An analytical study of scintigram interpretation

In order to know the effect of image quality on the physician's interpretation, 24 images of computer-simulated phantom which was established in the first coordinated programme on the ''Intercomparison of Computer-assisted Scintigraphic Techniques'' sponsored by IAEA, are processed by using the 'Optimum Filter' with medium frequency enhancing effect (OF-method) and the Gaussian filter with simple smoothing effect (GF-method), and are displayed as a contour map with same display factors by a curve plotter of computer system. The processed and displayed 48 images in random order are viewed by four physicians who are specialists in scintigraphic diagnosis. The results are analyzed with (1) total score method, (2) ROC curves and (3) values defined by McNeil. Among the results, the OF-method gives significantly better results compared with the GF-method, though the former are increased number of false positive compared with the latter. The cold lesions are more detectable compared with hot lesions of the phantom. The cold lesions are similar to a scintigram of human liver administrated 99m-Tc-colloid. Further investigation is being directed what kind of display can give the best results by using various displaying devices for same processed images, as the display method in this study seems to be not suitable for detecting the lesions in scintigraphic images. (J.P.N.)