title: Time-dependent image quality using 99mTc-pyrophosphate.
abstract: Technetium-99m-labeled pyrophosphate has proved to be a useful skeletal-imaging agent. In this study, specific areas of the skeleton were imaged at times ranging from 1/2 to 6 1/2 hr after injection of 99mTc-pyrophosphate. Count ratios between abnormal and normal bone with respect to adjacent soft tissue were obtained for selected regions of interest on computer-stored scintillation camera images. The results show that image quality improves most rapidly from 1/2 to 2 hr, but further modest gain in quality does occur on views recorded between 2 and 6 hr. All lesions detected on the later images were also observed on the early ones and the ratios of uptake between abnormal and normal bone from computer-processed scintillation camera images did not change appreciably with time after the 1/2-hr images. Our results confirm the clinical impression that overall image quality is better on views obtained at least 3 hr after injection. Further delays in imaging beyond 3-4 hr after injection probably will not result in any appreciable gain in diagnostic accuracy.
mesh_terms: D001859:Bone Neoplasms / Q000175:diagnosis*; D003936:Diagnosis, Computer-Assisted; D011756:Diphosphates / Q000097:blood / Q000652:urine; D006801:Humans; D009362:Neoplasm Metastasis; D011877:Radionuclide Imaging; D013667:Technetium; D013997:Time Factors
chemical_list: D011756:Diphosphates; D013667:Technetium