title: Usefulness of Colored 3D Imaging of Respiratory Impedance in Asthma.
abstract: OBJECTIVE
  Recently, the clinical application of the forced oscillation technique (FOT) has progressed with the spread of commercially available FOT devices, including the impulse oscillation system and MostGraph. We investigated the usefulness of color 3D imaging of respiratory impedance in asthma using MostGraph.
  
  
  METHODS
  Whole-breath and within-breath respiratory system resistance (Rrs) and reactance (Xrs) were measured in 78 patients with asthma. Color 3D images were classified into three patterns: the chronic obstructive pulmonary disease (COPD)-like pattern (high values of Rrs and Xrs with a marked respiratory cycle and frequency dependence), the asthma pattern (moderately high Rrs over the entire frequency and a respiratory cycle with slight Xrs changes), and a normal-like pattern (low Rrs and Xrs with few within-breath changes). The classification was performed by three researchers, who were unaware of the clinical information, and the clinical characteristics were compared among the three groups.
  
  
  RESULTS
  Color 3D imaging provided a COPD-like pattern in 25 patients, an asthma pattern in 39 patients, and a normal-like pattern in 14 patients. Patients with the COPD-like pattern were predominantly female with a higher body mass index, lower forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC), and higher Rrs and Xrs values (whole-breath and within-breath variation). Those with the normal pattern had higher FEV1 and FVC, and a lower single-breath nitrogen washout slope. There were no differences in asthma control or exhaled nitric oxide levels among the three groups.
  
  
  CONCLUSIONS
  These results suggest that color 3D imaging of respiratory impedance may show asthma phenotypes.
authors.affiliation: Department of Respiratory Medicine, Shizuoka General Hospital, Shizuoka, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Shirai
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Mori
authors.forename: Masashi
authors.initials: M
authors.lastname: Mikamo
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Shishido
authors.forename: Takefumi
authors.initials: T
authors.lastname: Akita
authors.forename: Satoru
authors.initials: S
authors.lastname: Morita
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Asada
authors.forename: Masato
authors.initials: M
authors.lastname: Fujii
authors.forename: Takafumi
authors.initials: T
authors.lastname: Suda
authors.forename: Kingo
authors.initials: K
authors.lastname: Chida
keywords: Forced oscillation technique; multi-frequency; phenotype; whole-breath; within-breath