11C-Metomidate PET/CT for Endocrine Hypertension and Characterisation of Adrenal Tumours

Overview

* 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