Uptake of Technetium-99m Sestamibi (99mTc-MIBI) as a Predictor of Fracture Risk in the Appendicular Skeleton of Multiple Myeloma Patients at a National Reference Center.

Background and objective Skeletal involvement in multiple myeloma frequently results in pathological fractures, which significantly increase morbidity and functional disability. Advanced imaging modalities such as PET/CT and whole-body MRI are considered reference techniques for disease assessment; however, their availability remains limited in many healthcare systems. The objective of this study is to evaluate the association between 99mTc-MIBI uptake and pathological fracture occurrence in the appendicular skeleton of patients with multiple myeloma and to determine whether radiotracer uptake and lesion morphology predict fracture timing. Methods A retrospective observational study was conducted, including patients with histologically confirmed multiple myeloma who underwent technetium-99m sestamibi (99mTc-MIBI) scintigraphy between 2014 and 2021. Radiotracer uptake was assessed qualitatively. Fractures were confirmed radiographically and classified as early (less than six months) or late (more than six months). Logistic regression analysis was performed to identify independent predictors. Results The cohort included 121 patients (median age 61.5 ± 12.5 years), including 69 men (57%) and 52 women (43%). Uptake of 99mTc-MIBI occurred most frequently in the humerus (31; 27.9%), axial skeleton (19; 17.1%), and femur (10; 9.0%). Pathological fractures occurred in 94 patients (77.7%), including 86 early fractures (71.1%) and eight late fractures (6.6%). In bivariate analysis, cortical erosion (χ² = 2.9; p = 0.023) and age >63 years (t = 2.4; p = 0.02) were associated with fracture. Multivariate logistic regression identified expansile lesions with cortical erosion as the strongest predictor of fracture (OR 2.1; 95% CI: 0.8-5.7). Conclusions 99mTc-MIBI scintigraphy may represent a valuable adjunct imaging modality for the assessment of skeletal involvement in patients with multiple myeloma, particularly in resource-limited settings where advanced imaging techniques such as whole-body MRI or PET/CT are not readily accessible. Although cortical erosion continues to be the most reliable structural predictor of impending fracture, 99mTc-MIBI uptake offers complementary functional insight into the metabolic activity and tumor burden of myelomatous lesions. This functional information may be especially relevant in identifying lesions at higher risk of progression or early structural compromise, even before overt radiographic changes become evident. Therefore, 99mTc-MIBI could potentially contribute to a more comprehensive risk assessment when integrated with conventional imaging findings and clinical parameters. However, given the heterogeneity of disease presentation and the limited sample size of current studies, including the present analysis, these findings should be interpreted with caution. Future prospective studies with larger cohorts and standardized imaging protocols are warranted to further elucidate the prognostic value of 99mTc-MIBI uptake and to determine its potential role in fracture risk stratification and treatment decision-making algorithms.