Dynamic Bone Imaging with 99mTc-Labeled Diphosphonates and 18F-NaF: Mechanisms and Applications

Ka Kit Wong; Morand Piert

doi:10.2967/jnumed.112.114298

FIGURE 1.
Diffusely increased ^99mTc-MDP uptake of left lower extremity on delayed-phase whole-body bone scan (anterior and posterior projections) as result of increased blood flow due to osteosarcoma in proximal tibia. INJ = injection site.
FIGURE 2.
An ¹⁸F-NaF 2-tissue-compartment model (3 compartments and 4 parameters).
FIGURE 3.
^99mTc-MDP bone scan for viability assessment of vascularized fibula graft in patient with osteonecrosis of jaw. On anterior, left, and right planar projections, angiographic (A) and soft-tissue (B) phases show nonspecific diffuse hyperemia overlying mandible due to surgical trauma. Delayed planar images (C) display focal increased uptake at genuine mandible near union sites of fibula graft. Transaxial and coronal SPECT/CT reveals photopenia in graft region (D). Regions of interest are defined in fibula graft (red) and calvarium (blue) on 3 consecutive slices to calculate graft-to-calvarium uptake ratio (41). Visual inspection and ratio result (0.72) are suggestive of nonviable graft.
FIGURE 4.
Plate fixation of vascularized fibula transplant (red arrow) after resection of osteosarcoma of right femur (A). Revision plate fixation was performed after fracture due to nonunion (yellow arrow). After injection of 370 MBq of ¹⁸F-NaF, dynamic PET study of mid thigh was performed for 60 min, followed by non–attenuation-corrected whole-body scan (B). Attenuation-corrected and axial slices (50–60 min) of hypertrophic nonunion (C) and fibular graft (D) areas show markedly increased uptake at nonunion and decreased uptake at level of fibula graft. Tissue time–activity curves (black squares) demonstrate rapid and sustained net-accumulation of radiotracer in nonunion but poor accumulation in fibula graft. Compartmental modeling was performed, providing estimates for total tissue activity (blue dots) and fraction of bound (red dots) and unbound (gray dots) radiotracer in tissue. At later time points, relationship of bound to unbound radiotracer is much higher in hypertrophic nonunion (C) than in failing graft (D).
FIGURE 5.
An 8-y-old boy with right hip pain and avascular necrosis of right femur head (Legg-Calve-Perthes disease). Anterior and posterior projection soft-tissue (A) and delayed-phase images (B) show focally decreased ^99mTc-MDP uptake in right femoral head.
FIGURE 6.
Breast cancer bone metastases identified on anterior and posterior projection whole-body bone scan in ribs, spine, pelvis, and left femur shaft (A). Treatment with denosumab results in near-normalization of scan findings (B), although with continued rise of tumor marker CA15-3. Three months after treatment, bone scan again identifies apparent disease progression (C).