The incremental value of radionuclide bone scintigraphy in fibrous dysplasia of bone

Objectives Fibrous dysplasia (FD) is a benign bony neoplasm in which the osteoblasts fail to differentiate normally, leading to osteolytic lesions. Although any bone may be involved, it frequently occurs in only one bone (monostotic). Typical sites of involvement include the skull, femur, tibia, and humerus. Objective: The purpose of our study is to determine the incremental value of radionuclide bone scans in FD.

Methods We evaluate 15 patients with FD including 4 cases of McCune-Albright syndrome. Planar 99mTc-hydroxymethyldiphosphonate (HMDP) bone scintigraphy± SPECT-CT, was performed 2 hours after intravenous injection of 10mega Becquerel per kilogram (10MBq/kg) of the radiotracer.

Results Although FD showed nonspecific increased 99m-Tc HMDP uptake, its appearance is different than bone metastases and other bone diseases. Combining scans with X-rays and other imaging modalities can improve the diagnostic accuracy of this disease. SPECT-CT when performed provided better identification and interpretation of the foci of radioiodine uptake, more correct anatomic localization and characterization, and precise differentiation between tumor lesions and physiologic uptake.

Conclusions Radionuclide bone scans are of certain value in the diagnosis of FD and useful in determining the extent of the skeletal involvement especially in polyostotic lesions. The diagnostic specificity of FD with radionuclide bone scanning can be improved in association with other imaging modalities such as X-rays. SPECT-CT enhances sensitivity for lesions detection over planar bone scintigraphy. In addition to improve anatomic localization of scintigraphic findings, this equipment offers the opportunity to add true diagnostic information derived from CT imaging.