[Kate]

F-18 FDG PET vs F-18 sodium fluoride (F-NaF) PET

by Kate on Sat Apr 25, 2015 4:34 pm

Hi All,

I am kind of wondering about the following statement on my first PET/CT scan (had other scans since late 2012):

"1. No suspicious hyper-metabolic osseous activity. Please note decreased sensitivity for F-18 FDG PET in the setting of multiple myeloma. Recommend consideration for F-18 sodium fluoride PET which has increased sensitivity for osseous disease ..."

No osseous activity sounds good to me. Means whatever they found previously is stable (right?) However, not even Dr. Prashant Kapoor in his Beacon article "To PET or not to PET" mentioned that F-18 sodium fluoride PET is better for osseous disease (e.g. bone connected).

If this is the case, why wasn't the F-18 sodium fluoride PET the first scan of choice as it was known that I have bone lesions?

I will ask my doc of course when I see him in 2 weeks, but am curious meanwhile if someone else had a similar experience.

Kate

[JimNY]

Re: F-18 FDG PET vs F-18 sodium fluoride (F-NaF) PET

by JimNY on Sat Apr 25, 2015 5:30 pm

Hi Kate,

I've never seen a statement like the one that was in your report. In fact, when I checked to see what research has been done comparing the two PET techniques in myeloma, the research I found suggests that FDG is the better of the two.

A German study with 60 multiple myeloma patients compared the two techniques and found that FDG was more appropriate for tracking multiple myeloma-related bone damage. The researchers wrote

"(18) F-FDG PET/CT proved to be a more specific biomarker than (18) F-NaF PET/CT in multiple myeloma skeletal assessment."

The sodium fluoride tracer seemed better at picking up "degenerative, traumatic and arthritic disease lesions." Here's a reference and link to the study (only the abstract is available):

C Sachpekidis et al, "PET/CT studies of multiple myeloma using 18 F-FDG and 18 F-NaF: comparison of distribution patterns and tracers’ pharmacokinetics," European Journal of Nuclear Medicine and Molecular Imaging, July 2014 (abstract)

I'd still discuss this further with your doctor, but it doesn't seem like you should be too worried about the comment based on the results of the study I just mentioned.

[Kate]

Re: F-18 FDG PET vs F-18 sodium fluoride (F-NaF) PET

by Kate on Sat Apr 25, 2015 7:37 pm

Thanks Jim,

I had done all kinds of searches and your link didn't come up. It's great info.

Kate

[Dr. Prashant Kapoor]

Re: F-18 FDG PET vs F-18 sodium fluoride (F-NaF) PET

by Dr. Prashant Kapoor on Mon Apr 27, 2015 9:00 am

Sodium fluoride 18F-NaF PET/ CT is used to detect many benign and cancerous bone lesions (prostate, thyroid, lung, and breast, etc.). Multiple myeloma is, unfortunately, not one of the cancers where NaF PET would have any significant value over FDG PET. NaF only accumu­lates in sites where bone remodeling is taking place – not necessarily in all lytic lesions alone.

I would advise against doing additional NAF PET on you. A recent study has compared the two modalities in myeloma and found FDG PET/CT to be superior. Moreover, many false positive results can occur with NaF PET/CT (old rib fractures, etc.).

The low dose CT portion of these tests helps in detecting lytic lesions of the bone. The PET scan assesses activity within those lesions.

The concept behind NaF PET is that the tracer gets accumulated even in early bone lesions by integrating to a mineral called hydroxyapatite within any areas of the bones that are actively undergoing remodeling. Therefore, the test is not specific for cancerous sites.

FDG PET, for that matter, also is not specific for cancerous lesions. However, it has consistently shown value in detecting areas of active bone involvement in myeloma as actively growing malignant plasma cells in myeloma bone lesions are consistently taking up and trapping the glucose of FDG, and they therefore are detected in FDG PET/CT scans.

[Kate]

Re: F-18 FDG PET vs F-18 sodium fluoride (F-NaF) PET

by Kate on Mon Apr 27, 2015 6:04 pm

This was my first PET/CT scan, Dr. Kapoor, and I based my consent for it on research and especially on your recent Myeloma Beacon forum posting "To PET or not to PET".

I am absolutely thrilled with the additional info you have provided, not only to me, but to many other interested members.

Your explanations validated my decision not to have the additional PET/CT (F-NaF).Thank you for giving some of your valuable time.

Kate