Department of Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
Division of Information Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara, Japan.
Sci Rep. 2024 Sep 14;14(1):21493. doi: 10.1038/s41598-024-72786-1.
The effect of gravity on the lungs has been evaluated using computed tomography (CT) in the supine and prone positions but not the standing position. However, as humans spend most of the daytime in the standing position, we aimed to compare lung attenuation gradients between the supine and standing positions, and to assess the correlations between the lung attenuation gradients and participant characteristics, including pulmonary function test results. Overall, 100 healthy participants underwent conventional/supine and upright CT, and lung attenuation gradients were measured. Lung attenuation gradients in anteroposterior direction were greater in the supine position than in standing position (all p values < 0.0001) in both upper lobes at the level of the aortic arch (right: standing/supine, -0.02 ± 0.19/0.53 ± 0.21; left: standing/supine, -0.06 ± 0.20/0.51 ± 0.21); in the right middle (standing/supine, -0.26 ± 0.41/0.53 ± 0.39), left upper (standing/supine, -0.35 ± 0.50/0.66 ± 0.54), and lower lobes at the level of the inferior pulmonary vein (right: standing/supine, -0.22 ± 0.30/0.65 ± 0.41; left: standing/supine, -0.16 ± 0.25/0.73 ± 0.54); and in both lower lobes just above the diaphragm (right: standing/supine, -0.13 ± 0.22/0.52 ± 0.32; left: standing/supine, -0.30 ± 0.57/0.55 ± 0.37). Craniocaudal gradients were greater in the standing position (right: standing/supine, 0.41 ± 0.30/0.00 ± 0.16; left: standing/supine, 0.35 ± 0.30/-0.02 ± 0.16, all p values < 0.0001). No moderate to very high correlations were observed between age, sex, height, weight, body index mass, or pulmonary function test results and each lung attenuation gradient. Lung attenuation gradients in anteroposterior direction, which was observed in the supine position, disappeared in the standing position. However, the craniocaudal lung attenuation gradient, which was not present in the supine position, appeared in the standing position.
重力对肺部的影响已通过仰卧位和俯卧位的计算机断层扫描（CT）进行了评估，但尚未评估直立位。然而，由于人类在白天大部分时间都处于直立状态，我们旨在比较仰卧位和直立位之间的肺衰减梯度，并评估肺衰减梯度与参与者特征之间的相关性，包括肺功能测试结果。
总体而言，100 名健康参与者接受了常规/仰卧位和直立位 CT，测量了肺衰减梯度。在主动脉弓水平的上叶中，前后方向的肺衰减梯度在仰卧位时大于直立位（所有 p 值均 < 0.0001）（右：站立/仰卧，-0.02 ± 0.19/0.53 ± 0.21；左：站立/仰卧，-0.06 ± 0.20/0.51 ± 0.21）；在右中叶（站立/仰卧，-0.26 ± 0.41/0.53 ± 0.39）、左上叶（站立/仰卧，-0.35 ± 0.50/0.66 ± 0.54）和下叶在肺下静脉水平（右：站立/仰卧，-0.22 ± 0.30/0.65 ± 0.41；左：站立/仰卧，-0.16 ± 0.25/0.73 ± 0.54）；以及在膈下的两个下叶（右：站立/仰卧，-0.13 ± 0.22/0.52 ± 0.32；左：站立/仰卧，-0.30 ± 0.57/0.55 ± 0.37）。前后梯度在直立位时更大（右：站立/仰卧，0.41 ± 0.30/0.00 ± 0.16；左：站立/仰卧，0.35 ± 0.30/-0.02 ± 0.16，所有 p 值均 < 0.0001）。
年龄、性别、身高、体重、体重指数或肺功能测试结果与每个肺衰减梯度之间未观察到中度至高度相关。在仰卧位观察到的前后方向的肺衰减梯度在直立位时消失。然而，在仰卧位时不存在的颅尾肺衰减梯度在直立位时出现。
