title: Reproducibility of 2-Dimensional Shear Wave Elastography Assessment of the Liver: A Direct Comparison With Point Shear Wave Elastography in Healthy Volunteers.
abstract: OBJECTIVE
  Two-dimensional shear wave elastography (2D-SWE) imaging for the noninvasive assessment of tissue stiffness was assessed for reproducibility in healthy volunteers in quantifying liver elasticity, compared with an established point shear wave elastography (p-SWE) technique also known as virtual touch quantification (VTQ) (SIEMENS).
  
  
  METHODS
  Eleven healthy volunteers were examined by four experienced operators on two occasions, separated by two weeks (sessions A and B). Ten 2D-SWE using LOGIQ E9 and p-SWE measurements using VTQ (in meters per second) were consecutively taken from deep portions of liver segments 5 or 6 away from vascular structures, using standard techniques. Inter- and intra-observer agreement was assessed by intraclass coefficient (ICC).
  
  
  RESULTS
  A total of 880 2D-SWE and p-SWE velocities were recorded. Mean values from the four operators ranged between 1.188 and 1.196 m/s for 2D-SWE and 1.170 to 1.207 m/s for p-SWE. Interobserver reproducibility was good for both sessions with ICCs of 0.88 and 0.93 (2D-SWE) and 0.87 and 0.93 (p-SWE). The overall intra-operator reproducibility between sessions A and B was good for both p-SWE and 2D-SWE with ICC of 0.87 and 0.83, respectively. For inter- and intra-observer variability, the ICC was more than or equal to 0.71, indicating that the results were reliable. There was a strong and significant correlation between the 2D-SWE and p-SWE measurements (r = 0.87, P = .0006), but their velocities did not agree equally across different velocities.
  
  
  CONCLUSIONS
  Two-dimensional SWE using LOGIQ E9 is a reliable and reproducible method for measuring elasticity in healthy volunteers and has a similar degree of reliability as p-SWE using VTQ, but absolute measurements from the two techniques should not be used interchangeably.
authors.affiliation: Department of Radiology, King's College Hospital, London, United Kingdom.
authors.forename: Cheng
authors.initials: C
authors.lastname: Fang
authors.affiliation: Department of Radiology, King's College Hospital, London, United Kingdom.
authors.forename: Eleni
authors.initials: E
authors.lastname: Konstantatou
authors.affiliation: Department of Radiology, King's College Hospital, London, United Kingdom.
authors.forename: Odyssefs
authors.initials: O
authors.lastname: Romanos
authors.affiliation: Department of Radiology, King's College Hospital, London, United Kingdom.
authors.forename: Gibran T
authors.initials: GT
authors.lastname: Yusuf
authors.affiliation: Department of Radiology, King's College Hospital, London, United Kingdom.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Quinlan
authors.affiliation: Department of Radiology, King's College Hospital, London, United Kingdom.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Sidhu
mesh_terms: D000328:Adult; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008099:Liver / Q000033:anatomy & histology*; D008297:Male; D015588:Observer Variation; D012016:Reference Values; D015203:Reproducibility of Results
keywords: ARFI; acoustic radiation force impulse imaging; reproducibility; shear wave elastography; ultrasound