title: Topical contrast agents to improve soft-tissue contrast in the upper airway using cone beam CT: a pilot study.
abstract: The purpose of this study is to explore the topical use of radiographic contrast agents to enhance soft-tissue contrast on cone beam CT (CBCT) images. Different barium sulphate concentrations were first tested using an airway phantom. Different methods of barium sulphate application (nasal drops, syringe, spray and sinus wash) were then tested on four volunteers, and nebulized iodine was tested in one volunteer. CBCT images were performed and then assessed subjectively by two examiners for contrast agent uniformity and lack of streak artefact. 25.0% barium sulphate presented adequate viscosity and radiodensity. Barium sulphate administered via nasal drops and sprays showed non-uniform collection at the nostrils, along the inferior and/or middle nasal meatuses and posterior nasal choana. The syringe and sinus wash showed similar results with larger volumes collecting in the naso-oropharynx. Nebulized iodine failed to distribute into the nasal cavity and scarcely collected at the nostrils. All methods of nasal application failed to adequately reach or uniformly coat the nasal cavity beyond the inferior nasal meatuses. The key factors to consider for optimum topical radiographic contrast in the nasal airway are particle size, flow velocity and radio-opacity.
authors.affiliation: Department of Dentistry, University of Alberta, Edmonton, AB, Canada. alsufyan@ualberta.ca
authors.forename: N A
authors.initials: NA
authors.lastname: Alsufyani
authors.forename: M L
authors.initials: ML
authors.lastname: Noga
authors.forename: W H
authors.initials: WH
authors.lastname: Finlay
authors.forename: P W
authors.initials: PW
authors.lastname: Major
mesh_terms: D000281:Administration, Intranasal; D016477:Artifacts; D001466:Barium Sulfate / Q000008:administration & dosage; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007455:Iodine / Q000008:administration & dosage; D055171:Nasal Cartilages / Q000000981:diagnostic imaging; D009296:Nasal Cavity / Q000000981:diagnostic imaging; D055556:Nasal Lavage; D059085:Nasal Sprays; D009305:Nasopharynx / Q000000981:diagnostic imaging; D009330:Nebulizers and Vaporizers; D009666:Nose / Q000000981:diagnostic imaging*; D009960:Oropharynx / Q000000981:diagnostic imaging; D010316:Particle Size; D019047:Phantoms, Imaging; D019999:Pharmaceutical Solutions; D010865:Pilot Projects; D012212:Rheology; D013594:Syringes; D014783:Viscosity
chemical_list: D003287:Contrast Media; D059085:Nasal Sprays; D019999:Pharmaceutical Solutions; D001466:Barium Sulfate; D007455:Iodine
keywords: administration; cone beam computed tomography; contrast agents; topical