Common Components of Image Guidance Platforms

MRI provides maps of the anatomy by imaging the response of protons present in different types of tissues to magnetic excitations of variable duration across different spatial directions [16]. As such, MRI acquisition is 

X-ray fluoroscopy has been used in percutaneous catheter-navigation procedures for almost two decades because of its abihty to depict surgical instruments such as guidewires, catheters, and other implantable devices such as stents and valves, but it has inherent limitations associated with soft 

An extension of traditional X-ray fluoroscopy are the recently developed cone-beam CT systems [17-19], which enable real-time imaging and 3D reconstruction of anatomical structures intraoperatively, therefore reducing the reliance on preoperative CT scans and providing superior visualization to traditional X-ray fluoroscopy. 

US makes images of the anatomy by mapping the amplitude and arrival time of the reflected sound waves to image intensity and axial distance, respectively. Although used mainly for diagnostic purposes, US has been adopted more recently for intraoperative monitoring and guidance, because of its noninvasive, versatile, portable, low-cost, and real-time capabilities. 

Often it is possible to provide clinicians with additional or enhanced image information not inherently present intraoperatively. Modahties such as CT and MRI are not typically available in the operating room, but are often the optimal source for clearly identifying target tissues. In such situations, the best approach is to register the preoperative image data with the intraoperative modalities, as for example during prostate biopsies [20]. 

---