This clinical trial is being conducted to study the use of a radioactive glucose tracer as an imaging test [Positron Emission Tomography (PET)scan] in adults who have or are suspected of having cancer and in another group of adults to assess for neurologic conditions.

Inclusion Criteria:

• Known or suspected primary or metastatic tumours
• A neurological presentation consistent with the list of indications
• 18 years of age or older of either sex
• Able to provide written informed consent
• Able to tolerate the physical and logistical requirements of completing a Positron Emission Tomography (PET)scan
• Karnofsky score > 60
• Women who are nursing may be included in the study if they are able to discontinue breast feeding for 12 hours

Exclusion Criteria:

• Age <18 years
• Pregnant women; if there is a possibility of pregnancy, bloodwork will be drawn to definitively establish pregnancy status
• Women who are unwilling or unable to discontinue breast feeding for 12 hours post 18F-Fluorodeoxyglucose(FDG) administration
• Subjects who are medically unstable
• Subjects unwilling to provide informed consent.
• Subjects who exceed the safe weight limit of the Positron Emission Tomography (PET) imaging bed or who cannot fit through the PET scanner bore