Performance Characteristics of Vibration-Controlled Transient Elastography for Evaluation of Non-Alcoholic Fatty Liver Disease

Background: Vibration-controlled transient elastography (VCTE) estimates liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) which are noninvasive assessments of hepatic fibrosis and steatosis respectively. However, prior VCTE studies reported high failure rate in patients with non-alcoholic fatty liver disease (NAFLD). Aim: To examine the performance characteristics of Fibroscan 502 Touch with two probes, medium (M+) and extra-large (XL+), in patients with NAFLD in a multicenter setting. Methods: A total of 1696 exams were attempted in 992 patients (BMI: 33.6 ± 6.5 kg/m2) with histologically confirmed NAFLD. Simultaneous assessment of LSM and CAP was performed using Fibroscan 502 Touch with an automatic probe selection tool. Testing was conducted twice in patients by either a single operator (88%) or two operators (12%). Failure was defined as the inability to obtain a valid examination. An examination was considered unreliable if LSM IQR/median was >30%. Significant disagreement between two readings was defined as greater than >95% limits of agreement between two readings. Results: A total of 1641 examinations yielded valid results with a failure rate of 3.2% (55/1696). The proportion of unreliable scans for LSM was 2.4%. The proportion of unreliable scans with operator experience in the top quartile (≥ 59 procedures) was significantly lower than lower three quarters combined (1.6% vs.4.7%, p=0.01 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. Conclusion: VCTE for estimation of LSM and CAP can be successfully deployed in a multicenter setting with low failure (3.2%) and high reliability (>95%) rates and high reproducibility