Feasibility of Transient Elastography with M and XL probes in real life

Reliable liver stiffness measurements (RLSM) using Transient Elastography (TE) with the standard M probe are difficult to obtain in overweight (BMI≥25kg/m2) and obese (BMI>30kg/m2) patients. The aim of our paper was to assess the feasibility of TE in daily practice using both M and XL probes. We studied retrospectively 3235 patients with chronic liver disease assessed by TE first by the M probe (standard probe – transducer frequency 3.5 MHz), and if the measurements were unreliable, with the XL probe (transducer frequency 2.5 MHz). Reliable measurements were defined as the median of 10 valid measurements with a success rate ≥ 60% and an interquartile range < 30%. Results of liver elasticity were expressed in kilo Pascals (kPa). RLSM by M probe were obtained in 62.2% (2015/3235) patients, and by XL probe in 1011/1220 (80%) of patients with unreliable measurements by M probe; thus we obtained RLSM in 93.5% of 3235 cases. In overweight patients we obtained RLSM in 89.9% (1039/1156) cases: in 63.1% (729) by M probe and in 26.8% (310) by XL probe. In obese patients we obtained RLSM in 83.8% (746/890): in 18.4% (164) by M probe and in 65.4% (582) by XL probe. Thus, by using both probes, RLSM were obtained in 1785 (87.2%) of overweight and obese patients. The feasibility of the M probe was 62.2% in our Department. Reliable measurements using M or XL probe allowed the evaluation of liver stiffness in 93.5% of cases. By using both M and XL probes, reliable LSM by TE can be obtained in the majority of obese and overweight patients (87.2%).