[11C]metomidate positron emission tomography of adrenocortical tumors in correlation with histopathological findings.
BACKGROUND
Adrenal incidentalomas are common findings necessitating extensive laboratory work-up and repetitive radiological examinations. Positron emission tomography (PET) using (11)C-labeled metomidate (MTO) has previously been described as a tool for specific adrenocortical imaging.


OBJECTIVE
We evaluated 212 MTO-PET examinations in 173 patients to identify its role in the management of adrenal tumors.


METHODS
Seventy-five histopathological examinations from 73 patients were retrospectively analyzed.


METHODS
All examinations were performed at a referral center.


METHODS
Patients who were operated or biopsied due to adrenal tumors had histopathological diagnoses of adrenocortical adenoma (n = 26), adrenocortical cancer (ACC; n = 13), adrenocortical hyperplasia (n = 8), pheochromocytoma (n = 6), metastasis (n = 3), and tumors of nonadrenal origin (n = 19).


METHODS
The main outcome measures were statistical analyses and findings while scrutinizing images. The hypothesis that MTO-PET is of value in the management of adrenal tumors, especially incidentaloma, was stated before data collection.


RESULTS
Sensitivity was 0.89 and specificity was 0.96 for MTO-PET in proving adrenocortical origin of the lesions. Pheochromocytomas, metastases to the adrenal gland, and nonadrenal masses were all MTO negative. PET measurements using standardized uptake values (SUV) in pathological adrenocortical tissue could differentiate lesions larger than 1-1.5 cm from normal adrenocortical tissue. SUV was higher in aldosterone-hypersecreting adenomas, and the SUV ratio between the tumor and the contralateral gland was significantly higher in all hormonally hypersecreting adenomas as well as in ACC.


CONCLUSIONS
MTO-PET is a specific and sensitive method for diagnosing adrenocortical tumors. MTO-PET is useful in the imaging work-up of adrenal incidentalomas and may be beneficial for the examination of patients with primary aldosteronism or ACC.
Hennings
Joakim
J
Department of Surgery, University Hospital, SE-751 85 Uppsala, Sweden.
Lindhe
Orjan
O
Bergström
Mats
M
Långström
Bengt
B
Sundin
Anders
A
Hellman
Per
P
D000306:Adrenal Cortex Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D000368:Aged; D000970:Antineoplastic Agents; D003627:Data Interpretation, Statistical; D004989:Ethics; D005045:Etomidate / Q000031:analogs & derivatives*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals
D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; C084586:metomidate; D005045:Etomidate