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[11C]metomidate positron emission tomography of adrenocortical tumors in correlation with histopathological findings
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Endocrine Surgery.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences. Endokrin tumörbiologi. (Britt Skogseid)
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2006 (English)In: Journal of Clinical Endocrinology and Metabolism, ISSN 0021-972X, E-ISSN 1945-7197, Vol. 91, no 4, 1410-4 p.Article in journal (Refereed) Published
Abstract [en]

CONTEXT: 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. DESIGN: Seventy-five histopathological examinations from 73 patients were retrospectively analyzed. SETTING: All examinations were performed at a referral center. PATIENTS: 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). MAIN OUTCOME MEASURES: 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. CONCLUSION: 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.

Place, publisher, year, edition, pages
2006. Vol. 91, no 4, 1410-4 p.
Keyword [en]
Adrenal Cortex Neoplasms/*pathology/*radionuclide imaging, Aged, Antineoplastic Agents/*diagnostic use, Data Interpretation; Statistical, Ethics, Etomidate/*analogs & derivatives/diagnostic use, Female, Humans, Image Processing; Computer-Assisted, Male, Middle Aged, Positron-Emission Tomography, Radiopharmaceuticals/diagnostic use
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-17464DOI: 10.1210/jc.2005-2273PubMedID: 16403816OAI: oai:DiVA.org:uu-17464DiVA: diva2:45235
Available from: 2008-06-24 Created: 2009-01-30 Last updated: 2010-09-14Bibliographically approved
In thesis
1. Clinical Studies on Adrenocortical Tumours using  [11C]-metomidate Positron Emission Tomography
Open this publication in new window or tab >>Clinical Studies on Adrenocortical Tumours using  [11C]-metomidate Positron Emission Tomography
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Adrenal tumours, discovered en passant in patients undergoing radiological examinations for non-adrenal disease, so-called adrenal incidentalomas, have increased dramatically in the recent era of more sophisticated diagnostic modalities such as high resolution multidetector computed tomography (CT) and magnetic resonance imaging (MRI). Furthermore, primary aldosteronism (PA) has been documented in several screening studies as being far more common than previously believed among hypertensive patients.

In this thesis, a long-term follow-up cohort of patients who had undergone surgery for PA revealed that there was an excellent effect on blood-pressure, reduction of anti-hypertensive medication and hypokalaemia after surgery, even though the majority of these patients still required some anti-hypertensive medication. This was also true, in the higher than expected number of dominant nodular hyperplasia (nIHA) found in the study, but was slightly less pronounced than in aldosterone producing adenomas (APA).  Surgery was thus effective in lateralized PA.

Metomidate positron emission tomography (MTO-PET) was explored in relation to histopathology in post-operative patients and found to be highly specific and sensitive in categorizing adrenocortical disease. Also, a higher standardized uptake value (SUV) ratio between tumours and normal adrenal cortex was found in hormonally hypersecreting adenomas as well as in adrenocortical cancer (ACC). The resolution limited the diagnosis of small tumours (<1-1.5 cm).

MTO-PET was compared to standard radiological modalities (CT and MRI) in the diagnostic work-up of adrenal incidentalomas. All three modalities categorized and characterized the lesions well, with MTO-PET showing the highest sensitivity and specificity.  However this method is currently recommended to be used as complementary to the others in unclear cases, due to high costs and less availability.

The resolution of MTO-PET was improved with respect to less noise and better delineation of small tumours when applying masked volume-wise principal component analysis (MVW-PCA), which will possibly enable future detection of small tumours in PA patients.

Dexamethasone suppression treatment prior to MTO-PET examinations in PA patients decreased SUV in normal adrenal cortex but could not be shown to increase the SUV ratio between adenoma and normal cortex enabling better detection of small tumours, even though all the tumours were readily categorized in the study. Heterogenic SUV reactions to dexamethasone treatment indicate a need for further studies and refinement of the suppression method.

In conclusion, long-term results of surgery for lateralized PA are good. MTO-PET is a highly sensitive and specific method for categorizing adrenocortical disease. Modulation of the method, e.g. by using MVW-PCA and refined dexamethasone suppression treatment, may improve the resolution of the method in delineating small tumours in PA, thus making MTO-PET a non-invasive and non-operator dependent future alternative to the currently recommended adrenal venous sampling (AVS) for lateralization diagnosis prior to surgery for PA.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 33 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 486
National Category
Research subject
urn:nbn:se:uu:diva-108797 (URN)978-91-554-7618-2 (ISBN)
Public defence
2009-11-14, Auditorium Minus, Museum Gustavianum, Uppsala, 09:15 (Swedish)
Available from: 2009-10-23 Created: 2009-09-29 Last updated: 2009-10-23Bibliographically approved

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