survival in children have improved substantially over the years; nevertheless, graft-related complications persist as the most important risk factor for mortality and graft loss. Doppler ultrasound evaluation is routinely used after liver transplantation; however, there is no consensus defining normal values, timing or frequency of Doppler ultrasound postoperative evaluation. Identification of patients who require an intervention or change in postoperative management is therefore challenging.

METHODS AND ANALYSIS

We will conduct a systematic review and meta-analysis to appraise and synthesise evidence describing Doppler ultrasound measurements and their association with graft complications in children who have received a liver transplant. We will search multiple databases: Ovid Medline, Embase, Wiley Cochrane Library, Web of Science-Science Citation Index Expanded, trial registry records and meeting abstracts using a combination of subject headings and keywords for liver transplantation, Doppler ultrasound and paediatric patients. All identified titles and abstracts of studies will be assessed for potential relevance. Selected studies will be retrieved and subjected to a second phase of screening, both selection phases will be done in duplicate by two independent reviewers, and discrepancies will be documented and resolved by a third reviewer. Data extraction will be done independently by two reviewers using a standardised data extraction form. Quality of evidence and risk of bias will be assessed, synthesised and pooled for meta-analysis if possible. We will perform a subgroup analysis if enough data are available.

ETHICS AND DISSEMINATION

Strategies to disseminate our review include presenting in liver transplant review sessions, publishing in high-impact peer-reviewed medical journals, and presenting at national and international paediatric radiology and liver transplant meetings, conference presentations, events, courses and plain-language summaries. This knowledge will allow easier identification of patients with a higher risk of developing graft-related complications and could potentially improve patient and graft outcomes. We wish to disseminate our results to discover potential areas for future research and drive improved future practices and policies. Our target audience includes researchers, institutions, healthcare professionals, health system decision-makers, policy-makers and research funders community.

TRIAL REGISTRATION NUMBER

CRD42019119986.

Transplant artery thrombosis and outcomes

Post-transplantation allograft arterial thrombosis is a well-recognized complication associated with solid organ transplantation. Much of the literature is centered on liver and kidney transplantation, which will therefore serve as the principle basis for this review, with a brief discussion on pancreas transplantation and associated arterial complications. The number of solid organ transplants has been steadily increasing over the past decade in parallel with growing demand for organs and expansion of the transplantation criteria for both donors and recipients. This increase has been accompanied by a number of innovative medical advances and surgical techniques, as well as improved imaging that has allowed for thoughtful exploration of vascular anatomic variants and the possibilities for transplant with which they are associated. It has also been accompanied by a growing field of behavioral research, as potential recipients must weigh the risk of accepting certain organs based on perceived outcomes that may differ according to the quality of the underlying organ. Improvements in imaging technology have brought greater sensitivity to detecting arterial complications in post-operative surveillance examinations and have allowed for further development of tailored endovascular and surgical interventions for transplant-associated vascular complications. This review will focus on post-transplantation solid organ allograft artery thrombosis, including discussion of risk factors, diagnostic imaging, natural history, and therapeutic options.