A tracer is a mildly radioactive substance that is either ingested or injected into an individual during a positron emission tomography (PET) scan. Once it enters the bloodstream, its concentration and movement can be tracked by a computer to monitor blood flow and identify active regions within the brain.

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Positron Emission Tomography (PET) is a technique used to create images of an active, living brain. The procedure involves administering a mildly radioactive substance, known as a tracer, to an individual either orally or via injection. This tracer enters the bloodstream, and its concentration in different brain regions is monitored. Since increased brain activity correlates with higher blood flow, a computer can track the tracer's movement to generate a map that distinguishes between active and inactive brain areas during a specific task.

Positron Emission Tomography (PET)

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

- Dynamic functional changes associated with cognitive skill learning of an adapted version of the Tower of London task

Studies Using PET Scans

Which Brain Imaging Technique Monitors Active Areas of the Brain by Measuring Blood Flow Using a Mildly Radioactive Substance?

Positron Emission Tomography (PET) scans have several significant drawbacks. They provide images with little detail, cannot precisely identify the timing of neural events, and necessitate exposing the brain to radiation. Due to these limitations, fMRI is often favored as an alternative diagnostic imaging technique.

Limitations of PET Scans

A Positron Emission Tomography (PET) scan creates pictures of the living, active brain by monitoring a tracer. As shown in the image, the scan produces a rough map where different parts of the brain are displayed in different colors to represent active and inactive areas during a given behavior.

Example of a PET Scan

Tracer

Although Positron Emission Tomography (PET) scans have largely been replaced by fMRI, hybrid CT/PET technology is still used in certain contexts because it combines the strengths of both techniques. In this approach, Computerized Tomography (CT) contributes clear images of brain structures, while PET shows the brain's activity. This combination allows for better imaging of neurotransmitter receptor activity, opening new avenues for research in areas such as schizophrenia.

Hybrid CT/PET Technology

Functional Magnetic Resonance Imaging (fMRI) offers significant advantages over Positron Emission Tomography (PET) scans. Specifically, fMRI produces images with greater structural detail and provides better temporal accuracy, meaning it can pinpoint the timing of brain activity more precisely than PET scans.

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