Clinical Presentation
A 68-year-old woman presents with fever of unknown origin. Because of limited venous access, 67Ga is selected as the radiopharmaceutical of choice for evaluation.
Fig. 105.1 Whole-body image, anterior, and posterior projections, 67Ga.
Technique
• A 7.5 mCi dose of 67Ga-citrate is injected intravenously 3 days before scan.
• Whole-body imaging in anterior and posterior projections
Dual-detector gamma camera
Medium-energy collimators
Energy peak at 93-, 185-, and 300-keV photopeaks
Image Interpretation
Whole-body images (Fig. 105.1) demonstrate a normal biodistribution pattern. Typically, 67Ga localizes in the nose, salivary glands, lacrimal glands, breasts, liver, spleen, genitalia, and skeleton; it is not unusual to have varying degrees of large-bowel activity. No abnormal tracer localization is seen to suggest active inflammation/infection.
Differential Diagnosis
• Normal 67Ga scan
Diagnosis and Clinical Follow-Up
Normal. No active inflammation/infection identified. Diagnosis final, no clinical follow-up.
Discussion
The best-known and most widely used inflammation/infection–seeking radiopharmaceuticals are 67Ga and autologous white blood cells (WBCs) radioactively labeled with either 111In or 99mTc. Each agent has its advantages, disadvantages, and preferred clinical indications (Table 105.1). As a general principle, they have comparable sensitivity rates on the order of 90% for inflammation, but WBCs are generally more specific than 67
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