Yang Xiaoyan, Yu Pengxin, Xu Wenqing, Sun Haishuang, Duan Jianghui, Han Yueyin, Zhu Lili, Xie Bingbing, Geng Jing, Luo Sa, Wang Shiyao, Ren Yanhong, Zhang Rongguo, Liu Min, Dai Huaping, Wang Chen
Capital Medical University.
National Center for Respiratory Medicine.
J Thorac Imaging. 2023 Sep 6;38(6):358-66. doi: 10.1097/RTI.0000000000000735.
To quantitatively analyze lung elasticity in idiopathic pulmonary fibrosis (IPF) using elastic registration based on 3-dimensional pulmonary magnetic resonance imaging (3D-PMRI) and to assess its' correlations with the severity of IPF patients.
Thirty male patients with IPF (mean age: 62±6 y) and 30 age-matched male healthy controls (mean age: 62±6 y) were prospectively enrolled. 3D-PMRI was acquired with a 3-dimensional ultrashort echo time sequence in end-inspiration and end-expiration. MR images were registered from end-inspiration to end-expiration with the elastic registration algorithm. Jacobian determinants were calculated from deformation fields on color maps. The log means of the Jacobian determinants (Jac-mean) and Dice similarity coefficient were used to describe lung elasticity between 2 groups. Then, the correlation of lung elasticity with dyspnea Medical Research Council (MRC) score, exercise tolerance, health-related quality of life, lung function, and the extent of pulmonary fibrosis on chest computed tomography were analyzed.
The Jac-mean of IPF patients (-0.19, [IQR: -0.22, -0.15]) decreased (absolute value), compared with healthy controls (-0.28, [IQR: -0.31, -0.24], P<0.001). The lung elasticity in IPF patients with dyspnea MRC≥3 (Jac-mean: -0.15; Dice: 0.06) was significantly lower than MRC 1 (Jac-mean: -0.22, P=0.001; Dice: 0.10, P=0.001) and MRC 2 (Jac-mean: -0.21, P=0.007; Dice: 0.09, P<0.001). In addition, the Jac-mean negatively correlated with forced vital capacity % (r=-0.487, P<0.001), forced expiratory volume 1% (r=-0.413, P=0.004), TLC% (r=-0.488, P<0.001), diffusing capacity of the lungs for carbon monoxide % predicted (r=-0.555, P<0.001), 6-minute walk distance (r=-0.441, P=0.030) and positively correlated with respiratory symptoms (r=0.430, P=0.042). Meanwhile, the Dice similarity coefficient positively correlated with forced vital capacity % (r=0.577, P=0.004), forced expiratory volume 1% (r=0.526, P=0.012), diffusing capacity of the lungs for carbon monoxide % predicted (r=0.435, P=0.048), 6-minute walk distance (r=0.473, P=0.016), final peripheral oxygen saturation (r=0.534, P=0.004), the extent of fibrosis on chest computed tomography (r=-0.421, P=0.021) and negatively correlated with activity (r=-0.431, P=0.048).
Lung elasticity decreased in IPF patients and correlated with dyspnea, exercise tolerance, health-related quality of life, lung function, and the extent of pulmonary fibrosis. The lung elasticity based on elastic registration of 3D-PMRI may be a new nonradiation imaging biomarker for quantitative evaluation of the severity of IPF.
基于三维肺部磁共振成像（3D-PMRI）利用弹性配准对特发性肺纤维化（IPF）患者的肺弹性进行定量分析，并评估其与IPF患者病情严重程度的相关性。
前瞻性纳入30例男性IPF患者（平均年龄：62±6岁）和30例年龄匹配的男性健康对照者（平均年龄：62±6岁）。在吸气末和呼气末采用三维超短回波时间序列采集3D-PMRI图像。利用弹性配准算法将吸气末的磁共振图像配准到呼气末。根据彩色图上的变形场计算雅可比行列式。采用雅可比行列式的对数均值（Jac-mean）和骰子相似系数来描述两组之间的肺弹性。然后，分析肺弹性与呼吸困难医学研究委员会（MRC）评分、运动耐力、健康相关生活质量、肺功能以及胸部计算机断层扫描上肺纤维化程度的相关性。
与健康对照者（-0.28，[四分位数间距：-0.31，-0.24]）相比，IPF患者的Jac-mean（-0.19，[四分位数间距：-0.22，-0.15]）降低（绝对值）（P<0.001）。呼吸困难MRC≥3级的IPF患者的肺弹性（Jac-mean：-0.15；骰子相似系数：0.06）显著低于MRC 1级（Jac-mean：-0.22，P=0.001；骰子相似系数：0.10，P=0.001）和MRC 2级（Jac-mean：-0.21，P=0.007；骰子相似系数：0.09，P<0.001）。此外，Jac-mean与用力肺活量百分比（r=-0.487，P<0.001）、第1秒用力呼气量百分比（r=-0.413，P=0.004）、肺总量百分比（r=-0.488，P<0.001）、预测的一氧化碳弥散量百分比（r=-0.555，P<0.001）、6分钟步行距离（r=-0.441，P=0.030）呈负相关，与呼吸症状呈正相关（r=0.430，P=0.042）。同时，骰子相似系数与用力肺活量百分比（r=0.577，P=0.004）、第1秒用力呼气量百分比（r=0.526，P=0.012）、预测的一氧化碳弥散量百分比（r=0.435，P=0.048）、6分钟步行距离（r=0.473，P=0.016）、末梢血氧饱和度（r=0.534，P=0.004）、胸部计算机断层扫描上的纤维化程度（r=-0.421，P=0.021）呈正相关，与活动度呈负相关（r=-0.431，P=0.048）。
IPF患者的肺弹性降低，且与呼吸困难、运动耐力、健康相关生活质量、肺功能以及肺纤维化程度相关。基于3D-PMRI弹性配准的肺弹性可能是一种用于定量评估IPF严重程度的新型无辐射成像生物标志物。
