Fibroscan - A Novel Ultrasound-Based Diagnostic Tool

Introduction:

The liver is one of the vital organs of the human body that performs multiple functions and hence is crucial to support life. Liver diseases may be congenital though a majority of them are acquired. Diagnosing liver conditions is challenging as they are symptomatically silent during the initial stages. Delayed diagnosis yields permanent damage negating the chances of a complete cure. However, advanced diagnostic aids, routine screening, and early detection can prevent fatal injuries and grave complications.

What Is Fibroscan?

Liver ultrasound is considered one of the most straightforward and noninvasive techniques to image any organ or tissue of the body. It uses sound waves to visualize the organs and is thus radiation safe. It is an excellent tool for diagnosing cysts, solid tumors, fatty liver, and inflammatory changes in the liver. However, ultrasound was found to have decreased sensitivity in certain conditions like liver cirrhosis. Cirrhosis is extensive scarring of liver tissues caused by a viral infection like hepatitis or chronic alcohol abuse. A biopsy is considered the gold standard for diagnosing cirrhosis. However, certain disadvantages, such as hospitalization, high cost, invasiveness, and surgical complications, render biopsy less desirable among patients and doctors. Additionally, incorrect staging, sampling error, and interobserver discrepancies in liver disease staging have led to the development of a noninvasive and superior diagnostic tool known as fibroscan.

Fibroscan is a novel ultrasound-based diagnostic tool that measures the stiffness or elasticity of the liver tissues. This procedure is also known as transient elastography or liver elastography. Fibroscan is a relatively quick, easy, painless, and noninvasive alternative to conventional liver biopsy. It is used to diagnose a condition by assessing and evaluating liver stiffness or hardness.

What Is the Principle Behind Fibroscan?

Fibroscan works on the principle of transient elastography. Tissue elasticity is a mechanical property of the tissue that permits it to distort upon being subjected to an external force and return to its original form when the force is removed. Every tissue in the body has an inherent elasticity based on which the response may vary to a certain extent. Fibroscan measures the elasticity or the hardness of the liver tissues to evaluate and assess the severity of the liver disease.

A 50 MHz vibration wave is sent into the liver utilizing a small handheld probe. The speed with which the vibration wave passes through the liver is measured by the transducer and is expressed as liver stiffness. Fibrous liver tissues are generally more rigid than normal liver tissues, and the value of hardness is directly proportional to the degree of fibrosis. A rigid or stiff liver is suggestive of scarring, also known as fibrosis. Cirrhosis is a severe and extensive form of fibrosis.

Where Is Fibroscan Indicated?

A Fibroscan is indicated for the following chronic liver conditions such as

• Fatty liver disease.

• Hepatitis B and C.

• Autoimmune hepatitis.

• Alcoholic liver disease.

• Cirrhosis.

• Genetic conditions.

• Liver fibrosis.

• Portal hypertension.

• Follow-up in liver transplant patients.

• Nonalcoholic steatohepatitis.

• Hemochromatosis (excess iron stored in the body).

Fibroscan is exceptionally beneficial for assessing the degree of damage, staging the disease, monitoring the disease progression, predicting the survival rate and prognosis, and guiding the treatment plan.

What Are the Instructions Before Undergoing a Fibroscan?

Fibroscan is a straightforward and painless procedure and does not require any special instructions. It is usually conducted as an outpatient procedure, and the entire process takes roughly around 30 minutes. Patients on prescription medicines such as blood thinners and anti-hypertensives should inform the doctor before the procedure. Patients are advised to carry their previous medical reports and medications for the procedure. Patients are advised not to eat or drink three hours before the procedure.

How Is a Fibroscan Done?

Patients should wear loose, comfortable clothes and remove any valuables or jewelry. They may be advised to change into a hospital gown and will be asked to lie on the examination table with their right arm raised above their head. The abdominal area will be exposed, and a clear water-based gel will be applied over the skin on the right abdominal quadrant. A small handheld probe will be moved over the skin. The patient might experience mild vibrations over the skin as the ultrasound waves penetrate the body.

What Are the Post-procedure Instructions?

There are no specific post-procedure instructions to be followed. Therefore, the patient can resume their normal activities unless otherwise instructed by their physician.

What Is a Normal Fibroscan Result?

The fibroscan results are given in the form of two scores, cap score and fibrosis score.

Cap Score - Cap score indicates the fatty change in the liver. It is measured in decibels per meter (dB/m).

Fibrosis Score – The scarring of the liver is given as a fibrosis score and is measured in kilopascals (kPa).

• Normal Score - No scarring or mild scarring.

• Moderate to Severe Score - Reversible changes in the liver that lifestyle modifications and a healthy diet can help manage. Patients may not be symptomatic.

• Advanced Score - The patient is cirrhotic with advanced liver diseases.

What Are the Benefits of Fibroscan Over Liver Biopsy?

The benefits of Fibroscan are mentioned below:

• Painless.

• Quick and simple.

• Noninvasive.

• No sedation is required.

• Well tolerated by the patients.

What Are the Pitfalls?

Although there are no absolute contraindications, fibroscan has limited usage in the following conditions:

• Patients with ascites.

• Obese patients or patients with increased waist circumference.

• Older patients.

• Pregnant women.

• Patients with pacemakers.

False positive results may be observed in:

• Inflammatory conditions such as active hepatitis.

• Biliary obstruction.

• Liver tumor.

• Secondary liver congestion due to cardiac failure.

Conclusion:

Various imaging tests are handy when it comes to diagnosing liver diseases. However, efficiency and accuracy are of prime importance for a better prognosis. The fear of invasive tests such as biopsies may deter the patients from seeking further medical advice. Though advanced liver diseases cannot be cured entirely, the damage can be well reversed, resulting in a positive outcome. With noninvasive and painless techniques such as fibroscan, liver ailments can be rapidly diagnosed and treated before fatal complications occur.