Frequency of technical success of two-dimensional ultrasound shear wave elastography in a large pediatric and young adult cohort: a clinical effectiveness study

Liver fibrosis assessment in pediatric population - can ultrasound elastography be an alternative method to liver biopsy? A systematic review

Liver diseases of various etiologies are becoming increasingly common in the pediatric population. So far, the gold diagnostic standard in these disorders is liver biopsy. This procedure is invasive, painful and requires general anesthesia in this group of patients. Due to the continuous development of new research techniques, such as liver elastography, it is necessary to evaluate them in the context of their diagnostic usefulness. Ultrasound elastography, as a quick and effective method, is being used more and more often in the assessment and monitoring of liver dysfunction in both adults and children. There are several techniques of liver elastography, such as transient elastography, shear wave elastography consisting of various subtypes such as two-dimensional shear wave elastography, acoustic radiation force impulse and point shear wave elastography, which differ in terms of the measurement technique and the achieved results. The purpose of our review was to determine whether techniques of liver elastography could replace liver biopsy. Although now, based on the analyzed papers, elastography cannot replace liver biopsy, in our opinion, the role of this tool in monitoring pediatric patients with liver diseases will grow in the coming years.

Performance of spleen stiffness measurement by 2D-shear wave elastography in evaluating the presence of high-risk varices: comparative analysis of idiopathic portal hypertension versus hepatitis B virus

BACKGROUND

Noninvasive assessment of high-risk varices (HRV) in idiopathic portal hypertension (IPH) is rare. The purpose of this study was to investigate the performance of spleen stiffness (SS) for evaluating the presence of HRV in IPH patients as compared the measurements in patients with hepatitis B virus (HBV).

METHODS

A retrospective single-center study was performed to evaluate the performance of SS for assessing HRV in IPH and HBV-infected patients, in comparison with liver stiffness (LS), spleen stiffness-to-liver stiffness ratio (SS/LS), LS spleen-diameter-to-platelet-ratio score (LSPS), portal hypertension risk score (PH risk score) and varices risk score, by using upper gastrointestinal endoscopy (UGE) as the gold standard. Finally, 86 IPH and 102 HBV-infected patients were enrolled. UGE, two-dimensional shear wave elastography (2D-SWE) and laboratory data were collected, and noninvasive parameters were calculated. Analysis of receiver operating characteristic (ROC) curves was conducted to acquire the optimal area under the ROC curve (AUC) and cutoff value for predicting the presence of HRV.

RESULTS

In patients with HRV, the significantly different parameters between IPH (34.9%) and HBV-infected patients (46.1%) were as follows: spleen size (diameter 18.5 ± 3.9 cm vs. 20.8 ± 2.7 cm), SS (50.2 kPa vs. 42.9 kPa), LS (11.1 kPa vs. 18.3 kPa) and PT (prothrombin time 15.1 s vs. 16.7 s). No statistically significant differences were found in liver function, platelet counts, spleen thickness and flow volumes in the portal venous system (p > 0.05). The AUCs of SS were 0.98 and 0.96 for predicting the presence of HRV in IPH (44.0 kPa cutoff value; 0.93 sensitivity; 0.96 specificity) and HBV-infected patients (35.2 kPa cutoff value; 1.00 sensitivity; 0.82 specificity), respectively, which were significantly better than other parameters.

CONCLUSION

SS shows the optimal overall performance for predicting the presence of HRV in IPH and HBV-infected patients, in comparison with other noninvasive parameters.

Ultrasound elastography in children - nice to have for scientific studies or arrived in clinical routine?

Ultrasound elastography (USE) is a modality that in addition to fundamental B-mode, Doppler, and contrast-enhanced sonography is suitable to make qualitative and quantitative statements about the stiffness of tissues. Introduced more than 20 years ago in adults, USE becomes now a diagnostic tool also in children. The aim of this paper is to describe current available techniques for USE in children. The significance for routine use in children is shown, and further interesting applications are reported.

Ultrasound shear wave elastography cannot discriminate between low- and high-pressure neurogenic bladders

BACKGROUND

Patients with neurogenic bladders are monitored with renal bladder ultrasounds and video urodynamics studies (VUDS) to assess upper urinary tract injury. Ultrasound shear wave elastography (US-SWE) can assess tissue stiffness. If bladder compliance is affected by bladder wall fibrosis and stiffening, then high-pressure bladders may be detectable by US-SWE therefore reducing the need for VUDS in some patients.

OBJECTIVE

To determine if US-SWE can differentiate between low- and high-pressure bladders and hence be used for noninvasive assessment of neurogenic bladder in children.

STUDY DESIGN

Prospective study of patients with neurogenic bladder undergoing clinically indicated VUDS between February and July of 2017. During VUDS, bladder wall US-SWE was measured at different filling percentages of estimated bladder capacity (EBC). The bladders were divided into cohorts according to the detrusor muscle pressure (P_det) reached at the maximum bladder capacity: normal (1 to <15 cmH₂O) and abnormal (≥15 cmH₂O) pressure. T-test was used to compare elastography values at different bladder volumes and P_det; (statistical significance set at p < 0.05).

RESULTS

30/31 enrolled children completed the protocol. With an empty bladder, as well as at all other bladder volumes, no relationship was observed between P_det and mean SWE of the anterior or posterior bladder wall. At maximum bladder capacity, there was no difference between mean SWE values of the anterior or posterior bladder walls in those with normal pressure, 2.97 m/s (SD ± 0.82) and 1.96 m/s (SD ± 0.75), compared to those with abnormal pressures 3.08 m/s (SD ± 0.84) and 2.39 m/s (SD ± 0.96), p = 0.75 and p = 0.2, respectively.

DISCUSSION

We found no difference between SWE values of either the anterior or posterior bladder wall in neurogenic bladders with normal and abnormal filling pressures measured during VUDS. Our study differs from previously reported studies with more positive results in that our cut-off for abnormal bladder pressure was (P_det ≥15 cmH₂O). This is lower than the more commonly used leak point pressure of 40 cmH₂O because our practice is to intervene earlier. Moreover, SWE would be most useful if it can identify changes before the bladder has reached such severe conditions, to allow for early intervention. Additional differences between ours and other studies include US manufacturer and younger age of the participating children.

CONCLUSIONS

US-SWE, while feasible, was not able to discriminate between low- and high-pressure bladders. Moreover, US-SWE did not show significant correlation with the current gold standard, VUDS.

Shear Wave Elastography in the Differentiation of Nonfibrotic Versus Fibrotic Liver Disease in Children: A Prospective Study With Histological Correlation

To evaluate the diagnostic accuracy of ultrasound shear wave elastography (SWE) prospectively and to determine cutoff value for nonfibrotic liver tissue in children with suspected or established liver disease.

Methods

In 90 consecutive pediatric patients, standardized 2D-SWE was performed during general anesthesia and free breathing. Liver stiffness was estimated with SWE followed by a percutaneous biopsy from the corresponding area. SWE values were compared with histology with fibrosis scored according to Batts & Ludwig classification (grade 0-4 = F0-F4) and to hepatic biomarkers.

Results

Four patients with SWE interquartile range (IQR)/median ≥ 30% kPa were excluded. The remaining 86 children (59% males) had a mean age = 10.2 years (0.1-18). The distribution of individuals with median (min;max) SWE values (kPa) within each fibrosis grade were; F0[n = 10; 5.0(3.4;6.3)], F1[n = 24; 5.0(3.6;8.7)], F2[n = 32; 5.8(3.5;13.4)], F3[n = 12, 7.5(4.0;14.4)], and F4[n = 8; 12.5(6.6;21.0)]. There was a significant difference between fibrosis grades (0.03 > P < 0.002) except between F0 and F1 respectively between F1 and F2. The AuROC differentiating F0-1 from F2-4 was 0.77(95% CI: 0.67-0.87). A cutoff SWE value of ≤4.5 kPa yielded 90% sensitivity and 68% specificity to rule out significant fibrosis (F2-F4). Out of the 18 children (21%) with SWE value ≤4.5 kPa, 12 had grade F0-1 and 6 had F2, although including some confounders for increased SWE measurements as steatosis/hepatitis/cholestasis.

Conclusions

2D-SWE ultrasound can reliably distinguish no/mild (F0/F1) from moderate/severe (F2-F4) fibrosis in children with suspected/established liver disease with good sensitivity and acceptable specificity. Our results show that in pediatric patients, when the indication for biopsy is to rule out significant fibrosis, SWE can be considered an alternative.

Elastography for Pediatric Chronic Liver Disease: A Review and Expert Opinion

In adults with chronic liver diseases, ultrasound and magnetic resonance shear wave elastography (SWE) can replace liver biopsy in several clinical scenarios. Several guidelines on the use of ultrasound SWE for the adult population have been published. However, the number of publications in the pediatric population is limited, and available guidelines on SWE do not specifically address pediatric chronic liver diseases. In this article, we review the literature on the use of SWE for pediatric chronic liver diseases and provide expert opinion on how to use SWE, both ultrasound and magnetic resonance techniques, in the pediatric population.

Spleen Stiffness Performance in the Noninvasive Assessment of Gastroesophageal Varices after Transjugular Intrahepatic Portosystemic Shunts

Objectives

To investigate the performance of spleen stiffness (SS) by using two-dimensional shear-wave elastography (2D-SWE) for assessing the severity of gastroesophageal varices (GEVs) after transjugular intrahepatic portosystemic shunt (TIPS).

Methods

102 eligible patients were categorized as in the post-TIPS short-term (n = 69) and long-term (n = 38) follow-up groups. The performance of SS by using 2D-SWE for evaluating the severity of GEVs was compared with liver stiffness (LS), spleen stiffness-to-liver stiffness ratio (SS/LS), liver stiffness spleen-diameter-to-platelet-ratio score (LSPS), portal hypertension (PH) risk score, platelet count-to-spleen diameter ratio (PSR), and varices risk score by using receiver operating characteristic (ROC) curve and DeLong test.

Results

In the post-TIPS short-term follow-up group, area under the receiver operating characteristic curves (AUCs) of SS were 0.585 for mild (cutoff value = 30.3 kPa), 0.655 for moderate (cutoff value = 30.6 kPa), and 0.739 for severe (cutoff value = 31.9 kPa) GEVs, which were higher than other parameters for severe GEVs. AUCs of SS were lower than other parameters for mild and moderate GEVs, but no difference was found (p > 0.05). In the post-TIPS long-term follow-up group, AUCs of SS were 0.778 for mild (cutoff value = 28.9 kPa), 0.82 for moderate (cutoff value = 29.9 kPa), and 0.824 for severe (cutoff value = 37.7 kPa) GEVs, which were higher than other parameters except for severe GEVs. AUC of SS was lower than other parameters for severe GEVs, but no significant difference was found (p > 0.05).

Conclusion

SS is an effective noninvasive tool to predict GEV severity during the post-TIPS follow-up.

Acoustic radiation force impulse imaging: normal values of spleen stiffness in healthy children

BACKGROUND

Acoustic radiation force impulse (ARFI) imaging is a noninvasive ultrasound elastography technique for evaluating tissue stiffness. The association of liver and spleen stiffness provides additional information in the assessment of portal hypertension. The technique and normal values of spleen stiffness by point shear wave elastography (p-SWE) in pediatrics have not been well documented.

OBJECTIVE

Our aim is to describe the feasibility and normal ARFI elastography values in the spleen for healthy children and to compare measurements in two different probe positions (the axial and sagittal planes).

MATERIALS AND METHODS

Spleen p-SWE using ARFI values were measured with a 6C1 probe in 102 healthy children (age range: 8 weeks to 17 years) divided into four age groups. An average of nine (standard deviation: two) spleen stiffness measurements were taken during free breathing in each plane (axial and sagittal). The impact of age and measurement plane in the spleen was analyzed using multivariate models.

RESULTS

There was no significant difference in spleen stiffness values taken at different ages, with an average of the medians of 2.43±0.31 m/s. There was no significant difference based on probe orientation: sagittal plane (median: 2.46±0.29 m/s) and axial plane (median: 2.43±0.32 m/s) with Student's t-test P=0.18. The mean depth of measurement varied between 2.3 cm and 3.7 cm, according to age.

CONCLUSION

Normal spleen stiffness values using ARFI imaging in children do not vary with age and correspond to a median of 2.43 m/s. No significant difference was found when using different probe positions.

Somatic regional oxygen saturation as an early marker of intra-abdominal hypertension in critically ill children: a pilot study

Background/aim

Intraabdominal hypertension is a common clinical condition with high mortality and morbidity in pediatric intensive care units. The aim of this study was to test the feasibility of regional tissue oxygenation (rSO2) measurement using near-infrared spectroscopy and to assess the correlation between rSO2 and perfusion markers of intraabdominal hypertension in high-risk pediatric patients.

Materials and methods

In this prospective observational cohort study in a tertiary pediatric intensive care unit in Çukurova University Faculty of Medicine, a total of 31 patients who were admitted between May 2017 and May 2018 with a risk of intraabdominal hypertension were included. Mesenteric and renal rSO2 measurements were taken and correlations with other tissue perfusion markers including mean arterial pressure, pH, lactate, intraabdominal pressure, abdominal perfusion pressure, mixed venous oxygen saturation, vasoactive inotropic score were assessed. Intraabdominal pressure was measured as ≥10 mmHg in 15 patients (48.3%) and these patients were defined as the group with intraabdominal hypertension.

Results

In the group with intraabdominal hypertension, mixed venous oxygen saturation was lower (P = 0.024), vasoactive inotropic score was higher (P = 0.024) and the mean abdominal perfusion pressure value was lower (P = 0.014). In the ROC analysis, the mesenteric rSO2 measurement was the best parameter to predict intraabdominal hypertension with area under the curve of 0.812 (P = 0.003) 95% CI [0.652–0.973].

Conclusion

Monitoring of mesenteric rSO2 is feasible in patients at risk for intraabdominal hypertension. Moreover, both mesenteric regional oxygen and perfusion markers may be used to identify pediatric patients at risk for intraabdominal hypertension.

Thromboembolic Events Are Independently Associated with Liver Stiffness in Patients with Fontan Circulation

Background: Thromboembolism (TE) and Fontan-associated liver disease (FALD) are common and lead to significant morbidity in Fontan circulations. Risk factors for TE and the potential link between TE and FALD are not well understood. The objective of this study was to evaluate the association between TE and the severity of FALD based on radiologic liver stiffness. Methods: Using a retrospective cohort study design, 85 Fontan patients (aged 27.7 ± 8.2 years) who had liver stiffness measurement were included. Multivariable logistic regression was used to determine independent associations with TE. Results: Sixteen patients (19%) had a history of TE after the Fontan procedure at a mean age of 21.4 ± 15.0 years. Patients with TE were significantly older at the time of the last evaluation (33.8 ± 11.7 vs. 26.3 ± 6.5 years, p = 0.03). Liver stiffness by MRI and ultrasound was higher in the TE group (5.1 ± 1.4 vs. 4.3 ± 1.2 kPa, p = 0.04 and 2.8 ± 0.4 vs. 2.4 ± 0.5 m/s, p = 0.04, respectively). On multivariable analysis, higher liver stiffness (odds ratio (OR): 2.12, p = 0.03) and older age (OR: 1.11, p = 0.03) were associated with TE. Conclusions: This study found an association between TE, age, and radiologic liver stiffness.