ABC | Volume 114, Nº2, February 2020

Update Update of the Brazilian Guideline on Nuclear Cardiology – 2020 Arq Bras Cardiol. 2020; 114(2):325-429 sensitivity of endomyocardial biopsy is extremely low (20% to 30%). 438 In comparison with MR, the advantages of FDG- 18 F - PET/CT include the value of functional metabolic information, the detection of active inflammation, the potential for identifying cardiac and extracardiac involvement (Figure 59) of sarcoidosis, and the possibility of performing imaging in patients with CIED or renal insufficiency. In order to evaluate extracardiac involvement, it is important to perform full-body imaging. Sarcoidosis normally manifests as an irregular focal uptake pattern. FDG- 18 F - PET/CT has demonstrated that it detects active cardiac and extracardiac forms reliably, with sensitivity between 81% and 89% and specificity between 78% and 82%, respectively. 439,440 It is necessary to pay attention to the patient preparation required for image acquisition in these cases. It is essential for the patient’s diet to be low in carbohydrates and rich in fat the day before the exam and for the patient to be in fasting conditions in order to guarantee that there is no physiological uptake in the myocardium. FDG- 18 F - PET/CT may often be combined with MPS synchronized with ECG (Figure 60), with the objective of ruling out CAD or even identifying resting perfusion defects suggestive of inflammation-induced tissue damage. 441,442 In addition to this, FDG- 18 F - PET/CT in combination with perfusion imaging has shown evidence of prognostic capability in patients with sarcoidosis, 443 orienting myocardial biopsy, 418 and demonstrating valor for predicting response and monitoring therapy. 444 Figure 59 – FDG- 18 F - PET/CT with suppression protocol for myocardial glucose uptake (diet), maximum-intensity-projection imaging (left) and coregistration with CT (right). Patient, age 88, with heart failure, reduced ejection fraction, and ventricular tachycardia. Endomyocardial biopsy was compatible with sarcoidosis. Images demonstrated abnormal tracer uptake in the right and left ventricles (arrows). Following immunosuppression, the patient showed clinical improvement and disappearance of abnormalities. Personal source (courtesy of Dr. Evandro T. Mesquita). 408