Parathyroid scintigraphy.

Parathyroid scintigraphy, first proposed in the seventies, has developed an irreplaceable role in the preoperative location of enlarged parathyroid tissues. The contribution of Ferlin, who in the early eighties proposed the use of the potassium analogue 201Thallium and subtraction scintigraphy to obviate thyroid tissue interference was especially important. At the present time, this imaging modality, is widely accepted for the preoperative localization of parathyroid adenomas owing to its high accuracy and reproducibility. Various modified acquisition and processing protocols have been reported and 201Thallium still continues to be used, but other radiopharmaceuticals, such as 99mTc-methoxyisobutyl isonitrile (99mTc-MIBI) and 99mTc-tetrofosmin are now often preferred, especially because of the more favourable physical properties of the Technetium labelling. In some cases, thyroid subtraction scintigraphy can be replaced by dual phase 99mTc-methoxyisobutyl isonitrile acquisition. There is also an increasing interest in SPECT studies, which have the potential to more accurately locate the sites of adenomas and allow for detection of smaller lesions, which further increases total sensitivity and accuracy of the technique.