Fibroscan consists of electronic system and control unit. The ultrasonic transducer in the probe sends low frequency (50 MHz) and amplitude vibrations to the liver tissue. The elastic wave (transverse wave; shear wave) created as a result of this propagates through the tissue. The transmission rate of the wave is related to the elasticity of the tissue it passes through.
As the stiffness increases, the propagation speed of the wave increases, this speed is determined by the detector in the probe, expressed in kilopascals (kPa) and reflects the the amount of fibrosis in the liver. The volume of the liver whose hardness was measured by Fibroscan is 3 cm3, which is at least 100 times larger than the tissue that can be taken with liver biopsy. Therefore, it is suggested that this method better reflects the liver parenchyma. The measurement depth varies between 15-75 mm depending on the probe used. Fibroscan application takes only a few minutes, is painless and does not cause discomfort. While the patient is lying on his back, he places his right arm behind his neck, the aim is to widen the costal space.
The measurement is made from the right lobe with the probe placed on the skin in the intercostal space. The validity of the measurement is instantly visible on the device screen. If the measurement could not be made properly due to reasons such as improper placement of the probe and inappropriate angle, it is defined as an invalid measurement.
The success rate is the ratio of the number of successful measurements to all measurements, it is calculated automatically by the device. To obtain an accurate result, it is recommended to take at least 10 valid measurements and have a success rate above 60%.
The median value of valid measurements is reported in the range of 2.5 to 75 kPa as the final value reflecting liver elasticity. The variability between measurements is calculated by the interquartile range (IQR). While the ratio of IQR to the median value (M) of valid measurements (IQR/M) less than 30% was found to be a factor that increased the accuracy of the transient elastography result in chronic hepatitis C patients, the relationship of IQR/M ratio with measurement accuracy could not be demonstrated in chronic hepatitis B patients.