Browsing by Author "Tonascia, James A."

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    Performance Characteristics of Vibration-Controlled Transient Elastography for Evaluation of Non-Alcoholic Fatty Liver Disease
    (Wiley, 2017) Vuppalanchi, Raj; Siddiqui, Mohammad S.; Van Natta, Mark L.; Hallinan, Erin; Brandman, Danielle; Kowdley, Kris; Neuschwander-Tetri, Brent A.; Loomba, Rohit; Dasarathy, Srinivas; Abdelmalek, Manal; Doo, Edward; Tonascia, James A.; Kleiner, David E.; Sanyal, Arun J.; Chalasani, Naga; Department of Medicine, School of Medicine
    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.
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    Vibration-controlled Transient Elastography to Assess Fibrosis and Steatosis in Patients With Nonalcoholic Fatty Liver Disease
    (Elsevier, 2018) Siddiqui, Mohammad S.; Vuppalanchi, Raj; Van Natta, Mark L.; Hallinan, Erin; Kowdley, Kris V.; Abdelmalek, Manal; Neuschwander-Tetri, Brent A.; Loomba, Rohit; Dasarathy, Srinivasan; Brandman, Danielle; Doo, Edward; Tonascia, James A.; Kleiner, David E.; Chalasani, Naga; Sanyal, Arun J.; Medicine, School of Medicine
    Background & Aims Vibration-controlled transient elastography (VCTE), which measures liver stiffness, has become an important tool for evaluating patients with nonalcoholic fatty liver disease (NAFLD). We aimed to determine the diagnostic accuracy of VCTE in detection of NAFLD in a multicenter cohort of patients. Methods We performed a prospective study of 393 adults with NAFLD who underwent VCTE within 1 year of liver histology analysis (median time, 49 days; interquartile range, 25–78 days), from July 1, 2014 through July 31, 2017. Liver stiffness measurement (LSM) cutoffs for pairwise fibrosis stage and controlled attenuation parameter (CAP) cutoffs for pairwise steatosis grade were determined using cross-validated area under the receiver operating characteristics curve (AUROC) analyses. Diagnostic statistics were computed at sensitivity fixed at 90% and specificity fixed at 90%. Results LSM identified patients with advanced fibrosis with an AUROC of 0.83 (95% CI, 0.79– 0.87) and patients with cirrhosis with an AUROC of 0.93 (95% CI, 0.90–0.97). At fixed sensitivity, a cutoff LSM of 6.5 kPa excluded advanced fibrosis with a negative predictive value of 0.91; a cut-off LSM of 12.1 kPa excluded cirrhosis with a negative predictive value of 0.99. At fixed specificity, LSM identified patients with advanced fibrosis with a positive predictive 0.71 and patients with cirrhosis with a positive predictive value of 0.41. CAP analysis detected steatosis with an AUROC of 0.76 (95% CI, 0.64–0.87). In contrast, the VCTE was less accurate in distinguishing lower fibrosis stages, higher steatosis grades, or presence of NASH. Conclusion In a prospective study of adults with NAFLD, we found VCTE to accurately distinguish advanced vs earlier stages of fibrosis, using liver histology as the reference standard.