**4. Vibration-controlled transient elastography (Fibroscan)**

Fibroscan, which has been developed for the measurement of liver stiffness, is currently con‐ sidered to reflect the degree of liver fibrosis directly and better than other methods. Fibro‐ Scan502 was developed by ECOSENS (Paris, France) to evaluate liver fibrosis noninvasively in a short examination period by measuring the propagation of low frequency signals of a mechanical shear wave running through the liver tissue. Fibroscan measures liver stiffness in a volume that approximates a cylinder 10-mm wide and 40-mm in length between 25 and 65 mm below the skin surface. This volume is at least 100 times greater than that obtained by liver biopsy and is therefore considered to be far more representative of the condition of the hepatic parenchyma [17-21].The results that were obtained from ten valid measurements with a success rate of at least 60% and an interquartile range under 30% were considered successful. Failure was defined as when fewer than ten valid measurements were obtained. The median of 10 valid measurements was expressed in kilopascals (kPa) and regarded as the liver stiffness of a given subject.

Reports in 2005 from Castera et al. and Ziol et al. were pioneering; the liver stiffness measure‐ ments could be useful for assessing the presence of significant fibrosis (F2-4) and for suggest‐ ing the presence of cirrhosis in cohorts of patients with chronichepatitis C. The AUROCs ranged from 0.79 to 0.83 for the prediction of F2-4 and were over 0.95 for the identification of cirrhosis [22, 23]. Moreover, reproducibility of Fibroscan has been shown to be excellent for both interobserver and intraobserver agreement with an intraclass correlation coefficient of 0.98 [24, 25]. Friedrich-Rust et al. [26] assessed the overall performance of TE for the diagnosis of liver fibrosis by a meta-analysis that included fifty articles; the mean AUROCs for the diag‐ nosis of significant fibrosis, severe fibrosis, and cirrhosis were 0.84, 0.89, and 0.94, respective‐ ly. A recent report from Degos et al. [27] of amulticenter prospective study reported that the AUROCs for the diagnosis of significant fibrosis and cirrhosis were 0.76 and 0.90, respectively. Table 2 shows concisely the diagnostic accuracy of Fibroscan. The limitations of this method al‐ so have been discussed; intraobserver agreement is influenced by variables, such as body mass index (particularly when<28 kg/m2), hepatic steatosis, and flares of transaminases [17.23].


Sen, Sensitivity; Spe, Specificity; PPV, Positive Predictive Value; NPV, Negative Predictive Value; AUC, Area Under the Receiver-Operator-Characteristic curve; CHC, chronic hepatitis C.

**Table 2.** Diagnostic accuracies of transient elastography

B-mode image (Fig. 1B). We chose an area where the tissue was free from large vessels and near the biopsy point. The measurement was fixed to a rectangle 30 mm in length and 20 mm in breadth located 5-10 mm below the surface of the liver (Fig. 1B). The color in the ROI was graded from blue (representing hard areas) to red (representing soft areas, Fig. 1B). We stored the RTE images for 2- 3min as moving digital images (Fig. 1B) and ten static images were captured at random from the moving images by the observer using AVI2JPG v6.10 converter software (Novo, Tokyo, Japan) and analyzed on a personal computer using the novel software Elasto\_ver 1.5.1,which was developed and donated by Hitachi Medical. Nu‐ merical values of pixels were from 0 to 255 (256 stepwise grading) according to color map‐ ping from blue (0) to red (255), and a histogram of the distribution was generated (Fig. 1C). The scale ranged from red for components with the greatest strain (i.e., the softest compo‐ nents) to blue for those with no strain (i.e., the hardest components). Green indicated aver‐ age strain in the ROI, and therefore intact liver tissue was displayed as a diffuse homogeneous green pattern. An appearance of unevenness in the color pattern was consid‐ ered to reflect a change in the liver stiffness. For quantification, all pixel data in the colored

image were transferred into a histogram and binary image (Fig. 1C, D).

**4. Vibration-controlled transient elastography (Fibroscan)**

the liver stiffness of a given subject.

284 Liver Biopsy – Indications, Procedures, Results

Fibroscan, which has been developed for the measurement of liver stiffness, is currently con‐ sidered to reflect the degree of liver fibrosis directly and better than other methods. Fibro‐ Scan502 was developed by ECOSENS (Paris, France) to evaluate liver fibrosis noninvasively in a short examination period by measuring the propagation of low frequency signals of a mechanical shear wave running through the liver tissue. Fibroscan measures liver stiffness in a volume that approximates a cylinder 10-mm wide and 40-mm in length between 25 and 65 mm below the skin surface. This volume is at least 100 times greater than that obtained by liver biopsy and is therefore considered to be far more representative of the condition of the hepatic parenchyma [17-21].The results that were obtained from ten valid measurements with a success rate of at least 60% and an interquartile range under 30% were considered successful. Failure was defined as when fewer than ten valid measurements were obtained. The median of 10 valid measurements was expressed in kilopascals (kPa) and regarded as

Reports in 2005 from Castera et al. and Ziol et al. were pioneering; the liver stiffness measure‐ ments could be useful for assessing the presence of significant fibrosis (F2-4) and for suggest‐ ing the presence of cirrhosis in cohorts of patients with chronichepatitis C. The AUROCs ranged from 0.79 to 0.83 for the prediction of F2-4 and were over 0.95 for the identification of cirrhosis [22, 23]. Moreover, reproducibility of Fibroscan has been shown to be excellent for both interobserver and intraobserver agreement with an intraclass correlation coefficient of 0.98 [24, 25]. Friedrich-Rust et al. [26] assessed the overall performance of TE for the diagnosis of liver fibrosis by a meta-analysis that included fifty articles; the mean AUROCs for the diag‐ nosis of significant fibrosis, severe fibrosis, and cirrhosis were 0.84, 0.89, and 0.94, respective‐ ly. A recent report from Degos et al. [27] of amulticenter prospective study reported that the
