For Phase I protocols, attach participant dose level assignment confirmation from t he sponsor. • The QACT Registrar will (a) review the eligibility checklist , (b) reg ister the participant on the protocol, and (c) randomize the participant when applicable. • An email confirmation of the registration and/or randomization will be sent to the Overall PI, study coordinator(s) from the Lead Site, treating investigator and registering person immediately following the registration and/or randomization. 4.3 General Guidelines for Other Investigative Sites NA 4.4 Registration Process for Other Investigati ve Sites NA 5. IMAGING PLAN 5.1 Treatment Regimen This study does not add any additional treatment to enrolled patients. All treatment decisions will be at the discretion of the treating physician. There will be no change in the diagnosis or management of the patient based on any procedures or tests carried out as a part of this study. There are no expected toxicities and potential risks for PBR . All scans will be performed at the Martinos Center for Biomedical Imaging in Charlestown on the combined MR PET scanner . For GBM patients with suspected pseudoprogression, MR- PET will be performed at the time of suspected pseudoprogression. For GBM patients treated with immunotherapy, MR -PET will be performed prior to start of the immunotherapy and then 2 cy cles later. For metastatic cancer patients treated with immunotherapy, MR -PET will be performed prior to start of the immunotherapy and then 3 cycles later. 5.2 Pre-MR-PET Scan Criteria Protocol A pilot study to evaluate PBR PET as an indicator of inflammation in brain tumor patients treated with chemoradiation or immunotherapy. Version Date: June 20, 2018 14 5.2.1 Genotyping for the Ala147Thr TSPO polymorphism in the TSPO gene (rs69 71). Venous blood (up to 50 ml) will be drawn during the Screening Visit for this purpose and sent Partners HealthCare Personalized Medicine Translational Genomics Core located at 65 Landsdown street at Cambridge. This lab performs this testing for all oth er current PBR PET studies conducted at MGH. 5.2.2 Stable dose of corticosteroids for 5 days prior to MR- PET scan as change in steroids can affect interpretation of the MRI scan. 5.2.3 Creatinine clearance >30 mL/min based on a serum creatinine level obtained within 30 days. 5.2.4 β-HCG in woman of childbearing age (prior to each MR- PET scans). Please see http://healthcare.partners.org/phsirb/Guidance/Pregnancy_Testing_in_Research_Involving_Radia tion.1.09.pdf for Pregnancy Testing guidelines) 5.3 MR-PET Scan Procedure 5.3.1 MRI Scan Image Acquisition Details : MR scans will be performed including T1- and T2-weighted volumetric images, fluid attenuated inversion recovery (FLAIR), contrast agent enhanced T1- weighted permeability, diffusion imaging , T2/T2*-weighted perfusion scans, and MR Spectroscopy. The “Autoalign” package available from the manufacturer will be used to achieve the same slice prescription in the same patient at each visit. Each MRI will last 60-75 minutes versus 45 minutes for standard brain MRIs. Gadolinium- diethylenetriaminepentaacetic acid (o r gadopentetate dimeglumine, Gd DTPA) will be used as a contrast agent. The maximum contrast dose that could be given is 0.3 mmol/kg per visit, in line with the FDA -approved dosing for this class of contrast agents. Image Analysis Details : MRI data will be analyzed per our usual techniques as have been reported previously. Image Interpretation Details : Interpretation will be performed at the Martinos Center for Biomedical Imaging. The results will not be automatically relayed to the patient or treating physician as it is unclear how these scans should be interpreted so should not influence patient management. If requested, we will share the data with the patient’s physician but again, should not Protocol A pilot study to evaluate PBR PET as an indicator of inflammation in brain tumor patients treated with chemoradiation or immunotherapy. Version Date: June 20, 2018 15 influence patient management . Patients and treating physic ians may be curious to see the images so we want to allow for sharing of the images. The detailed analysis required for interpretation of the data will not be in real time so will not be able to influence treatment decisions.