Effect of threshold on the correlation between airflow obstruction and low attenuation volume in smokers assessed by inspiratory and expiratory MDCT

Noriyuki Yanagawa, Naoko Kawata, Yukiko Matsuura, Toshihiko Sugiura, Toshio Suzuki, Hajime Kasai, Ryosuke Irie, Ken Iesato, Yuji Tada, Nobuhiro Tanabe, Yoichi Suzuki, Koichiro Tatsumi

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Background The estimation of emphysematous changes is very sensitive to computed tomography (CT) threshold level. In clinical practice, the predetermined threshold is usually set at -950 Hounsfield units (HU) for the detection of low attenuation volume (LAV). However, threshold levels that are tightly connected to pulmonary function abnormalities have not been determined. Purpose To determine the threshold level for calculating an LAV that closely reflects airflow limitation in patients with chronic obstructive pulmonary disease (COPD). Material and Methods Seventy-six consecutive non-COPD smokers and COPD patients underwent paired inspiratory and expiratory multidetector CT (MDCT). LAV% was segmented every 10 HU between -1000 and -750 HU to examine the correlation between LAV% and indexes of obstructive impairment. Results LAV% gradually increased as the threshold level increased on both inspiratory and expiratory images. LAV% on inspiratory images was higher than that on expiratory images at all threshold levels between -1000 and -750 HU. The threshold level that correlated with obstructive impairment differed between the two images: -930 HU on inspiratory and -870 or -880 HU on expiratory images. Conclusion LAV% dramatically changed according to the threshold level on both inspiratory and expiratory images, indicating that LAV% is dependent on the attenuation threshold level in patients with COPD. The threshold linking LAV% to airflow limitation was higher on expiratory than on inspiratory images.

Original languageEnglish
Pages (from-to)438-446
Number of pages9
JournalActa Radiologica
Volume56
Issue number4
DOIs
Publication statusPublished - 2015 Apr 1

Keywords

  • Chronic obstructive pulmonary disease
  • low attenuation volume
  • multidetector computed tomography
  • threshold

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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