Comparison between the M and XL probes for liver fibrosis assessment by Transient Elastography

Abstract

Objective: Liver stiffness measurement (LSM) using Transient Elastography (TE) for liver fibrosis assessment is difficult to be performed in obese and overweight patients by standard M probe, thus the XL probe was developed. The aim of our paper was to assess the usefulness of the XL probe in daily clinical practice. Material and method: Our study included 216 patients (mean BMI 30.1±4.1 kg/m2) with chronic hepatopathies, in which paired measurements were made using the M (3.5MHz) and XL (2.5 MHz) probes in the same session. In each patient 10 valid LSM were acquired with each probe, a median was calculated, expressed in kiloPascals (kPa). Unreliable TE measurements were considered: fewer than 10 valid shots; with a success rate (SR) <60% and/or interquartile range interval (IQR) ≥30%. Results: In 127 patients reliable LSM could not be obtained by standard M probe, 10 of them normal weight, 25 of them overweight, and 92 obese. By XL probe reliable measurements were obtained in 80/127(63%) of these patients: 8/10 (80%) of the normal weights, 17/25 (68%) of the overweight and 55/92 (59.8%) of the obese. In 98 patients with reliable M probe measurements, XL probe LSMs were also performed. XL LS values strongly and significantly correlated with those obtained by M probe (Spearman r=0.789, p<0.0001), but were significantly lower [median 6.4 kPa (range 3.1 -53.8) vs 7.7 kPa (range 3.7-69.1), Wilcoxon paired t test p<0.001)]. Conclusion: By using the XL probe, reliable LSM by TE can be obtained in more than 60% of patients with unreliable measurements by M probe. LSM by XL probe are significantly correlated, but lower, than those obtained by M probe.

Supersonic Shear Imaging and Transient Elastography With the XL Probe Accurately Detect Fibrosis in Overweight or Obese Patients With Chronic Liver Disease

“…We believe our results for detecting F4 differed because the LSMs obtained using the XL probe have been reported to be lower than those obtained by the M probe. 24 The rate of failure obtained using SSI on the left lobe was significantly higher than that obtained using SSI on the right lobe, and the actual values of LSMs from the left lobe were significantly higher than with the right lobe as reported previously using virtual touch tissue quantification. 25 We previously reported that 33.1% of the study cohort had a difference of at least one stage between the right and left lobes as determined by liver biopsy.…”

Noninvasive Evaluation of Liver Fibrosis Using Real‐time Tissue Elastography and Transient Elastography (FibroScan)

“…In addition, it is difficult in patients with a high body mass index or narrow intercostal spaces 28 , 29 . Recently, a new FibroScan probe (XL probe) has been developed to lessen the failure rate in obese patients, and its good efficacy has been shown in some investigations 26 , 27 …”

“…It can be used to accurately detect early hepatic fibrosis, 24 advanced fibrosis, 25 and cirrhosis 8 , 9 . Additionally, the recently developed XL probe has improved the feasibility of FibroScan in obese patients 26 , 27 . Nevertheless, there are technical limitations that may prevent accurate liver stiffness measurement in patients with ascites, severe hepatic atrophy, and narrow intercostal spaces 28 , 29 …”

Performance of 2D-SWE.GE for predicting different stages of liver fibrosis, using Transient Elastography as the reference method

“…The main disadvantages are that it cannot be performed in patients with ascites [7], and that it lacks B-mode gray scale ultrasound visualization of the liver. Furthermore, the method's reliability decreases from normal weight to overweight and obese patients [21]; this disadvantage has been partially overcame by the use of the XL probe [22,23]. Previous studies have shown that there are confounding factors that can increase LS values by TE: high levels of aminotransferases [24], extrahepatic cholestasis [25] and liver congestion in heart failure [26].…”