MIBG Case 1 Answers

1) Name the radiopharmaceutical

MIBG is 123I- metaiodobenzylguanidine - "hot guano". It is related to an adrenergic blocking drug which was originally developed for treatment of hypertension. Therefore when infusing it, it needs to be given slowly to prevent sudden bradycardia and hypotension.

2) Are there any abnormal areas of uptake?
3) If so, where?

This is a normal scan. MIBG is taken up into tissue that has strong adrenergic innervation, namely the heart and salivary glands. It is excreted via the enterohepatic circulation and uptake is seen in the liver and colon. Laxatives are given during the test to minimize bowel activity

4) What are the advantages of this test over CT?

MIBG is better for detecting tumours that are smaller (<2cm), extraadrenal, multiple or metastatic.

5) Name 2 other tumours well visualized by this technique

Other tumours such as neuroblastoma, paragangliomas and to a lesser extent, carcinoid and medullary cell thyroid carcinoma take up MIBG.

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