Quantitative imaging in vivo. Why? What is being done now? What are some of the problems? What may the future be?

The visual system is highly sophisticated, yet at the task of quantifying the information in images it is very easily misled. It is probably for this reason that medical imaging has often concentrated on the visual analysis of images and played down the value of extracting quantitative information. Yet nearly all modern medical imaging techniques use digital technology to some degree and numerical information can be readily extracted. Unless more use is made of this quantitative data, medical imaging will never make the transition from an art into a science.