Pulmonary Embolism: Ventilation/Perfusion Scintigraphy as a Proper Tool in Diagnosing Pulmonary Embolism and Frequent Pulmonary Comorbidities

Ventilation/perfusion single photon emission computed tomography (V/P SPECT) is the recommended method for proper diagnosis of pulmonary embolism (PE), according to the European Association of Nuclear Medicine (EANM) guidelines. Adequate V/P SPECT acquisition starts with ventilation and continues immediately with perfusion. The whole procedure takes 20 min by using an optimal combination of nuclide activities, collimators, and imaging matrix. For the ventilation studies, Technegas particles have an advantage over radiolabeled liquid aerosols due to the better penetration to the periphery. Radiolabeled macro aggregated human albumin (MAA) is the imaging agent of choice for perfusion scintigraphy. The method allows recognition of V/P pattern typical for PE, the sign of chronic obstructive pulmonary disease (COPD), pneumonia, left heart failure (LHF), chronic PE, and suspicion of other parenchymal processes like tumors. It gives a clear answer to the clinicians regarding PE. Furthermore, it is possible to quantify the extent of ventilation and perfusion changes. The radiation exposure is low, the sensitivity and specificity are above 95% and the method has no contraindications. It is possible to diagnose PE even in the presence of another pulmonary comorbidity. Hybrid V/P SPECT/CT might have additional value for tumor diagnostics.