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Our study has several limitations. First, we included only 172 volunteers, and additional studies on larger participant populations are required to confirm these preliminary findings. Second, we evaluated only the motion of the highest point of the diaphragms for the sake of simplicity, and three-dimensional motion of the dcb could not be completely reflected in our results. However, we believe that this simple method would be practical and more easily applicable in a clinical setting.
The time-resolved quantitative analysis of the diaphragms with dynamic X-ray phrenicography is feasible. The average excursions of the diaphragms are 11.0 mm (right) and 14.9 mm (left) during tidal breathing in a standing position in our health screening center cohort. The diaphragmatic motion of the left is significantly larger and faster than that of the right. Higher tidal volume and BMI are associated with increased excursions of the bilateral diaphragm.
AcknowledgmentsThe authors acknowledge the valuable assistance of Hideo Ogata, MD, PhD, Norihisa Motohashi, MD, PhD, Misako Aoki, MD, Yuka Sasaki, MD, PhD, and Hajime Goto, MD, PhD, from the Department of Respiratory Medicine; Yuji Shiraishi, MD, PhD, from the Department of Respiratory Surgery; and Masamitsu Ito, MD, PhD, Atsuko Kurosaki, MD, Yoichi Akiyama, RT, Kenta Amamiya, RT, and Kozo Hanai, RT, PhD, from the Department of Radiology, Fukujuji Hospital, for their important suggestions. The authors also acknowledge the valuable assistance of Alba Cid, MS, for editorial work on the manuscript. Yoshitake Yamada, MD, PhD, is a recipient of a research fellowship from the Uehara Memorial Foundation.
Appendix. Supplementary DataThe following is the supplementary data to this article:
A representative video of sequential chest radiographs obtained by chest dynamic radiography for the motion of the diaphragms (“dynamic X-ray phrenicography”). A board-certified radiologist placed a point of interest (red point) on the highest point of each diaphragm on the radiograph at the resting end-expiratory position. These points were automatically traced by the template-matching technique throughout the respiratory phase. Based on locations of the points on sequential radiographs, the vertical excursions and the peak motion speeds of the bilateral diaphragm were calculated (Fig 2c).Help with MP4 filesOptionsDownload video (1042 K)
Multivariate analysis of associations between the excursions and participant demographics using age, gender, BMI, tidal volume, VC, FEV1, and smoking history as factors (Model 2).Help with DOCX filesOptionsDownload file (23 K)
The bilateral diaphragm is the most important respiratory muscle. Diaphragmatic dysfunction is an underappreciated cause of respiratory difficulties and may be due to a wide variety of issues, including surgery, trauma, tumor, and infection (1). Several previous studies have evaluated diaphragmatic motion using fluoroscopy 2; 3; 4 ; 5, ultrasound 6 ; 7, magnetic resonance (MR) fluoroscopy (dynamic MR imaging [MRI]) 8; 9; 10; 11 ; 12, and computed tomography (CT) 13; 14; 15 ; 16. However, the data of the previous studies using ultrasound, MR fluoroscopy, or CT were obtained in a supine position 6; 7; 8; 9; 10; 11; 12; 13; 14; 15 ; 16, not in a standing position. Also, while the data of the previous studies using fluoroscopy were obtained in a standing position, the data were assessed under forced breathing 2 ; 3, not under tidal or resting breathing. Thus, diaphragmatic motion in a standing position during tidal breathing remains unclear, even though it is essential for understanding respiratory physiology in our daily life. Furthermore, the evaluation of diaphragmatic motion using fluoroscopy, ultrasound, dynamic