What further imaging studies are indicated to evaluate for possible

Additional imaging investigations indicated to evaluate potential cardiopulmonary causes of hypoxemia include:

• Chest radiography as a first-line imaging modality to assess for lung pathology such as infection, fibrosis, pulmonary edema, or other structural abnormalities contributing to impaired gas exchange and chronic hypoxemia NICE CKS.
• Cardiac transthoracic echocardiography to evaluate cardiac function and identify intracardiac shunts or right-to-left atrial shunting mechanisms, such as those potentially caused by persistent right venous valve with patent foramen ovale, which may contribute to hypoxemia despite normal lung parenchyma Mino et al. 2026 NICE CKS.
• Advanced imaging techniques such as computed tomography pulmonary angiography (CTPA) may be indicated to exclude chronic thromboembolic pulmonary hypertension or microthrombi that could impair pulmonary perfusion and oxygenation, especially in the context of suspected pulmonary vascular disease post-COVID NICE CKS.
• In selected cases, cardiac magnetic resonance imaging (MRI) can be utilized to further characterise cardiac structure and function when echocardiography findings are inconclusive or when cardiomyopathy is suspected NICE CKS.

These imaging modalities together assist in delineating the underlying cardiopulmonary causes of hypoxemia, including structural lung disease, intracardiac shunts, vascular obstructions, and cardiac dysfunction, all of which are important considerations in patients with long COVID or unexplained chronic hypoxemia NICE CKS Mino et al. 2026. Appropriate imaging selection should be guided by clinical presentation, initial investigations, and risk factors.