Validation of attenuation imaging coefficient, shear wave elastography, and dispersion as emerging tools for non-invasive evaluation of liver tissue in children

Abstract

IntroductionThe number of children with acute and chronic liver disease is rising. Moreover, liver involvement may be limited to subtle changes in organ texture especially in early childhood and some syndromic conditions, such as ciliopathies. Attenuation imaging coefficient (ATI), shear wave elastography (SWE), and dispersion (SWD) are emerging ultrasound technologies providing data about attenuation, elasticity, and viscosity of liver tissue. This additional and qualitative information has been correlated with certain liver pathologies. However, limited data are available for healthy controls and have mainly been raised in adults.MethodsThis prospective monocentric study was conducted at a university hospital with a specialization in pediatric liver disease and transplantation. Between February and July 2021, 129 children aged 0-17.92 years were recruited. Study participants attended outpatient clinics due to minor illnesses excluding liver or cardiac diseases, acute (febrile) infections or other conditions affecting liver tissue and function. ATI, SWE, and SWD measurements were performed on an Aplio i800 (Canon Medical Systems) with an i8CX1 curved transducer by two different investigators with long-standing experience in pediatric ultrasound according to a standardized protocol.ResultsConsidering multiple potential covariates, we derived percentile charts for all 3 devices relying on the Lambda-Mu-Sigma (LMS) approach. 112 children were considered for further analysis, excluding those with abnormal liver function and under-/overweight (BMI SDS<-1.96/> 1.96, respectively). Age range was 0-17.92 years (mean 6.89±0.50SD), 58% were male. The mean duration of the ultrasound examination (basic ultrasound plus SWE, SWD, and ATI) was 6.67±0.22 minutes and it was well tolerated in 83% (n=92) of cases. While ATI was related to age, SWD was found to depend on BMI SDS, and SWE on abdominal wall thickness and sex. ATI correlated with neither SWE nor SWD, but SWE was correlated with SWD.ConclusionsOur study provides norm values and reference charts for ATI, SWE, and SWD considering important covariates including age, sex and, BMI. This may help to implement these promising tools into imaging diagnostics of liver disease and to improve the diagnostic relevance of liver ultrasound. In addition, these noninvasive techniques proved to be time-effective and highly reliable, which make them ideal for application in children.

Ultrasound evaluation of kidney and liver involvement in Bardet-Biedl syndrome

“…The mean and standard deviation values are given in kPa (elastography) and [m/s/kHz] (dispersion). The classi cation of SWE measurements exceeding the 97th percentile was based on published normal values in relation to abdominal wall thickness (23). For abdominal wall thicknesses beyond the range covered by Cetiner et al (2023), SWE values were classi ed as pathological (> 97th percentile) when exceeding 6 kPa, consistent with published normal values for adults (29).…”

“…The classi cation of SWE measurements exceeding the 97th percentile was based on published normal values in relation to abdominal wall thickness (23). For abdominal wall thicknesses beyond the range covered by Cetiner et al (2023), SWE values were classi ed as pathological (> 97th percentile) when exceeding 6 kPa, consistent with published normal values for adults (29). SWD values were classi ed based on published normal values in relation to BMI SDS levels.…”

“…The mean and standard deviation of the attenuation coe cient in [dB/cm/MHz] are reported. In children and adolescents, the classi cation of an ATI measurement exceeding the 97th percentile was based on age-dependent normal values (23). For adults with BBS, values exceeding 0.63 [dB/cm/Mhz] were classi ed above the 97th percentile (23,30).…”

“…Considering a large number of potential covariates with complete information, most of which have been considered by previous studies (e.g., age [years], sex, height-SDS, weight-SDS, BMI-SDS, abdominal wall thickness [cm], fasting duration [hours], cooperation [calm vs. restless; dummy-coded], liver echogenicity, liver lower edge [dichotomized and dummy-coded: concave shape; pointed shape, rounded shape], liver size standardized to height-related mean value in %, spleen size standardized to height-related mean value in %), a two-step procedure as implemented in the FWRselect R-package was used to identify the most appropriate subset of covariates (independent variables) concerning the analysis of ATI, SWE, and SWD levels (dependent variables) in BBS patients by multiple linear regression (31). As previously described (23), a greedy forward selection algorithm was employed in a rst step, changing one variable at a time until no further improvement in model t assessed by the Akaike information criterion (AIC) was attained. Second, a bootstrap-based procedure evaluating the number of signi cant covariates as a tradeoff between model size and model t was performed at a signi cance level of p < .05.…”

“…Over the last decades, US technology has developed continuously, particularly regarding image resolution and microvascular perfusion imaging (22). Shear wave elastography (SWE), shear wave dispersion (SWD), and attenuation imaging coe cient (ATI) further improve liver assessment through the quantitative staging of liver brosis and steatosis as well as the detection of subtle changes in liver tissue at an early stage (23). Thus, they provide diagnostic alternatives to MRI and CT scans with high applicability and acceptance rates in children (24) and may even replace invasive diagnostic procedures such as liver biopsy in the future.…”