Aims: Measurement of liver stiffness (LS) by vibration-controlled transient elastography
[VCTE/Fibroscan] is limited in patients with obesity and ascites. We here test and
compare the recently developed more powerful XL probe versus the conventional M probe.
Methods: LS was measured in 129 obese and non-obese patients (BMI range 17.2–72.4) using both
the M and XL probe. In addition, BMI, waist to hip ratio, transaminases and liver
ultrasound parameters were obtained.
Results: LS was not measurable in 6 patients (4.6%) by the XL probe as compared to 32 patients
(24.8%) by the M probe. Almost halve of the patients not measurable with the M probe
showed fibrotic stiffness values with the XL probe. Notably, even patients with ascites
up to 31mm distance were measurable with the XL probe. ROC analysis indicates that
skin-liver capsula distance, hip circumference and BMI are the best clinical parameters
whether LS can be measured or not. Out of the 6 patients not measurable with the XL
probe, four had a BMI>30 but two were non obese. Even 10 non obese patients were
not measurable with the M probe. LS measurement failure in non obese patients especially
with the M probe was in two cases due to ascites but mainly to a specific type of
subcutaneous fat tissue with poor ultrasound propagation. LS by M and XL probe were
highly correlated (r=0.98, P<0.01). The mean difference between LS measured with
M-probe compared to XL-probe was ca. 10%. Only in three patients, this difference
was higher than 100% without affecting the fibrosis group allocation. Generelly, XL-probe
obtained LS tends to be slightly lower as compared to the M probe.
Discussion and conclusion: The novel more powerful XL probe drastically improves the success rate of LS measurements
in patients with obesity and ascites. Patients with a BMI above 40 and lean patients
with a specific type of subcutaneous fat tissue with poor ultrasound penetration are
still problematic despite the use of the XL-probe.
FibroScan - Liver stiffness - ascites - obesity - transient elastography