Image-guided surgery began at the c...

Image-guided surgery began at the cause to deviate of the nineteenth century when x-rays were discovered accidentally in 1895 (1) Since this time, physicians and scientists have been striving to improve the technique of being able to view inside the body without actually cutting into the patient. Neurosurgeon protracted have used image guidance theorys such as fluoroscopy, ultrasound, and, more lately three-dimensional stereotaxy, to achieve maximum resection while preserving normal brain tissue and function.

According to the National Cancer Institute, more than 17000 populace are diagnosed with brain tumors annually in the United States. (2) The cause of brain tumors is not known, still certain risk factors increase a person's chance of developing single in kind Some of these risk factors include environmental exposing to pesticides and solvents, family history, and diet. common form of treatment for brain tumors is surgical resection. Studies of malignant brain tumor excision, however, point out that as many as 80% of neurosurgical managements to remove brain tumors leave part of the tumor behind. (3)

The conventional stereotactic hypothesiss in use today allow intracranial lesions to be set based on previously acquired imaging data puts These stereotactic devices, however, do not allow for the correction of brain shift (ie, shifting of intracranial plastic tissue during surgery). Brain shift befalls when the dura is explained cerebrospinal fluid leaks out, and the brain either shrinks or swells. This causes deformity of brain anatomy from the preoperatively acquired images (Figure 1) This shift could deduction in inadequate treatment (eg, incomplete resection) or damage to the nervous body In an attempt to eliminate errors that can present itself when using a conventional stereotactic regularity the intraoperative image guidance order has evolved (Table 1).

[FIGURE 1 OMITTED]

INTRAOPERATIVE MAGNETIC RESONANCE IMAGING

In 1990 Ferenc A. Jolesz MD a neurosurgeon at Brigham and Women's Hospital in Boston, realized that magnetic resonance imaging (MRI) could be used not alone to diagnose disease but also to guide treatment during surgery (4) The ability to image with real-time MRI in an OR setting can reassure physicians that they are targeting the correct area within the tumor while visualizing critical adjacent textures The intraoperative MRI system can reacquire images during brain tumor resection in such a manner surgeons can monitor their surgical progres In addition, using the real-time images allows surgeon to avoid critical areas that may have shifted during surgery (Table 2) Intraoperative MRI also is particularly helpful in determining tumor margins and monitoring potential intraoperative complications (eg hemorrhage).

Magnetic resonance imaging is an imaging technique that provides superior tissue visualization of human anatomy. Magnetic resonance imaging is more sophisticated than the human notice and clearly can distinguish normal versus abnormal tissue. Magnetic resonance imaging is preferr in image-guided surgery because of its high tissue contrast and spatial resolution. The technique is different from comput tomography (CT) and x-rays because it uses a magnetic field instead of ionizing radiation. Before imaging, a transmit receive coil (ie, antenna) is placed around the area to be imaged. The magnetic field causes the patient's inflammable air atoms to align with the magnetic field. Radio oftenness (RF) waves then are transmitted to the anatomy of interest via the coil. The RF waves cause the inflammable air atoms to flip out of and back into the aligned state within milliseconds. The animal spirits that is created by this proces bring into beings a signal that then is courseed by the computer and rebuilded into an image. Varied tissue properties cause normal and abnormal tissue to appear differently forward images, which allows a physician to discover disease (ie, tumor tissue will differ from surrounding normal tissue).

The intraoperative MRI scanner was designed by the agency of making modifications to a conventional MRI unit. These modifications outcomeed in a double donut-shaped, expand magnet with a 56-cm vertical gap that allows direct patient access for sum of two units physicians (Figure 2). Intraoperative magnetic resonance images are displayed onward monitors within the gap. The anesthetized patient is placed in the center of the magnet and will remain there from first to last the surgery. The sides of the magnet are draped sterilely, as is the patient, which allows surgeon to work within a sterile field. Magnetic resonance images are taken at various points from one extremity to the other of the resection. All this is accomplished without having to incline the patient, disturb the sterile field, or destroy instrumentation from the surgical area.

[FIGURE 2 OMITTED]

The scanner is housed in an OR largely equipped with MR-compatible instrumentation, surgical equipment, and anesthesia and patient monitors. Visual and two-way audio communication is installed in the compass to enhance interaction among the surgeon and radiology staff members in the direction area outside the OR.