Automated reference region extraction and population-based input function for brain [(11)C]TMSX PET image analyses.

Area of Science:

• Neuroimaging
• Radiochemistry
• Pharmacology

Background:

• [(11)C]TMSX is a selective adenosine A2A receptor (A2AR) radioligand used in positron emission tomography (PET).
• A2ARs in the central nervous system (CNS) influence dopamine D2 receptor function and inflammation.
• Arterial blood sampling for input function is the gold standard but is invasive and burdensome.

Purpose of the Study:

• To evaluate alternative, noninvasive methods for acquiring the arterial input function for brain [(11)C]TMSX PET imaging.
• To develop and validate a supervised clustering method for gray matter reference region extraction (SCgm).
• To implement and assess a population-based arterial input function (PBIF).

Main Methods:

• Development of an automated supervised clustering method (SCgm) for gray matter reference region extraction.
• Implementation of a population-based arterial input function (PBIF) derived from study data.
• Validation of SCgm and PBIF using data from 28 subjects, including healthy controls and patients with neurological conditions.

Main Results:

• The population-based arterial input function (PBIF) showed good correlation with plasma input.
• The supervised clustering gray matter (SCgm) method produced results comparable to using the cerebellum as a reference region.
• Both SCgm and PBIF were found to be feasible and robust for dynamic [(11)C]TMSX brain PET analyses.

Conclusions:

• Noninvasive methods, including SCgm and PBIF, are viable alternatives to arterial blood sampling for [(11)C]TMSX PET.
• These methods can be reliably applied in patients with central nervous system (CNS) pathology.
• The developed techniques enhance the practicality and patient comfort of A2AR imaging.