Radioimaging of implants in rats using Tc‐99m‐MDP

Abstract

Radiopharmaceutical isotopes are widely used clinically to detect tumors of osteogenic origin. One example is Technetium-99m methylene diphosphonate (Tc-99m-MDP). When viewed with a gamma camera, the concentration of the isotope (increased gamma activity) indicates an area of increased bone activity. This technology provides an opportunity to measure bone growth around implants in vivo. The purpose of this study was to measure Tc-99m-MDP activity around titanium alloy implants placed in the tibiae of rats. Some implant sites were treated with a growth factor; other sites served as controls. The hypothesis tested was that implants placed with a growth factor would have greater associated Tc-99m-MDP activity. Twelve adult male Sprague-Dawley rats were anesthetized and surgical access to the medial proximal tibiae was obtained. Titanium alloy screw implants were placed in six animals along with 65 microgram of acidic fibroblast growth factor (FGF-1); the other six animals received implants only and served as controls. After five days, rats were injected with 1500 microCi of Tc-99m-MDP. After 3 hours, rats were imaged with a gamma camera. The Tc-99m-MDP intensity associated with each implant was quantified and the means for each group were compared using ANOVA. Implants treated with FGF-1 demonstrated significantly more Tc-99m-MDP activity than implants alone. This suggests that Tc-99m-MDP analysis may be a useful tool for determining bone growth around implants in laboratory animals in vivo.

Changes in Bone Metabolisim Around Osseointegrated Implants Under Loading

“…These results suggest that osseointegration is obtained about four weeks after implant insertion. In addition, the timing of the peak level of and subsequent decrease in bone metabolic activity found in this study correspond very well to those of a previous report on Tc99m-MDP activity around implants using bone scintigraphy (McCracken et al, 2001). Therefore, it should be possible to observe in real time the osseointegration process and the degrees and stages of bone metabolism using this method longitudinally.…”

Does acute swimming exercise alter the bioavailability of the radiopharmaceutical technetium-99m methylenediphosphonate (99mTc-MDP) in Wistar rats?

“…After the swimming exercise, all animals were anaesthetized with sodic thiopental (67 mg/kg, intra peritoneally), 0.3 mL of the radiopharmaceutical 99m Tc-MDP (7.4 MBq, with labeling efficiency of 96%) was administered via ocular plexus, as previously reported (Moreno et al, 2004), and after 180 min (McCracken et al, 2001) the animals were sacrificed by exsanguination, as previously published (Moreno et al, 2004), following the ethical procedures. Samples of blood (1 mL), soleus muscle and tibial bone were isolated, and the various organs (pancreas, thyroid, brain, testis, spleen, kidney, heart, stomach, lungs, liver and duodenum) were separated.…”

“…Technetium-99m methylenediphosphonate ( 99m Tc-MDP) has been used in a variety of clinical situations to identify bone areas due to the strong affinity of hydroxyapatite crystals in mineral phase of the bone with the diphosphonate compounds (McCracken et al, 2001;Saha, 2004), and allow quantitative measurements in bone that reflect blood flow and osteoblastic activity (Blake et al, 2001). The differential accumulation of the radiopharmaceutical is related to diseased tissue on the basis of perfusion.…”

Methylene diphosphonate-conjugated adriamycin liposomes: preparation, characteristics, and targeted therapy for osteosarcomas in vitro and in vivo

“…MDP is preferentially adsorbed by newly produced minerals, and the results can be quantified to facilitate comparative studies. For clinical imaging, MDP has been utilized in vivo to study the bone response to implants and to osteogenic cytokines with high uptake by tumor cells (Spector et al 1981;McCracken et al 2001); therefore, it targets osteogenic tumors with sufficient binding ability. The bone uptake mechanisms of phosphonate compounds are ion exchange and chemisorption in the inorganic matrix of bone, which consist of ionic hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ].…”