Inflammation in Primary and Secondary Malignancies of the Central Nervous System Using [C-11]-CS1P1

Inclusion Criteria: * Male or female, any race * Age ≥ 18 years * Capable of providing written informed consent OR having a legally authorized representative (LAR) to provide informed consent for volunteering to undergo research procedure * Has a clinical, radiographic, or pathological diagnosis of primary or secondary CNS malignancy that has not been treated with radiotherapy Exclusion Criteria: * Hypersensitivity to \[C-11\]-CS1P1 or any of its excipients * Contraindications to PET, CT or MRI (e.g. certain incompatible electronic medical devices, inability to lie still for extended periods) that make it potentially unsafe for the individual to participate * Prior cranial radiotherapy * Severe claustrophobia that would require general anesthesia * Women who are currently pregnant or breastfeeding * Any condition that, in the opinion of the Sponsor-Investigator or designee could increase risk to the participant, limit the participant's ability to tolerate the research procedures or interfere with the collection of the data (e.g., advanced renal or liver failure) * Current or recent (within 12 months prior to screening) participation in research studies involving radioactive agents such that the total research-related radiation dose to the participant in any given year would exceed the limits set forth in the U.S. Code of Federal Regulations (CFR) Title 21 Section 361.1. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?FR=361.1.