title: The influence of size and radiopharmaceutical concentration ratio on the detection of abnormalities in clinical radionuclide imaging.
abstract: The effect of the size of an abnormality on its detectability was measured. The cylindrical abnormalities studied, with diameters ranging from 3 mm to 4 cm, were superimposed on a uniform background. To avoid artefacts produced by the imaging devices, the images were simulated by computer. The method of constant stimulus was used to determine the detectability of the abnormalities. By using a Perspex phantom filled with 99Tcm, measurements were made of the concentration ratio between abnormality and background which permitted detection of the abnormality. This allowed evaluation of the effectiveness of 99Tcm pertechnetate in the detection of small abnormalities. Assuming a concentration ratio between abnormal and normal tissue of 22.5:1, then at a depth of 50 mm in the brain a cylindrical abnormality of about 8 mm diameter was the smallest detectable under the chosen scanning conditions.
mesh_terms: D001927:Brain Diseases / Q000000981:diagnostic imaging*; D006801:Humans; D008961:Models, Structural; D011854:Radiochemistry; D011877:Radionuclide Imaging; D013667:Technetium
chemical_list: D013667:Technetium