99mTc-DPD is a radiopharmaceutical used in nuclear medicine for bone imaging. It is commonly used in single-photon emission computed tomography (SPECT) imaging to assess bone metabolism and detect abnormalities in the skeletal system. The compound consists of the radioisotope technetium-99m (99mTc) bound to 3,3-diphosphono-1,2 propane dicarboxylic acid (DPD), which has a high affinity for bone tissue. By injecting 99mTc-DPD into the body, healthcare providers can visualize bone structures and identify conditions such as fractures, infections, tumors, and metabolic bone diseases. The use of 99mTc-DPD in bone scintigraphy has proven to be valuable in diagnosing and monitoring various bone-related disorders.
Bone metabolism refers to the continuous process of bone formation and resorption that occurs in the skeletal system. It is a dynamic process regulated by various factors such as hormones, growth factors, and mechanical stress. Healthy bone metabolism is crucial for maintaining bone strength, density, and overall skeletal integrity.
Abnormalities in bone metabolism can lead to various skeletal disorders, including:
- Osteoporosis: a condition characterized by low bone mass and deterioration of bone tissue, leading to increased bone fragility and risk of fractures.
- Osteomalacia: a softening of the bones due to inadequate mineralization, often caused by vitamin D deficiency.
- Paget’s disease: a chronic disorder characterized by abnormal bone remodeling, leading to enlarged and weakened bones.
- Bone tumors: abnormal growths in bone tissue that can be benign or malignant.
- Metastatic bone disease: the spread of cancer to the bones from primary tumors in other parts of the body.
By using imaging agents like 99mTc-DPD in bone scintigraphy, healthcare providers can detect these abnormalities in the skeletal system. The radiopharmaceutical is taken up by bone tissue based on its affinity for hydroxyapatite crystals, which are abundant in bones. The gamma rays emitted by the technetium-99m isotope can then be detected by a gamma camera during SPECT imaging, allowing for the visualization of bone structures and identification of any areas of increased or decreased uptake of the radiopharmaceutical.
This imaging technique helps healthcare providers assess bone metabolism, identify areas of abnormal bone turnover, detect fractures, evaluate bone lesions, and monitor the progression of skeletal disorders. It plays a crucial role in the diagnosis, staging, and management of various bone-related conditions, ultimately contributing to better patient care and treatment outcomes.
Description
99mTc-DPD (3,3-diphosphono-1,2 propane dicarboxylic acid, Teceos®) is a generic SPECT imaging agent used for bone scintigraphy.
Clinical applications
99mTc-DPD like all phosphonate derivatives has a high affinity for hydroxyapatite crystals which form the inorganic structure of the bone tissue. 99mTc-DPD is therefore, indicated for the bone metastases detection, the imaging of altered bone metabolism in primary bone tumors, the imaging of bone inflammation, bone post-traumatic lesions, rheumatoid lesions or aseptic necrosis as well as the examination of the repair process in damaged bone tissue. In certain cases, 99mTc-DPD finds some applications in cardiac imaging (e.g., cardiac amyloidosis, but more common tracers have substituted DPD in cardiology. Doses per patient are in the range 10 to 20 mCi.
Availability
99mTc-DPD is manufactured by IBA Molecular (Curium) and sold under the name Teceos® (marketed since 1995).
Competition
There are several marketed agents useful for bone scintigraphy in both SPECT (99mTc- HEDP, 99mTc-HDP, 99mTc-MPD) and PET modalities (18F-NaF). All of them are generics. Their use is dependent upon local availability and authorizations, as well as price, but it seems that the most commonly used agent is 99mTc-MDP and the highest quality of images is obtained with the PET tracer 18F-NaF, which is also the most expensive.
Comments
New radiopharmaceuticals for therapy in bone metastasized cancers such as 188Re-HEDP or 177Lu-HEDP, or even 223Ra-Chloride, show a beta emission that provides a signal sufficient for imaging and in certain cases could substitute the 99mTc-derivatives in the future.