How does a PET scan work? | Nuclear medicine

Summary

Paulien, a Belgian nuclear medicine resident, introduces PET-imaging, distinguishing it from CT, X-ray, and MRI as a functional imaging technique. PET scans use radioactive tracers like (18F)-FDG to highlight areas of high glucose uptake, such as cancer cells, making them visible as bright spots. The technique is safe, with radiation exposure comparable to natural sources or a pilot's cosmic exposure, and is crucial for early cancer detection before structural changes are evident in other imaging methods.

Takeaways

• 📚 Paulien is a Belgian nuclear medicine resident introducing PET-imaging.
• 🌟 PET, CT, X-ray, and MRI are common imaging techniques with distinct purposes.
• 🔍 CT, X-ray, and MRI are structural imaging techniques focusing on detailed images of organs and tissues.
• 🌀 PET is a functional imaging technique showing how tissues work on a molecular level.
• 🩺 X-ray or CT scans are used for diagnosing bone injuries, while MRI is preferred for soft tissue injuries.
• 🦴 PET scans are performed when a bone tumor is suspected to examine organ function using a radioactive tracer.
• 🍬 The most common PET tracer is (18F)-FDG, a radioactive glucose molecule.
• ⏳ FDG's radioactivity decays, requiring timely scans to capture accurate images.
• 🌟 Cancer cells appear as bright spots on PET scans due to their high glucose uptake.
• 🔎 PET scans can detect cancer and monitor tumor changes before they are visible on other imaging techniques.
• 🛡️ PET scans are considered safe with radiation exposure comparable to natural sources or experienced by pilots on long flights.

Q & A

What is the primary difference between PET and other imaging techniques like CT, X-ray, and MRI?

The primary difference is that CT, X-ray, and MRI create detailed images of organs, bones, and tissues (structural imaging), whereas PET shows how tissues work on a molecular level (functional imaging).

Which medical field does PET imaging belong to?

PET imaging belongs to the field of nuclear medicine.

In what scenario might a doctor order a PET scan instead of an X-ray, CT, or MRI?

A doctor might order a PET scan if a bone tumor is suspected, as PET can detect cancer and show how big it is and whether it has spread.

What is the most commonly used tracer in PET scans, and what is it composed of?

The most commonly used tracer in PET scans is (18F)-FDG, which is a glucose molecule with a radioactive part attached to it.

How does a PET scan detect cancer cells in the body?

PET scans detect cancer cells by using a radioactive tracer that accumulates in cells using a lot of energy, such as cancer cells. These cells show up as bright spots on the scan.

What makes PET scans advantageous in detecting cancer compared to traditional imaging techniques?

PET scans are advantageous because they can detect changes in glucose use by tumors before changes in size, which can be seen earlier than with CT or X-rays.

Is the radiation exposure from a PET scan considered dangerous?

The radiation exposure from a PET scan is low and comparable to what you are exposed to over two or three years from natural sources or 25 long-distance flights. It is considered a safe procedure with benefits outweighing the risks.

How long does it take for half of the radioactivity from the FDG tracer to decay?

It takes a little under two hours for about half of the radioactivity from the FDG tracer to decay.

Why might a doctor choose an MRI scan for a ligament injury instead of a CT or X-ray?

A doctor might choose an MRI scan for a ligament injury because MRIs are better suited for examining soft tissue injuries, particularly in the ligaments or tendons.

What particles are emitted by the radioactive material in a PET scan, and how are they recorded?

The radioactive material in a PET scan emits tiny positively charged particles called positrons, which are recorded by a camera and turned into images on a computer.