Combined FDG-PET and 123I-Iodometomidate Imaging for Adrenal Neoplasia

Study Overview
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Brief Summary
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Adrenal masses are highly prevalent and detected with high frequency by conventional imaging. Conventional imaging often fails to rule out a malignant lesion. Accordingly, most hormonally inactive adrenal masses removed by surgery are benign adenomas for which surgical removal is unnecessary and poses an avoidable risk to the patients. We hypothesize that the combination of FDG-PET and 123I-Iodometomidate imaging has the potential to noninvasively identify benign adrenocortical adenomas with high accuracy, thereby avoiding unnecessary surgery. Uptake of 123I-Iodometomidate by the adrenal mass demonstrates the presence of CYP 11B enzymes which specifically bind metomidate with high avidity establishing the adrenocortical origin of the lesion, while low uptake of FDG-PET in an adrenocortical lesion establishes its benign nature and excludes the presence of adrenocortical cancer (ACC). The proposed trial will assess the sensitivity, specificity, positive and negative predictive value of the combined imaging for the diagnosis of adrenocortical adenoma. A secondary focus is on the performance of the combined test for differentiating ACC from non-ACC lesions. We expect that the results of our trial will help to greatly reduce the need for surgery in hormonally inactive adrenal masses.

Detailed Description
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Histopathology of a surgically removed adrenal mass by an expert surgeon is considered to be the gold standard for the differential diagnosis of an adrenal neoplasia. Thus we will only recruit patients scheduled for surgery for an adrenal mass of uncertain origin. Patients will be eligible for the trial when an adrenal mass has been discovered and standard imaging (CT and/or MRI) has not led to a clear characterization of the malignant potential of the lesion (Hounsfield units in unenhanced CT ≥10). In addition, patients with adrenal neoplasia will be only recruited when a hormonally active lesion has been excluded and surgery is planned because of a perceived risk of malignancy. Patients will be evaluated by both [123I]Iodometomidate SPECT/CT and [18F]fluorodeoxyglucose PET/CT. Computed tomography will be performed as low dose CT of the adrenal region. Imaging can be started with either [123I]Iodometomidate SPECT/CT or [18F]fluoro- deoxyglucose PET/CT and can be performed at two consecutive days. The time interval between [123I]Iodometomidate SPECT/CT and [18F]fluorodeoxyglucose PET/CT should not exceed 6 weeks. Patients will have a follow up visit 2-4 weeks after [123I]Iodometomidate SPECT/CT and [18F]fluorodeoxyglucose PET/CT (or immediately before surgery, if earlier than 2 weeks post imaging). Thirty days after surgery patients will be contacted by phone for assessment of adverse events related to surgery.

Official Title
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￼Combined 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) and 123I-Iodometomidate (123I-IMTO) Imaging for Adrenal Neoplasia

Conditions
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Adrenal Gland Neoplasms

Intervention / Treatment
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* Other: FDG positron emission tomography
* Other: Iodometomidate imaging


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with a solid indeterminate adrenal mass scheduled for surgery with a diameter > 3 cm or an increase in tumour diameter after the initial evaluation of > 1 cm during follow-up, age ≥30 years Exclusion Criteria: Patient unfit or unwilling to undergo surgery, biochemical evidence of phaeochromocytoma, primary hyperaldosteronism or overt clinical Cushing's syndrome

Ages Eligible for Study
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Minimum Age: 30 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: FDG positron emission tomography and Iodometomidate imaging<br>Combined FDG PET and Iodometomidate imaging prior adrenal surgery of uncertain adrenal neoplasms | Other: FDG positron emission tomography<br>* 2 consecutive imaging studies (diagnostic study) within 1-2 weeks: FDG-PET and 123I-Iodometomidate imaging in patients with an indeterminate adrenal neoplasm<br>* Other names: FDG PET;Other: Iodometomidate imaging<br>* 2 consecutive imaging studies (diagnostic study) within 1-2 weeks: FDG-PET and 123I-Iodometomidate imaging in patients with an indeterminate adrenal neoplasm<br>* Other names: 123I-Iodometomidate imaging;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Specificity of combined FDG-PET and 123I-IMTO imaging for diagnosing adrenocortical adenoma | Diagnostic study with combined FDG-PET and 123I-IMTO imaging in which an indeterminate adrenal mass with negative FDG-PET test (FDG-) and positive 123I-IMTO test (IMTO+) is diagnosed as a benign adrenocortical adenoma (AA+). Primary efficacy endpoint: Specificity (rate estimation) of the diagnostic AA test and likelihood ratio of a positive diagnostic test (using rate estimation of the sensitivity). The outcome measure does not assess a change but the diagnostic accuracy of both FDG-PET and IMTO imaging. | within 1 to 2 weeks (minimum 2 days, maximum 6 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensitivity of combined FDG-PET and 123I-IMTO imaging for diagnosing adrenocortical adenoma | Sensitivity of the diagnostic adrenocortical adenoma (AA) test and likelihood ratio of a negative diagnostic AA test, a priori rates of AA, adrenocortical cancer (ACC) and other benign as well as malignant indeterminate adrenal neoplasias. Detection rates similar to sensitivity and specificity for ACC and indeterminate adrenal neoplasias other than AA and ACC of combined 18F-FDG-PET imaging and 123I-Iodometomidate imaging in identifying ACC. Predictive values will be determined and economic analysis of cost effectiveness of diagnostic evaluation versus surgery for all indeterminate lesions will be performed. The outcome measure does not assess a change but the diagnostic accuracy of both FDG-PET and IMTO imaging. | within 1 to 2 weeks (minimum 2 days, maximum 6 weeks) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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123I Iodometomidate imaging, 18F FDG positron emission tomography, Adrenal tumour