Two-Dimensional Shear Wave Elastography Evaluation of Post-transplantation Complications in Pediatric Receipt: A Retrospective Cohort

Elastography-The New Standard in the Assessment of Fibrosis After Pediatric Liver Transplantation?

BACKGROUND

The development of graft fibrosis after pediatric liver transplantation (PLT) remains a major concern as it can lead to graft failure and ultimately graft loss. Elastography is a non-invasive method to assess liver fibrosis, but its role in the posttransplant setting is unclear. The aim of our study was to evaluate shear wave elastography (SWE) in the assessment of liver fibrosis after PLT, including split-liver recipients.

METHODS

We retrospectively analyzed data from PLT recipients who underwent surveillance liver biopsy and concurrent 2D-SWE during the study period from April 2018 to July 2021. Spearman's correlation was used to compare histologic fibrosis stages with liver stiffness measurements (LSM) by 2D-SWE. AUROC analysis was performed to evaluate the performance. One sample t-test was used to compare results with reference values of healthy children.

RESULTS

62 cases were included. 29% showed histologic fibrosis. LSM by 2D-SWE were feasible in all children regardless of age or graft type. There was a significant correlation between LSM and fibrosis stage for all three scoring systems used (Ishak, p = 0.003; METAVIR, p = 0.005; LAF Score, p = 0.003). Patients with a history of biliary complications had increased liver stiffness (p = 0.015). The AUROC of 2D-SWE for predicting significant liver graft fibrosis was 0.81. Liver stiffness after PLT without graft fibrosis was higher than in healthy subjects, but comparable to that in children with chronic liver disease without fibrosis.

CONCLUSION

2D-SWE can reliably detect children with significant liver graft fibrosis, even in split-liver recipients. This study demonstrates the value of a non-invasive tool for fibrosis staging after PLT. 2D-SWE has the potential to improve long-term outcomes after PLT and to reduce the number of surveillance liver biopsies. But elastography is not a substitute for liver biopsy.

Quantitative Liver Imaging in Children

ABSTRACT

In children and adults, quantitative imaging examinations determine the effectiveness of treatment for liver disease. However, pediatric liver disease differs in presentation from liver disease in adults. Children also needed to be followed for a longer period from onset and have less control of their bodies, showing more movement than adults during imaging examinations, which leads to a greater need for sedation. Thus, it is essential to appropriately tailor and accurately perform noninvasive imaging tests in these younger patients. This article is an overview of updated imaging techniques used to assess liver disease quantitatively in children. The common initial imaging study for diffuse liver disease in pediatric patients is ultrasound. In addition to preexisting echo analysis, newly developed attenuation imaging techniques have been introduced to evaluate fatty liver. Ultrasound elastography is also now actively used to evaluate liver conditions, and the broad age spectrum of the pediatric population requires caution to be taken even in the selection of probes. Magnetic resonance imaging (MRI) is another important imaging tool used to evaluate liver disease despite requiring sedation or anesthesia in young children because it allows quantitative analysis with sequences such as fat analysis and MR elastography. In addition to ultrasound and MRI, we review quantitative imaging methods specifically for fatty liver, Wilson disease, biliary atresia, hepatic fibrosis, Fontan-associated liver disease, autoimmune hepatitis, sinusoidal obstruction syndrome, and the transplanted liver. Lastly, concerns such as growth and motion that need to be addressed specifically for children are summarized.

European Society of Pediatric Radiology survey of perioperative imaging in pediatric liver transplantation: (3) postoperative imaging

BACKGROUND

Liver transplantation is the state-of-the-art curative treatment for end-stage liver disease. Imaging is a key element in the detection of postoperative complications. So far, limited data is available regarding the best radiologic approach to monitor children after liver transplantation.

OBJECTIVE

To harmonize the imaging of pediatric liver transplantation, the European Society of Pediatric Radiology Abdominal Taskforce initiated a survey addressing the current status of imaging including the pre-, intra-, and postoperative phases. This paper reports the responses related to postoperative imaging.

MATERIALS AND METHODS

An online survey, initiated in 2021, asked European centers performing pediatric liver transplantation 48 questions about their imaging approach. In total, 26 centers were contacted, and 22 institutions from 11 countries returned the survey.

RESULTS

All sites commence ultrasound (US) monitoring within 24 h after liver transplantation. Monitoring frequency varies across sites, ranging from every 8 h to 72 h in early, and from daily to sporadic use in late postoperative phases. Predefined US protocols are used by 73% of sites. This commonly includes gray scale, color Doppler, and quantitative flow assessment. Alternative flow imaging techniques, contrast-enhanced US, and elastography are applied at 31.8%, 18.2%, and 63.6% of sites, respectively. Computed tomography is performed at 86.4% of sites when clarification is needed. Magnetic resonance imaging is used for selected cases at 36.4% of sites, mainly for assessment of biliary abnormalities or when blood tests are abnormal.

CONCLUSION

Diagnostic imaging is extensively used for postoperative surveillance of children after liver transplantation. While US is generally prioritized, substantial differences were noted in US protocol, timing, and monitoring frequency. The study highlights potential areas for future optimization and standardization of imaging, essential for conducting multicenter studies.

Shear wave elastography and shear wave dispersion correlated to biopsy at the scheduled follow-up of pediatric liver grafts

BACKGROUND

It is unknown how shear wave dispersion (SWD) is displayed in pediatric liver transplant recipients and not fully elucidated how ultrasound shear wave elastography (2D-SWE) display within this cohort, which is important to determine to improve noninvasive surveillance of these patients. The study aimed to compare SWE and SWD values with histopathology in pediatric liver recipients.

METHODS

Forty-eight pediatric liver recipients were examined with SWE in conjunction with an elective liver biopsy (clinically without complication). Additionally, SWD values were measured in 21 children. SWE and SWD values were compared to histologically determined fibrosis graded as none-to-mild (F0-1) and moderate-to-severe (F2-4), and inflammation graded as low (grade 0-1) and high (grade 2-4).

RESULTS

Two children were excluded due to SWE IQR/median > 30% kPa. The mean age across 46 included patients was 10.9 years (range 1.4-18). The number of patients and median (range) SWE value (kPa) for each stage of fibrosis were: F0-1 [n = 23; 5.8 (3.2-16.1)], F2 [n = 22; 6.0 (4.5-25.9)], F3 [n = 1; 33.3], and F4 [n = 0]. Significantly higher SWE values and greater variability were registered in F2-4 vs. F0-1 (p = .05). Grade of fibrosis correlated weakly to SWE values (r = .3; p = .05), but not to SWD values (r = .2; p = .27). In patients with low-grade inflammation, median SWD was 13.7 m/s KHz (10.7-17.6). Only one patient had high-grade inflammation.

CONCLUSIONS

Uncomplicated transplanted liver grafts in a small pediatric cohort revealed slightly increased SWE and SWD values compared to previously reported values in healthy children. This likely reflect both the fibrotic and inflammatory elements in the grafts; however, other confounders impacting the liver's viscoelastic properties are also probable factors.