Assessment of femoral neck bone metabolism using 18F-sodium fluoride PET/CT imaging.

BACKGROUND: Standard of care metabolic bone disease assessment relies on changes to bone quantity, which can only be detected after structural changes occur. PURPOSE: To investigate the usefulness of Bone Metabolism Score (BMS), derived from fluorine 18 labeled sodium fluoride (18F-NaF) PET/CT imaging as a biomarker of localized metabolic changes at the femoral neck. METHODS: In this retrospective study, 139 participants (68 females and 71 males, ages 21-75 years) that had undergone 18F-NaF PET/CT were included. BMS was calculated as the ratio of standard uptake value (SUV) in the bone region to that of the total region. Correlations and linear regressions of BMS with age, CT-derived bone mineral density (BMD), body mass index (BMI), height, and weight were conducted. Differences in BMS between women younger and older than the age of 50 years were assessed. Inter- and intra-operator reproducibility was evaluated by coefficient of variation (CV) and intra-class correlation coefficient (ICC). RESULTS: Among females, age was negatively correlated with left and right whole BMS (5.61% and 4.90% drop in BMS per decade of life) and left and right cortical BMS (10.50% and 10.09% drop in BMS per decade of life). BMS of women older than 50 years was lower than BMS of women younger than 50 years (P < .0001). Among males, age was negatively correlated with left and right whole BMS (4.29% and 4.25% drop in BMS per decade of life) and left and right cortical BMS (9.13% and 10.30% drop in BMS per decade of life). BMD was positively correlated with whole (r = 0.80, P < .0001) and cortical (r = 0.92, P < .0001) BMS. CONCLUSIONS: BMS could provide functional insight regarding bone metabolism in the femoral neck to complement bone health status assessed through conventional structural imaging. The methodology described herein could be potentially useful for assessing hip fracture risk in individuals when BMD tests provide borderline determination of bone disease.

18F-sodium fluoride PET/CT provides prognostic clarity compared to calcium and Framingham risk scoring when addressing whole-heart arterial calcification.

AIMS: To investigate the benefit of utilizing 18F-sodium fluoride (NaF) PET/CT over calcium and Framingham scoring for potential preventative coronary artery disease (CAD) intervention. METHODS AND RESULTS: This retrospective study included 136 participants (ages 21-75, BMI 18-43 kg/m2): 86 healthy controls and 50 patients. CT heart segmentations were superimposed onto PET images and standard uptake values (SUV) were calculated by a semi-auto segmentation method of drawing volumes of interest around the heart. Intergroup comparisons were made matching 37 patient/control pairs based on age, gender, and BMI. ROC curves were generated to determine how well SUV and Framingham methods predicted patient status. Regressions including all 136 participants were performed between SUV, age, and BMI. Patients exhibited higher average SUV (SUVmean; P = 0.006) and Framingham scores (P = 0.02) than controls. However, ROC curves indicated that SUVmean could discriminate patients from controls (AUC = 0.63, P = 0.049), but Framingham scores could not (AUC = 0.44, P = 0.38). Calcium scores and maximum SUV (SUVmax) did not differ between patients and controls. SUVmean correlated with age and BMI among females (age, partial R2 = 0.16, P = 0.001; BMI, partial R2 = 0.12, P = 0.004) and males (age, partial R2 = 0.28, P < 0.0001; BMI, partial R2 = 0.22, P < 0.0001). CONCLUSION: Unlike calcium scores, NaF PET/CT-derived values differed between patients and controls. Framingham risk score patterns echoed those of SUVmean, but were not sensitive enough to predict patient status. SUVmean values increased with age and BMI. Therefore, incorporation of NaF PET/CT into routine prognostic CAD assessment might prove beneficial for assessing early stage plaque calcification in coronary arteries. TRIAL REGISTRATION: ClinicalTrials.gov (NCT01724749).