Interest of ventilation/perfusion SPECT/CT in patients with post-COVID condition: a multicenter observational study

PURPOSE: The COVID-19 pandemic has led to a significant number of survivors experiencing persistent health issues, now recognized as long COVID. Respiratory symptoms, such as dyspnea, chronic cough, and reduced exercise capacity, are prevalent and can severely impact quality of life. Ventilation/Perfusion (V/Q) SPECT/CT is a hybrid imaging modality that offers both functional and anatomical insights and has proven valuable in evaluating pulmonary embolism (PE). However, its role in long COVID remains underexplored. METHODS: A retrospective, multicenter study was conducted using a national registry included V/Q SPECT/CT in symptomatic patients after COVID infection. Centralized, blinded reviews assessed for mismatched, matched, and reverse mismatch defects, as well as morphological lung abnormalities. Descriptive statistics and comparative analyses were performed to evaluate the prevalence of PE and post-embolic sequelae. A secondary objective is to determine the prevalence of normal versus abnormal imaging findings suggestive of post infectious sequelae. RESULTS: A total of 217 patients with persistent respiratory symptoms (mean time from infection to scan: 26.7 weeks ± 20 weeks) were evaluated between January 2020 and April 2023. Among the 217 patients, 6 (2.8%) exhibited mismatched perfusion defects consistent with PE, including 3 cases of previously undiagnosed PE (1 de novo and 2 recurrent). Post-embolic sequelae were identified in only 3 of 72 patients (4.2%) with a prior PE history. Non-thromboembolic lung abnormalities were found in 116 (53.4%) patients, while 95 (44.8%) had entirely normal V/Q SPECT/CT findings. Matched ventilation-perfusion defects were observed in 83 (38.2%) patients. Reverse mismatched defects were identified in 13 (6.0%) patients. CT abnormalities were present in 107 (49.3%) cases, predominantly subpleural and bilateral. CONCLUSION: V/Q SPECT/CT proved valuable in differentiating organic pulmonary abnormalities from non-organic causes in long COVID patients. While PE was rare (2.8%), it remains a serious complication requiring prompt identification and treatment. Notably, 44.8% of patients showed normal V/Q SPECT/CT findings, effectively ruling out organic pulmonary involvement. Hybrid imaging techniques, such as V/Q SPECT/CT, may be considered a valuable tool in the diagnostic assessment of long COVID. Future prospective studies are needed to validate these findings and explore the long-term clinical implications of pulmonary abnormalities in this population.