[11C]Metomidate PET-CT vs Usual Care for People With Primary Aldosteronism: a Proof-of-concept Study

Inclusion Criteria: * Diagnosis of PA made based on Endocrine Society guidelines: * Participants should demonstrate a positive screening test for primary aldosteronism, defined as: * Paired measurement of renin and aldosterone demonstrating a raised aldosterone-to-renin ratio \>550 pmol/L/ng/mL/h AND * Suppressed renin \<=1ng/ml/h * AND participants should demonstrate autonomous aldosterone secretion following salt-loading confirmatory tests, defined as: * 1\) Non-suppressed aldosterone \>162pmol/L following seated saline infusion OR * 2\) raised 24-hour urine aldosterone \>38 nmol/d following oral salt loading test * For participants with spontaneous hypokalemia with renin \<0.2ng/ml/h and plasma aldosterone \> 416 pmol/L(by LC-MS) at screening, the above confirmatory tests can be omitted due to high pre-test probability as proposed by latest guidelines . * Adrenal nodule on CT Exclusion Criteria: * Unable to give informed consent * Participants who neither agree to AVS nor MTO-PET * Patients who indicate they will not proceed to adrenalectomy * Patients contraindicated for mineralocorticoid receptor antagonists * Patients who are unable/unwilling or contraindicated for dexamethasone required for MTO-PET * Estimated GFR \< 30 ml/min/1.73m2 * Any illness or condition that is considered unfit for study by the investigators