Gallium-68-Pentixafor PET/CT for Subtyping Diagnosis of Primary Aldosteronism: A Pictorial Essay

Primary aldosteronism (PA) is one of the prevalent causes of secondary hypertension, characterized by the autonomous hypersecretion of aldosterone and concurrent renin inhibition. Clinical and biochemical remission rates for patients with PA achieved through surgery are far higher compared to those achieved through drug treatment; hence, subtyping PA is crucial for identifying patients who will benefit most from surgery. Computed tomography (CT) scan with adrenal protocol and adrenal venous sampling (AVS) is used conventionally for PA subtype classification. CT scans, being structural imaging, cannot provide functional information, while AVS is an invasive, technically challenging method with a limited success rate and a high risk of complications. The C-X-C chemokine receptor type 4 (CXCR4) is overexpressed in aldosterone-producing tissue but is almost negligibly expressed in nonfunctional adenoma. The positron emission tomography tracer 68Ga-pentixafor, a specific ligand for CXCR4, can detect aldosterone-producing adenoma noninvasively, which can guide surgical treatment. The image series below demonstrates the utility and patterns of findings on Ga-68-pentixafor for subtyping PA.