This prospective observational study aims to validate three-dimensional electrical impedance tomography (3D-EIT) as a non-invasive bedside tool for the diagnosis and longitudinal monitoring of pulmonary embolism (PE). The study will include a PE cohort and a control cohort without PE or venous thromboembolism (VTE). Using algorithms that separate ventilation and perfusion signals, 3D-EIT-derived indices, including the Matching Index (MI), Dead Space Index (DI), and Shunt Index (SI), will be quantified. The diagnostic performance of MI and DI will be evaluated against computed tomography pulmonary angiography (CTPA), and their associations with PE severity, risk stratification, and treatment response will be explored. This study is expected to support the clinical translation of 3D-EIT as a radiation-free bedside functional imaging tool for PE management.