In vivo measurement of dopamine receptors in pituitary adenomas using positron emission tomography.
Patients with pituitary adenomas were examined with positron emission tomography (PET) with the administration of the 11C-labelled dopamine-D2 antagonists N-methylspiperone and raclopride. The studies were repeated after protection of the D2-receptors with Haloperidol to enable a separation of specific and unspecific receptor binding. The receptor binding was evaluated by visual inspection and with the application of a kinetic model. The results showed marked specific dopamine-D2 receptor binding in the prolactinomas and minimal or no such binding in the hormonally inactive adenomas. The two tracers 11C-raclopride and 11C-N-methylspiperone showed qualitatively the same result although raclopride resulted in a higher tumor to normal brain ratio. In conclusion, PET is a valuable complement to other radiologic techniques like computed tomography and magnetic resonance imaging in the evaluation of pituitary adenomas. An assessment of the dopamine-D2 receptors in the adenomas has a direct influence on the choice of treatment because adenomas with high amounts of receptors are in most cases effectively treated with dopamine agonists like bromocriptine.
Muhr
C
C
Department of Neurology, University Hospital, Uppsala, Sweden.
Bergström
M
M
Lundberg
P O
PO
Bergström
K
K
Långström
B
B
D000236:Adenoma / Q000737:chemistry / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000737:chemistry / Q000000981:diagnostic imaging*; D011954:Receptors, Dopamine / Q000032:analysis*; D014055:Tomography, Emission-Computed
D011954:Receptors, Dopamine