Evaluation of digital image enhancement techniques for liver scintigrams

Digital image enhancement techniques were employed in an effort to improve the resolution of Anger camera liver images. The premise employed was that methods which improve lesion detectability in liver phantoms should also do so in actual liver scintigrams. The types of image processing evaluated were: contrast enhancement, finite and infinite impulse response, modulation transfer function correction, homomorphic and median filtering. Observers were used to evaluate each method for its ability to improve lesion detectability using a five category rating system. The Localization Receiver Operating Characteristic (LROC) curve was used as the primary rank ordering method. A point system and analysis of variance were used as corroborative methods, incorporating measures of accuracy and consistency of the observers' answers.