Tanaka Rie, Sanada Shigeru, Okazaki Nobuo, Kobayashi Takeshi, Fujimura Masaki, Yasui Masahide, Matsui Takeshi, Nakayama Kazuya, Nanbu Yuko, Matsui Osamu
Department of Radiology, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan.
Invest Radiol. 2006 Oct;41(10):735-45. doi: 10.1097/01.rli.0000236904.79265.68.
Dynamic flat panel detectors (FPD) permit acquisition of distortion-free radiographs with a large field of view and high image quality. The present study was performed to evaluate pulmonary function using breathing chest radiography with a dynamic FPD. We report primary results of a clinical study and computer algorithm for quantifying and visualizing relative local pulmonary airflow.
Dynamic chest radiographs of 18 subjects (1 emphysema, 2 asthma, 4 interstitial pneumonia, 1 pulmonary nodule, and 10 normal controls) were obtained during respiration using an FPD system. We measured respiratory changes in distance from the lung apex to the diaphragm (DLD) and pixel values in each lung area. Subsequently, the interframe differences (D-frame) and difference values between maximum inspiratory and expiratory phases (D-max) were calculated. D-max in each lung represents relative vital capacity (VC) and regional D-frames represent pulmonary airflow in each local area. D-frames were superimposed on dynamic chest radiographs in the form of color display (fusion images). The results obtained using our methods were compared with findings on computed tomography (CT) images and pulmonary functional test (PFT), which were examined before inclusion in the study.
In normal subjects, the D-frames were distributed symmetrically in both lungs throughout all respiratory phases. However, subjects with pulmonary diseases showed D-frame distribution patterns that differed from the normal pattern. In subjects with air trapping, there were some areas with D-frames near zero indicated as colorless areas on fusion images. These areas also corresponded to the areas showing air trapping on computed tomography images. In asthma, obstructive abnormality was indicated by areas continuously showing D-frame near zero in the upper lung. Patients with interstitial pneumonia commonly showed fusion images with an uneven color distribution accompanied by increased D-frames in the area identified as normal on computed tomography images. Furthermore, measurement of DLD was very effective for evaluating diaphragmatic kinetics.
This is a rapid and simple method for evaluation of respiratory kinetics for pulmonary diseases, which can reveal abnormalities in diaphragmatic kinetics and regional lung ventilation. Furthermore, quantification and visualization of respiratory kinetics is useful as an aid in interpreting dynamic chest radiographs.
动态平板探测器（FPD）能够采集到大视野且图像质量高的无失真X线片。本研究旨在使用动态FPD进行呼吸胸部X线摄影来评估肺功能。我们报告了一项临床研究的主要结果以及用于量化和可视化相对局部肺气流的计算机算法。
使用FPD系统在18名受试者（1名肺气肿患者、2名哮喘患者、4名间质性肺炎患者、1名肺结节患者和10名正常对照者）呼吸过程中获取动态胸部X线片。我们测量了从肺尖到膈肌的距离（DLD）的呼吸变化以及每个肺区域的像素值。随后，计算帧间差异（D-frame）以及最大吸气和呼气阶段之间的差值（D-max）。每个肺中的D-max代表相对肺活量（VC），区域D-frame代表每个局部区域的肺气流。D-frame以彩色显示（融合图像）的形式叠加在动态胸部X线片上。将我们的方法所获得的结果与在纳入研究之前所检查的计算机断层扫描（CT）图像和肺功能测试（PFT）的结果进行比较。
在正常受试者中，在所有呼吸阶段，D-frame在双肺中呈对称分布。然而，患有肺部疾病的受试者表现出与正常模式不同的D-frame分布模式。在有气体潴留的受试者中，融合图像上有些区域的D-frame接近零，显示为无色区域。这些区域也对应于计算机断层扫描图像上显示气体潴留的区域。在哮喘患者中，上肺区域持续显示接近零的D-frame表明存在阻塞性异常。间质性肺炎患者通常显示融合图像颜色分布不均匀，且在计算机断层扫描图像上被认定为正常的区域D-frame增加。此外，测量DLD对于评估膈肌动力学非常有效。
这是一种快速且简单的评估肺部疾病呼吸动力学的方法，它可以揭示膈肌动力学和区域肺通气的异常。此外，呼吸动力学的量化和可视化有助于解释动态胸部X线片。
