EANM guidelines for ventilation/perfusion scintigraphy : PPPPart 1. Pulmonary imaging with ventilation/perfusion single photon emission tomography

Pulmonary embolism (PE) can only be diagnosed with imaging techniques, which in practice is performed using ventilation/perfusion scintigraphy (V/PSCAN) or multidetector computed tomography of the pulmonary arteries (MDCT). The epidemiology, natural history, pathophysiology and clinical presentation of PE are briefly reviewed. The primary objective of Part 1 of the Task Group's report was to develop a methodological approach to and interpretation criteria for PE. The basic principle for the diagnosis of PE based upon V/PSCAN is to recognize lung segments or subsegments without perfusion but preserved ventilation, i.e. mismatch. Ventilation studies are in general performed after inhalation of Krypton or technetium-labelled aerosol of diethylene triamine pentaacetic acid (DTPA) or Technegas. Perfusion studies are performed after intravenous injection of macroaggregated human albumin. Radiation exposure using documented isotope doses is 1.2-2 mSv. Planar and tomographic techniques (V/PPLANAR and V/PSPECT) are analysed. V/PSPECT has higher sensitivity and specificity than V/PPLANAR. The interpretation of either V/PPLANAR or V/PSPECT should follow holistic principles rather than obsolete probabilistic rules. PE should be reported when mismatch of more than one subsegment is found. For the diagnosis of chronic PE, V/PSCAN is of value. The additional diagnostic yield from V/PSCAN includes chronic obstructive lung disease (COPD), heart failure and pneumonia. Pitfalls in V/PSCAN interpretation are considered. V/PSPECT is strongly preferred to V/PPLANAR as the former permits the accurate diagnosis of PE even in the presence of comorbid diseases such as COPD and pneumonia. Technegas is preferred to DTPA in patients with COPD. © 2009 Springer-Verlag.