Jump to content

Has anyone had any false positives on thier PET scan?


Recommended Posts

Has anyone had any "hot spots" light up on thier PET that was later determined to not be cancer? I had my spine light up the first time, they then later decided via CT it was arthritis that can be metabolically active.

I also have one node in my pelvis that lit up, but they don't think its anything. Its a tough spot to biopsy. They also said it would be a weird place for a met, a line node in my pelvis and nowhere else.

They told me "cold" is usually accurate, but "hot" can sometimes be something else.




Link to comment
Share on other sites


I asked this question a few months back and heres what everyone told me. False positives are far more common than false negatives. Things light up all the time that just plainly arent cancer. My dad had something light up in his neck that turned out not to be cancer.

I know that false negatives, although not unheard of... dont happen nearly as much as a false positive.

Hope this helps


Link to comment
Share on other sites

They thought cancer had metasticized to my Dad's femur because the PET lit up. As a matter of fact, he was treated as Stage 4 for awhile. Then another CT and no change in the femur, followed by a PET which again lit up. We were told it was very small.... I asked for another opinion from a radiation oncologist as well as a second opinion at Sloan. Final decision, it wasn't a metasticis. Don't know what it was but it wasn't a mets. So there you have it. These sophisitcated tests aren't perfect.

Gail P-M

Link to comment
Share on other sites

My mom actually had a false negative. However, the false negative was only for the mediastinal lymph nodes and not the actual lung tumor. If you read below, the PET is a little less accurate for mediastinal lymph nodes.

http://www.petscaninfo.com/zportal/port ... ensitivity

Sensitivity The fraction of those with the disease correctly identified as positive by the test.

Specificity The fraction of those without the disease correctly identified as negative by the test

False positives are possible 4% of the time according to the above website.

False negatives are possible 27% according to the above website


The above web site about says 90% specific and 92% sensitive

Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.

PURPOSE: To determine the accuracy of 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in the evaluation of regional lymph nodes in patients with stage I non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Imaging and clinical findings obtained during 5 years in 84 patients (mean age, 66 years) were reviewed. Patients had thoracic computed tomographic findings of stage I NSCLC, an FDG PET study, and histopathologic proof of lung cancer. At the time of diagnosis, disease stage was assigned on the basis of FDG PET results and was compared with the histopathologic stage to determine the accuracy of PET. RESULTS: When PET stage was compared with histopathologic stage, the disease in 72 (86%) patients was accurately staged with PET, understaged in two (2%), and overstaged in 10 (12%). The overall sensitivity, specificity, and positive and negative predictive values for PET of regional lymph nodal metastases were 82%, 86%, 47%, and 97%, respectively. CONCLUSION: FDG PET enables accurate staging of regional lymph node disease in patients with stage I NSCLC. A negative PET scan in these patients suggests that mediastinoscopy is unnecessary and that these patients can proceed directly to thoracotomy.


Link to comment
Share on other sites

Jen, I had a hot spot show up in my groin on one of my PET Scans. I had the scan shortly after I had a proceedure to retrieve my catheter from my port which had floated up into my neck. They went into a vein in my groin with a wire all the way up into my neck and "fished" and pulled the catheter back into place. I think a PET scan will pick up any area with trauma to it.

David C

Link to comment
Share on other sites


My mother had a spot or 2 on her lower lumbar region light up. From the onset the radiologist thought it was arthritis or trauma but her oncologist performed a bone biopsy just to be sure and that came back clean. We haven't given it much thought since. I've heard this is quite common but needs to be checked out. The biopsy was not bad at all for her, her onc believes in lots of lidocaine. We stopped for lunch on the way home from the biopsy. Hope you get some peace of mind soon.

Thinking of you.


Link to comment
Share on other sites

Guest bean_si (Not Active)


Following is from article geared to professionals who read PET scans - link below. Now, it seems to me, if they have to address the professionals to be careful in the interpretation of scans, there definitely is a problem! That is, false positives could be a possibility depending on who is reading the scan.

"Such pitfalls include variable physiologic FDG uptake in the digestive tract, thyroid gland, skeletal muscle, myocardium, bone marrow, and genitourinary tract and benign pathologic FDG uptake in healing bone, lymph nodes, joints, sites of infection, and cases of regional response to infection and aseptic inflammatory response. In many instances, these physiologic variants and benign pathologic causes of FDG uptake can be specifically recognized and properly categorized; in other instances, such as the lymph node response to inflammation or infection, focal FDG uptake is nonspecific."

http://intl-radiographics.rsnajnls.org/ ... ll/19/1/61

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.