Noninvasive Assessment Of Liver Fibrosis By Virtual Touch Tissues Quantification Technique

Chronic liver diseases are common diseases in the world, especially in areas with a high incidence of hepatitis virus infection. China is the country with a high incidence of hepatitis B virus. The prognosis, surveillance and treatment decisions of chronic liver diseases depend on the degree of liver fibrosis. Liver fibrosis, i.e. excessive accumulation of extracellular matrix, occurs in chronic liver diseases.At present, liver biopsy is still the gold standard for assessing liver fibrosis. However, it is invasive and in rare cases with serious complications. In addition, the accuracy of liver biopsy is limited due to intraobserver and interobserver variability and sampling errors. Therefore, simple, reliable and noninvasive tests are needed to assess the stage of fibrosis.Virtual Touch Tissues Quantification (VTQ) technique is a new method for the evaluation of liver stiffness. Its brief principle is as follows:the probe transmits a longitudinal wave, inducing an elastic shear wave that propagates through the tissue. In the meantime, pulse-echo ultrasound acquisitions are performed to follow the propagation of the shear wave and to measure its velocity (results are expressed in a unit of m/s), which is directly related to tissue stiffness. The harder the tissue is, the faster the shear wave propagates.In this study, we investigated the clinical value of VTQ in the noninvasive assessment of liver fibrosis.Objective:To investigate the feasibility of VTQ technique in the assessment of liver stiffness and to find the suitable measuring position of VTQ.Methods:Liver stiffness was measured with ACUSON S2000 ultrasound system in totally 533 subjects including patients with hepatitis B virus (HBV) (n=191), patients with fatty liver (n=40) and control subjects (n=302). There were 329 males and 204 females with an average age of 49.16±15.60 yrs. Patients with HBV included inactive HBsAg carriers and patients with chronic hepatitis B or liver cirrhosis. Those who had ascites were excluded. Patients with fatty liver were diagnosed by B mode ultrasound. Control subjects were those who had no history of chronic liver diseases. Each subject received VTQ measurements in four parts (superficial and deep parts of right lobe and superficial and deep parts of left lobe) and every part was measured five times to get five values. The reproducibility of different part of VTQ was analyzed with intraclass correlation coefficient (ICC). Statistical analyses were performed with SPSS 15.0 software.Results:The achievement ratio of measurement was 99.8%,99.6%,92.3% and 83.1% in the superficial and deep parts of right lobe, and superficial and deep parts of left lobe, respectively. The achievement rate was high in both right and left lobes, while the lowest rate was from the deep part of left lobe. Except deep part of left lobe in fatty liver, all parts of liver in all groups of patients were with ICC higher than 0.75. In deep part of right lobe, VTQ values were 1.12±0.19 m/s in control group subjects, 1.83±0.62 m/s in patients with hepatitis B virus and 1.05±0.25 m/s in patients with fatty liver. There was significant difference of VTQ value between control group and patients with HBV (P=0.000), also between patients with HBV and patients with fatty liver (P=0.000). There is no statistical difference of VTQ value in different age groups of control subjects.Conclusion: It is stable to measure liver stiffness with VTQ technique. Right hepatic lobe is the suitable position to be measured. VTQ is a new method for the noninvasive evaluation of liver stiffness.Objective:To investigate the clinical value of VTQ technique in the assessment of liver fibrosis.Methods:One hundred and eighty-three patients who would receive liver resection or liver biopsy and had received liver resection within one month in our hospital were examined by using VTQ technique. There were 148 males and 33 females with an average age of 53.25±12.97 yrs. ACUSON S2000 ultrasound system was used and each subject received VTQ measurements in deep part of right lobe of the liver for five times. Liver fibrosis was evaluated according to the Scheuer scoring system for a S0-S4 scale. The receiver operating characteristic (ROC) curves and areas under the curves as well as 95% CI were computed. Sensitivity and specificity were computed for the cutoff value at the maximum sum of sensitivity and specificity.Results:The mean values of VTQ in S0-S4 were 1.27±0.33m/s,1.26±0.29 m/s,1.27±0.26 m/s,1.57±0.46 m/s and 1.96±0.49 m/s, respectively. There were no significant differences between the mean value of VTQ in the SO and S1 subgroup, or S1 and S2 subgroup. There were significant differences between the mean value of VTQ in the S0-S2 and S3 subgroup, and S3 and S4 subgroup. The areas under ROC curves were 0.841 (95% CI:0.784-0.897) for S≥S3 and 0.842 (95% CI:0.784-0.899) for S=S4. In our study, the optimal cutoff value was 1.43 m/s for S0-S2 vs. S3-S4, with a sensitivity of 80%, specificity of 75%, and 1.51 m/s for S0-S3 vs. S4, with a sensitivity of 84%, specificity of 70%.Conclusion: VTQ technique is a new, noninvasive and promising method in the assessment of liver fibrosis. Future studies on larger patient cohorts are necessary for improvement.