ZENG Jie¹, LIU GuangJian², ZHENG RongQin¹, LU MingDe²

Jie ZENG¹, GuangJian LIU², RongQin ZHENG¹, MingDe LU²

¹Department of Medical Ultrasonics, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, China, ²Department of Medical Ultrasonics, The First Affiliated Hospital of Sun Yat-Sen University, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, China

キーワード :

【Purpose】
To evaluate the diagnostic performance of real-time shear wave elastography （SWE） in detection of liver fibrosis in patients with chronic hepatitis B virus （HBV） infection.
【Materials and Methods】
A total of 306 patients with chronic HBV infection were prospectively enrolled in this study. Informed consent was obtained from all patients, and the study was approved by the institutional ethics review board. The whole cohort was divided into a training set （patients included between May 2010 and April 2012, n=204, 66.7％） and a validation set （patients included between May 2012 and November 2012, n=102, 33.3％）. Real-time SWE examination and liver biopsy were performed for all the patients. The Aixplorer US system （SuperSonic Imagine S.A., Aix-en-Provence, France） with a convex broadband probe （SC6-1） were used for SWE evaluation. Percutaneous liver biopsy was performed using the 16G Temno or Menghini needle under ultrasound guidance 3 days before or after SWE examination. Liver fibrosis was staged on a 0-4 scale according to the METAVIR scoring system. Significant fibrosis was defined as F≥2 and severe fibrosis F≥3 in the present study. The correlations between real-time SWE and fibrosis stages were evaluated. Receiver-operating characteristics （ROC） curves were constructed to assess the overall accuracy of liver stiffness measured by SWE in diagnosis of liver fibrosis and to identify optimal cut-off values for different fibrosis stages.
【Results】
The distributions of baseline characteristics of patients between training group and validation group were comparable. For liver stiffness assessed by SWE, a steady stepwise increase in elasticity value was observed with increasing severity of hepatic fibrosis. The median elasticity values increased from 5.7 KPa for F0, to 6.3 KPa for F1, to 8.3 KPa for F2, to 11.4 KPa for F3 and to 20.1 KPa for F4 in the training set. Patients with each fibrosis stage had significantly higher elasticity values than those with less fibrosis （p<0.05）. The real-time SWE values showed a high correlation with degree of fibrosis with correlation coefficient of 0.83 （P<0.05）. The accuracies of real-time SWE to detect F2 or higher, F3 or higher, and F4 disease in the training set were good, with areas under the receiver operating curve （AUROCs） of 0.92, 0.95, and 0.95, respectively. Optimal cut-off values for the different fibrosis stages were determined as 7.5KPa for ≥F2, 9.2KPa for ≥F3 and 11.5KPa for F4, respectively. The ROC curves for the diagnosis of significant, severe fibrosis and cirrhosis indicated no significant differences between the training set and validation set, with AUROCs for significant fibrosis of 0.92 vs 0.90, severe fibrosis of 0.95 vs 0.94 and cirrhosis of 0.95 vs 0.95, respectively （P=0.45）. Using the cut-off values developed in the training set, good diagnostic performance of SWE in evaluation of liver fibrosis were obtained in the validation set, with the sensitivity for the diagnosis of F≥2, F≥3 and F=4 of 84.7 ％, 92.3％ and 95.0％, and the specificity of 85.2 ％, 77.7％ and 85.0％, respectively.
【Conclusion】
Real-time SWE showed high diagnostic performance in the assessment of liver fibrosis in HBV patients. Considering its noninvasiveness, easy and quick usage and wide availability, SWE could be a reliable tool to identify hepatic fibrosis and cirrhosis for HBV patients in the clinical practice.