Quantitative analysis of minimum detectable lesion-to-background uptake ratios for nuclear medicine imaging systems

Quantitative analysis of lesion contrast in nuclear medicine images requires the use of two transfer functions for specification of the imaging system characteristics. The familiar modulation transfer function is needed to describe the effects of resolution and gamma-ray scattering on lesion contrast, and a second, grey-scale transfer function is needed to describe the effects of photographic film, or CRT systems, used to display the final image. An analytical model of nuclear medicine imaging systems which uses both of these transfer functions provides a direct, quantitative relationship between lesion visibility in the image and the uptake ratio between lesion and background in the object. In addition, such a model shows that an observer's subjective impression of diagnostic image quality is highly correlated with the probability of a statistical error for lesions displayed in the image at threshold contrast for the human visual system. (author)