Simmons Austin, Mummy David, Zhang Shuo, Leewiwatwong Suphachart, Palmer Scott, Driehuys Bastiaan, Ali Hakim Azfar
Campbell University School of Osteopathic Medicine, Buies Creek, North Carolina.
Department of Radiology, Duke University, Durham, North Carolina.
JHLT Open. 2024 Jun 7;5:100117. doi: 10.1016/j.jhlto.2024.100117. eCollection 2024 Aug.
There is currently no sensitive, noninvasive method of screening for chronic lung allograft dysfunction (CLAD), the primary barrier to long-term survival after lung transplant. Conventional pulmonary function testing is imprecise absent a sustained decline. Hyperpolarized Xe magnetic resonance imaging (MRI) is a sensitive tool for 3-dimensional imaging of regional pulmonary ventilation and gas-exchange abnormalities and may aid in early detection of CLAD.
Adult patients, post bilateral lung transplant, were screened for CLAD based on the International Society for Heart and Lung Transplantation criteria. Those with established allografts ( = 10) underwent Xe gas-exchange MRI and spectroscopy and were compared to results from 16 young healthy volunteers and 16 age-matched healthy volunteers. One lung transplant recipient was excluded from the final data analysis due to a concurrent lung infection found incidentally after MRI. Imaging provided quantitative maps of the ventilation defect percent (VDP), membrane high percent, and red blood cell (RBC) defect percent. Spectroscopy yielded RBC/membrane ratio, oxygenation-dependent RBC shift, and RBC oscillation amplitude.
The analysis included 9 lung transplant recipients, 7 with CLAD and 2 without. CLAD patients exhibited VDP values consistent with their forced expiratory volume in 1 second (FEV) decline (rho = 0.79, = 0.048). Hemoglobin-corrected RBC transfer was reduced in all transplant recipients vs young healthy controls (median [first quartile-third quartile] of 13% [9%-22%] vs 2% [1.75%-3%], = 0.003) as well as vs age-matched controls (5.5% [2%-9.25%], = 0.039). Spectroscopy demonstrated reduced RBC/membrane signal (0.26 [0.17-0.31] vs 0.62 [0.50-0.66], < 0.001 and vs 0.48 [0.42-0.55], = 0.002), reduced RBC chemical shift (217.4 [217.2-217.7] ppm vs 218.2 [218.0-218.5] ppm, = 0.009 and vs 218.3 [218.2-218.5] ppm, = 0.003), and increased RBC oscillation amplitude vs the young healthy controls (14.1% [12.2%-16.4%] vs 11.1% [9.9%-11.9%], = 0.003).
Patients with CLAD exhibited significant ventilation defects that correlated with FEV decline, which, along with RBC transfer defects and other Xe gas-exchange and hemodynamic abnormalities, could provide a promising means of early detection of physiological changes in patients with CLAD.
目前尚无用于筛查慢性肺移植功能障碍（CLAD）的敏感、非侵入性方法，而CLAD是肺移植后长期存活的主要障碍。在没有持续下降的情况下，传统肺功能测试并不精确。超极化氙磁共振成像（MRI）是用于区域肺通气和气体交换异常的三维成像的敏感工具，可能有助于CLAD的早期检测。
根据国际心肺移植学会标准，对成年双侧肺移植患者进行CLAD筛查。对那些已植入移植物的患者（n = 10）进行氙气交换MRI和光谱分析，并与16名年轻健康志愿者和16名年龄匹配的健康志愿者的结果进行比较。一名肺移植受者因MRI后偶然发现并发肺部感染而被排除在最终数据分析之外。成像提供了通气缺陷百分比（VDP）、膜高百分比和红细胞（RBC）缺陷百分比的定量图。光谱分析得出RBC/膜比率、氧依赖性RBC位移和RBC振荡幅度。
分析包括9名肺移植受者，其中7名患有CLAD，2名未患CLAD。CLAD患者的VDP值与其1秒用力呼气量（FEV）下降一致（rho = 0.79，P = 0.048）。与年轻健康对照组相比，所有移植受者的血红蛋白校正RBC转移均降低（中位数[第一四分位数 - 第三四分位数]为13% [9% - 22%] 对2% [1.75% - 3%]，P = 0.003），与年龄匹配的对照组相比也降低（5.5% [2% - 9.25%]，P = 0.039）。光谱分析显示RBC/膜信号降低（0.26 [0.17 - 0.31] 对0.62 [0.50 - 0.66]，P < 0.001，与0.48 [0.42 - 0.55]相比，P = 0.002），RBC化学位移降低（分别为217.4 [217.2 - 217.7] ppm对218.2 [218.0 - 218.5] ppm，P = 0.009，与218.3 [218.2 - 218.5] ppm相比，P = 0.003），与年轻健康对照组相比，RBC振荡幅度增加（14.1% [12.2% - 16.4%] 对11.1% [9.9% - 11.9%]，P = 0.003）。
CLAD患者表现出与FEV下降相关的显著通气缺陷，这与RBC转移缺陷以及其他氙气交换和血流动力学异常一起，可能为早期检测CLAD患者的生理变化提供一种有前景的方法。
