Radionecrosis and FDG PET

Study Overview
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Brief Summary
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Gliomas are the most common malignant primary central nervous system (CNS) tumours. When high-grade gliomas (HGG) recur, subsequent magnetic resonance (MRI) imaging, with additional sequences is required.The Positron Emission Tomography (PET) radiotracer [18F]-fluorodeoxyglucose (FDG) will be used in this study to distinguish between changes seen on MRI which can be a reflection of pseudoprogression, radiation necrosis, or recurrence.

Detailed Description
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Molecular imaging has been used to distinguish recurrent tumor from post-treatment changes through the use of positron emission tomography (PET) as well as other techniques. The best-studied PET radiotracer for this application is [18F]-fluorodeoxyglucose (FDG). Normal brain matter is very FDG-avid, making it more difficult to identify lesions and in addition, inflammation associated with radiation injury has been shown to be FDG avid. In light of this, variations of the standard FDG protocols have been proposed in order to increase overall accuracy, including dual time point imaging (DTPI), consisting of injecting the patient with the standard radiotracer and acquiring two sets of images several hours apart, typically the normal initial images in addition to a delayed acquisition set. There is good reason to suspect that DTPI FDG-PET would be useful a technique for characterizing lesions in the brain. It's been shown that FDG uptake by normal brain parenchyma initially increases then decreases with time, while tumor uptake typically increases and then plateaus. This pattern of increasing and then decreasing FDG activity has also been seen in inflammatory tissue. The difference in FDG uptake at different times is what allows for a better distinction between malignant and benign tissue.

Official Title
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A Dual Time Point FDG-PET to Differentiate Between Recurrent Brain Tumor and Radionecrosis

Conditions
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Malignant Glioma

Intervention / Treatment
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* Other: Positron Emission Tomography Imaging


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 18 years old Able and willing to comply with the study procedures The patient must be followed at The Ottawa Hospital for a tissue-proven, grade III or IV glioma. The patient must have been treated in the past with radiotherapy for glioma. A disease recurrence is suspected based on clinical symptoms and/or imaging results. Exclusion Criteria: Missing information regarding tumor type and grade Brain biopsy in the ten days preceding DTPI FDG-PET Breastfeeding or pregnancy Claustrophobia or inability to lie still in a supine position Unwillingness or inability to provide informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Positron Emission Tomography Imaging<br>Dual time point imaging with 250 MBq of 18F-Fluorodeoxyglucose (18F-FDG) | Other: Positron Emission Tomography Imaging<br>* Participants will receive an intravenous injection of 250 MBq (megabecquerels) of 18F-Fluorodeoxyglucose (18F-FDG). The first Positron Emission Tomography (PET) acquisition of the head will occur one hour post-injection. The second acquisition will take place 3 hours post-injection. Both early and late PET images will be manually co-registered with the participant's most recent magnetic resonance images.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| sensitivity and specificity percentages | The sensitivity and specificity of dual time point imaging (DTPI) FDG-PET/CT will be compared to the sensitivity and specificity of MR imaging obtained as standard of care for identifying glioma recurrence post-treatment. | 3 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cost efficiency analysis | At the conclusion of the trial, a cost-efficiency analysis will be performed in an attempt to determine an optimally accurate and cost-efficient imaging strategy for the diagnosis of glioma recurrence. | 3 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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central nervous system tumours, [18F]-fluorodeoxyglucose