The Kinetics and Reproducibility of ¹⁸F-Sodium Fluoride for Oncology Using Current PET Camera Technology

Abstract

We evaluated the kinetics of 18F-sodium fluoride (NaF) and reassessed the recommended dose, optimal uptake period, and reproducibility using a current-generation PET/CT scanner. Methods In this prospective study, 73 patients (31 patients with multiple myeloma or myeloma precursor disease and 42 with prostate cancer) were injected with a mean administered dose of 141 MBq of 18F-NaF. Sixty patients underwent 3 sequential sessions of 3-dimensional PET/CT of the torso beginning ~15 min after 18F-NaF injection, followed by a whole-body 3-dimensional PET/CT at 2 h. The remaining 13 prostate cancer patients were imaged only at 2 and 3 h after injection. Twenty-one prostate cancer patients underwent repeat baseline studies (mean interval, 5.9 d) to evaluate reproducibility. Results The measured effective dose was 0.017 mSv/MBq, with the urinary bladder, osteogenic cells, and red marrow receiving the highest doses at 0.080, 0.077, and 0.028 mGy/MBq, respectively. Visual analysis showed that uptake in both normal and abnormal bone increased with time; however, the rate of increase decreased with time. A semiautomated workflow provided objective uptake parameters, including the mean standardized uptake value of all pixels within bone with SUVs greater than 10 and the average of the mean SUV of all malignant lesions identified by the algorithm. The values of these parameters for the images beginning at ~15 min and ~35 min were significantly different (0.3% change/minute). Differences between the later imaging time points were not significant (P < 0.01). Repeat baseline studies showed high intraclass correlations (>0.9) and relatively low critical percent change (the value above which a change can be considered real) for these parameters. The tumor-to-normal bone ratio, based on the SUVmax of identified malignant lesions, decreased with time; however, this difference was small, estimated at ~0.16%/min in the first hour. Conclusion 18F-NaF PET/CT images obtained with modest radiation exposures can result in highly reproducible imaging parameters. Although the tumor-to-normal bone ratio decreases slightly with time, the high temporal dependence during uptake periods < 30 min may limit accurate quantitation. An uptake period of 60 ± 30 min has limited temporal dependence while maintaining high tumor-to-normal bone ratio.

Prospective Study Evaluating Na18F PET/CT in Predicting Clinical Outcomes and Survival in Advanced Prostate Cancer

“…These results have been previously reported (15). The secondary objective of the study, as reported here, was to assess changes in Na 18 F over time and their ability to predict clinical outcomes.…”

“…Several studies have evaluated the ability of Na 18 F PET/CT to detect bone metastases compared with other nuclear and radiologic modalities, with highly favorable results for Na 18 F PET/CT (7)(8)(9)(10)(11)(12)(13)21,22). Na 18 F PET/CT demonstrated high reproducibility in a prospective study of dual baseline scans in patients with prostate cancer and multiple myeloma (15), supporting its clinical value in oncology practice. Still, many clinicians are reluctant to embrace Na 18 F PET/CT as it is unclear whether it is overly sensitive and thus does not accurately represent disease status.…”

Repeatability of Quantitative 18F-NaF PET: A Multicenter Study

“…Radiolabeled sodium fluoride, 18 F-NaF, was first introduced by Blau et al in 1972 (3) for the detection of bone lesions with PET. However, 18 F-NaF was largely replaced by bone scintigraphy using 99m Tc because of superior imaging characteristics with conventional g-cameras and the readily available supply of 99m Tc (3)(4)(5)(6).…”

“…However, 18 F-NaF was largely replaced by bone scintigraphy using 99m Tc because of superior imaging characteristics with conventional g-cameras and the readily available supply of 99m Tc (3)(4)(5)(6). With recent technologic advances in PET, 18 F-NaF PET has been increasingly used for detecting bone metastases because of its higher specificity and sensitivity as compared with planar bone scintigraphy and SPECT (4,5,(7)(8)(9)(10).…”

“…With recent technologic advances in PET, 18 F-NaF PET has been increasingly used for detecting bone metastases because of its higher specificity and sensitivity as compared with planar bone scintigraphy and SPECT (4,5,(7)(8)(9)(10). 18 F-NaF PET shows potential for longitudinal disease assessment, as its SUV in both normal and pathologic bone is representative of changes in bone metabolism (11)(12)(13).…”