[risper6]

Why do a PET scan if MRI is negative?

by risper6 on Thu Jan 30, 2014 1:31 pm

OK ... I'm completely confused.

My mom is 3 yrs. s/p SCT and has been doing great. After SCT she received no treatment at all. At her follow up in November her bloodwork and urine were good -- still in CR.

Come December, she had severe pain at T1. Initial diagnosis was plasmacytoma at T11.

Just saw the doctor ast week. d/t this new pain that's been persistent and it's causing her to be SOB and have chest "heaviness" and heart rate that goes up to 150 at times (usual heart rate prior to his horrible pain was 80-90).

MRI was negative, bloodwork still good. MD has now ordered PET scan.

I guess I'm just confused because the MRI was negative, bloodwork negative, chest x-ray negative, EKG and 24 hr. monitor negative to r/o any cardio issues.

I know a PET is expensive and also exposes her to a lot of radiation. I have to assume there's something he thinks the PET may find that the MRI didn't find?

Oh, I should mention that she was found to have a hiatal hernia. Other than that ... healthy.

I guess maybe I'm not sure about what a PET would show if the MRI didn't show anything. Is it common to see nothing on MRI but then see something on PET scan?

Thanks.

[Multibilly]

Re: Why do a PET scan if MRI is negative?

by Multibilly on Thu Jan 30, 2014 2:01 pm

Did she have a whole body MRI, or just an MRI of her spine? A lot of places simply aren't equipped for whole body MRIs (sadly, no place in my state offers one). On the other hand a PET/CT is set up to scan one's entire body. It seems prudent to be doing whole-body imaging under the circumstances.

But if she already had a whole body MRI, it seems reasonable to be questioning if a PET/CT is necessary.

You might find this to be insightful.

http://www.ncbi.nlm.nih.gov/pubmed/19304704

BTW, on the subject of X-ray versus PET/CT or MRI, I always like to point folks to Dr. Landgren's recent findings on p 20 below. One of the discoveries as he was screening patients for a smoldering trial was that 30% of allegedly smoldering patients were found to be symptomatic by virtue of being misdiagnosed through the use of X-ray imaging alone.

http://static9.light-kr.com/documents/IMW2013/Landgren%20-%20CRd%20Smoldering%20Myeloma.pdf

So, while I hate the thought of all the extra radiation with PET/CT and since I can't get a whole body MRI, I reluctantly embrace PET/CTs as a tool to be used periodically and judiciously.

[rocco24]

Re: Why do a PET scan if MRI is negative?

by rocco24 on Tue Feb 04, 2014 8:07 pm

Hi risper6,

You have valid questions, the same I also had prior to my PET/CT scan after a finding of an extramedullary plasmacytoma on my tonsil.

Remember, these tools are meant to create a correct diagnosis of the disease, correct being a keyword. I don't have the paper on me at the moment, but I remember reading stats saying that the use of a PET/CT helped many patients who were previously misdiagnosed receive correct treatment. Once I understood the need, I was more comfortable with the tests. Second, the amount of radiation might look concerning; however, the amount (if you search yourself) has a max of 50 mSv and an average amount lower than that. Compared to the amount of radiation needed to treat a plasmacytoma (45 Gray or higher i.e. 45000 mSv), the amount is a footnote to the greater amount.

If I were in your position, I would definitely do the PET/CT. The amount the tests help far outweigh the negatives.

Hope I have helped.