Biliary atresia (BA) is a pediatric hepatic disease of unknown etiology that is characterized by biliary obliteration and progressive liver fibrosis [
At present, the ultrasound-guided percutaneous liver biopsy is regarded as the most effective method and the gold standard for preoperative BA diagnosis [
Ultrasonography is the most common noninvasive examination method used for BA investigation [
In this study, we performed SWE to obtain Young’s modulus value on infants less than 90 days old in whom cholestatic hepatitis was suspected clinically, in combination with grey-scale ultrasonic findings, with the aim to assess SWE diagnostic performance in identifying and differentiate BA from cholestatic hepatitis in infants younger than 90 days by comparing this approach with grey-scale ultrasonography.
The study was approved by the Ethics Committee of Hunan Children’s Hospital (ChangSha City, Hunan Province, China, Number: HCHLL-2017-03). Informed written consent was obtained from each of the participant’s parents and was conducted between 1 November 2016 and 1 December 2017.
A total of 138 infants (76 males and 62 females, 5-90 days old) clinically suspected of having cholestatic hepatitis were included in our study. These infants were further classified into BA and non-BA groups according to their operative and postoperative pathological findings, or liver biopsy, blood biochemistry examination, and clinical assessment after medical treatment. An automatic biochemical analyzer (AU5800, Beckman Coulter, America) was used for measurements; approximately 2 ml of venous blood from each infant was collected after fasting 4 hours within three days before or after SWE examination. Measurements of total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL), and
The ultrasound and SWE examinations were performed by a radiologist with more than 10 years’ experience in abdominal sonography and 3 years’ experience in elastography on a TUS-Aplio 500 scanner (Toshiba Medical Systems, Tokyo, Japan). All scans were performed using a 14L5 linear array probe (10 MHz).
The grey-scale ultrasonography examination was performed after placing the infants in the supine position and the 14L5 linear probe was placed on the abdomen to carefully scan the liver, gall bladder, and spleen. Infants should fast at least for 4 hours and the gall bladder size was measured 2 times: the first time was before the meal and the second time was one hour after the last feed. Then the contractibility of the gall bladder was calculated. The existence of these grey scale ultrasonic signs should be carefully identified as follows: (1) the triangular cord (TC) sign: a triangular or layer of high echo in front of the portal vein, with a thickness≥3 mm; (2) abnormal gallbladder (AbGB): stiff, small or irregular gallbladder or absence of gall bladder; the gallbladder contractibility<50% was considered to be abnormal.
SWE measurements of liver stiffness were obtained while the infants were breathing quietly. The infants lay supine in a resting state and the examination was performed by placing the transducer probe vertically just below the right costal margin. The rectangular sample frame was approximately 15 × 15 mm in size and was placed 10 mm below the hepatic capsule of the lower segment of the right anterior hepatic lobe. A circular region of interest (ROI) of approximately 8 to 10 mm in diameter was then drawn in the center of the sample frame, avoiding hepatic vessels and the gallbladder. The display modes for SWE including speed, elasticity, and propagation modes were obtained and could change when images were frozen. The elastic modulus was obtained in the form of an SWE map in kPa in the elasticity mode and the arrival time contour through the propagation mode. Regular and straight contour lines indicated that elastic waves propagated as expected and the reliability of the data was high. Conversely, bent and irregular contour lines suggested low data reliability and that another SWE measurement was required to achieve a reasonable result. Moreover, the wider the interval between the contour lines, the harder the tissue. Five elastography images were obtained for each participant in accordance with the following quality control specifications: the arrival time contour was regular and straight with a standard deviation (SD) less than 10% of the average value. Young’s modulus value of the elastography images was calculated and the mean values were included in the statistical analysis.
Statistical analysis was performed using SPSS version 18.0 software (IBM Corporation, Armonk, NY). Data were reported as mean ± SD. Multiple comparisons among multiple samples were performed by one-way ANOVA and least significant difference (LSD)-
To assess the SWE intraobserver error, 40 subjects were randomly recruited. SWE was performed by the same radiologist before and after two-dimensional gray-scale ultrasonography examination and in both before and after examination the SWE value was measured 5 times. The mean was calculated for further statistical analysis. Intraclass correlation coefficient (ICC) and 95% confidence intervals (95% CI) were calculated; ICC values greater than 0.75 indicated excellent reliability.
Among the 138 infants suspected of having cholestatic hepatitis, 51 were diagnosed as having BA via surgery and pathological findings. The remaining 87 infants had a condition other than BA (e.g., neonatal hepatitis, infantile hepatitis syndrome, cytomegalovirus infection, or Citrin protein deficiency syndrome) diagnosed by surgery or liver biopsy and/or blood biochemistry examination and clinical assessment and for this reason they were assigned into the non-BA group. Gender and age characteristics of the three groups are shown in Table
Gender and age characteristic of the three groups.
Group | all ages | ≤30 days old | 31-60 days old | 61-90 days old | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
n | gender | median | n | gender | median | n | gender | median | n | gender | median | |
(M/F) | (range)age | (M/F) | age | (M/F) | age | (M/F) | age | |||||
control | 62 | 28/34 | 35(7-90) days | 29 | 12/17 | 23 days | 20 | 11/9 | 48 days | 13 | 5/8 | 75 days |
non-BA | 87 | 58/29 | 30(5-90) days | 48 | 30/18 | 20 days | 28 | 21/7 | 50 days | 11 | 7/4 | 72 days |
BA | 51 | 18/33 | 43(5-88) days | 20 | 8/12 | 25 days | 19 | 5/14 | 49 days | 12 | 5/7 | 67 days |
Among the 51 BA patients, 14 were without TC sign, including 13 within 30 days of age and one with 49 days of age. The TC sign was negative in all non-BA patients. Among all BA patients, only in 2 the typical gallbladder abnormalities were absent, while 7 of the 87 non-BA patients had an abnormal gall bladder.
An excellent reliability was found within repeated measurements by the same radiologist, with an ICC of 0.873 and 95% CI from 0.772 to 0.931.
No statistically significant difference was observed in Young’s modulus values between genders within the same group (
Comparison of the Young’s modulus values among infants of different genders within the same group and in different groups with same gender.
Group | male | female | ||
---|---|---|---|---|
n | Hepatic Young’s modulus values (kPa) | n | Hepatic Young’s modulus values (kPa) | |
control | 28 | | 34 | |
non-BA | 58 | | 29 | |
BA | 18 | | 33 | |
Box-and-whisker plot showing the distribution of liver stiffness values in control, non-BA and BA group when stratified by gender. Circle with a red cross in plots indicates the maximum stiffness value.
Young’s modulus values varied significantly between groups (
Comparison of the Young’s modulus values in the same group with different ages and in different groups with same age.
Group | all ages | ≤30 days | 31-60 days | 61-90 days | ||||
---|---|---|---|---|---|---|---|---|
n | Young's modulus | n | Young's modulus | n | Young's modulus | n | Young's modulus | |
value (kPa) | value (kPa) | value (kPa) | value (kPa) | |||||
Control | 62 | | 29 | | 20 | | 13 | |
non-BA | 87 | | 48 | | 28 | | 11 | |
BA | 51 | | 20 | | 19 | | 12 | |
Box-and-whisker plot showing the distribution of liver stiffness values in control, non-BA and BA group when stratified by all ages, ≤30 days, 31-60 days, and 61-90 days. Circle with a red cross in plots indicates the maximum stiffness value.
Biliary atresia in a 45-days-old boy. (a) SWE map in the elasticity mode; Young’s modulus value of ROI was 19.2 kPa, SD=1.2 kPa. (b) SWE map in the propagation mode; the arrival time contour of the same case was regular and the interval between the contour lines was wider.
All the blood biochemical tests were performed within 3 days of SWE examination. A correlation analysis showed that age, TBIL, DBIL, and
Spearman correlation between Young’s modulus values( kPa) and age, TBIL, DBIL, IBIL, and
mean ± standard deviation (range) | | | |
---|---|---|---|
Age (day) | 43 | 0.642 | <0.001 |
TBIL ( | | 0.467 | 0.001 |
DBIL ( | | 0.548 | <0.001 |
IBIL ( | | 0.222 | 0.117 |
| | 0.678 | <0.001 |
Scatter plot of the correlation between Young’s modulus values (kPa) and age (day) in the BA group, the correlation coefficient was 0.642,
Scatter plot of the correlation between Young’s modulus values (kPa) and
Scatter plot of the correlation between Young’s modulus values (kPa) and TBIL (
Scatter plot of the correlation between Young’s modulus values (kPa) and DBIL (
Scatter plot of the correlation between Young’s modulus values (kPa) and IBIL (
A linear regression analysis showed that age (
Linear regression analysis of hepatic Young's modulus value ( kPa) correlated with age, TBIL, DBIL and
Unstandardised coefficients | standard error | standardised coefficients | | | |
---|---|---|---|---|---|
Constant | 5.574 | 2.125 | 2.622 | 0.012 | |
Age (day) | 0.099 | 0.035 | 0.341 | 2.842 | 0.007 |
TBIL ( | 0.009 | 0.029 | 0.106 | 0.316 | 0.753 |
DBIL ( | 0.024 | 0.039 | 0.209 | 0.615 | 0.542 |
| 0.011 | 0.004 | 0.313 | 2.553 | 0.014 |
The AUC of Young’s modulus value to diagnose BA in patients who were clinically suspected of having cholestatic hepatitis was 0.937. The best cut-off value was 12.35 kPa, with a sensitivity of 84.3% and a specificity of 89.7%. The combination of TC sign and AbGB in the parallel test resulted in the best diagnostic performance, with an AUC of 0.960, while the combination of SWE and AbGB in the serial test resulted in the best diagnostic performance, with an AUC of 0.902, as shown in Table
Diagnostic performance of hepatic Young’s modulus values, typical grey scale ultrasound findings, and their combination to diagnose BA for all infants with cholestatic hepatitis.
| AUC | | 95%CI | Sensitivity | Specificity | PPV | NPV | Accuracy | |
---|---|---|---|---|---|---|---|---|---|
SWE | <0.001 | 0.937 | 0.894,0.978 | 84.3% | 89.7% | 82.7% | 90.7% | 87.7% | |
TC | <0.001 | 0.863 | >0.05 | 0.787,0.939 | 72.5% | 100% | 100% | 86.1% | 89.8% |
AbGB | <0.001 | 0.94 | >0.05 | 0.895,0.986 | 96.1% | 92.0% | 87.5% | 97.6% | 93.5% |
SWE or TC | <0.001 | 0.899 | >0.05 | 0.839,0.959 | 90.2% | 89.7% | 83.6% | 94.0% | 89.8% |
SWE or AbGB | <0.001 | 0.908 | >0.05 | 0.857,0.959 | 100% | 81.6% | 76.1% | 100% | 88.4% |
TC or AbGB | <0.001 | 0.96 | >0.05 | 0.926,0.994 | 100% | 92.0% | 87.9% | 100% | 94.9% |
SWE or TC or AbGB | <0.001 | 0.908 | >0.05 | 0.857,0.959 | 100% | 81.6% | 76.1% | 100% | 88.4% |
SWE and TC | <0.001 | 0.833 | <0.05 | 0.751,0.915 | 66.7% | 100% | 100% | 83.6% | 87.7% |
SWE and AbGB | <0.001 | 0.902 | >0.05 | 0.849,0.975 | 80.4% | 100% | 100% | 90.6% | 93.5% |
TC and AbGB | <0.001 | 0.843 | <0.05 | 0.763,0.923 | 68.6% | 100% | 100% | 84.5% | 88.4% |
SWE and TC and AbGB | <0.001 | 0.814 | <0.05 | 0.728,0.899 | 62.7% | 100% | 100% | 82.1% | 86.2% |
Biliary atresia in a 60-days-old girl. (a) The arrow points to the triangular cord sign and its thickness was 3.9 mm. (b) The arrow points to the abnormal gall bladder, small in size, and irregularly shaped. (c) The SWE image shows Young’s modulus value of 13.7 kPa and SD of 0.9 kPa. (d) The quality control SWE images show that the shear wave propagation curve was regular.
ROC of SWE, typical grey-scale ultrasound findings, and their combination to diagnose biliary atresia in all infants with cholestatic hepatitis (AbGB: abnormal gall bladder, SWE: shear wave elastography, TC: triangular cord sign, or: in the parallel test, and: in the serial test).
In patients without TC sign, the AbGB was more useful to diagnose BA and the AUC was 0.960, with a sensitivity of 100% and a specificity of 92%. The cut-off value of hepatic Young’s modulus to diagnose BA was 11.55 kPa and the AUC was 0.842, with a sensitivity of 78.6% and a specificity of 82.8%. If the combination of SWE measurement and the AbGB was used in the serial test to diagnose BA, the specificity raised to 100%, as shown in Table
Diagnostic performance of SWE, abnormal gallbladder, and their combination to diagnose BA in patients without TC sign.
| AUC | | 95%CI | Sensitivity | Specificity | PPV | NPV | Accuracy | |
---|---|---|---|---|---|---|---|---|---|
SWE | <0.001 | 0.842 | 0.724, 0.961 | 78.6% | 82.8% | 42.3% | 96.7% | 82.2% | |
AbGB | <0.001 | 0.960 | <0.05 | 0.924, 0.996 | 100% | 92.0% | 65.0% | 100% | 93.1% |
SWE or AbGB | <0.001 | 0.874 | >0.05 | 0.806, 0.941 | 100% | 74.7% | 37.1% | 100% | 78.2% |
SWE and AbGB | <0.001 | 0.893 | >0.05 | 0.000, 1.000 | 78.60% | 100% | 100% | 96.7% | 97.0% |
ROC of hepatic Young’s modulus values of SWE, grey-scale ultrasound finding, and their combination to diagnose biliary atresia in patients without TC sign. (AbGB: abnormal gall bladder, SWE: shear wave elastography, or: in the parallel test, and: in the serial test).
The development of elastography ultrasound techniques led to widespread and standard application in hepatic diseases. Although few reports are available describing the use of SWE in the diagnosis and differential diagnosis of BA, the comparability between them is hardly possible because of the ultrasound systems and their elastography imaging mode that are not completely the same [
In this study, we used the SWE developed by Toshiba Aplio 500. Few reports are available regarding the use of Aplio 500 for liver elastography in adults and infants [
On the basis of our results, these values were higher in the BA and non-BA groups than in the control group, and the mean of Young’s modulus values in BA group was significantly higher than in the non-BA group. This was likely the result of the differences in the disease process, with BA involving destruction and proliferation of the intrahepatic bile duct, cholestasis of hepatic cells and bile capillaries, and progressive portal fibrosis [
In our study, we found that Young’s modulus values were higher in the BA group than in the non-BA group in patients within the same age group. As regards the BA group, the values were higher in the 31 to 60 days of age group than in the ≤30 days of age group, and in the 61 to 90 days of age group than in the 31 to 60 days group. The correlation analysis results showed that Young’s modulus values positively correlated with age in patients with BA, and this was consistent with other studies [
The best cut-off value in the ROC curve to diagnose BA in all suspected patients was 12.35 kPa, with a sensitivity of 84.3%, a specificity of 89.7%, and an area under the ROC curve of 0.937. This indicated that SWE was a useful tool for the early differential diagnosis of BA, as previously observed [
As regards SWE combined with the grey-scale ultrasound to diagnose BA in all patients with cholestatic hepatitis, the results showed that the combination of TC sign and AbGB in the parallel test achieved the best diagnostic performance, while grey-scale ultrasound findings in combination with SWE could not increase the AUC and diagnostic accuracy of ultrasound. This indicated that the routine ultrasonography was most reliable in diagnosing BA as also demonstrated by Zhou [
Hwang SH et al. [
Although the results of our study were encouraging, there are several limitations. First, our study was a single center one. Thus, a larger multicenter study is needed to further confirm our findings. Second, as the duration between SWE examination and Kasai procedure is a bit long in some patients, we failed to perform correlation analysis between hepatic Young’s modulus values and grading of hepatic fibrosis. In the future, we will investigate the correlation between extent of hepatic fibrosis and Young’s modulus values.
In conclusion, both SWE and grey-scale ultrasound have good performance in diagnosing BA. SWE could not only help differentiate BA from cholestatic hepatic diseases but also increase the diagnostic specificity when combined with grey-scale ultrasound in the serial test.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that they have no conflicts of interest.
This research received a research grant from Natural Science Foundation of Hunan province (No. 2017JJ2141) and Hunan Health and Family Planning Commission (No. B2017120).