¹¹C-metomidate PET in the diagnosis of adrenal masses and primary aldosteronism: a review of the literature

Background: Adrenal masses are commonly encountered in clinical practice, many of whom are incidental. Identifying malignancy, and excess hormone production is essential for appropriate management. Biochemical workup and imaging tests (dedicated adrenal CT and/or MRI) are used to determine the likelihood of excessive hormone function and malignancy, respectively. However, imaging cannot provide information about function and biochemical workup cannot localize the source. Furthermore, in primary aldosteronism, adrenal vein sampling, the gold standard for lateralization, has important limitations such as the technical expertise required, the elevated costs, and potential complications. Over the last decades, there has been a renewed interest in alternative noninvasive imaging techniques that provide information about adrenal function without the need for invasive procedures. In this review, we will evaluate the evidence and the potential role of ¹¹C-metomidate as a promising positron emission tomography (PET) tracer in clinical practice. Methods: A review of the English literature for articles describing the use of the tracer ¹¹C-metomidate in adrenal disorders. Results: A total of 12 studies were included in the systematic review, which altogether addressed the use of ¹¹C-metomidate in adrenal masses and the application of this tracer in primary aldosteronism. Conclusions: ¹¹C-metomidate, a selective inhibitor of 11-β-hydroxylase, demonstrated a high specificity for adrenocortical tissue. In addition, ¹¹C-metomidate is correlated with this enzyme activity making it a potentially useful PET tracer for the identification primary aldosteronism, in addition to detection of adrenocortical masses.