Ventilation/Perfusion SPECT Imaging—Diagnosing Other Cardiopulmonary Diseases Beyond Pulmonary Embolism

Ventilation/perfusion single-photon emission computed tomography (V/P SPECT) is the scintigraphic technique recommended primarily for the diagnosis of acute pulmonary embolism (PE) and is golden standard for the diagnosis of chronic PE. Furthermore, interpreting ventilation and corresponding perfusion images enables pattern recognition of many other cardiopulmonary disorders that affect lung function and also allows quantification of their extent. Using Technegas for the ventilation imaging, grading of small airway disease in COPD is possible and the method is recommended for PE diagnosis in patients with severe COPD that is not possible with radiolabelled liquid aerosols. An optimal combination of nuclide activities, acquisition times for ventilation and perfusion, collimators, and imaging matrix yields an adequate V/P SPECT study in approximately 20 minutes of imaging time. The holistic interpretation strategy of V/P SPECT uses all relevant information about the patient and ventilation/perfusion patterns. PE is diagnosed when there is more than one subsegment showing a V/P mismatch representing an anatomic lung unit. Apart from PE, other pathologies should be identified and reported, such as obstructive lung disease, heart failure, and pneumonia according to the European Association of Nuclear Medicine guidelines.