Transposition of the great arteries: a myocardial perfusion PET-CT study.

: We report the case of a 20-year-old woman with surgically corrected transposition of the great arteries, pulmonary valve defects, and absence of left coronary ostium at a previous cardiac catheterization. Because of worsening dyspnea, she underwent myocardial perfusion PET/CT study with 13N-ammonia at rest and during pharmacological stress, which showed extensive ischemia in the left coronary territory and signs of severe left ventricle dysfunction. Quantitative PET data showed impaired regional coronary flow reserve (<2.0) in the left coronary territory, thus allowing a precise and reliable evaluation of the myocardial perfusion defect because of the absence of left coronary ostium.