Oral Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

Identification of aldosterone-producing adrenal adenomas using novel nuclear imaging (#155)

Elisabeth Ng 1 2 , Ian Jong 3 , Kenneth K Lau 4 , Mohammad B Haskali 5 6 , Peter J Fuller 1 2 , Jimmy Shen 1 2 , Jun Yang 1 2 7
  1. Department of Endocrinology, Monash Health, Clayton, Victoria, Australia
  2. Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Clayton, Victoria, Australia
  3. Department of Nuclear Imaging, Monash Health, Clayton, Victoria, Australia
  4. Department of Diagnostic Imaging, Monash Health, Clayton, Victoria, Australia
  5. Department of Radiopharmaceutical Sciences, The Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  6. Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
  7. Department of Medicine, Monash University, Melbourne, Australia

Primary aldosteronism (PA) is the most common endocrine cause of hypertension. Subtyping is critical for identifying unilateral aldosterone-producing adenomas (APA) which can be surgically resected. Adrenal vein sampling (AVS), the current standard for subtyping, is resource-intensive and invasive. 68Ga-PentixaFor PET/CT is a novel nuclear imaging modality for non-invasive subtyping. We aimed to evaluate the diagnostic accuracy of 68Ga-PentixaFor PET/CT compared to AVS for identifying APA.

This prospective pilot study recruited adults with PA and an adrenal adenoma visible on CT. Unilateral disease was defined by a lateralisation index (LI)>4 on AVS, with sampling pre- and post-ACTH. On PET/CT, maximum standardised uptake values (SUVmax) at 10 and 40 minutes (min) after tracer injection were used to calculate the PET-LI (dominant SUVmax over contralateral gland SUVmax). Published PET-LI criteria from China (>1.65 at 10min) and the Netherlands (>1.4 at 40min) were tested in our cohort.

68Ga-PentixaFor PET/CT and AVS were performed in 34 patients (median age 60, 16 female). On CT, 16 had left-sided nodules, 14 right-sided and 4 bilateral. At AVS, 15 lateralised (10 left, 5 right) and were recommended for surgery. Testing of published PET-LI criteria showed a 74-89% specificity and 20-60% sensitivity, lower than the published values of 80-100% and 60-100% respectively. Concordance with AVS was 68% for a PET-LI>1.65 at 10min and PET-LI>1.4 at 40min. Of the 8 patients who underwent adrenalectomy, biochemical cure was achieved in all; 4 of them lateralised on PET/CT based on published criteria (either >1.65 at 10min or >1.4 at 40min). 

Our initial findings suggest that 68Ga-PentixaFor PET/CT has a potential role in PA subtyping in individuals with a visible adrenal adenoma. Further evaluation of patient characteristics which may impact diagnostic accuracy is needed. A complete set of surgical outcomes will be used to determine the optimal PET-LI cut-off for diagnosing unilateral PA.