Extended Pattern of Uptake

Extended pattern of uptake, also referred to as contiguous bone activity, is a potential diagnostic pitfall in interpreting bone scans where there is increased uptake in normal bone adjacent to a focal lesion.

This uptake in bone definitely beyond the proven limit of a focal bone lesion can be seen in both benign and malignant conditions and is thought to be related to hyperemia. It has been reported in the setting of trauma, osteomyelitis, benign giant cell tumor, avascular necrosis, and thrombophlebitis, as well as malignancies like primary bone tumors (e.g., osteosarcoma), metastatic disease (rare), and soft-tissue neoplasms.

The images above are from a patient with a giant cell tumor of the lateral proximal tibia complicated by a fracture. The bone scan shows intense uptake in the proximal tibia and mild/moderate uptake in the distal femur.

References

• Chew FS, Hudson TM. Radionuclide bone scanning of osteosarcoma: falsely extended uptake patterns. AJR Am J Roentgenol. 1982 Jul;139(1):49-54.
• Thrall JH, Geslien GE, Corcoron RJ, Johnson MC. Abnormal radionuclide deposition patterns adjacent to focal skeletal lesions. Radiology. 1975 Jun;115(3):659-63.