Role of nuclear medicine in musculoskeletal imaging
What role does nuclear medicine have in musculoskeletal imaging?
• Bone scintigraphy (bone scan) is routinely performed with 99mTc-labeled diphosphonates, which are adsorbed onto the surface of the bone proportional to the local osteoblastic activity and skeletal vascularity. Bone scans are therefore sensitive in detecting bone abnormalities but somewhat nonspecific as tumor, trauma, infection, or other pathology can all cause increased tracer uptake. Bone scintigraphy is the screening examination of choice for the evaluation of bony metastatic disease and Paget’s disease, as it images the entire skeleton. Bone scans commonly detect metastatic disease or osteomyelitis while plain radiographs are still normal, as up to 50% of bone must be decalcified for radiographic detection of tumor or infection versus a tiny fraction for bone scan. Bone scintigraphy can also detect stress fractures earlier than radiographs.
In arthritis, MRI and ultrasonography have replaced bone scintigraphy. Other common indications for bone scanning are in the evaluation of chronic regional pain syndrome or metabolic bone disease.
- • Single-photon emission CT allows increased sensitivity and specificity when assessing spinal pathology. It is frequently combined with conventional CT scanning to map an abnormality on bone scan to an exact anatomic site (facet joint, pars intraarticularis, or vertebral body)
- • Positron emission tomography (PET) typically uses 18 F-Fluorodeoxyglucose which goes to the sites of increased glucose utilization to map metabolically active bone and soft tissue, providing precise anatomic localization of lesions. Rheumatic diseases such as large vessel vasculitis, osteomyelitis, and sarcoidosis may be encountered. It is most commonly used in oncologic imaging for both diagnosis and monitoring of treatment.