Reproducibility of liver stiffness measurement by ultrasonographic elastometry.

BACKGROUND & AIMS: Fibroscan is a noninvasive device that assesses liver fibrosis by liver stiffness evaluation (LSE) with ultrasonographic elastometry. We evaluated LSE reproducibility and its influencing factors. METHODS: LSE was performed by 4 experienced physicians (>100 LSEs) in 46 patients with chronic liver disease at 4 different anatomic sites. Additional LSEs were performed for ancillary aims, so that 534 LSEs were available. RESULTS: Overall interobserver agreement for LSE results was considered as excellent, with intraclass coefficient correlation (Ric) of 0.93. Low LSE level, nonrecommended sites, LSE interquartile range >25%, and body mass index > or =25 independently decreased agreement. Thus, agreement was fair (Ric = 0.53) for LSE <9 kilopascals and excellent (Ric = 0.90) beyond. The best measurement site for LSE reproducibility was the median axillary line on the first intercostal space under the liver dullness upper limit, with the patient lying in dorsal decubitus. When LSE results were categorized into fibrosis Metavir stages, interobserver discordance was noticed in about 25% of the cases and was the highest for F2 and F3 stages and the lowest for F4. Intraobserver (Ric = 0.94), intersite (Ric = 0.92-0.98), and interequipment (Ric = 0.92) agreements for LSE results were excellent. Preliminary standard ultrasonography or probe pressure changes did not improve interobserver agreement. CONCLUSIONS: The best measurement site for LSE is the one generally used for liver biopsy. Reproducibility of LSE is globally excellent but is fair in patient with low liver stiffness. The fibrosis diagnosis by ultrasonographic elastometry in low stages or categorized into fibrosis Metavir stages must be interpreted with caution.

Learning curve and interobserver reproducibility evaluation of liver stiffness measurement by transient elastography.

BACKGROUND/AIMS: Fibroscan allows liver stiffness examination (LSE) that is well correlated with fibrosis stages. Our main objective was to evaluate LSE learning curve. METHODS: LSE results of five novice observers with different medical status were compared with those of five expert observers (physicians with >100 examinations) in 250 patients with chronic liver disease. Each novice-expert pair had to blindly examine 50 consecutive patients divided into five consecutive subgroups of 10 patients. RESULTS: In each observer group, novice-expert agreement [intraclass correlation coefficient (Ric)] for LSE results was excellent from the first to the last subgroup. Novice-expert agreement for LSE results varied with liver stiffness level: <9 kPa: Ric=0.49; >or=9 kPa: Ric=0.87. Relative difference (%) between novice and expert LSE results was independently associated with the number of valid LSE measurements, and stabilizes around 20-30% after the fourth valid measurement. In each observer group, novice-expert agreement (Ric) for LSE success rate progressively increased as a function of time. CONCLUSION: LSE requires no learning curve: a novice is able to obtain a reliable result after a single training session, whatever the professional status. However, success rate will progressively increase. An LSE with less than four valid measurements should not be considered as reliable.