11C-metomidate positron emission tomography after dexamethasone suppression for detection of small adrenocortical adenomas in primary aldosteronism.
OBJECTIVE
To evaluate whether dexamethasone suppression treatment can improve (11) C-metomidate positron emission tomography (MTO-PET) detection of small adrenocortical adenomas in primary aldosteronism (PA).


METHODS
Eleven patients with proven PA and two patients with non-hyperfunctioning adrenocortical incidentalomas and small adrenocortical tumours observed on CT underwent MTO-PET before and 3 days after administration of oral dexamethasone suppression treatment. Small "hot-spot" regions of interest comprising 4 pixels (SUVhs) and 1 pixel (SUVmax) were placed in the tumour area with the highest radioactivity concentration and their respective standardised uptake values (SUV) were recorded.


RESULTS
All tumours were detected and categorised as adrenocortical by MTO-PET. SUVhs as well as SUVmax were higher in PA compared to nonfunctional adenomas. Normal adrenal cortex was suppressed after dexamethasone (p < 0.05), but tumour SUV was not significantly decreased after suppression in either PA or nonfunctional tumours (p > 0.05). However, these changes caused no significant increase in the tumour-to-normal adrenal ratio (p > 0.05).


CONCLUSIONS
MTO-PET is a highly sensitive method for detecting and categorising even small adrenocortical tumours in PA. In this series, dexamethasone-suppressed MTO-PET was unable to increase the tumour-to-normal adrenal ratio to further facilitate detection of small adenomas in PA as an alternative to adrenal venous sampling.
Hennings
J
J
Department of Surgical Sciences, Uppsala University, SE-751 85 Uppsala, Sweden. joakim.hennings@surgsci.uu.se
Sundin
A
A
Hägg
A
A
Hellman
P
P
D000284:Administration, Oral; D018246:Adrenocortical Adenoma / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D003907:Dexamethasone / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005045:Etomidate / Q000031:analogs & derivatives; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006929:Hyperaldosteronism / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D012494:Sampling Studies; D016896:Treatment Outcome; D047368:Tumor Burden / Q000187:drug effects
D003907:Dexamethasone; C084586:metomidate; D005045:Etomidate