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Virtual touch quantification accurately measures fibrosis stage

Virtual touch quantification provided a noninvasive method for fibrosis staging and was more accurate than Fibrosis-4 index and aminotransferase-to-platelet ratio index in patients with hepatitis C, according to a recently published study. However, skin liver capsule distance longer than 17.5 mm may result in measurement failures.

“Liver biopsy (LB) remains the gold standard for liver fibrosis staging, but it is invasive, has sampling errors, and there is variation in diagnosis among pathologists,” the researchers wrote. “[Virtual touch quantification (VTQ)] is easily performed using conventional [ultrasound] probes during abdominal ultrasonography. VTQ can be used in patients with ascites, whereas [transient elastography] cannot be used in these patients.”

The study comprised 302 patients with HCV. All patients underwent liver biopsy and liver stiffness measurement with VTQ, FIB-4 index and APRI. Biopsy results showed that 108 patients had fibrosis stage 1, 93 patients had stage 2, 62 patients had stage 3 and 39 patients had stage 4.

At any fibrosis stage, VTQ had a higher area under receiver operating curve compared with FIB-4 index and APRI.

Based on the velocity of the shear wave values, the VTQ cut-off values were 1.33 m/s for fibrosis stage 2 or higher (sensitivity 76%, specificity 80%), 1.51 m/s for stage 3 or higher (sensitivity 80%, specificity 79%), and 1.92 m/s for stage 4 (sensitivity 90%, specificity 84%).

The researches defined the estimated VTQ range for each fibrosis stage as 0.81 m/s to 1.72 m/s for fibrosis stage 1, 0.88 m/s to 2.1 m/s for stage 2, 1.04 m/s to 2.8 m/s for stage 3, and 1.15 m/s or higher for stage 4.

Multivariate analysis showed that skin liver capsule distance (SCD) correlated significantly with discrepancy between estimated fibrosis stage in VTQ measurement and liver biopsy (OR = 1.315; 95% CI, 1.18-1.465). The SCD cutoff value was 17.5 mm (sensitivity 79%, specificity 69%).

“The accuracy of [acoustic radiation force impulse (ARFI)] seems to be lower in patients with a long SCD, although steatosis, hepatic inflammation, and hepatocyte ballooning have little effect on ARFI measurement failures,” the researchers wrote. “Because we can measure the SCD easily at the same time as performing the usual ultrasonography, it is beneficial to set the cut-off value of SCD as an indicator of reliability.” – by Talitha Bennett

Disclosure: The authors report no relevant financial disclosures.