A FibroScan procedure is a non-invasive diagnostic tool used to provide a rapid assessment of liver health. It uses specialized ultrasound technology to measure the degree of scarring and fat accumulation within the liver tissue, offering a safe and painless alternative to a traditional liver biopsy. This quick test provides objective, quantifiable data that helps physicians monitor the progression of chronic liver diseases and determine the effectiveness of treatment.
The Technology Behind FibroScan
The core principle behind the FibroScan device is a technique called Transient Elastography (TE), which utilizes mechanical shear waves. The procedure begins when a specialized probe sends a low-frequency pulse or vibration into the liver, generating a shear wave that travels through the tissue. The FibroScan machine uses high-speed ultrasound to measure the velocity of this shear wave. Scarred or hardened liver tissue (fibrosis) is stiffer than healthy tissue, causing the shear wave to travel faster. The device uses the measured wave speed to calculate a quantifiable liver stiffness score. This non-invasive method samples a larger volume of tissue than a typical biopsy, minimizing sampling error.
Key Metrics: Assessing Fibrosis and Steatosis
The FibroScan procedure delivers two distinct measurements that provide a comprehensive picture of liver health. The first quantifies liver stiffness, a direct indicator of fibrosis (scarring), expressed in kilopascals (kPa); a higher kPa value correlates to a greater extent of scarring. The second measurement is the Controlled Attenuation Parameter (CAP) score, which assesses steatosis (fat accumulation). The CAP score is measured in decibels per meter (dB/m). This score measures how much the ultrasound signal is attenuated as it passes through the fatty liver tissue; a higher CAP score indicates a greater level of fat content.
Preparing for and Undergoing the Test
Preparation for a FibroScan test typically requires fasting. Patients are instructed not to eat or drink anything for at least three hours before the procedure to ensure accurate results. Wearing loose-fitting clothing is helpful, as the right side of the abdomen needs to be exposed for the examination. During the test, the patient lies on their back with their right arm raised behind their head while a technician applies gel and places the probe between the ribs over the liver area. The probe delivers multiple vibrations, causing a slight, painless thumping sensation, and the procedure usually takes less than 15 minutes.
Understanding Your FibroScan Score
The raw kilopascal (kPa) and Controlled Attenuation Parameter (CAP) measurements are translated into clinically meaningful scores. The kPa reading assigns a Fibrosis score (F-score), which ranges from F0 to F4. F0 or F1 indicates minimal scarring, F2 is moderate, F3 is severe, and F4 signifies advanced scarring consistent with cirrhosis. Stiffness scores vary by disease, but a value above 14 kPa is often associated with cirrhosis in common liver diseases.
The CAP score determines a Steatosis grade (S-score), which ranges from S0 (minimal fat accumulation) to S3 (severe steatosis). For instance, an S1 grade (mild steatosis) corresponds to a CAP score between 238 and 260 dB/m, indicating 11% to 33% fatty change.
These results must be interpreted by a healthcare professional alongside the patient’s full medical history and other laboratory tests. The FibroScan provides a snapshot of liver health, but only a physician can determine the correct diagnosis and next steps.