Lung perfusion scan

A lung perfusion scan is a specialized imaging procedure designed to evaluate blood flow within the pulmonary vasculature, providing critical information for the diagnosis and management of various respiratory and cardiovascular conditions. By visualizing areas of reduced or absent perfusion, clinicians can identify pulmonary embolism, chronic thromboembolic pulmonary hypertension, and other vascular abnormalities. The technique is often combined with a ventilation scan to create a ventilation-perfusion (V/Q) study, which distinguishes perfusion defects caused by vascular obstruction from those related to airway disease.

During a lung perfusion scan, a radiopharmaceutical agent is injected intravenously, traveling through the pulmonary circulation. Gamma cameras detect the distribution of the tracer, producing detailed images that highlight areas of diminished blood flow. Interpretation focuses on patterns of perfusion loss, which may be segmental or subsegmental, aiding in risk stratification and treatment planning. This non-invasive method is particularly valuable for patients with contraindications to contrast-enhanced computed tomography, such as those with renal impairment or contrast allergies. The clinical utility of lung perfusion scanning extends beyond diagnosis. It can guide anticoagulation therapy, monitor disease progression, and assess postoperative outcomes in patients undergoing pulmonary thromboendarterectomy or other vascular interventions. Advances in imaging software and hybrid techniques, including SPECT/CT, are enhancing spatial resolution and diagnostic accuracy. By combining physiological assessment with high-resolution imaging, lung perfusion scans provide a precise evaluation of pulmonary blood flow, informing tailored management strategies and improving clinical decision-making in vascular and respiratory disorders.