The normal dexamethasone-suppression adrenal scintiscan.

To establish the parameters of adrenal imaging under dexamethasone suppression (DS), 18 normotensive, normal male volunteers underwent dexamethasone-suppression adrenal scintiscanning. Five control groups were established and given dexamethasone, either 8 mg for 2 days or 4 mg for 7 days before 6 beta-[131I]iodomethyl-norcholesterol (NP-59) administration. NP-59 was given in doses of 2, 1, or 0.5 mCi. Early visualization (3--5 days) of the adrenals was noted in the groups on the 8 mg DS regimen with either 1 or 2 mCi of NP-59. Late visualization (5--7 days) was noted in the groups that received 4 mg DS and either 2, 1, or 0.5 mCi of NP-59, respectively. The normal adrenal will demonstrate uptake of NP-59 under DS, and the duration of DS before imaging is the critical factor as to when discernible adrenal visualization will occur. The documentation of the noraml suppression interval on these DS regimens provides a basis for the correct diagnostic interpretation of adrenal hyperfunction as seen on the dexamethasone-suppression NP-59 adrenal scan.