Imaging, mainly due to its impact on medicine and biology, has been selected as one of the greatest achievements of the twentieth century by the National Academy of Engineering. In the last several decades, medical imaging systems have advanced in quantum leaps. There have been substantial improvements on their characteristics such as sensitivity, resolution and acquisition speed. Multislice, 320-slice currently, computer tomography (CT) scanners, for instance, allow the visualization of the entire coronary tree, even atherosclerotic plaques within the coronaries with extremely high accuracy and detail. Similar advances have occurred in the other medical imaging modalities such as magnetic resonance imaging (MRI) and positron emission tomography (PET).
Substantial effort has been put into the integration of different modalities. These systems are also called hybrid systems. The integration of CT and PET scanners has enabled physicians to localize biochemical activity (functional) with a high degree of certainty in the human body. As a result of the significant advances in small animal imaging, a new research discipline known as molecular imaging, which can be defined as in-vivo imaging of biochemical or molecular activity in an organ, is emerging. In-vitro molecular imaging has already been contributing to the advancement of the study of genome and efficacy of new drugs. With the help of imaging, now biologists can get a snapshot of almost the entire genomic activity (expression or disexpression of genes) within a diseased tissue in a matter of days. It will not be long before physicians can visualize, in-vivo, the biochemical processes triggered by a disease. All of this may soon result in a paradigm shift in healthcare. It may open up the possibility of designing drugs as per a patient's individual genetic profile (i.e., personalized medicine).