Functional imaging with 11C-metomidate PET for subtype diagnosis in primary aldosteronism

Area of Science:

• Endocrinology
• Nuclear Medicine
• Radiology

Background:

• Adrenal venous sampling (AVS) is recommended by Endocrine Society guidelines for primary aldosteronism (PA) when adrenalectomy is considered.
• Accurate subtype classification of PA is crucial for guiding treatment decisions.

Purpose of the Study:

• To evaluate 11C-metomidate positron emission tomography (11C-MTO-PET) as a noninvasive tool for PA subtype classification.
• To compare the diagnostic performance of 11C-MTO-PET with AVS and adrenal CT.

Main Methods:

• Prospective study of 58 patients with confirmed PA eligible for surgery.
• Patients underwent both AVS and 11C-MTO-PET without dexamethasone pretreatment.
• Lateralization by 11C-MTO-PET and adrenal CT were compared to AVS, with confirmation by CYP11B2 immunohistochemistry in a subgroup.

Main Results:

• Overall concordance between AVS and 11C-MTO-PET was 51%, not significantly different from AVS and adrenal CT (53%).
• Concordance was 55% in unilateral PA and 44% in bilateral PA.
• 11C-MTO-PET showed suboptimal sensitivity (55%) and specificity (44%) in predicting treatment allocation.

Conclusions:

• 11C-MTO-PET demonstrated clinically suboptimal concordance with AVS for PA subtype classification.
• The imaging modality did not outperform adrenal CT and was found to be inferior to AVS.
• In a subgroup with CYP11B2-positive adenoma, 11C-MTO-PET identified only 53% of cases.