Normal Images Prepared By Dr Gabriel Castro    (Costa Rica)

 

 

Clinical indications

 

        Metaiodobenzylguanidine (MIBG) is the combination of the benzyl group of bretylium and the guanidine group of guanethidine. Since MIBG structurally resembles norepinephrine, it enters neuroendocrine cells by an active uptake mechanism and is stored in the neurosecretory granules, resulting in a specific concentration in contrast to cells of other tissues.

        1)Oncological:Detection, localisation, staging and follow-up of neuroendocrine tumours and their metastases, in particular: - phaeochromocytomas - neuroblastomas - ganglioneuroblastomas - ganglioneuromas - paragangliomas - carcinoid tumours - medullary thyroid carcinomas -Merkel cell tumours.
        2) Other (non-oncological) indications  Functional studies of the adrenal medulla (hyperplasia), sympathetic innervation of themyocardium, salivary glands and lungs.

        MIBG is normally taken up mainly by the liver; smaller uptake is described in spleen, lungs, salivary glands, thyroid, skeletal muscles and myocardium. Normal adrenal glands are usually not seen, but faint uptake may be visible 48-72 hours after injection in up to 15% of cases. MIBG may accumulate to a variable degree in nasal mucosa, lungs, gallbladder, colon, and uterus. Free iodine in the bloodstream may cause some uptake in the digestive system and also in the thyroid (if not properly blocked). Bone is not seen after MIBG administration.

        References:

        1)Imaging of catecholamine-secreting tumours: uses of MIBG in diagnosis and treatment. Baillieres Clin Endocrinol Metab. 1993 Apr;7(2):491-507.
        2)131I/123I-Metaiodobenzylguanidine (MIBG) scintigraphy: procedure guidelines for tumour imaging. Eur J Nucl Med Mol Imaging (2003) 30:BP132–BP139
 

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