The added value of lung perfusion scintigraphy semiquantitative measures in post-COVID patients with persistent dyspnea without pulmonary embolism

Persistent dyspnea is frequent in post-COVID patients, even in the absence of pulmonary embolism (PE). In this scenario, the role of lung perfusion scintigraphy is unclear. The present study correlated scintigraphy-based semiquantitative perfusion parameters with chest high-resolution computed tomography (hrCT) volumetric indexes and clinical data in post-COVID patients with persistent dyspnea. Sixty patients (30 post-COVID and 30 not previously affected by COVID-19) with persistent dyspnea submitted to lung perfusion scintigraphy and hrCT were retrospectively recruited. Perfusion rates of the pulmonary fields and hrCT-based normalized inflated, emphysematous, infiltrated, collapsed, and vascular lung volumes were calculated. Inflammatory and coagulation biomarkers were collected. PE at imaging was an exclusion criterion. Compared to controls, reduced perfusion rates of the lower pulmonary fields and higher perfusion rates of the middle ones were observed in post-COVID patients, while hrCT findings were superimposable between the two groups. Perfusion rates of lower pulmonary fields were significantly associated only with abnormal lung volumes at hrCT. In post-COVID dyspnea without PE, lung perfusion scintigraphy may reveal a pulmonary involvement not detectable by hrCT. Post-COVID patients may show decreased perfusion rates of lower pulmonary fields in the presence of normal vascular density and markers of inflammation/coagulation.

新冠感染后患者常出现持续性呼吸困难，即便未合并肺栓塞（PE）亦是如此。在此类临床场景中，肺灌注显像（lung perfusion scintigraphy）的临床价值尚不明确。本研究针对合并持续性呼吸困难的新冠感染后患者，分析了基于显像的半定量灌注参数与胸部高分辨率计算机断层扫描（hrCT）容积指数及临床数据之间的相关性。本研究回顾性招募了60例合并持续性呼吸困难的受试者，其中30例为新冠感染后患者，30例为既往未感染新冠病毒的对照个体，所有受试者均接受了肺灌注显像及hrCT检查。研究人员计算了各肺野的灌注率，以及基于hrCT的标准化充气肺容积、肺气肿性肺容积、浸润性肺容积、萎陷肺容积与血管肺容积；同时收集了炎症与凝血生物标志物数据。本研究的排除标准为影像学检出PE。与对照组相比，新冠感染后患者的下肺野灌注率降低，中肺野灌注率升高，但两组的hrCT影像学表现无显著差异。下肺野灌注率仅与hrCT检出的异常肺容积存在显著相关性。在未合并PE的新冠感染后呼吸困难患者中，肺灌注显像可检出hrCT无法识别的肺部受累情况。新冠感染后患者在血管密度及炎症/凝血标志物水平正常的情况下，仍可能出现下肺野灌注率降低的表现。