title: Effect of computed tomography scanning parameters on gold nanoparticle and iodine contrast.
abstract: OBJECTIVE
  Gold nanoparticles (gold-NPs) have lately been proposed as alternative contrast agents to iodine-based contrast agents (iodine-CA) for computed tomography (CT) angiography. The aims of this study were to confirm an appropriate environment in which to evaluate such novel contrast agents, to investigate the comparative contrast of iodine-CA versus gold-NP, and to determine optimal scanning parameters for gold-NP.
  
  
  METHODS
  Three different clinical scanners were used to acquire CT images. A range of concentrations (10 mM to 1.5 M) of gold-NP and iodine-CA were scanned with varying x-ray tube voltages and currents, reconstruction kernels, protocols, and scanner models. The different environments investigated were air, water, and water with a bone simulant (Ca3(PO4)2). Regression coefficients were derived from the attenuation values plotted against concentration and compared for statistical significance using t values.
  
  
  RESULTS
  As expected, contrast was linearly related to concentrations up to 500 to 1000 mM, depending on the conditions used, whereupon a plateau of 3000 Hounsfield units was reached. Attenuation was significantly different depending on the environment used (air, water, or water and bone simulant). Contrast is dependent on the x-ray tube voltage used, with the contrast produced from iodine-CA sharply declining with increasing voltage, whereas the contrast of gold-NP varied less with tube voltage but was maximal at 120 kV in water with bone simulant. Current, reconstruction kernels, protocols, and scanner model had less effect on contrast.
  
  
  CONCLUSIONS
  Water with a bone simulant is a preferable environment for evaluating novel cardiac CT contrast agents. Relative iodine-CA versus gold-NP contrast is dependent on the scanning conditions used. Optimal scanning conditions for gold-NP will likely use an x-ray tube voltage of 120 kV.
authors: Translational and Molecular Imaging, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors: Merav Weill
authors: MW
authors: Galper
authors: May Tun
authors: MT
authors: Saung
authors: Valentin
authors: V
authors: Fuster
authors: Ewald
authors: E
authors: Roessl
authors: Axel
authors: A
authors: Thran
authors: Roland
authors: R
authors: Proksa
authors: Zahi Adel
authors: ZA
authors: Fayad
authors: David Peter
authors: DP
authors: Cormode
mesh_terms: D000792:Angiography / Q000379:methods; D002985:Clinical Protocols; D003287:Contrast Media; D017612:Gold Compounds; D006801:Humans; D017613:Iodine Compounds; D053758:Nanoparticles; D019047:Phantoms, Imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D017612:Gold Compounds; D017613:Iodine Compounds