Quantitative Analysis of Minimum Detectable Uptake Ratios for Nuclear Medicine Imaging Systems

Abstract

A diagnostic medical image is nothing more, nor less, than a display of measured data, and specifically for nuclear medicine it is a display of radio-pharmaceutical uptake as a function of position within some object. As with any measuring device, the important characteristics of an imaging system are its precision, accuracy, and range of measurement scale. When the output of an imaging system is viewed by a human observer, the measured quantity of interest is contrast, or incremental change of input signal level divided by the average signal level. Thus the precision of the imaging systems’ measurement capability is determined by the minimum detectable contrast which can be observed, the imaging system’s accuracy, which is determined by the fidelity with which a specific object contrast is represented in the image, and the range of measurement scale, which is simply the dynamic range, as determined by the largest value of object contrast which can be accurately reproduced in the image.