Use of FibroScan VCTE for hepatic evaluation of overweight patients
In the past few years, the most important predictive factor of failed and unreliable FibroScan liver stiffness measurements (LSM) was the patient body mass index (BMI). In previously published studies, the rate of failed and unreliable measurements by Vibration Controlled Transient Elastography (VCTE) using the standard M probe was 18.9% to 29.2% [1, 2]
To overcome this limitation, a dedicated probe, named the XL probe, was designed specifically to scan overweight patients. This probe makes measurements deeper below the skin to ensure targeting liver parenchyma (i.e., 35-75 vs 25-65 mm) by using a lower ultrasound frequency transducer (2.5 vs 3.5 MHz) to increase ultrasound penetration. As it is for the conventional M probe, the XL probe also computes the Controlled Attenuation Parameter (CAP), thus allowing fatty liver evaluation.
-> As of today The use of FibroScan is possible on a wide spectrum of patients including the overweight population for both fibrosis (with liver stiffness in kPa) and steatosis (with CAP in dB/m) concomitant assessment, using either the M or the XL probe.
Advancement of XL Probe
for Hepatic Steatosis Evaluation 
On tissue-mimicking phantoms, Controlled Attenuation Parameter (CAP) was successfully adapted to the XL probe of the FibroScan with the same measurement range as the CAP with the M probe
In a cohort of patients spanning the range of steatosis, the diagnostic performance of CAP to assess the MRI-based hepatic fat fraction was good to excellent using both the M and XL probes (cf Figure 1)
Use of FibroScan in Screening both NAFLD & Fibrosis on Type 2 Diabetic Patients 
72.8% of diabetic patients with M probe had an increased CAP value > = 222 dB/m, suggestive of presence of fatty liver (S >= 1 , cf Figure 2)
17.7% of diabetic patients scanned with M or XL probe had increased LSM value, suggestive of advanced fibrosis or cirrhosis (cf Figure 2)
114 patients failed M probe examination but had successful LSM by the XL probe
Diabetic patients with high BMI and dyslipidemia are at high risk associated with NAFLD and increased LSM, and may be the target for liver assessment
FibroScan is a reasonable initial assessment for patients with type 2 diabetes
REMINDER: Added value of the XL Probe on Hepatic Fibrosis Evaluation
The added value of the use of XL probe has already been evaluated in several studies:
By using the XL probe, a reliable LSM was obtained in 59% to 93% of those who had an unreliable study using the M probe [5,6,7]
A more recent study reported that 95% (103 of 106) of patients could be evaluated successfully with LSM using the XL probe 
83% of NAFLD or NASH patients (BMI >= 30 kg/ m2) who could not be measured with the M probe could be examined without failure with the XL probe 
FibroScan XL probe reduces TE failure and facilitates reliable LSM in obese patients with chronic liver disease including viral hepatitis and NAFLD 
Echosens recommends the use the XL probe only on patients with a Skin to Liver Capsule Distance (SCD) ≥25mm ; SCD is now automatically measured by the FibroScan devices, all equipped with the “Probe recommendation tool “.
Castera L, Foucher J, Bernard PH, Carvalho F, Allaix D, Merrouche W, Couzigou P, de Ledinghen V. Pitfalls of liver stiffness measurement: A 5-year prospective study of 13,369 examinations. Hepatology 2010; 51: 828-835.
Sirli R, Soprea I, Bota S, et al. Factors influencing reliability of liver stiffness measurements using transient elastography (M-probe) – monocentric experience. Eur J Radiol 2013; 82: e313-6.
Sasso M, Audiere S, Fournier C, Sandrin L, et al. Liver steatosis assessed by controlled attenuation parameter (CAP) measured with the XL probe of the fibroscan: A pilot study assessing diagnostic accuracy. Ultrasound in Med. & Biol. 2015. In press.
Kwok R, Choi KC, Wong GL, Zhang Y , Chan HL, et al. Screening diabetic patients for non-alcoholic fatty liver disease with controlled attenuation parameter and liver stiffness measurements: A prospective cohort study. Gut 2015. In press.
de Ledinghen V, Vergniol J, Foucher J, et al. Feasibility of liver transient elastography with FibroScan using a new probe for obese patients. Liver International 2010; 30: 1043-8.
Friedrich-Rust M, Hadji-Hosseini H, Kriener S, Hermann E, et al. Tranisent Elastography with a new probe for obese patients for non-invasive staging of non-alcoholic steatohepatitis. Eur Radiol 2010; 20: 2390-6.
Sirli R, Sporea I, Deleanu A, et al. Comparison between the M and XL probes for liver fibrosis assessment by transient elastography. Med Ultrason 2014; 16 : 119-22.
Cassinotto C, Lapuyade B, Mouries A, et al. Non-invasive assessment of liver fibrosis with impulse elastography: Comparison of Supersonic Shear Imaging with ARFI and FibroScan®. J Hepatol 2014; 61: 550-7.
Myers RP, Pomier-Layrargues G, Kirsch R, Pollett A, et al. Feasibility and diagnostic performance of the FibroScan XL probe for liver stiffness measurement in overweight and obese patients. Hepatology 2011; 55:199-208.
Fibroscan® is used worldwide in routine clinical practice and research. It made radical changes in the way hepatologists diagnose and follow-up patients with chronic liver diseases. The advantages of the technology have been demonstrated in more than 1 000 scientific publications since 2003.