title: Evaluation of the usefulness of spectral analysis of inspiratory lung sounds recorded with phonopneumography in patients with interstitial pneumonia.
abstract: OBJECTIVE
  We investigated whether spectral analysis with fast Fourier transform (FFT) of inspiratory lung sounds is useful in the diagnosis and evaluation of the severity of interstitial pneumonia (IP).
  
  
  METHODS
  The study population included 10 healthy volunteers (healthy group) and 21 patients with IP (IP group). We generated inspiratory averaged linear intensities using FFT and determined frequency at maximum sound intensity (Fmax), and quartile frequencies (f25, f50, and f75), compared these values between the groups, generated receiver operating characteristic curves to compare the detectability of IP between the indices and auscultation in all cases, and tested for the correlation of these indices with pulmonary function tests and the fibrosis scores from high-resolution computed tomography images assessed by 3 observers.
  
  
  RESULTS
  Both f50 and f75 were significantly higher in the IP group, but their ability to detect IP was inferior to that of auscultation. They had negative correlations with percent vital capacity and had positive correlations with the fibrosis scores calculated by the 3 different observers.
  
  
  CONCLUSIONS
  These results were considered to reflect the presence of fine crackles and alterations in pulmonary sound-conduction characteristics caused by IP and indicate that spectral analysis of lung sounds is useful in the diagnosis and evaluation of the severity of IP, although future study is necessary to improve its utility.
authors.affiliation: Division of Pulmonary Medicine, Infection Diseases and Oncology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan. h-ono@nms.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ono
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Kinya
authors.initials: K
authors.lastname: Shinoda
authors.forename: Tetsu
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Shoji
authors.initials: S
authors.lastname: Kudoh
authors.forename: Akihiko
authors.initials: A
authors.lastname: Gemma
mesh_terms: D000328:Adult; D000368:Aged; D001314:Auscultation / Q000379:methods*; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests / Q000379:methods*; D012135:Respiratory Sounds; D012720:Severity of Illness Index