UC San Diego

Vibration-controlled transient elastography estimates liver stiffness measurement (LSM) and controlled attenuation parameter (CAP), which are noninvasive assessments of hepatic fibrosis and steatosis, respectively. However, prior vibration-controlled transient elastography studies reported high failure rates in patients with nonalcoholic fatty liver disease. We examined the performance characteristics of the FibroScan 502 Touch with two probes, medium (M+) and extra large (XL+), in patients with nonalcoholic fatty liver disease in a multicenter setting. A total of 1,696 exams were attempted in 992 patients (body mass index, 33.6 ± 6.5 kg/m² ) with histologically confirmed nonalcoholic fatty liver disease. Simultaneous assessment of LSM and CAP was performed using the FibroScan 502 Touch with an automatic probe selection tool. Testing was conducted twice in patients by either a single operator (87%) or two operators (13%). Failure was defined as the inability to obtain a valid examination. An examination was considered unreliable if LSM interquartile range/median was >30%. Significant disagreement between two readings was defined as >95% limits of agreement between two readings. A total of 1,641 examinations yielded valid results with a failure rate of 3.2% (55/1,696). The proportion of unreliable scans for LSM was 3.9%. The proportion of unreliable scans with operator experience in the top quartile (≥59 procedures) was significantly lower than that in the lower three quarters combined (1.6% versus 4.7%, P = 0.02 by Fisher's exact test). The significant disagreement between first and second readings for LSM and CAP when obtained back to back was 18% and 11%, respectively.

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