Diagnosis of Acute Rejection of Liver Grafts in Young Children Using Acoustic Radiation Force Impulse Imaging.

OBJECTIVE. Frequency of acute rejection (AR) after pediatric liver transplant remains high despite progress in immunosuppression. Liver biopsy (LB) is the reference standard for the diagnosis of AR despite its potential for morbidity. The purpose of our study was to evaluate the ability of acoustic radiation force impulse (ARFI) imaging to distinguish AR from other causes of short- and medium-term liver dysfunction and to identify liver transplant cases with normal liver function. MATERIALS AND METHODS. ARFI imaging was used to evaluate shear wave velocity (SWV) after liver transplant in young children. All pediatric liver grafts that had LB and ARFI examination between January 2014 and December 2017 were included in this retrospective study. Results of LB were compared with those of SWV. Collected data included age at biopsy and transplant, sex, weight, height, body mass index, interval between liver transplant and shear wave elastography and LB, kind of graft, type of donor, and diagnosis at transplant. ROC curve analysis was performed to assess the diagnostic performance of SWV. Optimal cutoff of SWV using ARFI imaging in predicting AR was identified using the Youden index. RESULTS. Statistical analysis was performed on 54 children; six of the original 60 were excluded because of confounding alterations or changes in outcome. Median SWV was higher in patients with AR (2.03 m/s; interquartile range [IQR], 1.80-2.45 m/s) compared with those with idiopathic hepatitis (1.33 m/s; IQR, 1.12-1.53 m/s), portal hypertension (1.42 m/s; IQR, 1.32-1.72 m/s), cholangitis (1.56 m/s; IQR, 1.07-1.62 m/s) or normal liver function (1.23 m/s; IQR 1.12-1.29 m/s) at protocol biopsies (all comparisons, p < 0.01). SWV higher than 1.73 m/s was predictive for AR (AUC, 0.966). SWV also showed good diagnostic accuracy in normal liver function (AUC, 0.791). ARFI imaging was not predictive for hepatitis (AUC, 0.402), portal hypertension (AUC, 0.556), or cholangitis (AUC, 0.420). CONCLUSION. ARFI imaging could be routinely used in place of LB in pediatric patients with liver dysfunction after liver transplant, restricting indication and risks of biopsy to selected cases.

Hepatic veins in presurgical planning of hepatic resection: what a radiologist should know.

Hepatic resection is considered to be feasible when all malignant nodules can be technically excised. The goal of the surgical approach is to optimize the oncologic resection (negative margins), sparing the non-cancerous hepatic parenchyma. The outflowing hepatic vein (HV) of that particular liver remnant must be intact in order to preserve its function. The purpose of this article is to familiarize radiologists with anatomy and anatomical variants of HVs, with special emphasis on segmental venous drainage for presurgical planning of hepatic resections. We focus on information which radiologist should give to hepatic surgeon to choose proper surgical approach. Radiologist's familiarity with the anatomy and anatomical variants of HVs is essential for accurate surgical planning to avoid venous congestion as postoperative complication. Any clinically important hepatic vein variation detected on presurgical imaging should be carefully recorded in the radiology report.

Sarcopenia in children with chronic liver disease: Prevalence and impact on liver transplant outcomes.

Sarcopenia is a clinical condition characterized by a reduction in muscle mass, which typically affects adult patients; however, it has recently been recognized in pediatric literature. Few studies in children with chronic liver disease (CLD) undergoing liver transplantation (LT) have investigated the role of sarcopenia, with controversial results. The aim of our study was to assess the prevalence and impact of sarcopenia among children with CLD who are candidates for LT. We conducted a retrospective, single-center study at Bambino Gesù Children's Hospital (Rome, Italy) from July 2016 to July 2021, evaluating all children (0-16 years old) with CLD listed for LT with an abdomen computed tomography imaging available before LT. The total psoas muscle surface area (t-PMSA) was defined as the sum of left and right psoas muscle surface area measured at L4-L5 on axial images. The t-PMSA z-score was calculated according to reference data, and sarcopenia was defined as a t-PMSA z-score of ≤-2 (1-16 years) or a psoas muscle index [PMI; PMI = t-PMSA/(100 × BSA)] of <50th percentile of the population examined (<1 year). Clinical, laboratory, and LT outcome data were collected from all the patients with CLD. 27 out 48 (56%) of the patients aged 1-16 years were sarcopenic. No differences were noted in anthropometrics, nutritional support, liver function tests, model for ESLD (MELD), or pediatric ESLD (PELD) scores between patients with and without sarcopenia. The former showed a higher prevalence of respiratory complications (66.7% vs. 42.1%) and need for inotropes (40.7% vs. 10.8%) after LT. Among patients aged 0-1 years (n: 36), those with reduced muscle mass (50%) had a longer hospitalization time (44 vs. 24 days) and higher incidences of multi-organ failure syndrome (38.9% vs. 0%) and intensive care unit-related infections (61.1% vs. 27.8%) compared to those with greater muscle mass. t-PMSA and PMI were statistically significant predictors of LT outcomes. Sarcopenia is a reliable index of frailty in children with CLD, as its presence is associated with the risk of a more challenging LT. Future studies will have to investigate the functional aspects of sarcopenia and conceive preventive measures of muscle wasting in CLD patients.