Before the research starts (screening): After signing the consent form, the participant will be asked to undergo some screening tests or procedures to find out if they can be in the research study. Many of these tests and procedures are likely to be part of regular cancer care and may be done even if it turns out that the participant does not take part in the research study. If the participant has had some of these tests or procedures recently, they may or may not have to be repeated.
* A medical history, which includes questions about the participant's health, current medications, and any allergies.
* Physical Exam including measuring the participant's height, weight, and vital signs
* Performance status, which evaluates how the participant is able to carry on with your usual activities.
* Blood tests.
* Blood pregnancy test for women of childbearing potential
* Urine test.
If these tests show that the participant is eligible to participate in the research study, the participant will begin the study treatment. If the participant does not meet the eligibility criteria, the participant will not be able to participate in this research study.
After the screening procedures confirm that the participant is eligible to participate in the research study:
Please note that this study does not add any additional treatment to participants with your type of cancer. There will be no change in your treatment with bevacizumab and daily temozolomide based on the results of any procedures or tests carried out as a part of the study.
Before each set of scans the participant will have the following tests and procedures:
* Routine blood tests to check the participant's overall health
* Creatinine clearance blood test to check for proper kidney function
* Blood pregnancy test for women of childbearing potential
After the participant have been taking oral TMZ for 7-13 days, the participant will have:
\- An assessment of their tumor by DCE-MRI (Dynamic Contrast Enhanced-Magnetic Resonance Imaging) scans and PET (Positron Emission Tomography) scan
MRI-PET Scan Procedure:
The participant will have their scans performed in Charlestown, MA at the Martinos Center. The participant will be injected with two separate intravenous (IV) lines for:
* \[11C\] temozolomide for PET scan and a contrast dye for the MRI scan
* Drawing blood to assess the radioactivity of \[11C\] temozolomide \[11C\] temozolomide PET Scans (TMZ PET Scan):
* The PET scan will take approximately 90 minutes. The participant will receive one injection of \[11C\] temozolomide. Following the injection of the radioactive substance, blood samples will be taken from the second IV line.
MRI Scan:
\- MRI scans will last about 60-75 minutes. This will occur at the same time as the PET scan. The participant will be injected with contrast dye twice during the MRI scan.
The MR-PET scan(s) will be performed again on Day 1 after initiation of bevacizumab (or Day 15 after initiation of temozolomide) and Day 30 after initiation of bevacizumab (on Day 45 after initiation of temozolomide).
Blood samples will be collected during both scans in order to measure how your blood vessels are processing the radiotracer \[11C\] temozolomide and how well it is being delivered to the tumor tissue. Blood samples will be drawn 2.5, 5, 10, 20, 40, 60, 75, and 90 minutes after the \[11C\] temozolomide injection.
The participant will be assessed for side effects via clinic visit or phone call about 24 hours after each of the visits above.
\- Planned Follow-up: The investigators would like to call the participant every 3 months for three years after their second MR-PET scan to see how they are doing and if the participant is experiencing any side effects. If the participant was removed from the study due to an unacceptable side effect, the participant will be followed until it has been resolved.
