Can voxel analysis of [11C]Metomidate PETCT be used to detect micronodular disease and predict outcome from adrenalectomy?

Jessica Kearney; Daniel Gillett; Bal Sanghera; Heok Cheow; Mohan Krishnamurthy; Emily Goodchild; Xilin Wu; Kate Laycock; Mark Gurnell; William Drake; Morris Brown

doi:10.1530/endoabs.109.OC5.1

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Endocrine Abstracts (2025) 109 OC5.1 | DOI: 10.1530/endoabs.109.OC5.1

SFEBES2025 Oral Communications Adrenal and Cardiovascular (6 abstracts)

Can voxel analysis of [11C]Metomidate PETCT be used to detect micronodular disease and predict outcome from adrenalectomy?

Jessica Kearney ^1,2 , Daniel Gillett ³ , Bal Sanghera ² , Heok Cheow ³ , Mohan Krishnamurthy ² , Emily Goodchild ¹ , Xilin Wu ¹ , Kate Laycock ¹ , Mark Gurnell ³ , William Drake ^1,2 & Morris Brown ¹

Author affiliations

¹Queen Mary’s University London, London, United Kingdom; ²Bart’s Health NHS Trust, London, United Kingdom; ³University of Cambridge, Cambridge, United Kingdom

Background: [¹¹C]Metomidate PET-CT (MTO) is a non-invasive method of lateralisation for the diagnosis of unilateral Primary Aldosteronism An SUVmax lateralisation index of 1.25 of tumour:contralateral normal gland has previously been established. Despite lateralisation, most patients do not have complete PASO clinical success after adrenalectomy, which may be due to the presence of bilateral disease. Using entire gland voxel analysis, we seek to test the hypothesis that multifocal, bilateral disease has a more uniform isotope uptake compared to unilateral disease, in which a single discrete nodule has higher uptake than the remainder of the ipsilateral and contralateral gland.

Methods: 40 adrenal glands on pre-operative MTO scans were analysed. Those with complete PASO biochemical and clinical success were compared to those with medically managed bilateral disease. Glands were manually outlined on CT by combining the region of interest (ROI) on each CT slice into a volume of interest (VOI) encompassing the entire gland. The following parameters were calculated from all voxel SUV values within the gland: mean, maximum, total gland uptake (TGU, volume x SUVmean), standard deviation (SD), skewness (asymmetry of distribution) and kurtosis (distribution around the mean).

Result: The contralateral ‘normal’ gland of the patients who were cured post-operatively had a smaller mean volume (4.38 cm³±1.46) and markers of tracer uptake (SUVmean 11.46±3.6, max 17.69±4.71, TGU 50.42±23.3) than the ‘unilateral’ diseased gland (7.59 cm³±2.52, mean 15.68±3.95 max 31.79±12.77, TGU 310.4±103.23). The bilateral glands had values between ‘normal’ and ‘unilateral’ (6.24 cm³±3.67, mean 13.9±2.75, max 22.08±5.26, TGU 90.37±66.67). The ‘unilateral’ gland was more positively skewed with a less negative kurtosis.

Conclusion: This exploratory, retrospective analysis identifies potential novel radiological measures of CYP11B2 activity, using all available voxel data, that may provide additional information to the standard analysis of SUVmax values alone.