What is the primary purpose of Tc HDP and Tc MDP scans?

• A. Cancer detection
• B. Cardiac evaluation
• C. Bone scan for cancer, infection, or trauma
• D. Thyroid imaging

Answer: (C)

The primary purpose of Tc HDP (technetium-99m hydroxymethylene diphosphonate) and Tc MDP (technetium-99m methylene diphosphonate) scans is to perform bone imaging, which is crucial for assessing various conditions such as cancer, infection, or trauma. These radiopharmaceuticals are specifically designed to localize in bone tissue, allowing for the visualization of bone metabolism and abnormalities.

During a bone scan, Tc HDP and Tc MDP bind to areas of increased osteoblastic activity. This is particularly useful in oncology for detecting bone metastases from various cancers, as abnormal bone growth often occurs in these cases. Additionally, these scans can identify other conditions like osteomyelitis (bone infection) and stress fractures, as they reveal changes in bone density and activity that correlate with these conditions.

The use of Tc HDP and Tc MDP in this context supports their role in providing valuable insights into skeletal health, allowing for an effective evaluation of both benign and malignant processes involving the bones. This focus on bone pathology distinguishes their purpose from the other options, which target different organ systems or disease states.