None listed
Conditions
Brief summary
Tumours of the pituitary gland (located beneath the brain) are common, affecting 1/1000 people. Prolactinomas (defined by hypersecretion of prolactin hormone) are the most frequent pituitary tumour subtype. Currently, no functional imaging tests are routinely available in for the diagnosis of prolactinomas. In this study, we will assess the ability of a radiotracer, 18F-FDOPA, to provide functional information about these tumours and aid in their diagnosis. 18F-FDOPA is currently used to assess Parkinson’s disease and is therefore an established, safe radiotracer. Here, we will assess its ability to diagnose prolactinomas and inform management decisions e.g., surgical planning and responsiveness to medications.
Interventions
The intervention is a single 18F-FDOPA PET/CT (Positron emission tomography/computer tomography) scan, performed by a Nuclear medicine specialist. A single 150MBq dose of radiotracer FDOPA will be administered over 15 seconds with a line flush with 20mL saline. A co-registered, non-contrast, low dose CT will be performed, with the PET acquisition, for anatomical localisation. Scan duration up to 1 hour.
The main cohort is a comparison of prolactinomas and non-functional pituitary adenomas, wh
The intervention is a single 18F-FDOPA PET/CT (Positron emission tomography/computer tomography) scan, performed by a Nuclear medicine specialist. A single 150MBq dose of radiotracer FDOPA will be administered over 15 seconds with a line flush with 20mL saline. A co-registered, non-contrast, low dose CT will be performed, with the PET acquisition, for anatomical localisation. Scan duration up to 1 hour. The main cohort is a comparison of prolactinomas and non-functional pituitary adenomas, which is the cross-sectional arm of the study. The intervention group is prolactinomas (microprolactinomas and macroprolactinomas) and the disease control group is non-functional pituitary adenomas. There will also be an exploratory sub-study which will also have the single intervention of a FDOPA PET/CT (administered as above, by a nuclear medicine specialist). It will include possible occult microprolactinomas defined as persistent serum prolactin greater than or equal to 2-fold normal but nil pituitary adenoma on MRI. This is to determine if FDOPA avidity is present in this patients despite normal MRI scans. There will also be a prospective arm of the study which will be all patients with a baseline FDOPA PET/CT (including those from the cross sectional and exploratory arms of this study), who then receive dopamine agonist therapy as routine clinical care. Therefore all cross-sectional arm patients who commence on DA therapy will be invited to participate. The cross sectional, exploratory and prospective arms will then collect prolactin levels and MRI results performed by the treating clinicians in the usual clinical care of prolactinoma and pituitary adenoma patients with MRI scans at 3 and 12 months and serum prolactin at 3-6 months and 12 months. Audit of imaging reports, clinical records and lab results will be performed regularly by the investigators to monitor adherence.
Sponsors
Royal Adelaide Hospital (RAH)
Study design
Allocation
Non-randomised trial
Primary purpose
Diagnosis
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Cross sectional arm criteria: 1) Unequivocal macro prolactinomas (pituitary adenoma greater than or equal to 10mm on MRI + serum prolactin greater than or equal to 10-fold normal) 2) Unequivocal microprolactinomas (pituitary adenoma 5-9mm on MRI + serum prolactin greater than or equal to 4-fold normal) 3) Unequivocal macro NFPAs (pituitary adenoma greater than or equal to 10mm on MRI + serum prolactin less than or equal to 2-fold normal). 4) Unequivocal micro NFPAs (pituitary adenoma 5-9mm on MRI + serum prolactin normal) Exploratory arm criteria: Possible occult microprolactinomas defined as persistent serum prolactin greater than or equal to 2-fold normal but nil pituitary adenoma on MRI. Prospective arm criteria: All patients with a baseline FDOPA PET/CT (including those from the cross sectional and exploratory arms of this study), who then receive Dopamine Agonist (DA) therapy.
Exclusion criteria
1. Inability to obtain consent; 2. Age 10 half-lives for each drug): a) Cabergoline within 4 weeks* b) Bromocriptine within 2 days** 6. Previous radiotherapy with pituitary in the field of therapy; 7. Inability to interrupt confounding medications; a) DA use for other conditions: Parkinson’s disease, restless leg syndrome b) Dopamine antagonists: i) 24 hours for antiemetics: metoclopramide, prochlorperazine, domperidone. ii) 3 days for Antipsychotics, : Haloperidol, quetiapine, olanzapine, risperidone, paliperidone*** 8. Alternative explanation for hyperprolactinemia as determined by an endocrinologist *Cabergoline, half-life 63 to 109 hours **Bromocriptine, half-life 3 to 6 hours, although biphasic ***Longer half-life antipsychotics, such as aripiprazole or IM formations, may require longer washout periods to ensure >10 half-lives and will be reviewed individually by the study team.
Outcome results
None listed