(11C)N-Desmethyl-Loperamide as a Marker of P-Glycoprotein Function in Patients With Gliomas

Background:

• The blood-brain barrier helps to protect the central nervous system (brain and spinal cord) from harmful toxins, but also prevents potentially useful chemotherapy from reaching brain tumors. The barrier is formed by tight connections between blood vessel cells and molecules found on the surface of brain blood vessels such as Permeability-glycoprotein (Pgp). Pgp may influence whether patients with brain tumors known as gliomas respond to chemotherapy and what side effects they may experience. The compound (11C)N-desmethyl-loperamide ((11C)dLop) reacts to Pgp molecules, and therefore may be used with positron emission tomography (PET) imaging to study the blood brain barrier.

Objectives:

• To study the ability of PET imaging with (11C)dLop to evaluate the blood brain barrier in brain tumor patients.

Eligibility:

• Individuals at least 18 years of age who have a brain tumor with characteristics that may be imaged with techniques such as magnetic resonance imaging (MRI) andPET.

Design:

• Participants will be screened with a full physical examination and medical history, blood and urine tests, and tumor imaging studies (fluorodeoxyglucose PET and MRI scans with contrast agent).
• The (11C)dLop scan will take 1 hour to perform. Participants will be asked to return for blood and urine tests approximately 24 hours after the PET scan.
• Participants will have followup visits at least every 4 months by repeating a complete history and physical exam and brain MRI. Participants may have repeat scans with (11C)dLop at various points in the course of cancer treatment, but will not have these scans more than twice in a 12-month period.
• Participants will be followed for as long as possible during treatment to see if imaging with (11C)dLop correlates with response to the treatments.