title: Development and validation of an intrinsic landmark-based gating protocol applicable for functional and molecular ultrasound imaging.
abstract: OBJECTIVE
  To implement a retrospective intrinsic landmark-based (ILB) gating protocol for contrast-enhanced ultrasound (CEUS) and to compare its efficiency to non-gated, manually gated and extrinsically gated CEUS.
  
  
  METHODS
  CEUS of the liver was performed in healthy mice (n = 5) and in NEMO knockout mice with dysplastic livers (n = 5). In healthy animals, first-pass kinetics of non-specific microbubbles was recorded. Knockout mice were analysed regarding retention of VEGFR2-specific microbubbles. For retrospective gating, a landmark which showed respiratory movement was encircled as a region of interest (ROI). During inspiration, the signal intensity within the ROI altered, which served as gating signal. To evaluate the accuracy, non-gated, extrinsically gated and ILB-gated time-intensity curves were created. For each curve, descriptive parameters were calculated and compared to the gold standard (manual frame-by-frame gating).
  
  
  RESULTS
  No significant differences in the variation of ILB- and extrinsically gated time-intensity curves from the gold standard were observed. Non-gated data showed significantly higher variations. Also the variation of molecular ultrasound data was significantly lower for ILB-gated compared to non-gated data.
  
  
  CONCLUSIONS
  ILB gating is a robust and easy method to improve data accuracy in functional and molecular ultrasound liver imaging. This technique can presumably be translated to contrast-enhanced ultrasound examinations in humans.
  
  
  CONCLUSIONS
  • Quantitative analysis of the uptake of contrast agents during ultrasound is complex. • Intrinsic landmark-based gating (ILB) offers a simple implementable method for motion correction. • Results using ILB-gating are comparable to extrinsic gating using external biomonitoring devices. • Functional and molecular imaging of mobile organs will benefit from ILB gating.
authors.affiliation: Department of Experimental Molecular Imaging, RWTH-Aachen University, Aachen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Grouls
authors.forename: Max
authors.initials: M
authors.lastname: Hatting
authors.forename: Isabelle
authors.initials: I
authors.lastname: Tardy
authors.forename: Jessica
authors.initials: J
authors.lastname: Bzyl
authors.forename: Georg
authors.initials: G
authors.lastname: Mühlenbruch
authors.forename: Florian F
authors.initials: FF
authors.lastname: Behrendt
authors.forename: Tobias
authors.initials: T
authors.lastname: Penzkofer
authors.forename: Christian
authors.initials: C
authors.lastname: Trautwein
authors.forename: Christiane
authors.initials: C
authors.lastname: Kuhl
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
authors.forename: Moritz
authors.initials: M
authors.lastname: Palmowski
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000494:pharmacology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008099:Liver / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D045423:Microbubbles; D015203:Reproducibility of Results; D012119:Respiration; D055425:Respiratory-Gated Imaging Techniques; D012189:Retrospective Studies; D013997:Time Factors; D014463:Ultrasonography / Q000379:methods*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D003287:Contrast Media; D040301:Vascular Endothelial Growth Factor Receptor-2