Acta radiologica (Stockholm, Sweden : 1987) · 2014
Effect of threshold on the correlation between airflow obstruction and low attenuation volume in smokers assessed by inspiratory and expiratory MDCT.
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Yanagawa Noriyuki, Kawata Naoko, Matsuura Yukiko, Sugiura Toshihiko, Suzuki Toshio, Kasai Hajime, Irie Ryosuke, Iesato Ken, Tada Yuji, Tanabe Nobuhiro, Suzuki Yoichi, Tatsumi Koichiro
Аннотация
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.
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.