True about Hybrid PET/CT scans:

Hybrid imaging allows the superimposition of PET and CT images, a technique known as functional-anatomical mapping. Hybrid PET/CT scans provide images that help pinpoint the abnormal metabolic activity to anatomical structures seen on CT and provide more accurate diagnoses than the two scans performed separately. FDG-PET : It can differentiate benign from malignant lesions as small as 1 cm. However, false-negative findings can occur in lesions with low metabolic activity such as carcinoid tumors and bronchioloalveolar cell carcinomas, or in lesions <1 cm in which the required threshold of metabolically active malignant cells is not present for PET diagnosis. False-positive results can be seen due to FDG uptake in inflammatory conditions such as pneumonia and granulomatous diseases. Areas of normal physiological uptake in PET CT:- - Brown fat - Thymus - Brain tissue - Myocardium - GI Tract