[18F] NaF PET Ki vs SUV — which one to use?

The choice between SUV (Standardized Uptake Value) and Ki (Plasma Clearance Method) for quantification in [18F]NaF PET depends on the context:

1. Use SUV: When bone metabolism and its treatment do not significantly alter the plasma clearance curve (AUC) of [18F]NaF. Why? SUV is easier, faster, and more practical for routine clinical settings, and it correlates well with Ki under normal conditions.

2. Use Ki: When there is a significant alteration in the AUC due to potent treatments or active disease. Examples of altered AUC conditions: (i) Potent anabolic treatment (stimulating bone growth). (ii) Active or extensive Paget’s disease. (iii) Extensive or highly active metastatic bone disease, such as in breast cancer. Why? In these cases, Ki provides a more reliable and precise measurement of bone metabolism than SUV.

Recent Developments: Methods to calculate Ki using a shorter scan (4–12 minutes) make it more practical and less costly than before, reducing barriers to its use in specific cases.

Conclusion: Use SUV for most routine clinical applications. Use Ki when there is evidence of altered plasma clearance due to potent treatment or aggressive bone disease.

Puri T, Frost ML, Moore AEB, Cook GJR, Blake GM. Input function and modeling for determining bone metabolic flux using [18F] sodium fluoride PET imaging: A step-by-step guide. Med Phys. 2023 Apr;50(4):2071–2088. doi: 10.1002/mp.16125. Epub 2022 Dec 17. PMID: 36433629.