Association of Respiratory Functional Indices and Smoking with Pleural Movement and Mean Lung Density Assessed Using Four-Dimensional Dynamic-Ventilation Computed Tomography in Smokers and Patients with COPD

Abstract

Purpose

To correlate the ratio of the non-dependent to dependent aspects of the maximal pleural movement vector (MPMV_ND/D) and gravity-oriented collapse ratio (GCR_ND/D), and the mean lung field density (MLD) obtained using four-dimensional (4D) dynamic-ventilation computed tomography (DVCT) with airflow limitation parameters and the Brinkman index.

Materials and Methods

Forty-seven patients, including 22 patients with COPD, 13 non-COPD smokers, and 12 non-smokers, with no/slight pleural adhesion confirmed using a thoracoscope, underwent 4D-DVCT with 16 cm coverage. Coordinates for the lung field center, as well as ventral and dorsal pleural points, set on the central trans-axial levels in the median and para-median sagittal planes at end-inspiration, were automatically measured (13–17 frame images, 0.35 seconds/frame). MPMV_ND/D and GCR_ND/D were calculated based on MPMV and GCR values for all the included points and the lung field center. MLD was automatically measured in each of the time frames, and the maximal change ratio of MLD (MLD_CR) was calculated. These measured values were compared among COPD patients, non-COPD smokers, and non-smokers, and were correlated with the Brinkman index, FEV₁/FVC, FEV₁ predicted, RV/TLC, and FEF_25–75% using Spearman’s rank coefficients.

Results

MPMV_ND/D was highest in non-smokers (0.819±0.464), followed by non-COPD smokers (0.405±0.131) and patients with COPD (−0.219±0.900). GCR_ND/D in non-smokers (1.003±1.384) was higher than that in patients with COPD (−0.164±1.199). MLD_CR in non-COPD smokers (0.105±0.028) was higher than that in patients with COPD (0.078±0.027). MPMV_ND/D showed positive correlations with FEV₁ predicted (r=0.397, p=0.006), FEV₁/FVC (r=0.501, p<0.001), and FEF_25–75% (r=0.368, p=0.012). GCR_ND/D also demonstrated positive correlations with FEV₁ (r=0.397, p=0.006), FEV₁/FVC (r=0.445, p=0.002), and FEF_25–75% (r=0.371, p=0.011). MPMV_ND/D showed a negative correlation with the Brinkman index (r=−0.398, p=0.006).

Conclusion

We demonstrated that reduced MPMV_ND/D and GCR_ND/D were associated with respiratory functional indices, in addition to a negative association of MPMV_ND/D with the Brinkman index, which should be recognized when assessing local pleural adhesion on DVCT, especially for ventral pleural aspects.

Keywords:

• chronic obstructive pulmonary disease
• smoking burden
• four-dimensional dynamic-ventilation computed tomography
• pleural movement
• mean lung density
• gravity-oriented distance

Acknowledgement

Collaborators Role of the funding Source This study was also arranged as part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases (ACTIve) Study, an ongoing multicenter research project in Japan. Each participating institution receives a research grant from Canon Medical Systems. Any other competing interests, such as employment, consultancy, patents, products in development, or marketed products, do not exist regarding this manuscript. The ACTIVe study group The ACTIVe study group currently consists of the following institutions: Osaka Medical College, Takatsuki, Osaka, Japan(Mitsuhiro Koyama, M.D., PhD., Keigo Osuga, M.D., PhD.); Osaka University, Suita, Osaka, Japan (Masahiro Yanagawa, M.D., PhD., Mitsuko Tsubamoto, M.D., PhD., Noriyuki Tomiyama, M.D., PhD.); Fujita Health University, Toyoake, Aichi, Japan (Yoshiharu Ohno, M.D., PhD.); Ohara General Hospital, Fukushima, Fukushima, Japan (Hiroshi Moriya, M.D., PhD.); Tenri Hospital, Tenri, Nara, Japan (Takeshi Kubo M.D., PhD., Satoshi Noma, M.D., PhD.); Yokohama City University, Yokohama, Kanagawa, Japan (Tsuneo Yamashiro M.D.); University of the Ryukyus, Nishihara, Okinawa, Japan (Nanae Tsuchiya, M.D., Akihiro Nishie M.D. PhD.); Kanagawa Respiratory Cardiovascular Center, Yokohama, Kanagawa, Japan (Tae Iwasawa M.D. PhD.); University of Occupational and Environmental Health, Kitakyushu, Fukuoka, Japan (Takatoshi Aoki M.D. PhD.); Urazoe General Hospital, Urazoe, Okinawa, Japan (Sadayuki Murayama M.D. PhD.); Shiga University of Medical Science, Otsu, Shiga, Japan(Ryo Uemura M.D., Yukihiro Nagatani, M.D., Akinaga Sonoda, M.D. PhD., Yoshiyuki Watanabe, M.D., PhD.)

Disclosure

The authors report no conflicts of interest in this work.