[18F]SF12051 for Imaging the 18-kDa Translocator Protein (TSPO) in Brain and Whole Body of Healthy Subjects

Background:

Inflammation in the brain plays a role in many diseases. Being able to measure inflammation in a person's brain might help to diagnose and treat these diseases. One protein (TSPO) appears in higher numbers when inflammation affects the brain. To see TSPO when a person's body is scanned, researchers need a substance called a radiotracer that will attach to this protein and no other molecules.

Objective:

This study will test whether a new radiotracer (\[18F\]SF12051) can make TSPO appear on PET scans of a person's brain and body.

Eligibility:

Healthy people aged 18 and older.

Design:

This study requires 2 to 4 visits to the clinic.

All participants will be screened. They will have a physical exam. They will have blood tests and a test of their heart function.

Some participants will have a positron emission tomography (PET) scan of the whole body. The radiotracer will be injected through a tube (catheter) placed in a vein in the arm. The PET scanner is a machine shaped like a doughnut. Participants will lie on a bed that slides in and out of the scanner. The scan will take about 2 hours.

Some participants will have a PET scan of just their head. After they are injected with the radiotracer, they will lie on a bed with their head in the scanner. Blood will be drawn from a catheter in the wrist during the scan.

Some participants will have a magnetic resonance imaging (MRI) scan of the brain. They will lie on a narrow bed that slides into a tube.

Study Description:

This study is intended to provide information on the novel \[18F\]SF12051 radioligand and its ability to localize and measure TSPO in the brain and body of healthy individuals.

Objectives:

Primary Objective: To study the brain uptake of \[18F\]SF12051 and perform kinetic modeling of the \[18F\]SF12051 in the three different TSPO genotypes.

Secondary Objectives: To study the brain retest characteristics, biodistribution and dosimetry of \[18F\]SF12051 in healthy subjects.

Endpoints:

Primary Endpoint: The distribution volume of the radioligand and stability over time calculated with compartmental modeling, attention paid to differences in mean distribution volumes between TSPO genotypes for determining genotype sensitivity.

Secondary Endpoints: Retest variability and reliability and organ time- activity curves to determine biodistribution and dosimetry.

Eligibility Criteria:
* INCLUSION CRITERIA:

To be eligible to participate in this study, an individual must meet all of the following criteria:

* Aged 18 years or older.
* Healthy based on medical history, physical examination, and laboratory testing.
* Able to provide informed consent.
* Willing and able to complete all study procedures.
* Have been screened for TSPO genotype under 01-M-0254 "The Evaluation of Patients with Mood and Anxiety Disorders and Healthy Participants".
* Have their radial artery pulse checked for the presence of adequate ulnar collateral flow and the absence of any metal or foreign objects in both wrists\*.
* Agree to adhere to the lifestyle considerations

  * Does not apply to Phase 1 and 3 participants as they will not have an arterial line.

EXCLUSION CRITERIA:

An individual who meets any of the following criteria will be excluded from participation in this study:

* Clinically significant abnormalities on EKG or laboratory testing. This includes CBC; acute care panel (Na, K, Cl, CO2, creatinine, glucose, urea nitrogen); hepatic panel (alkaline phosphatase, ALT, AST, bilirubin total, and bilirubin direct); mineral panel (albumin, calcium, magnesium, phosphorus); prothrombin and partial prothrombin tests.
* Participants should not have taken NSAIDs or willow bark tea for two weeks prior to the PET scan.
* Any current Axis I diagnosis.
* Positive test for HIV.
* Unable to have an MRI scan\*.
* History of neurologic illness or injury with the potential to affect study data interpretation.
* History of seizures, other than in childhood and related to fever.
* Recent exposure to radiation (i.e., PET from other research) which when combined with this study would be above the allowable limits.
* Inability to lie flat on camera bed for at least two hours, including claustrophobia and weight greater than the maximum for the scanner (500 lbs).
* Pregnancy or breast feeding.
* Able to get pregnant but does not use birth control.
* Participants must not have substance use disorder or alcohol use disorder. However, alcohol or cannabis use by themselves are not exclusion criteria, unless that use affects the function of daily life.
* Unable to travel to NIH.
* National Institute of Mental Health (NIMH) staff or an NIH employee who is a subordinate/relative/co-worker of the investigators.

  * Phase 1 and 3 participants will not get an MRI.