title: Distribution of 99mTc-Sn diphosphonate and free 99mTc-pertechnetate in selected soft and hard tissues.
abstract: Because increased uptake of 99mTc-diphosphonate (ethane-hydroxy-1, 1-diphosphonate) occasionally occurs in the anterior neck region, the possible increased affinity of the diphosphonate bone-scanning agent for cartilage was investigated. In vivo scintigraphic studies and organ analyses from rats and rabbits injected with this bone scintigraphic agent were performed. Trachea-to-muscle uptake ratios were a high 45:1 in adult Sprague-Dawley rats and approached the femur-to-muscle ratio of 93:1. Technetium-99m-diphosphonate uptake was also increased, but to a lesser extent, in xiphoid cartilage, tendon, and ear cartilage; this was proportional to the calcium content of the organ. The thyroid showed a high affinity for free pertechnetate but not 99mTc-diphosphonate, providing further evidence that the increased neck uptake of this 99mTc-diphosphonate is due to tracheal, not thyroid activity. In addition, premedication of three patients with 200 mg of potassium-perchlorate did not block this neck uptake. Interpretation of scintigraphs performed with 99mTc-diphosphonate that show lesions in the cervical spine should take into account the potential for false-positive readings caused by this increased tracheal uptake.
mesh_terms: D000125:Achilles Tendon / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D002356:Cartilage / Q000378:metabolism; D002574:Cervical Vertebrae / Q000378:metabolism; D006801:Humans; D008334:Mandible / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D063065:Organophosphonates / Q000378:metabolism*; D010472:Perchlorates / Q000494:pharmacology; D011292:Premedication; D011817:Rabbits; D011877:Radionuclide Imaging; D051381:Rats; D013667:Technetium; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D014132:Trachea / Q000378:metabolism
chemical_list: D063065:Organophosphonates; D010472:Perchlorates; D013667:Technetium