11c-metomidate pet/ct for endocrine hypertension and characterisation of adrenal tumours

Conditions: Primary Aldosteronism Due to Aldosterone Producing Adenoma; Primary Aldosteronism; Adrenal Tumors

Summary: * 10% of patients with hypertension potentially have the treatable condition - primary aldosteronism (pa). this is caused by either bilateral adrenal disease (\~40%), managed with lifelong medications; or unilateral disease (\~60%), cured with laparoscopic surgery (adrenalectomy). current diagnosis of pa includes a screening test with aldosterone-renin ratio, followed by a confirmatory salt loading test (in most patients) to demonstrate unsuppressed aldosterone levels. of note, some patients with suppressed aldosterone after confirmatory tests (also termed low-renin hypertension) may also have unilateral adrenal tumors. * the difficulty with identifying curable unilateral disease is due to adrenal vein sampling (avs): an invasive, and technically-difficult procedure. an alternative novel imaging, 11c-metomidate positron emission tomography-computed tomography (pet-ct), can detect adrenal tumors which are over-producing aldosterone. it is non-invasive, non-operator-dependent, and potentially may identify more patients with curable unilateral disease. the results from our pilot study in 25 patients with confirmed pa (clinicaltrials.gov nct03990701, pa_cure) showed that 11c-metomidate pet-ct exhibited comparable performance to avs in subtyping pa, and this should be validated in a larger study. * in addition, 11c-metomidate is also able to differentiate adrenocortical lesions in the adrenal gland from other lesions found in adrenal tissue, such as adrenomedullary lesions (e.g. pheochromocytoma). * hence, the investigators hypothesize that 11c-metomidate pet-ct can accurately (1) identify patients with surgically curable unilateral adrenal disease among hypertensive asians with primary aldosteronism (pa_cure 2 / pa_mto eh study) and (2) differentiate adrenocortical lesions from other lesions in patients with adrenal tumors (pa_mto at study)

* the investigators aim to recruit 100 patients with confirmed, or likely, primary aldosteronism to undergo conventional tests, ct, avs, and 11c-metomidate pet-ct. * results will be reviewed and discussed at a multidisciplinary meeting, and patients with unilateral pa or adrenal tumor will be offered surgery. patients will be reviewed 6 months post-surgery. * in a separate study, the investigators will recruit 10 patients with adrenal tumors to differentiate adrenocortical lesions from other lesions in patients with adrenal tumors

Eligibility criteria:
inclusion criteria: * for patients with primary aldosteronism (pa_cure 2 / pa_mto eh): 1. confirmed diagnosis of primary aldosteronism, as defined in endocrine society guidelines 2016, with positive confirmatory test (post-salt loading aldosterone \>140pmol/l); or hypokalemia with undetectable renin levels and aldosterone \>550pmol/l; or likely primary aldosteronism / low-renin hypertension (inappropriate aldosterone levels and suppressed renin levels) 2. keen for surgical treatment if shown to have unilateral adrenal disease. * for patients with suspected adrenal tumors (pa_mto at) 1. all patients with suspected adrenal tumors based on imaging and clinical suspicion. exclusion criteria: * inability to provide written informed consent. * chronic renal failure of stage 3b or greater severity, estimated glomerular filtration rate (egfr) \< 45ml/min/1.73m2 using chronic kidney disease epidemiology collaboration (ckd-epi) formula. (only applicable for pa_cure 2 / pa_mto eh) * severe or terminal medical condition(s) that in the view of the investigator prohibits participation in the study or interferes with possible treatment or health-related quality of life, e.g. cancer, end-stage liver disease, end stage renal failure (only applicable for pa_cure 2 / pa_mto eh) * contraindications to isotope scanning (e.g. female patients who are pregnant (self-declared or via positive pregnancy test), intending to become pregnant (within 3 months of scan) or breastfeeding) or ct scan, which includes but not limited to waist circumference \>140cm, morbid obesity or claustrophobia (limiting entry in ct scanner) * contraindication to ingestion of corticosteroids (e.g. poorly controlled diabetes, hba1c \>13%)

Keywords: 11-c metomidate pet/ct functional imaging secondary / endocrine hypertension adrenal vein sampling subtyping; localization testing adrenalectomy