Comparison of Clinical Usefulness between N-13 Ammonia PET/CT and Tc-99m Sestamibi SPECT in Coronary Artery Disease / 핵의학분자영상

PURPOSE: N-13 ammonia uptake and retention in the myocardium is related to perfusion and metabolism. There are several potential advantages of N-13 ammonia positron emission tomography (PET) to detect myocardial ischemia, such as higher spatial resolution, greater counting efficiencies, and robust attenuation correction. But there are few reports comparing Tc-99m myocardial perfusion single photon emission tomography (MPS) and N-13 ammonia PET. We thus compared adenosine stress N-13 ammonia PET/CT and Tc-99m sestamibi MPS in patients with suspected coronary artery stenosis. MATERIALS AND METHODS: Seventeen patients (male 13 : 63+/-11 years old) underwent adenosine stress N-13 ammonia PET/CT (Discovery ST, GE), Tc-99m sestamibi MPS (dual head gamma camera, Hawkeye, GE) and coronary angiography within 1 week. N-13 ammonia PET/CT and Tc-99m sestamibi MPS images were assessed with a 20-segment model by visual interpretation and quantitative analysis using automatic quantitative software (Myovation, GE). RESULTS: Both sensitivities and specificities of detecting an individual coronary artery stenosis were higher for N-13 ammonia PET/CT than Tc-99m sestamibi MPS (PET/CT: 91%/ 89% vs MPS: 65%/ 82%). N-13 ammonia PET/CT showed reversibility in 52% of segments that were considered non-reversibile by Tc-99m sestamibi MPS. In the 110 myocardial segments supplied by the stenotic coronary artery, N-13 ammonia PET/CT showed higher count densities than Tc-99m MPS on rest study (p<0.01), and the difference of count density between the stress and the rest studies was also larger on N-13 ammonia PET/CT. CONCLUSION: Adenosine stress N-13 ammonia PET/CT had higher diagnostic sensitivity and specificity, more reversibility of perfusion defects and greater stress/rest uptake differences than Tc-99m sestamibi MPS. Accordingly, N-13 ammonia PET/CT might offer better assessment of myocardial ischemia and viability.

A Case of Fungal Vegetation on Aortic Graft

A 40-year-old man who underwent 2 times of operation for the graft interposition with aortic valve replacement because of aortic dissection was admitted due to high fever and multiple petechiae on extremities for several days. We performed Transthoracic echocardiogram and MRI, revealed vegetation in the aortic arch and descending aorta. Re-do operation of aortic segment replacement and vegetation removal was carried out. Histological evaluation of vegetatation found fungal mass of aspergillus fumigatus.