To PE or Not to PE: Perfusion SPECT/CT Avoids Overdiagnosis.

A 41-year-old woman with metastatic breast cancer presented with dyspnea, hypoxia, and elevated d -dimer. Perfusion planar imaging followed by SPECT/CT of the chest was performed due to the patient's iodinated contrast allergy. Planar images showed multiple pleural-based wedge-shaped defects concerning for bilateral pulmonary embolism (PE). Perfusion SPECT/CT of the chest confirmed multiple areas of perfusion defects but was considered negative for PE and attributed the perfusion defects to the compressing of pulmonary vasculature from metastatic lymph nodes and pulmonary masses. Given the high pretest probability of PE, a CT pulmonary angiogram was performed after premedication for contrast allergy confirming absence of PE.