Virtual Touch Quantification to diagnose and monitor liver fibrosis in chronic hepatitis B and C

The Virtual Touch Quantification (VTq; Siemens) software application uses acoustic radiation force impulse (ARFI) imaging technology to measure the elasticity of liver tissue. VTq is used in combination with a Siemens Acuson S2000 or S3000 ultrasound platform. Liver tissue can be damaged by inflammation, causing high levels of collagen to be deposited in the liver cells (fibrosis), which become stiff. ARFI imaging involves generating a shear wave by applying an acoustic 'push pulse' lateral to the area of interest identified during a conventional ultrasound scan. The speed of the shear wave is proportional to the stiffness of the tissue.

The VTq investigation comprises multiple measurements and is both non‑invasive and painless. The software generates a report which includes a statistical summary of the median and mean shear‑wave velocities. The reliability of VTq measurements is usually confirmed by calculating the ratio of the interquartile range to median, which should be less than 0.30. VTq is indicated for adults or children needing assessment of liver fibrosis.

This evaluation focuses on the use of VTq to diagnose and monitor liver fibrosis in adults and children with chronic hepatitis B or C. The use of VTq to assess liver fibrosis associated with other conditions was outside the scope and so is not considered here.

The cost of the VTq software stated in the company's submission is £4,415. A compatible Siemens Acuson S2000 ultrasound system costs from £50,000 with annual maintenance costs, starting in year 2, from £2,000. The cost varies with the system configuration; the cost model includes typical values of £59,700 for the ultrasound system and £2,246 for the annual maintenance costs. All costs are excluding VAT.

The claimed benefits of VTq as presented by the company are as follows:

• VTq is painless and may be safer than liver biopsy as the standard of care.

• No hospital stay or post‑procedure monitoring is needed with VTq because it can be done in an outpatient setting.

• VTq may avoid the need for serial biopsies over several years to monitor fibrosis progression, improving quality of life and reducing procedure costs (if fibrosis progression is monitored with VTq).

• VTq provides a more complete assessment of the liver; during the procedure, a sonogram allows visualization of the liver parenchyma, portal and hepatic veins, portal and hepatic venous and arterial blood flow measurements, and the biliary tree for possible obstructions.

• Hepatic cellular carcinoma surveillance is included during the sonogram in patients with cirrhosis.

• Early identification of fibrosis in people with viral hepatitis may allow earlier intervention with antiviral drugs, which can reverse the course of early disease.

• Potential for increased capacity because the VTq procedure does not need to be done by a consultant.

• Reduced resource costs because no hospital admission or stay is needed for VTq measurements in an outpatient setting.

NICE's guideline on hepatitis B indicates that initial assessment usually takes place in primary care, through blood tests. All patients who test positive for hepatitis B surface antigen are then referred to a hepatologist, gastroenterologist or infectious diseases specialist with an interest in hepatology (children are referred to a similar paediatric specialist in a secondary or tertiary centre).

In secondary or tertiary care patients are provided with information on disease progress, long‑term prognosis, transmission and antiviral treatment options. Adults are then offered transient elastography as an initial test for chronic liver disease. Transient elastography (using, for example, the FibroScan device) is a non‑invasive method of assessing liver fibrosis by measuring liver stiffness based on a mechanical wave generated by vibration. Children and young people are offered liver biopsy to determine the need for antiviral therapy, with appropriate information provided on biopsy limitations and risks.

NICE's guideline on hepatitis B recommends:

• Transient elastography as the initial test for chronic liver disease, offering antiviral treatment (without a liver biopsy) to patients with a transient elastography score of 11 kPa or above.

• Considering liver biopsy in patients with a transient elastography score of 6 to 10 kPa.

• Offering liver biopsy to patients with a transient elastography score of less than 6 kPa if they are younger than 30 years of age and have hepatitis B virus DNA of more than 2,000 IU/ml and abnormal alanine aminotransferase (ALT) on 2 consecutive tests conducted months apart.

• Annual reassessment of patients who are not taking antiviral treatment.

The therapy pathway for people with hepatitis C is described in NICE's clinical knowledge summary on hepatitis C. Presently, patients who test hepatitis C virus RNA‑positive on a blood test are referred to a hepatology clinic. The degree of fibrosis is assessed and treatment options then depend on specific patient characteristics and the severity of their liver disease. There is a NICE guideline on the management and assessment of cirrhosis.

Liver biopsy is considered to be the gold standard for assessing liver fibrosis for both hepatitis B and C. Histological assessment uses the METAVIR score, based on an assessment of fibrosis and the degree of liver architecture disorganisation, and classifies the severity of liver disease from none (F0), through mild, moderate and severe (F1 to F3), to cirrhosis (F4).