title: Doughnut phenomenon in bone scintigraphy.
abstract: A doughnut phenomenon was observed in bone scintigraphy in three cases of metastatic thyroid carcinoma to the skull. Additional dynamic and static studies were performed to evaluate the relative roles of vascularity, vessel permeability and new bone formation in producing this phenomenon. This was accomplished through the use of 99mTc-diphosphonate, 99mTc-labeled red blood cells and 99mTc-pertechnetate. The important factor was found to be a new  bone formation. Late uptake of diphosphonate was shown only in the periphery of the lesion, where formation of new bone takes place. This occurred even in the presence of increased vascularity and vessel permeability in the lesion as a whole.
mesh_terms: D000230:Adenocarcinoma / Q000098:blood supply / Q000000981:diagnostic imaging*; D004164:Diphosphonates; D006801:Humans; D008722:Methods; D009362:Neoplasm Metastasis; D011877:Radionuclide Imaging; D012888:Skull Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging*; D013667:Technetium; D013964:Thyroid Neoplasms / Q000473:pathology
chemical_list: D004164:Diphosphonates; D013667:Technetium