Placental Imaging With 113mIn Transferrin and 99mTc Serum Albumin

Radionuclide placentography is a diagnostic procedure in which the placental blood pool is imaged by the accumulation of a radiopharmaceutical that had been injected intravenously. By this method, the placenta is localized directly. Analysis of 84 patients who had placentograms at The Johns Hopkins Hospital revealed that this technic is accurate and reliable. The specificity of this test can be increased by using a vaginal radionuclide marker to localize the cervical os. Of the radionuclides in common use, In transferrin and Tc-HSA are preferred. Bladder radioactivity is more common with Tc-HSA and may be difficult to distinguish from activity in the placenta.