Other Imaging Techniques: Computed Tomography and Positron Emission Tomography
Both computed tomography (CT) and positron emission tomography (PET) may be useful in addition to echocardiography and magnetic resonance (MR) imaging to study cardiac tumors. CT scan may be used as an alternative imaging modality in patients who cannot undergo MR because it is contraindicated or in patients already examined with other noninvasive methods without obtaining adequate images. High-speed equipments with electrocardiographic (ECG) gating can provide images with resolution <1 mm; multiplanar and tridimensional reconstructions are also possible. PET is based on the detection of metabolic activity after injection of radionuclides. The most commonly used tracing in oncology is fluorodeoxyglucose (18F-FDG), which concentrates in tissue with high glucose metabolism. PET is usually performed together with computed tomography (PET/CT). To quantify the glucose metabolism, the maximum standardized uptake value (SUV) is used. Malignant tumors have usually a high SUV, which may increase with the proliferative index. Some other organs, such as the liver and heart, may have variable uptake according to different metabolic conditions. The myocardial 18FDG uptake may vary widely between different patients and – in the same patient – between different exams. In order to improve the accuracy of 18FDG-PET in cardiac tumor imaging, a carbohydrate- poor and fat-rich meal followed by a fasting period of 12–18 h is suggested before the exam.
- 10.Korn RL, Coates A, Millstine J. The role of glucose and FDG metabolism in the interpretation of PET studies. In: Lin EC, Alavi A, editors. PET and PET/CT. A clinical guide. 2nd ed. New York: Thieme; 2009.Google Scholar
- 11.Lin EC, Alavi A. Normal variants and benign findings. In: Lin EC, Alavi A, editors. PET and PET/CT. A clinical guide. 2nd ed. New York: Thieme; 2009.Google Scholar
- 14.Manabe O, Yoshinaga K, Ohira H, et al. The effects of 18-h fasting with low-carbohydrate diet preparation on suppressed physiological myocardial (18)F-fluorodeoxyglucose (FDG) uptake and possible minimal effects of unfractionated heparin use in patients with suspected cardiac involvement sarcoidosis. J Nucl Cardiol. 2015 Aug 5.Google Scholar
- 15.Masuda A, Naya M, Manabe O, et al. Administration of unfractionated heparin with prolonged fasting could reduce physiological 18F-fluorodeoxyglucose uptake in the heart. Acta Radiol. 2015 Sep.Google Scholar