Magnetic resonance imaging or metaiodobenzylguanidine scintigraphy for the demonstration of paragangliomas? Correlations and disparities.

Paragangliomas are tumours arising from paraganglionic tissue dispersed from the base of the skull to the pelvic diaphragm. These tumours produce symptoms by secreting catecholamines (functioning tumours) or by local tumour expansion. They can be part of several hereditary disorders. The introduction of magnetic resonance (MR) imaging and metaiodobenzylguanidine (MIBG) scintigraphy has provided new insights into paragangliomas and has tremendously changed the topographic diagnosis of paragangliomas. Both techniques have proven to be adequate in localising paragangliomas. In this report, the performance of these two noninvasive imaging methods in the examination of paragangliomas is compared and the merits and deficits of the two techniques are discussed. Both techniques produce comparable results in the detection of functioning paragangliomas. MR imaging, however, also demonstrates tumours that do not take up MIBG. MR imaging does not involve the use of ionising radiation and is not hampered by medication. Moreover, MR imaging has a higher spatial resolution. Because of these merits it is concluded that for demonstration of paragangliomas, whole-body MR imaging is the preferred and initial method of investigation. MIBG scintigraphy, on the other hand, continues to be a reliable method for non-invasive detection of functioning paragangliomas. At present it is clearly faster in whole-body imaging than MRI and it is definitely patient-friendly (no claustrophobia). It could be reserved for cases where a strong suspicion of a functioning paraganglioma persists, despite normal MR imaging findings, and for cases where doubt exists about the functional activity of one or more multicentric tumours. MIBG scintigraphy must be used in the evaluation of patients referred for iodine-131 MIBG treatment.