FDG PET/CT (Oncology, Whole Body)

Indications

• Staging/restaging of most solid malignancies and lymphoma
• Treatment response assessment
• Detection of recurrence; characterization of indeterminate lesions
• Radiation therapy planning
• Cancer of unknown primary

Patient prep

• Fast at least 4-6 hours (water only); no caloric intake during uptake
• Check blood glucose: should be <200 mg/dL (optimal <140-150); reschedule or manage if high
• Avoid strenuous exercise 24 h (muscle uptake)
• Keep patient warm and resting/quiet during uptake (reduce brown fat/muscle uptake)
• Diabetics: schedule appropriately, hold short-acting insulin per protocol
• Verify pregnancy/breastfeeding status

Contrast

Technique

• Integrated PET/CT, skull base to mid-thigh (eyes-to-thighs); add limbs for melanoma/sarcoma
• Low-dose CT for attenuation correction and localization (+/- diagnostic CT with IV/oral contrast)
• Arms up if possible to reduce artifact; void before scan (urinary excretion)
• ~2-4 min per bed position

Series / Sequences

Key points

• Strict glucose control and consistent ~60-min uptake essential for reliable SUV
• Keep patient warm/still to minimize brown fat and muscle uptake
• Physiologic uptake: brain, myocardium (variable), liver, GU tract, bowel, lymphoid tissue
• Hyperglycemia/recent insulin shifts FDG to muscle and lowers tumor conspicuity
• Inflammation/infection and post-treatment changes can cause false positives

References