正子斷層攝影{positron emission tomography,PET)應用葡萄糖的類似物fluorine-18-2-fluoro-2-deoxy-D-glucose(FDG) 作為示蹤劑，在臨床上可作為癌症偵測及分期。不同的器官對FDG攝取的差異性極大，醫者必需瞭解FDG示蹤劑在體內正常生理上的分佈及良性病變FDG的攝取，才不致與惡性腫瘤攝取FDG產生混淆臨床上受檢者若因生理變化或良性病變導致FDG攝取時可依其特性給予適當的分類，局部淋巴結、發炎或感染造成的FDG攝取，則未必具有特異性。另外，骨骼肌在運動後或處於壓力的情況下亦會有FDG的攝取，此乃屬於正常之影像；針對膀胱及腸道所造成之假影，通常可運用靜脈點滴注射、使用利尿劑、膀胱灌洗生理食鹽水及等滲溶劑灌腸等方式，以避免生理性FDG攝取假影的產生，如此可獲得較準確的影像，並有助於研究判讀。而將功能性影像與解剖影像作融合(fusion)時，則有助於分辨是否為正常組織變異。另外，病史的收集、理學檢查及實驗室的檢驗數據等資料，皆為影像判讀上很重要的參考依據。

A rapidly emerging clinical application of positron emission tomography (PET) is the detection and staging of cancer with the glucose analogue tracer 2-[fiuorine-18]fluoro-2-deoxy-D-glucose (FDG). The uptake of FDG in different organs varies among patients. Proper interpretation of FDG PET images requires knowledge of the normal physio- logic distribution of the tracer, frequently encountered physiologic variants, and benign pathologic causes of FDG uptake that can be confused with a malignant neoplasm. In many instances, physiologic variants and benign patho- logic causes of FDG uptake can be specifically recognized and properly categorized. In other instances, such as the lymph node response to inflammation or infection, focal FDG uptake is nonspecific. Uptake of FDG may be seen normally in the skeletal muscle after exercise or under tension. Urinary artifacts are avoided with intravenous hydra- tion, administration of furosemide, and catheterization and retrograde filling of the bladder with saline solution. Colonic artifacts are avoided by cleansing the bowel with an isosmotic solution. Some causes of increased physio- logical uptake are avoidable, and measures can be taken to minimize accumulation, thus aiding study interpretation. Fusion of functional images and anatomical images may distinguish normal variants from juxtaposed neoplastic lesions. In addition, history taking, physical examination, and laboratory data are important information to image interpretation.