title: Quantitative analysis of hyperpolarized 3He ventilation changes in mice challenged with methacholine.
abstract: The capability to use high-resolution (3)He MRI to depict regional ventilation changes and airway narrowing in mice challenged with methacholine (MCh) offers the opportunity to gain new insights into the study of asthma. However, to fully exploit the value of this novel technique, it is important to move beyond visual inspection of the images toward automated and quantitative analysis. To address this gap, we describe a postprocessing approach to create ventilation difference maps to better visualize and quantify regional ventilation changes before and after MCh challenge. We show that difference maps reveal subtle changes in airway caliber, and highlight both focal and diffuse regional alterations in ventilation. Ventilation changes include both hypoventilation and compensatory areas of hyperventilation. The difference maps can be quantified by a histogram plot of the ventilation changes, in which the standard deviation increases with MCh dose (R(2) = 0.89). This method of analysis is shown to be more sensitive than simple threshold-based detection of gross ventilation defects.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina 27710, USA.
authors.forename: Nilesh N
authors.initials: NN
authors.lastname: Mistry
authors.forename: Abraham
authors.initials: A
authors.lastname: Thomas
authors.forename: S Sivaram
authors.initials: SS
authors.lastname: Kaushik
authors.forename: G Allan
authors.initials: GA
authors.lastname: Johnson
authors.forename: Bastiaan
authors.initials: B
authors.lastname: Driehuys
mesh_terms: D000280:Administration, Inhalation; D000465:Algorithms; D000818:Animals; D001249:Asthma / Q000175:diagnosis*; D003287:Contrast Media / Q000008:administration & dosage; D006371:Helium / Q000008:administration & dosage; D007089:Image Enhancement / Q000379:methods*; D007554:Isotopes / Q000008:administration & dosage; D008279:Magnetic Resonance Imaging / Q000379:methods*; D016210:Methacholine Chloride; D051379:Mice; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D007554:Isotopes; D016210:Methacholine Chloride; D006371:Helium