title: Quantification of Calcium Amount in a New Experimental Model: A Comparison between Ultrasound and Computed Tomography.
abstract: OBJECTIVE
  Calcification is an important prognostic factor in aortic valve stenosis. However, there is no ultrasound (US) method available to accurately quantify calcification in this setting to date. We aimed to validate a new US method for measuring the amount of calcium in an in vitro model, and compare it to computed tomography (CT), the current imaging gold standard.
  
  
  METHODS
  An agar phantom (2% agar) was made, containing 9 different amounts of calcium-hydroxyapatite Ca5(PO4)3OH (2 to 50 mg). The phantoms were imaged with micro-CT and US (10 MHz probe). The calcium area (areacalcium) and its maximum pixel value (PVmax) were obtained. These values were summed to calculate CT and US calcium scores (∑(areacalcium × PVmax)) and volumes (∑areacalcium). Both US- and CT-calcium scores were compared with the calcium amounts, and with each other.
  
  
  RESULTS
  Both calcium scores correlated significantly with the calcium amount (R2 = 0.9788, p<0.0001 and R2 = 0.8154, p<0.0001 for CT and US respectively). Furthermore, there was a significant correlation between US and CT for calcium volumes (R2 = 0.7392, p<0.0001) and scores (R2 = 0.7391, p<0.0001).
  
  
  CONCLUSIONS
  We developed a new US method that accurately quantifies the amount of calcium in an in vitro model. Moreover it is strongly correlated with CT.
authors: In vivo Cellular and Molecular Imaging (ICMI) laboratory, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium.|Centrum voor Hart- en Vaatziekten (CHVZ), Department of Cardiology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussel, Belgium.
authors: Kris
authors: K
authors: Gillis
authors: In vivo Cellular and Molecular Imaging (ICMI) laboratory, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium.|Centrum voor Hart- en Vaatziekten (CHVZ), Department of Cardiology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussel, Belgium.
authors: Gezim
authors: G
authors: Bala
authors: In vivo Cellular and Molecular Imaging (ICMI) laboratory, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium.|Centrum voor Hart- en Vaatziekten (CHVZ), Department of Cardiology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussel, Belgium.
authors: Bram
authors: B
authors: Roosens
authors: In vivo Cellular and Molecular Imaging (ICMI) laboratory, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
authors: Isabel
authors: I
authors: Remory
authors: In vivo Cellular and Molecular Imaging (ICMI) laboratory, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
authors: Sophie
authors: S
authors: Hernot
authors: In vivo Cellular and Molecular Imaging (ICMI) laboratory, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium.|Centrum voor Hart- en Vaatziekten (CHVZ), Department of Cardiology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussel, Belgium.
authors: Steven
authors: S
authors: Droogmans
authors: In vivo Cellular and Molecular Imaging (ICMI) laboratory, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium.|Centrum voor Hart- en Vaatziekten (CHVZ), Department of Cardiology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussel, Belgium.
authors: Bernard
authors: B
authors: Cosyns
mesh_terms: D001024:Aortic Valve Stenosis / Q000175:diagnosis; D002114:Calcinosis / Q000000981:diagnostic imaging*; D017886:Durapatite / Q000032:analysis; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D019047:Phantoms, Imaging; D014463:Ultrasonography; D055114:X-Ray Microtomography
chemical_list: D017886:Durapatite