Tc-methylene Diphosphonate Research Articles

153Sm-EDTMP for bone pain palliation in skeletal metastases.

153Sm-ethylene diamine tetramethylene phosphonate (EDTMP) is a widely available and extensively tested radiopharmaceutical for systemic radionuclide therapy in patients with symptomatic multiple skeletal metastases. Its use is approved for any secondary bone lesion which has been shown to accumulate (99m)Tc-methylene diphosphonate, including breast carcinoma. The molecule is stable in vitro and upon injection more than 50% of the dose is avidly fixed by lesional and non-lesional bone, with the rest being rapidly eliminated unchanged via the urine. The short half-life (46.3 h), the relatively low-energy beta emissions (E(ave)=233 keV) and the gamma emission (103 keV) make (153)Sm a very attractive radionuclide, allowing therapeutic delivery of short-range electrons at relatively high dose rates with external imaging to corroborate biodistribution and possible dosimetric estimates. For a standard dose of 2,590 MBq/70 kg, the estimated radiation dose to metastases is 86.5 Gy. Critical organs are the bladder wall (2.5 Gy/2,590 MBq) and red marrow (4 Gy/2,590 MBq), with the latter being the critical factor in clinical practice as the dose-limiting factor is marrow radiotoxicity. The therapy has, however, proved safe provided that the platelet count exceeds 100 x 10(9)/l and the white blood cell count exceeds 3.5 x 10(9)/l. Clinical data obtained in fewer than 250 patients, within several studies, lead to the following conclusions: a dose of 37 MBq/kg has a better therapeutic ratio than a dose of 18.5 MBq/kg; the mean pain palliation rate after a single treatment in breast cancer is about 80%; toxicity is generally mild and transitory; and re-treatments are effective and safe provided that haematological values have fully recovered.

Soft tissue uptake on 99mTc methylene diphosphonate bone scan imaging: pictorial review.

99mTechnetium methylene diphosphonate (MDP) bone isotope may accumulate in many extra-osseous sites due to a variety of both benign and malignant conditions. This finding on a bone scan can be crucial to the diagnosis and may not be apparent in other imaging or the clinical evaluation of the patient. We present a pictorial review sampling some of the many causes of extra-osseous 99mTc MDP accumulation.

Quantitative studies of bone using (18)F-fluoride and (99m)Tc-methylene diphosphonate: evaluation of renal and whole-blood kinetics.

We report a study of the renal and whole-blood kinetics of (18)F-fluoride and (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) and their effect on the evaluation of the skeletal kinetics of the two bone tracers. Data were obtained during an investigation of postmenopausal women taking hormone replacement therapy who were compared with untreated, age-matched controls. After intravenous injection of 18F-fluoride (1 MBq), (99m)Tc-MDP (1 MBq), (51)Cr-ethylenediaminetetraacetic acid (51Cr-EDTA) (3 MBq) and (125)I-human serum albumin ((125)I-HSA) (0.25 MBq), multiple blood samples and urine collections were taken between 0 and 4 h after injection. (51)Cr-EDTA data were used to evaluate the glomerular filtration rate (GFR) and the completeness of each timed urine collection. (125)I-HSA data were used to evaluate the plasma volume and the red cell uptake of the other three tracers. At 4 h, the cumulative urine excretions (and standard deviations, SDs) were: (99m)Tc-MDP, 58.2% (4.8%); (18)F-fluoride, 36.1% (5.7%); (51)Cr-EDTA, 81.5% (4.5%). Plots of the renal clearance of (18)F-fluoride against urine volume showed that urine flow rates greater than 5 ml.min-1 were necessary to ensure a constant renal clearance of (18)F and hence stable conditions for the evaluation of bone tracer kinetics. In contrast, a low urine flow rate had no effect on the renal kinetics of (99m)Tc-MDP. For MDP, the evaluation of skeletal kinetics requires data on protein binding so that calculations can be performed for free MDP. In the present study, protein binding of MDP was evaluated from the ratio of total (99m)Tc-MDP renal clearance to GFR based on the principle that free (99m)Tc-MDP is a GFR tracer. Between 0 and 4 h after injection, the fractional protein binding of MDP increased linearly with time, changing from 21+/-5% immediately after injection to 58+/-5% at 4 h. Although red cell uptake of (99m)Tc-MDP was negligible, for (18)F-fluoride around 30% of circulating tracer was transported in red cells. In view of the data showing the rapid transport of (18)F-fluoride across the red cell membrane, bone kinetic data for (18)F are more accurately reported as whole-blood clearance rather than plasma clearance.

核医学検査における被検者の被ばく量低減の検討 : <sup>99m</sup>Tc-MDP について

^<99m>Tc-methylene diphosphonate (^<99m>Tc-MDP), which is excreted through the urinary tract and partly accumulated on the content of bladder, is the most common radiopharmaceutical form among the current bone scintigraphy. In order to find the methods decreasing the exposure of the whole body and the bladder, 15 patients were selected for the present study. Neither of them had renal disorder, nor demonstrated abnormal radionuclide increased uptake over the whole bones. They were divided into two groups; i. e 10 patients were forced to take fluid during examination and the other 5 patients were orderd not to take fluid. After administration of ^<99m>Tc-MDP, whole body activity was compared between these 2 groups. At the same time, exposure of patients' wall of the bladder was estimated from their urine activity. Forced fluid intake group received less radioactive exposure to the whole body than no fluid intake group did. For the forced fluid intake group, it is estimated that expousure of the wall of bladder can be reduced about 40% if one avoids urine in 50 minutes after administration of ^<99m>Tc-MDP insted of avoiding urine in 120 minutes.

A study of protein-binding of 99 mTc-methylene diphosphonate in plasma

The extent of plasma protein-binding of 99 m Tc-methylene diphosphonate (MDP) at 10 min, 1, 2 and 3 h after injection into patients has been determined by trichloroacetic acid and ammonium sulfate precipitation, dialysis and Sephadex gel chromatography. The percent administered dose bound to plasma proteins decreases with time, whereas the fraction of the plasma activity bound to plasma proteins increases with time after injection. Urinary excretion of the tracer is about 38% at 2 h and 62% at 24 h. The results suggest that the rate of removal of 99 m Tc-MDP by bone uptake and urinary excretion is much faster than the rate of disappearance of the protein-bound tracer.

Radionuclide demonstration of relative increased blood flow in uniappendicular secondary hypertrophic osteoarthropathy.

A rare case of hypertrophic osteoarthropathy (HO) limited to one lower extremity is described in a male with a history of familial polyposis coli and bilateral aortofemoral grafts. The precise etiology remains unknown. Radiography depicted the HO, but 99m Tc-methylene diphosphonate imaging showed more extensive involvement. An intra-aortic injection of 99m Tc-macroaggregates of albumin portrayed a larger blood flow to the involved limb compared to the contralateral extremity. The major part of this increase was in bone rather than in the adjacent soft tissue.