Image-guided surgery (IGS) involves correlating pre-surgical images of an operative area and its adjacent anatomic structures to a surgical instrument, and achieving this with a high degree of precision, in real time.
IGS, in some senses, can be considered as an enhancement of minimally invasive surgery (MIS), which became widespread during the 1980s and early 1990s. Like IGS, MIS too had the goal of providing precise access and reducing collateral damage to nearby tissue during a surgical procedure.

IGS and Computer Assisted Surgery
IGS is now seen as a key component of computer assisted surgery (CAS), a methodology to use computers in the surgical process, all the way from pre-operative planning to intervention and post-surgery assessments. The two terms were often used interchangeably in the past, and still overlap in several features and applications, such as the use of virtual or augmented reality.
However, given the emergence in its own right of another specialty application, robotic surgery, CAS is now differentiating itself from IGS.

Graphic processor capabilities drive IGS
Both CAS and IGS were driven by the explosive growth of computing power in the late 1990s and the consequent availability of structured patient information in the operating theatre.
IGS, however, has a more targeted heritage in the field of graphic processor units (GPUs). Aided by advanced algorithms in areas such as dynamic texture binding, texture sampling, rendering and image compositing, these have enabled