Objective  The factors related to the maximum standardized value (SUV_max) of bone metastases in ¹⁸F-sodium fluoride (NaF) PET/CT whole-body bone imaging were analyzed.

Methods  A retrospective analysis was performed on 233 patients who underwent ¹⁸F-NaF PET/CT whole-body bone imaging in the Affiliated Hospital of Guilin Medical College from August 2020 to December 2022 and were clinically diagnosed as malignant tumor with bone metastases, including 113 males and 120 females, aged (57.9±10.7) years. Clinical diagnosis included clinical data, other imaging examinations (CT, MRI, ⁹⁹Tc^m-methylenediphosphonate SPECT/CT, ¹⁸F-fluorodeoxyglucose PET/CT) and histopathology. We analyzed the relationship between type of bone destruction, the parts of bone metastasis, the primary malignant tumor, the history of treatment and SUV_max of bone metastases. The patients were divided into treated group and untreated group according to whether they received antitumor therapy. Two independent sample t-test, corrected t-test and Mannu-Whitney U test were used for comparisons between the two groups, and one-way analysis of variance was used for comparisons between multiple groups.

Results  A total of 2 737 bone metastases were found in 233 patients with malignant tumor. The incidence of bone metastasis in all parts of the body varied from high to low as follows: spine bone 41.1% (1 126/2 737), chest bone 26.1% (714/2 737), pelvic bone 20.9% (571/2 737), quadrilateral bone 7.0% (192/2 737), and skull 4.9% (134/2 737). Analysis of the type of bone destruction in bone metastases revealed that the SUV_max of mixed type was higher than that of osteolytic and osteogenic types, and the difference was statistically significant (22.8 vs. 19.7 vs. 16.7; Z=5.323, 7.160; both P<0.001).When analyzed according to the parts of bone metastases, SUV_max decreased in the following order: pelvic bone 21.8 (15.5, 31.7), spine bone 21.6 (15.0, 32.0), quadrilateral bone 19.4 (13.6, 29.1), chest bone (including clavicle, scapula, sternum, and ribs) 17.4 (12.6, 24.2), and skull 14.8 (11.4, 19.3). In terms of primary malignant tumors, small cell lung cancer, gastric cancer, rectal cancer, and nasopharyngeal carcinoma had higher SUV_max values than other malignant tumors. The SUV_max of bone metastasis from malignant tumor in the untreated group was higher than that in the treated group, and the difference was statistically significant 22.0 (15.1, 32.5) vs. 18.9 (13.5, 28.9); Z=6.005; P<0.001.

Conclusion  The SUV_max of bone metastases in ¹⁸F-NaF PET/CT whole-body bone imaging was related to the type of bone destruction, parts of bone metastases, primary malignant tumor, and the history of treatment.