Preparation and preclinical pharmacological study on a novel bone imaging agent 99mTc-EMIDP

Men who stare at bone: multimodal monitoring of bone healing

Knowledge of the physiological and pathological processes, taking place in bone during fracture healing or defect regeneration, is essential in order to develop strategies to enhance bone healing under normal and critical conditions. Preclinical testing allows a wide range of imaging modalities that may be applied both simultaneously and longitudinally, which will in turn lower the number of animals needed to allow a comprehensive assessment of the healing process. This work provides an up-to-date review on morphological, functional, optical, biochemical, and biophysical imaging techniques including their advantages, disadvantages and potential for combining them in a multimodal and multiscale manner. The focus lies on preclinical testing of biomaterials modified with artificial extracellular matrices in various animal models to enhance bone remodeling and regeneration.

Molecular imaging of bone metastases using bone targeted tracers

Molecular imaging using bone targeted tracers has been used in clinical practice for almost fifty years and still plays an essential role in the diagnosis and follow-up of bone metastases. It includes both [99mTc]bisphosphonates for bone scan and [18F]NaF for positron emission tomography/computed tomography (PET/CT) which are very sensitive to detect osteoblastic activity, but it is important to consider several aspects to increase the specificity of reported findings (such as specific tracer characteristics and mechanism of action, patient's clinical history, common metastatic patterns, changes after treatment, limitations of the technique, variations and pitfalls). This will enable useful information for clinical management being provided in the report. Furthermore, iatrogenic skeletal adverse events are common and they should also be identified, as they have impact on patient's quality of life. This review makes a brief summary of the mechanism of action of bone targeted tracers, followed by a discussion of classic patterns of bone metastasis, treatment response assessment and iatrogenic skeletal complications. The value of hybrid imaging techniques with bone targeted tracers, including single photon emission computed tomography and PET/CT is also explored. The final part summarizes new bone targeted tracers with superior imaging characteristics that are being developed, and which may further enhance the applications of radionuclide bone imaging.

Synthesis and biological evaluation of bisphosphonate compound labeled with (99m)Tc(CO)3(+)

In this study, radiolabeling of a bisphosphonate, alendronate (Alendronate sodium), was performed with the help of a bifunctional chelating agent. For that purpose, DTPA-NHS (Diethylenetriaminepentaacetic acid dianhydride-N-hydroxysuccinimide) was synthesized with an esterification between DTPA and NHS. Combining the DTPA-NHS ester with alendronate yields the DTPA-Alendronate compound. The structure of synthesized compound was analyzed by (1) H/(13) C/(31) P-NMR and HPLC. After then, the labeling with [(99m) Tc(CO)3 ](+) core of synthesized compound was provided. Performing quality controls of newly synthesized [(99m) Tc(CO)3 -DTPA-Alendronate] complex with thin layer radiochromatography (TLRC) and high-performance liquid radiochromatography (HPLRC), the labeling yield was found as 99%. It was observed that the compound conserves its stability for 24 h in serum media. Biodistribution of the radiolabeled complex was performed on Wistar Albino rats to determine radiopharmaceutical potential of the [(99m) Tc(CO)3 -DTPA-Alendronate] complex. It is thought that the data gained from this study will contribute to the development of complexes with bisphosphonate.

Synthesis and biological evaluation of novel (99m)Tc-labelled bisphosphonates as superior bone imaging agents

A series of novel zoledronic acid (ZL) derivatives 1-hydroxy-3-(2-methyl-1H-imidazol-1-yl)propane-1,1-diyldiphosphonic acid (MIPrDP), 1-hydroxy-4-(2-methyl-1H-imidazol-1-yl)butane-1,1-diyldiphosphonic acid (MIBDP), and 1-hydroxy-5-(2-methyl-1H-imidazol-1-yl)pentane-1,1-diyldiphosphonic acid (MIPeDP) were prepared and successfully labeled with ^99mTc in high labeling yields. The in vitro stability and in vivo biodistribution of ^99mTc-MIPrDP, ^99mTc-MIBDP and ^99mTc-MIPeDP were investigated and compared. The biodistribution studies indicate that the radiotracer ^99mTc-MIPrDP has highly selective uptake in the skeletal system and rapid clearance from soft tissues. The present findings indicate that ^99mTc-MIPrDP holds great potential for use in bone imaging.