¹¹C‐Metomidate PET/CT is a useful adjunct for lateralization of primary aldosteronism in routine clinical practice

Abstract

Summary Objective To describe clinical practice experience of 11C‐Metomidate PET/CT as an adjunct to adrenal vein sampling (AVS) in the lateralization of aldosterone‐producing adenomas (APA) in primary aldosteronism (PA). Context Accurate lateralization of APA in the setting of PA offers the potential for surgical cure and improved long‐term cardiovascular outcomes. Challenges associated with AVS, the current gold standard lateralization modality, mean that only a small proportion of potentially eligible patients currently make it through to surgery. This has prompted consideration of alternative strategies for lateralization, including the application of novel molecular PET tracers such as 11C‐Metomidate. Design Clinical Service Evaluation/Retrospective audit. Patients Fifteen individuals with a confirmed diagnosis of PA, undergoing lateralization with 11C‐Metomidate PET/CT prior to final clinical decision on surgical vs medical management. Measurements All patients underwent screening aldosterone renin ratio (ARR), followed by confirmatory testing with the seated saline infusion test, according to Endocrine Society Clinical Practice Guidelines. Adrenal glands were imaged using dedicated adrenal CT. 11C‐Metomidate PET/CT was undertaken due to equivocal or failed AVS. Management outcomes were assessed by longitudinal measurement of blood pressure, ARR, number of hypertensive medications following adrenalectomy or institution of medical therapy. Results We describe the individual lateralization and clinical outcomes for 15 patients with PA. Conclusion 11C‐Metomidate PET/CT in conjunction with adrenal CT and AVS provided useful information which aided clinical decision‐making for PA within a multidisciplinary hypertension clinic.

Adrenal Incidentaloma

“…CYP11B1 (11-beta-hydroxylase) and CYP11B2 (aldosterone synthetase) enzymes are key regulators of adrenal cortisol and aldosterone synthesis ( 362 ). Carbon-11 ( 11 C) metomidate (MTO) PET-CT is a sensitive and specific technique for diagnosing adrenocortical tumors ( 363 ) and has high accuracy for lateralizing aldosterone secretion by Conn’s adenomas ( 364 , 365 ). The 20-minute half-life of 11 C restricts the use of this tracer to centers with an on-site cyclotron and consequently, this technique is not widely available ( Fig.…”

Use of Steroid Profiling Combined With Machine Learning for Identification and Subtype Classification in Primary Aldosteronism

“…Moreover, the use of distinctive profiles to identify patients with unilateral APAs due to KCNJ5 variants further illustrates the potential of steroid profiling for disease stratification at a single screening step. Along with advances in functional imaging 49 , 50 , 51 and other measurements, such as the angiotensin peptidome, 52 , 53 steroid profiling combined with machine learning may facilitate more rapid identification of patients with PA for appropriate therapeutic interventions. As detailed in eAppendix 3 in the Supplement , such strategies are now being tested in further patient populations, and with those developments it may become possible to screen more than the small proportion of patients with PA who are currently tested and treated according to disease subtype.…”

Response to Letter on use of functional imaging by 11C-metomidate PET for primary aldosteronism subtyping

“…(4) and O'Shea et al (10). However, previous studies by the nuclear medicine specialists in our group show that a plateau activity is reached in approximately 10 min and tracer kinetics of 11 40 min (11).…”