Does a bone scan show increased activity in areas affected by arthritis?

From the Guidelines

Yes, a bone scan can show increased activity in areas affected by arthritis, as the inflammatory process and increased bone turnover associated with arthritis can lead to increased uptake of the radioactive tracer used in the scan. During a bone scan, a radioactive tracer is injected into the bloodstream, which accumulates in areas of increased bone metabolism or inflammation 1. In arthritis, the affected joints experience inflammation and increased bone turnover, causing the radioactive tracer to concentrate in these regions. This appears as "hot spots" or areas of increased uptake on the scan images. Different types of arthritis may show distinctive patterns - for example, rheumatoid arthritis often shows symmetric uptake in multiple joints, while osteoarthritis might show more localized increased activity in weight-bearing joints. The degree of uptake generally correlates with the severity of inflammation or disease activity. However, bone scans are not specific for arthritis alone, as other conditions like fractures, infections, or tumors can also cause increased tracer uptake. For this reason, bone scans are typically used alongside other diagnostic tools such as X-rays, blood tests, or MRIs to confirm an arthritis diagnosis and assess its extent and activity.

Some key points to consider when interpreting bone scan results in the context of arthritis include:

• The accuracy of bone scans for diagnosing septic arthritis has been reported to be around 81% 1
• Bone scans can show increased activity related to normal postoperative healing for up to 2 years or longer after joint replacement surgery, but activity increasing over time can indicate a prosthetic problem 2
• The specificity of bone scans in differentiating osteomyelitis versus aseptic prosthetic loosening is limited, and other imaging modalities such as indium-111-labeled leukocyte scans may be more useful in these cases 2

Overall, while bone scans can be a useful tool in the diagnosis and management of arthritis, they should be used in conjunction with other diagnostic modalities and clinical evaluation to ensure accurate interpretation of results.

From the Research

Bone Scan and Arthritis

• A bone scan can show increased activity in areas affected by arthritis, as it detects changes in bone metabolism and turnover 3, 4.
• Inflammatory arthritis, such as rheumatoid arthritis, can cause periarticular bone erosions and increased bone resorption, which can be detected by a bone scan 5, 6.
• Osteoarthritis, a degenerative joint disease, can also show increased activity on a bone scan, particularly in the late phase, which correlates with biochemical markers of bone turnover in the synovial fluid 4.
• However, it's essential to note that a bone scan is not specific for arthritis and can be positive in other conditions, such as infection, fracture, or malignancy 3, 7.
• The scan results should be interpreted in the context of clinical symptoms, laboratory tests, and other imaging modalities to confirm the diagnosis of arthritis.

Types of Arthritis and Bone Scan

• Rheumatoid arthritis: bone scan can detect periarticular bone erosions and increased bone resorption 5, 6.
• Osteoarthritis: bone scan can show increased activity in the late phase, correlating with biochemical markers of bone turnover in the synovial fluid 4.
• Gouty arthritis: bone scan can be positive, but it's not specific and can be misleading, as it may mimic infection 7.

Clinical Utility of Bone Scan in Arthritis

• Bone scan can be useful in confirming or excluding a diagnosis of arthritis, localizing the site of pain, and assessing the extent of disease 3.
• It can also alter the clinical diagnosis and change the course of disease management in some cases 3.
• However, the scan results should be interpreted with caution, considering the potential pitfalls and limitations of the test 7.