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Objective: This study aimed to investigate the difference between the extent of centrilobular emphysema (CLE) and paraseptal emphysema (PSE) on follow-up chest CT scans and their relationship to the cross-sectional area (CSA) of small pulmonary vessels., Methods: Sixty-two patients (36 CLE and 26 PSE) who underwent 2 chest CT scans were enrolled in this study. The percentage of low attenuation volume (%LAV) and total CSA of the small pulmonary vessels <5 mm 2 (%CSA < 5) were measured at the 2 time points. Analysis of the initial %CSA < 5 and the change in the %LAV and %CSA < 5 on follow-up imaging was performed., Results: The initial %CSA < 5 was not significantly different between the CLE and the PSE groups (CLE, 0.66 vs. PSE, 0.71; P = 0.78). There was no significant difference in the longitudinal change in the %LAV between the 2 groups (CLE, -0.048% vs. PSE, 0.005%; P = 0.26). The longitudinal change in the %CSA < 5 in patients with PSE significantly decreased compared with those with CLE (CLE, 0.025% vs. PSE, -0.018%; P = 0.02)., Conclusions: The longitudinal change in the %CSA < 5 was significantly different for patients with CLE and PSE, demonstrating an important pathophysiological difference between the subtypes., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

The percentage of low attenuation volume ratio (LAVR), which is measured using computed tomography (CT), is an index of the severity of emphysema. For LAVR evaluation, ultra-high-resolution (U-HR) CT images are useful. To improve the image quality of U-HRCT, iterative reconstruction is used. There are two types of iterative reconstruction: hybrid iterative reconstruction (HIR) and model-based iterative reconstruction (MBIR). In this study, we physically and clinically evaluated U-HR images reconstructed with HIR and MBIR, and demonstrated the usefulness of U-HR images with MBIR for quantitative measurements of emphysema. Both images were reconstructed with a slice thickness of 0.25 mm and an image matrix size of 1024 × 1024 pixels. For physical evaluation, the modulation transfer function (MTF) and noise power spectrum (NPS) of HIR and MBIR were compared. For clinical evaluation, LAVR calculated from HIR and MBIR were compared using the Wilcoxon matched-pairs signed-rank test. In addition, the correlation between LAVR and forced expiratory volume in one second (FEV 1 %) was evaluated using the Spearman rank correlation test. The MTFs of HIR and MBIR were comparable. The NPS of MBIR was lower than that of HIR. The mean LAVR values calculated from HIR and MBIR were 19.5 ± 12.6% and 20.4 ± 11.7%, respectively (p = 0.84). The correlation coefficients between LAVR and FEV 1 % that were taken from HIR and MBIR were 0.64 and 0.74, respectively (p < 0.01). MBIR is more useful than HIR for the quantitative measurements of emphysema with U-HR images., (© 2021. Australasian College of Physical Scientists and Engineers in Medicine.)

Purpose: To evaluate the advantages of ultra-high-resolution computed tomography (U-HRCT) scans for the quantitative measurement of emphysematous lesions over conventional HRCT scans., Materials and Methods: This study included 32 smokers under routine clinical care who underwent chest CT performed by a U-HRCT scanner. Chronic obstructive pulmonary disease (COPD) was diagnosed in 13 of the 32 participants. Scan data were reconstructed by 2 different protocols: i) U-HRCT mode with a 1024×1024 matrix and 0.25-mm slice thickness and ii) conventional HRCT mode with a 512×512 matrix and 0.5-mm slice thickness. On both types of scans, lesions of emphysema were quantitatively assessed as percentage of low attenuation volume (LAV%, <-950 Hounsfield units). LAV% values determined for scan data from the U-HRCT and conventional HRCT modes were compared by the Wilcoxon matched-pairs signed rank test. The association between LAV% and forced expiratory volume in 1 s per forced vital capacity (FEV 1 /FVC) was assessed by the Spearman rank correlation test., Results: Mean values for LAV% determined for the U-HRCT and conventional HRCT modes were 8.9 ± 8.8% and 7.3 ± 8.4%, respectively ( P <0.0001). The correlation coefficients for LAV% and FEV 1 /FVC on the U-HRCT and conventional HRCT modes were 0.50 and 0.49, respectively (both P <0.01)., Conclusion: Compared with conventional HRCT scans, U-HRCT scans reveal emphysematous lesions in greater detail, and provide slightly increased correlation with airflow limitation., Competing Interests: The University of the Ryukyus and Ohara General Hospital receive a research grant from Canon Medical Systems. Ynayan Xu receives a scholarship (Sasagawa scholarship) from the Japan-China Medical Association. Tsuneo Yamashiro reports a grant from Canon Medical Systems during the conduct of the study, and grants from Ziosoft and JSR outside the submitted work. Sadayuki Murayama reports a research grant from Canon Medical Systems during the conduct of the study. The authors report no other conflicts of interest for this work., (© 2019 Xu et al.)

Rationale and Objectives: To evaluate the relationship between measurements of lung volume (LV) on inspiratory/expiratory computed tomography (CT) scans, pulmonary function tests (PFT), and CT measurements of emphysema in individuals with chronic obstructive pulmonary disease., Materials and Methods: Forty-six smokers (20 females and 26 males; age range 46-81 years), enrolled in the Lung Tissue Research Consortium, underwent PFT and chest CT at full inspiration and expiration. Inspiratory and expiratory LV values were automatically measured by open-source software, and the expiratory/inspiratory (E/I) ratio of LV was calculated. Mean lung density (MLD) and low attenuation area percent (<-950 HU) were also measured. Correlations of LV measurements with lung function and other CT indices were evaluated by the Spearman rank correlation test., Results: LV E/I ratio significantly correlated with the following: the percentage of predicted value of forced expiratory volume in the first second (FEV(1)), the ratio of FEV(1) to forced vital capacity (FVC), and the ratio of residual volume (RV) to total lung capacity (TLC) (FEV(1)%P, R = -0.56, P < .0001; FEV(1)/FVC, r = -0.59, P < .0001; RV/TLC, r = 0.57, P < .0001, respectively). A higher correlation coefficient was observed between expiratory LV and expiratory MLD (r = -0.73, P < .0001) than between inspiratory LV and inspiratory MLD (r = -0.46, P < .01). LV E/I ratio showed a very strong correlation to MLD E/I ratio (r = 0.95, P < .0001)., Conclusions: LV E/I ratio can be considered to be equivalent to MLD E/I ratio and to reflect airflow limitation and air-trapping. Higher collapsibility of lung volume, observed by inspiratory/expiratory CT, indicates less severe conditions in chronic obstructive pulmonary disease., (Copyright 2010 AUR. Published by Elsevier Inc. All rights reserved.)

Rationale and Objectives: Pulmonary vascular alteration is one of the characteristic features of chronic obstructive pulmonary disease (COPD). Recent studies suggest that vascular alteration is closely related to endothelial dysfunction and may be further influenced by emphysema. However, the relationship between morphological alteration of small pulmonary vessels and the extent of emphysema has not been assessed in vivo. The objectives of this study are: to evaluate the correlation of total cross-sectional area (CSA) of small pulmonary vessels with the extent of emphysema and airflow obstruction using CT scans and to assess the difference of total CSA between COPD phenotypes., Materials and Methods: We measured CSA less than 5 mm(2) and 5-10 mm(2), and calculated the percentage of the total CSA for the lung area (%CSA < 5, and %CSA5-10, respectively) using CT scans in 191 subjects. The extent of emphysema (%LAA-950) was calculated, and the correlations of %CSA < 5 and %CSA5-10 with %LAA-950 and results of pulmonary function tests (PFTs) were evaluated. The differences in %CSA between COPD phenotypes were also assessed., Results: The %CSA < 5 had significant negative correlations with %LAA-950 (r = -0.83, P < .0001). There was a weak but statistically significant correlation of %CSA < 5 with forced expiratory volume in 1 second (FEV1)% predicted (r = 0.29, P < .0001) and FEV1/forced vital capacity (r = 0.45, P < .0001). A %CSA 5-10 had weak correlations with %LAA-950 and results of PFTs. %CSA < 5 was significantly higher in bronchitis phenotype than in the emphysema phenotype (P < .0001)., Conclusions: Total CSA of small pulmonary vessels at sub-subsegmental levels strongly correlates with the extent of emphysema (%LAA-950) and reflects differences between COPD phenotypes.

Rintaro Onoe,1 Tsuneo Yamashiro,2,3 Hiroshi Handa,1 Shinya Azagami,1 Shin Matsuoka,2 Takeo Inoue,1 Teruomi Miyazawa,1 Masamichi Mineshita1 1Division of Respiratory Medicine, Department of Internal Medicine, St Marianna University School of Medicine, Kawasaki, Japan; 2Department of Radiology, St Marianna University School of Medicine, Kawasaki, Japan; 3Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara, Japan Purpose: To assess tracheobronchial angles and their changes on combined inspiratory and expiratory thoracic computed tomography (CT) scans and to determine correlations between tracheobronchial angles and several indices of chronic obstructive pulmonary disease (COPD). Materials and methods: A total of 80 smokers underwent combined inspiratory and expiratory CT scans. Of these, 65 subjects also performed spirometry and 55 patients were diagnosed with COPD. On CT scans, 3-dimensinal tracheobronchial angles (trachea–right main bronchus [RMB], trachea–left main bronchus [LMB], and RMB–LMB) were automatically measured by software. Lung volumes at inspiration and expiration were also automatically calculated. Changes in tracheobronchial angles between inspiration and expiration were assessed by the Mann–Whitney test. Correlations of the angles with lung volume, airflow limitation, and CT-based emphysema index were evaluated by Spearman rank correlation. Results: The trachea–LMB angle was significantly smaller and the RMB–LMB angle was significantly larger at expiration than inspiration (P

Tsuneo Yamashiro,1 Hiroshi Moriya,2 Shin Matsuoka,3 Yukihiro Nagatani,4 Maho Tsubakimoto,1 Nanae Tsuchiya,1 Sadayuki Murayama1 On behalf of the ACTIve Study Group 1Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara, Okinawa, Japan; 2Department of Radiology, Ohara General Hospital, Fukushima-City, Fukushima, Japan; 3Department of Radiology, St Marianna University School of Medicine, Kawasaki, Kanagawa, Japan; 4Department of Radiology, Shiga University of Medical Science, Otsu, Shiga, Japan Purpose: Four-dimensional dynamic-ventilation CT imaging demonstrates continuous movement of the lung. The aim of this study was to assess the correlation between interlobar synchrony in lung density and spirometric values in COPD patients and smokers, by measuring the continuous changes in lung density during respiration on the dynamic-ventilation CT. Materials and methods: Thirty-two smokers, including ten with COPD, underwent dynamic-ventilation CT during free breathing. CT data were continuously reconstructed every 0.5 sec. Mean lung density (MLD) of the five lobes (right upper [RU], right middle [RM], right lower [RL], left upper [LU], and left lower [LL]) was continuously measured by commercially available software using a fixed volume of volume of interest which was placed and tracked on a single designated point in each lobe. Concordance between the MLD time curves of six pairs of lung lobes (RU-RL, RU-RM, RM-RL, LU-LL, RU-LU, and RL-LL lobes) was expressed by cross-correlation coefficients. The relationship between these cross-correlation coefficients and the forced expiratory volume in one second/forced vital capacity (FEV1.0/FVC) values was assessed by Spearman rank correlation analysis. Results: In all six pairs of the pulmonary lobes, the cross-correlation coefficients of the two MLD curves were significantly positively correlated with FEV1.0/FVC (ρ =0.60–0.73, P

Tsuneo Yamashiro,1 Hiroshi Moriya,2 Maho Tsubakimoto,1 Shin Matsuoka,3 Sadayuki Murayama1 On behalf of ACTIve Study Group 1Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara, Okinawa, 2Department of Radiology, Ohara General Hospital, Fukushima-shi, Fukushima, 3Department of Radiology, St Marianna University School of Medicine, Kawasaki, Kanagawa, Japan Purpose: Four-dimensional dynamic-ventilation computed tomography (CT) imaging demonstrates continuous movement of the airways and lungs, which cannot be depicted with conventional CT. We aimed to investigate continuous changes in lung density and airway dimensions and to assess the correlation with spirometric values in smokers.Materials and methods: This retrospective study was approved by the Institutional Review Board, and informed consent was waived. Twenty-one smokers including six patients with COPD underwent four-dimensional dynamic-ventilation CT during free breathing (160 mm in length). The mean lung density (MLD) of the scanned lung and luminal areas (Ai) of fixed points in the trachea and the right proximal bronchi (main bronchus, upper bronchus, bronchus intermedius, and lower bronchus) were continuously measured. Concordance between the time curve of the MLD and that of the airway Ai values was expressed by cross-correlation coefficients. The associations between these quantitative measurements and the forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) values were assessed by Spearman’s rank correlation analysis.Results: On the time curve for the MLD, the Δ-MLD1.05 values between the peak inspiratory frame to the later third frame (1.05 seconds later) were strongly correlated with the FEV1/FVC (ρ=0.76, P