ECE2021 Oral Communications Young Investigator Awards (12 abstracts)
Use of 11C-methionine PET-CT scanning to guide management of acromegaly following primary therapy – A pragmatic prioritisation strategy to achieve maximal cost effectiveness
Roby Rajan 1 , D Bhatt 1 , S Philip 1 , AJ Graveling 2 , M Kamel 3 , S Olson 2 , F Mckiddie 2 , D Gillett 4 , W Bashari 4 , M Gurnell 4 & P Abraham 1
1Aberdeen Royal Infirmary, Department of Endocrinology, Aberdeen, United Kingdom; 2Aberdeen Royal Infirmary, Department of Nuclear Medicine, Aberdeen, United Kingdom; 3Aberdeen Royal Infirmary, Department of Neurosurgery, Aberdeen, United Kingdom; 4Welcome–MRC Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge Endocrine Molecular Imaging Group, Cambridge, United Kingdom
Background
11C-methionine (11C-Met) positron emission tomography co-registered with MRI is a new imaging technique used for functioning pituitary adenomas, permitting targeted intervention (Transphenoidal Surgery (TSS) or Radiotherapy)1. The 11C-Met PET-CT scan has been available in our centre since Dec 2016. With limited availability in 2019/2020 (due to cyclotron refurbishment) we re-audited our patients to prioritise those most likely to benefit.
Methods/Results
Retrospective study of patients with acromegaly under active follow-up in a tertiary hospital. Fifty-one patients included (61% female, mean age 59 years) with median follow-up of 13 years with 23 on active treatment. Patients were categorised into groups according to acromegaly treatment status as outlined in the below table. Poor control defined as IGF1> 1.3 × ULN, suboptimal control defined as IGF1 1.1–1.3 × ULN. Eighteen patients from Groups 1, 2 and 3 (2017) were initially considered suitable for 11C-Met PET-CT. Progress to date: five scanned; two declined; eleven pending. Of the five patients scanned, two underwent TSS and have been cured (cost saving of £46822 per annum). One patient awaits surgery and no surgical target was identified in two patients (both in Group 3). We have subsequently reassessed our prioritisation criteria for Group 3 and will now predominantly offer 11C-Met PET-CT if adverse effects to SSA therapy are experienced.
| Group | Acromegaly Treatment Status | 2017 | 2020 |
| 1a | Poor control on SSA/pegvisomant | 7* | 0* |
| 1b | Poor control, SSA intolerant/unsuitable (may have tried DA) |
0 | 2 |
| 1c | Suboptimal control on SSA | 2 | 2 |
| 2 | Good control, very high-cost medication pegvisomant/pasireotide | 1 | 1 |
| 3 | Good control, high-cost medication SSA | 8 | 12 |
| 4 | Poor control DA – switch to SSA | 4 | 0 |
| 5 | Good control on DA | 2 | 3 |
| 6 | Good control on no medication | 27 | 29 |
| 7 | Deceased/Lost to follow-up | 0 | 2 |
| Total | 51 | 51 |
*Comparing 2017 with 2020: 2 operated and cured, 1 moved to category 1b, 2 moved to category 1c, 2 moved to category 3
SSA–somatostatin analogue, DA–dopamine agonist.
Conclusion
11C-Met PET-CT can help localise residual functioning pituitary adenomas in patients with uncontrolled acromegaly but no visible tumour on MRI. However, its availability is currently limited. We present a pragmatic prioritisation strategy targeting those with poor control, ideally prior at the point of consideration of expensive medication such as pegvisomant and pasireotide. There is potential to extend this strategy nationwide.
References
1. Koulouri O et al. European Journal of Endocrinology (2016).
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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