Lung Perfusion SPECT: Application in a Patient With Tetralogy of Fallot and Suspected Pulmonary Thromboemboli

A 22-year-old woman presented with acute left-sided pleuritic chest pain and dyspnea 6 days after surgery for revision of the stenotic central aortopulmonary shunt. she had a history of tetralogy of fallot (tof), pulmonary valve stenosis, ventricular septal defect and major aortopulmonary collateral artery. her waterston shunt was placed when she was 5 years old and stented and re-dilated after stenosis. acute pulmonary thromboemboli (pte) was suspected and pulmonary perfusion scan was performed with 4 mci 99m technetium labeled macroaggregated albumin. the left lung was globally hypoperfused with evident uptake in the brain, renal parenchyma and thyroid. spect images revealed a segmental wedge-shaped peripheral defect in the posterior segment of the left upper lobe. the scan was interpreted as acute/chronic pte or vascular abnormality. ct angiography excluded pte; nevertheless the patient was treated with a therapeutic dose of heparin changed to warfarin and was discharged with improvement of the symptoms. pulmonary artery angiography was not performed.