Ultrasound Technique Effective in Measuring Liver Stiffness in Hepatitis Patients

The growing incidence of obesity, alcohol abuse and viral hepatitis are factors that have contributed to the increasing incidence of chronic liver disease worldwide.

The liver’s attempt to repair and replace damaged cells results in the formation of scar tissue is called fibrosis. If fibrosis advances to cirrhosis it can result in an increased risk of developing complications such as liver cancer, and eventually lead to liver failure.

Therefore, it is important to catch fibrosis early, particularly since long-term viral therapy can reduce the risk of developing complications associated with cirrhosis, said researcher Tung-Hung Su, MD, PhD, of the Division of Gastroenterology, Department of Internal Medicine, National Taiwan University Hospital, Taipei.

While liver biopsy has long been the gold standard for evaluating the severity of liver fibrosis, the procedure has limitations, Dr. Su said. For example, liver biopsy is invasive and can only sample a small portion of the liver. Recently, noninvasive methods of evaluating liver fibrosis have been developed, such as transient elastography, as measured by Fibroscan®. But that method cannot be used in individuals with ascites (abnormal accumulation of fluid in the abdominal cavity) and is associated with unreliable results in morbidly obese patients

In a study recently published in Radiology, lead author Dr. Su and colleagues investigated the clinical utility of another alternative for measuring liver fibrosis — acoustic radiation force impulse (ARFI) imaging.

ARFI imaging — performed with ultrasound (US) — allows for the assessment of tissue stiffness by evaluating wave propagation speed.

“The advantage of ARFI is a direct visualization of the region of interest (ROI),” Dr. Su said. “The target ROI can be adjusted manually to avoid major vessels, or ascites, and performed in patients with thick subcutaneous tissue.”

Dr. Su and his colleagues examined the clinical utility of ARFI for evaluating fibrosis in a group of patients with Hepatitis B. The retrospective cohort study comprised 559 patients who underwent serial ARFI examinations at National Taiwan University Hospital between 2012 and 2016.

The researchers collected clinical information as well as results from liver stiffness measurement tests and compared serial ARFI measurements in patients without antiviral therapy to those with antiviral therapy.

Accoustic Radiation Force Impulse (ARFI) Imaging Yields Positive Results

Dr. Su and his colleagues found that the ARFI value correlated with both fibrosis-4 index (FIB-4) (correlation coefficient = 0.55, P <0.001), and Fibroscan (correlation coefficient = 0.69, P < 0.001) results.

Results showed that ARFI value remained unchanged in the group without antiviral therapy. However, it significantly declined in the group with antiviral therapy (from 1.63 to 1.37 m/sec, time trend P < 0.001), both in patients with cirrhosis (from 2.15 to 1.75 m/sec, time trend P < 0.001) and in those without (from 1.27 to 1.11 m/sec, time trend P < 0.001).

“As documented by serial ARFI examinations, antiviral therapy reduces liver stiffness in chronic hepatitis B patients,” Dr. Su said. “We concluded that ARFI ultrasound is an important clinical noninvasive test for liver stiffness measurement and can be used for serial measurements in the management of chronic hepatitis B.”

Dr. Su said there are other potential applications of ARFI US imaging, as well.

ARFI can measure the shear wave velocity in diffuse disease of solid organs, including kidney (interstitial fibrosis), pancreas (acute or chronic pancreatitis), thyroid (fibrosis and thyroiditis), spleen (for portal hypertension), brain (neonatal brain development), breast (to differentiate benign and malignant lesions), and muscle (to assess muscle stiffness), according to Dr. Su.

And for liver disease, ARFI can also help to differentiate between benign and malignant tumors in the liver — a technique that can also be applied to measure liver stiffness in animal models, he said.

Web Extras

• Access the Radiology study, “Acoustic Radiation Force Impulse US Imaging: Liver Stiffness in Patients with Chronic Hepatitis B with and without Antiviral Therapy,” at https://pubs.rsna.org/doi/10.1148/radiol.2018171116