Study of detection times for liver stiffness evaluation by shear wave elastography

AIM: To investigate enough valid measurements (VMs) to assess liver fibrosis in chronic hepatitis B patients (CHB). METHODS: One hundred and twelve CHB patients (25 women, 87 men) with a mean age of 38.43 years received liver stiffness evaluations using real-time shear wave elastography for 10 VMs. All patients underwent liver biopsy. Based on the biopsy pathology, the liver stiffness data obtained from different VMs (1, 2, 3, 5 and 10 times) were compared for the evaluation of liver fibrosis. The correlation between the elastic modulus means of the liver obtained from different VMs of detection at each pathological stage was analysed. The receiver operating characteristic (ROC) curve was employed to determine the diagnostic performance of different VMs of detection, and the areas under the ROC curve of different groups were compared. RESULTS: The liver stiffness values obtained from 1 VM, 2 VMs, 3 VMs, 5 VMs and all 10 VMs for stage F0 were 6.95 +/- 2.01 kPa, 6.87 +/- 1.83 kPa, 6.90 +/- 1.88 kPa, 6.95 +/- 1.93 kPa and 7.15 +/- 1.89 kPa, respectively (F = 0.043, P = 0.996). For stage F1, these values were 7.12 +/- 1.72 kPa, 7.24 +/- 1.72 kPa, 7.21 +/- 1.747kPa, 7.10 +/- 1.78 kPa and 7.04 +/- 1.70 kPa, respectively (F = 0.075, P = 0.990). For stage F2, they were 9.37 +/- 3.87 kPa, 9.18 +/- 3.68 kPa, 9.19 +/- 3.81 kPa, 9.18 +/- 3.81 kPa and 9.19 +/- 3.53 kPa, respectively (F = 0.012, P = 1.000). For stage F3, these were 11.91 +/- 3.88 kPa, 11.78 +/- 4.04 kPa, 11.83 +/- 4.07 kPa, 11.94 +/- 4.17 kPa and 12.00 +/- 4.02 kPa, respectively (F = 0.010, P = 1.000). For stage F4, the readings were 19.30 +/- 7.63 kPa, 19.40 +/- 7.36 kPa, 19.54 +/- 7.43 kPa, 19.73 +/- 7.21 kPa and 20.25 +/- 7.22 kPa, respectively (F = 0.054, P = 0.995). There were no significant differences between these groups. Intraclass correlation coefficients among different pathological stages (F0-F4) with different detection VMs were 0.995, 0.993, 0.996, 0.994 and 0.996, respectively. The mean elasticity values from 1 VM, 2 VMs, 3 VMs, 5 VMs and 10 VMs can accurately distinguish fibrosis stages (F0 vs F1234, F01 vs F234, F012 vs F34 and F0123 vs F4) with no significant differences in the five groups (P > 0.05 for all). CONCLUSION: One VM may be sufficient to assess liver fibrosis by using SWE without any significant loss of accuracy in patients with CHB. However, future studies of larger patient samples are necessary for the validation of this method. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.