Liver Stiffness Measurement With FibroScan: Use the Right Probe in the Right Conditions!

INTRODUCTION: FibroScan's M and XL probes give significantly different results, which could lead to misevaluation of liver fibrosis if the correct probe is not chosen. According to the manufacturer, the M probe should be used when the skin-liver capsule distance q(SCD) is <25 mm, and the XL probe should be used when SCD is >= 25 mm. We aimed at validating this recommendation and defining the conditions of use for FibroScan probes in clinical practice. METHODS: Four hundred thirty-nine patients with biopsy-proven chronic liver disease were included. Of them, 382 had successful examinations with both M and XL probes. Advanced fibrosis was defined as Nonalcoholic Steatohepatitis Clinical Research Network q(NASH CRN) F >= 3 or Metavir F >= 2. RESULTS: In a same patient, XL probe results were significantly lower thanMprobe results: 7.9 q(5.6-11.7) vs 9.5 q(6.7-14.6) kPa, respectively q(P < 0.001). After matching for age, sex, liver fibrosis, and serum transaminases, M probe results in patients with SCD < 25 mm and XL probe results in those with SCD >= 25 mm did not significantly differ: 8.8 q(6.0-12.0) vs 9.1 q(6.7-12.8) kPa, respectively q(P = 0.175). Of note, 81.4% of patients with body mass index q(BMI) <32 kg/m(2) had SCD <25 mm, and 77.7% of patients with BMI >= 32 kg/m(2) had SCD >= 25 mm. A practical algorithm using BMI first and then the FibroScan Automatic Probe Selection tool was proposed to help physicians accurately choose which probe to use in clinical practice. CONCLUSIONS: There is no significant difference in results between M and XL probes when they are used in the right conditions. In clinical practice, the probe should be selected according to the BMI and the Automatic Probe Selection tool.