Potential conflict of interest: Nothing to report.
Feasibility and performance of the FibroScan XL probe†
Article first published online: 27 MAR 2012
Copyright © 2011 American Association for the Study of Liver Diseases
Volume 55, Issue 4, pages 1308–1309, April 2012
How to Cite
Kemp, W. and Roberts, S. (2012), Feasibility and performance of the FibroScan XL probe. Hepatology, 55: 1308–1309. doi: 10.1002/hep.25521
- Issue published online: 27 MAR 2012
- Article first published online: 27 MAR 2012
- Accepted manuscript online: 12 DEC 2011 07:01AM EST
To the Editor:
We read with interest the article by Myers et al.,1 who examined the feasibility and performance of the M and XL FibroScan probes in a cohort of patients with chronic liver disease. Although there are substantial data validating the use of the M probe as a noninvasive assessment of hepatic fibrosis,2 there are few data regarding the use of the XL probe.3, 4 This represents a particularly important issue considering the high prevalence of obesity in western communities and the relationship between body mass index (BMI) and frequency of liver stiffness measurement (LSM) failure and/or unreliability.5 Our analysis of over 2000 FibroScan referrals indicates that 23% of subjects have a BMI >30 kg/m2.
In a recent single-center prospective study, we used both the M and XL probes on 98 consecutive patients attending our liver clinic (53% men; mean age, 54 years [interquartile range (IQR), 48-62]; BMI, 26 kg/m2 [IQR, 23.5-30.1]). Two experienced operators (>1,000 FibroScan examinations) performed all the procedures using sonographic images to optimize positioning of the probes. The etiology of liver disease was distributed as follows: hepatitis C, 38%; hepatitis B, 21%; nonalcoholic fatty liver disease, 14%; and other, 27%. Overall, we found there was no difference in the LSM success rate between the M probe (78%) and the XL probe (82%) using the accepted criteria6 of ≥10 valid readings, ≥60% success rate, and an IQR/median LSM ratio of ≤0.30. In 65 subjects, liver stiffness was successfully determined by both the M probe and the XL probe. A further 16 subjects had successful LSMs with the XL probe despite unsuccessful LSMs with the M probe. Twelve subjects had successful LSMs with the M probe only. Therefore, overall, a successful valid FibroScan examination was obtained in 94% of individuals using a combination of the M and/or XL probes. The success rate for the M probe (P > 0.001) was influenced by the BMI, with a substantial decrease in the rate of successful examination in those with a BMI ≥35 kg/m2. This pattern was not observed for the XL probe, with similar success rates observed across the full spectrum of BMI categories (Fig. 1).
Our findings support the data presented by Myers et al.1 in that the use of the M probe alone is associated with a substantial failure rate that is BMI-dependent. The XL probe is therefore useful in those subjects in whom a valid LSM cannot be obtained with the M probe. However, similar to Myers et al.1 and the data previously published by de Ledinghen et al.,3 we observed that the LSMs were lower with the XL probe (6.1 [range, 4.9-7.9]) compared with the M probe (6.5 [range, 5.1-9.5]) (P > 0.005). This reinforces the concept that the currently published cutoffs for various fibrosis stages may be probe-specific, and revalidation of these cutoffs is required for use of the XL probe.
- 1Duarte-Rojo A, Wong D, et al. Feasibility and diagnostic performance of the FibroScan XL probe for liver stiffness measurement in overweight and obese patients. HEPATOLOGY 2012; 55: 199-208., , , ,
- 2Performance of transient elastography for the staging of liver fibrosis: a meta-analysis. Gastroenterology 2008; 134: 960-974., , , , , , et al.
- 3Feasibility of liver transient elastography with FibroScan using a new probe for obese patients. Liver Int 2010; 30: 1043-1048., , , , , .
- 4Transient elastography with a new probe for obese patients for non-invasive staging of non-alcoholic steatohepatitis. Eur Radiol 2010; 20: 2390-2396., , , , , , et al.
- 5Pitfalls of liver stiffness measurement: a 5-year prospective study of 13,369 examinations. HEPATOLOGY 2010; 51: 828-835., , , , , , et al.
- 6Non-invasive evaluation of liver fibrosis using transient elastography. J Hepatol 2008; 48: 835-847., , .
William Kemp Ph.D.* , Stuart Roberts M.D.* , * Gastroenterology Department, Alfred Hospital, Melbourne, Australia, Department of Medicine, Monash University, Melbourne, Australia.