Abstract
Several radiological imaging modalities are available to assist with the clinical diagnosis of pulmonary embolism (PE). The most frequently used techniques—nuclear medicine ventilation‐perfusion (VP) scan, computed tomography (CT), magnetic resonance angiography (MRA), and pulmonary angiography (PA)—all have literature‐supported, substantial limitations with respect to timeliness and patient safety. Hyperpolarized ^3^He magnetic resonance gas distribution imaging (HP ^3^He MRI) recently has shown potential as a safer and faster alternative. In this study, we performed HP ^3^He MRI on a porcine model (N = 6) of simulated PE using selective occlusion balloon catheterization (N = 4) and nonselective aged autologous clot injection (N = 1). The technique was also performed on a normal pig and again after the animal was killed. Temporal depletion of regional HP ^3^He MRI signal intensity provided for a qualitative assessment of simulated PE (N = 4), and regional P~A~O~2~ (alveolar partial pressure of oxygen) was calculated in affected airspaces for a quantitative assessment of simulated PE (N = 1). The preliminary results suggest that HP ^3^He MRI shows promise as a means of assessing regional pulmonary perfusion abnormalities in the porcine models of simulated PE that were used in this study. Magn Reson Med 51:291–298, 2004. © 2004 Wiley‐Liss, Inc.