title: [Approaches to objective assessment of differences in tissue textures by ultrasound equipment as a contribution to quality assurance].
abstract: OBJECTIVE
  For clinical investigators the increasing number of ultrasonic machines with different technological equipment makes it difficult to reliably assess their ability to differentiate between the textures of various tissues. We investigated a procedure for a standardised method to measure the tissue texture when using different ultrasonic machines.
  
  
  METHODS
  The texture parameters concern brightness, standard deviation, coefficient of variation and spatial coefficient of variation. These were calculated for three tissue phantoms with changing levels of gain and distance. These parameters, well established in literature for speckle detection, texture differentiation and contrast monitoring were useful for rapid comparison of the texture differentiation achieved by several ultrasonic machines.
  
  
  RESULTS
  A linear relationship between standard deviation and mean image brightness seems to be an important factor for the detection of small changes in ultrasonic textures. We noticed great differences between the various ultrasonic machines tested by us. The best parameter in our set was the spatial coefficient of variation.
  
  
  CONCLUSIONS
  The method allows rapid orientation regarding the ability of a machine to distinguish between several textures depending on the brightness, and offers an opportunity of determining the best working point for a given machine.
authors.affiliation: Abteilung Gastroenterologie und Hepatologie, Medizinische Hochschule Hannover.
authors.forename: J S
authors.initials: JS
authors.lastname: Bleck
authors.forename: M
authors.initials: M
authors.lastname: Gebel
authors.forename: J D
authors.initials: JD
authors.lastname: Satrapa
authors.forename: M
authors.initials: M
authors.lastname: Caselitz
authors.forename: M
authors.initials: M
authors.lastname: Westhoff-Bleck
authors.forename: S
authors.initials: S
authors.lastname: Wagner
authors.forename: M
authors.initials: M
authors.lastname: Manns
mesh_terms: D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D019047:Phantoms, Imaging; D011785:Quality Assurance, Health Care; D012680:Sensitivity and Specificity; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*
vernacular_title: Ansätze zur Objektivierung der Gewebeunterscheidbarkeit von Ultraschallgeräten als Beitrag zur Qualitätssicherung.