11C-metomidate positron emission tomography after dexamethasone suppression for detection of small adrenocortical adenomas in primary aldosteronism

• Purpose: 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). Materials and 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 (ROIs) 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 non-functional adenomas. Normal adrenal cortex was suppressed after dexamethasone (p<0.05) but tumour SUV was not significantly decreased after suppression in either PA or non-functional tumours (p>0.05).  However, these changes caused no significant increase in the tumour-to-normal adrenal ratio (p>0.05). Conclusion: 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 ubable to increase the tumour-to-normal-adrenal ratio to further facilitate detection of small adenomas in PA as an alternative to adrenal venous sampling.

Keyword

Metomidate

PET

Primary aldosteronism

Dexamethasone

Adrenal

Suppression

MEDICINE

MEDICIN

Publication and Content Type

ref (subject category)

art (subject category)