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Direct comparison of the FibroScan XL and M probes for assessment of liver fibrosis in obese and nonobese patients

Research output: Contribution to journalJournal articlepeer-review

  • Esteban Durango
  • Christian Dietrich
  • Helmut Karl Seitz
  • Cornelia Ursula Kunz
  • Gilles T. Pomier-Layrargues
  • Andres Duarte-Rojo
  • Melanie Beaton
  • Magdy Elkhashab
  • Robert P. Myers
  • Sebastian Mueller
<mark>Journal publication date</mark>4/07/2013
<mark>Journal</mark>Hepatic Medicine: Evidence and Research
Issue number5
Number of pages10
Pages (from-to)43-52
Publication StatusPublished
<mark>Original language</mark>English


BACKGROUND: A novel Fibroscan XL probe has recently been introduced and validated for obese patients, and has a diagnostic accuracy comparable with that of the standard M probe. The aim of this study was to analyze and understand the differences between these two probes in nonobese patients, to identify underlying causes for these differences, and to develop a practical algorithm to translate results for the XL probe to those for the M probe.

METHODS AND RESULTS: Both probes were directly compared first in copolymer phantoms of varying stiffness (4.8, 11, and 40 kPa) and then in 371 obese and nonobese patients (body mass index, range 17.2-72.4) from German (n = 129) and Canadian (n = 242) centers. Liver stiffness values for both probes correlated better in phantoms than in patients (r = 0.98 versus 0.82, P < 0.001). Significantly more patients could be measured successfully using the XL probe than the M probe (98.4% versus 85.2%, respectively, P < 0.001) while the M probe produced a smaller interquartile range (21% versus 32%). Failure of the M probe to measure liver stiffness was not only observed in patients with a high body mass index and long skin-liver capsule distance but also in some nonobese patients (n = 10) due to quenching of the signal from subcutaneous fat tissue. In contrast with the phantoms, the XL probe consistently produced approximately 20% lower liver stiffness values in humans compared with the M probe. A long skin-liver capsule distance and a high degree of steatosis were responsible for this discordance. Adjustment of cutoff values for the XL probe (<5.5, 5.5-7, 7-10, and >10 kPa for F0, F1-2, F3, and F4 fibrosis, respectively) significantly improved agreement between the two probes from r = 0.655 to 0.679.

CONCLUSION: Liver stiffness can be measured in significantly more obese and nonobese patients using the XL probe than the M probe. However, the XL probe is less accurate and adjusted cutoff values are required.