ABC | Volume 114, Nº2, February 2020

Update Update of the Brazilian Guideline on Nuclear Cardiology – 2020 Arq Bras Cardiol. 2020; 114(2):325-429 Figure 58 – Male patient, age 19, with biological prosthesis in the aorta and mitral annuloplasty for 45 days. He evolved with fever, bacteremia, and blood culture positive for S. Epidermidis . FDG- 18 F - PET/CT study was positive for infection in the aortic prosthesis; maximum standard uptake value (SUV) = 9.7. Source: INCOR, FMUSP, SP. Using FDG- 18 F - PET/CT, following adequate patient preparation with a carbohydrate-free diet, it is possible to visualize acute inflammation suggestive of active myocarditis. PET imaging may help distinguish active and chronic forms of the disease, following established working protocols. 424,425 In a prospective study of 65 patients with suspected myocarditis, FDG- 18 F - PET was in agreement with MR findings. 426 MR and FDG- 18 F - PET/CT seem to be complementary in nature. 419 For this reason, cardiac PET/ MR has potential as a diagnostic tool for myocarditis and a new field of research. 427-429 14.4. Pericarditis There are multiple causes of acute or chronic pericardial inflammation, including infections (viral, bacterial, or fungal), myocardial infarction, trauma, malign diseases (primary pericardial neoplasm, pericardial metastases, or paraneoplastic syndrome), autoimmune or inflammatory diseases, and metabolic disorders (uremia). Pericarditis may also be iatrogenic, as a collateral effect of medication. Radiotherapy or idiopathic causes are other possible origins. Although its etiology is variable, the pericardium’s response to different causes is not specific. Inflammation of pericardial layers and increased production of pericardial fluids are the most common, and they often manifest as chest pain. In the same manner, Doppler echocardiography stands out as a priority for diagnosis and therapeutic follow-up of pericarditis, externalizing findings such as pericardial effusion and thickness. Generally, CT and MR also allow for evaluation of pericardial effusion and thickness, allowing for better differentiation of pericardium and pericardial fluid. 430 The use of FDG- 18 F - PET/CT in pericarditis is generally complementary, and it demonstrates the ability to detect inflammatory tissue, even in the absence of obvious anatomical changes. 431,432 Non-infectious inflammatory pericarditis shows mild to moderate FDG- 18 F - PET uptake in the pericardium, with diffuse or focal uptake pattern. The literature is still scarce on the utility of FDG- 18 F - PET/CT for differential diagnosis of the underlying causes of this pathology. Some studies relate the possibility of differentiating infectious/inflammatory pericardial disease and neoplastic/metastatic disease, given that malignity, generally, presents intense metabolic activity. 433 Constrictive or effusive pericarditis, an uncommon complication of chemotherapy, may also present pericardial uptake of FDG- 18 F, with mild intensity and wide distribution. 431 Only a few case reports are available in the literature, and larger studies are still necessary to determine the accuracy of FDG- 18 F - PET/ CT for pericarditis. 14.5. Cardiac Sarcoidosis Sarcoidosis is a granulomatous disease whose etiology is unknown. It most commonly affects the lymphatic ganglia and the lungs, but it may involve any system of organs. 434 The heart is frequently affected, 435,436 and this represents one of the main causes of death due to this pathology in Japan and the USA. 437 Due to its multifocal aspect and the irregular manner in which sarcoidosis affects the myocardium, the 407