413 Evaluation of Osteoporosis in the Lumbar Spine in Multiple Myeloma Patients Using 18F-NaF PET/CT

Abstract

INTRODUCTION: Multiple myeloma (MM) is a plasma cell malignancy that structurally damages and weakens the bone, most commonly in the spine, by inducing osteoporosis, osteolytic lesions and pathological fractures. Detecting molecular changes in bone metabolism, such as reduced osteoblastic activity and bone remodeling associated with MM, would allow for early diagnosis of osteoporosis in the lumbar spine and reduce risk for surgical spinal interventions. One such imaging candidate is 18F-NaF PET/CT, a molecular imaging technique sensitive to bone formation. METHODS: The FULIMA clinical trial (NCT02187731) was conducted with 70 newly diagnosed MM patients, with exclusion criteria leaving 33 patients for analysis (9 females, 24 males; mean age 66.6y). Patients’ trabecular body of the L1-L4 vertebrae was analyzed using 18F-NaF PET/CT scans to calculate and evaluate the linear associations among mean standardized NaF uptake value (SUVmean), mean Hounsfield unit (HU) values, and age. Receiver-operating characteristic (ROC) curve analysis with area under the curve (AUC) using the Wilson/Brown method assessed the predictive value of NaF uptake via SUVmean for osteoporosis determined by HU threshold. RESULTS: There was significant positive correlation between HU value and SUVmean (r = 0.64, p < 0.0001) and negative correlations between age and both HU value (r = -0.59, p < 0.0003) and SUVmean (r = -0.53, p = 0.002). Additionally, on average, there was a 29.1% difference in the NaF uptake of MM patients with osteoporosis (SUVmean = 7.0 ± 1.48) compared to normal MM patients (SUVmean = 4.96 ± 1.46). Predictive value of NaF per AUC analysis was 0.857 with p = 0.002. CONCLUSIONS: 18F-NaF PET/CT detects the decreased osteoblastic activity of osteoporosis in the lumbar spine with high precision and accuracy in MM patients, facilitating timely interventions and reducing risk for invasive procedures.