PET scan for thyroid cancer before surgery

zeyd · February 26

Hi,

Is there a recommended guideline for utilizing PET scans in identifying cancerous thyroid nodules and possible metastasis to the neck lymph nodes?

I recognize that ultrasound (US), computed tomography (CT), and ultimately fine-needle aspiration (FNA) are preferred methods. However, if these techniques fail to provide a conclusive diagnosis, how effective or practical is a PET scan? Additionally, for the radiotracer, would FDG be used, or would another substance be preferable?

Thank you!

wbcgaruss · February 26

Hello, zeyd, I don't know if I have the answers you are seeking but I already have some knowledge on this and your questions got me searching a little. And there is a lot of information so I am not going to post it all here. I will post some links further down. I learned a lot from this.

I think the answer to guidelines for PET Scans is going to be if the patient has any of a handful of ailments it covers. PETs are not just used for cancer...so depending on your disease would be if a pet is considered.

What does a PET scan check for?

Your healthcare provider may order a PET scan to check for signs of:

Cancer, including breast cancer, lung cancer and thyroid cancer.
Coronary artery disease, heart attack or other heart problems.
Brain disorders, such as brain tumors, epilepsy, dementia and Alzheimer’s disease.

Positron Emission Tomography (PET)—Overview

Positron emission tomography (PET)Positron emission tomography (PET) is a test that uses a special type of camera and a tracer (radioactive substance) to look at organs in the body. The tracer usually is a special form of a substance (such as glucose) that collects in cells that are using a lot of energy, such as cancer cells.

During the test, the tracer liquid is put into a vein (intravenous, or IVIV) in your arm. The tracer moves through your body, where much of it collects in the specific organ or tissue. The tracer gives off tiny positively charged particles (positrons). The camera records the positrons and turns the recording into pictures on a computer.

PET scan picturesPET scan pictures do not show as much detail as computed tomography (CT) scans computed tomography (CT) scans or magnetic resonance imaging (MRI)magnetic resonance imaging (MRI) because the pictures show only the location of the tracer. The PET picture may be matched with those from a CT scan to get more detailed information about where the tracer is located.

A PET scan is often used to evaluate cancer, check blood flow, or see how organs are working.

As far as the second part of your question regarding ultrasound (US), computed tomography (CT), and ultimately fine-needle aspiration (FNA) and you are asking what if as far as if they fail. Well, I don't think there is a failure there as far as what the final result is supposed to be and that is to identify if a person has cancer and if so what type. Your first testing item you listed was ultrasound which is used but I don't recall in my cases or many others being used. It seems the standard protocol is if you have a soreness in your throat, H&N area anywhere many times people will go to their primary care doctor and then be sent to an ENT. If the ENT sees anything suspicious or feels a lump or bump he will then send you for a CT Scan with Contrast, as far as I know, this scan will almost always or in fact always indicate to them if someone has cancer or in fact there is something suspicious there. Then the next step in to get some direct tissue from the suspected area, a biopsy to have it lab checked for any cancer and what type. It can be a fine needle biopsy or as I had in my first cancer the ENT I think took a direct sample of my throat cancer but I never asked, just assumed because I don't know exactly how it was done because I was asleep. So I won't say it is impossible but I don't see a fail here. I think your doctors will keep diggin till they get you an answer.

After this is completed and they find the patient does in fact have cancer then they do the PET scan which shows on the scan and it is a whole body scan (Eyes to Thighs) to determine whether cancer has spread to anywhere else in the body so they know what they are dealing with. Generally, most people with H&N cancer I read about on the forum and elsewhere seldom have a second location of cancer to deal with, a metastasis.

As far as radio tracers I believe FDG is the prominent one that is generally used but I have a ling to an explanation and a list of 14 different tracers that can be used...

https://radiopaedia.org/articles/pet-radiotracers

Below are links to pages with a lot of good information on them. From Mayo and Cleveland Clinic and from Cigna Healthcare, and a couple of links to videos.

Positron emission tomography scan-Mayo Clinic

https://www.mayoclinic.org/tests-procedures/pet-scan/about/pac-20385078

PET Scan-Cleveland Clinic

https://my.clevelandclinic.org/health/diagnostics/10123-pet-scan

Positron Emission Tomography (PET) Cigna Healthcare

https://www.cigna.com/knowledge-center/hw/medical-tests/positron-emission-tomography-aa80345

Some videos.

Here is the first one which is technical but explanatory and shows and discusses scan results at the end showing you how it works...

How do PET scans work to detect things such as cancer?

https://www.youtube.com/watch?v=I7ZYRkafj8Q

Here is another good one explaining things well...

How and when should PET Scans be used? What do they show?