Virtual Fluoroscopy (FluoroNav)

A virtual fluoroscopy system (FluoroNav) for spinal and musculoskeletal procedures offers several distinct advantages over conventional C–arm fluoroscopy.  Radiation exposure is reduced, the need to obtain multiple images to update instrument position is eliminated by real-time tracking of the instrument by the system, and bilateral localization at any given spinal level(s) can be performed using a single image thus reducing fluoroscopy time and radiation.  Virtual fluoroscopy eliminates the repetitive C–arm repositioning and improves a surgeon’s efficiency.  Additionally, the computational power of the system allows further enhancement of standard fluoroscopy by providing real–time quantitative information.

Despite these advantages, virtual fluoroscopy is still a two–dimensional navigational system; it does not provide the detailed multi-planar imaging generated by three-dimensional systems.  Errors in the clinical interpretation of 2–D images and the extrapolation of 2–D information to 3–D anatomy are still dependent on the expertise of   the technologist and surgeon.  Furthermore, inherent to the nature of fluoroscopy, some disadvantages remain.  A virtual fluoroscopy system cannot compensate for causes of substandard image quality.  Clinical misinterpretation of a low quality, poorly oriented image cannot be compensated for by navigational system.

X-Rays:

X-rays utilize ionizing radiation to provide imaging of the spine and other regions of the body.  X-ray is particularly helpful in providing structural detail about the integrity of bone and the relationship between adjacent bony structures.  X-ray can also be used to evaluate soft tissue abnormalities.  X-ray is used to help identify spinal segment instability, spinal subluxation, degenerative arthritis, degenerative disc disease, fracture, dislocations and tumors.  X-rays is one of the best methods for imaging the level and degree of vertebral subluxation, malposition and abnormal movement.

X-ray studies are performed by sending an X-ray beam through the body.  The dense calcium levels in the bone blocks some of the X-ray beam penetration therefore providing a characteristic radio-opaque or white appearance of the bone on X-ray film.  Normal intervertebral discs and nerve roots do not contain calcium and therefore do not typically show up on X-ray studies.  For this reason an X-ray study cannot usually confirm the presence of a disc herniation or soft tissue compression of a spinal nerve root.

X-rays are often taken of a patient from different positions of bending. These x-ray projections are called functional or positional X-ray studies. These views may taken be while standing (neutral), bending forward (flexion) and bending backward (extension).  The object of this is to see if the bones (vertebrae) of the spine are limited in their movement or are moving too much relative to one another. Flexion and extension X-rays can be used to evaluate regional and segmental spinal movement.  They also allow for comparison movement at different segmental levels. They may also be used to evaluate the dynamics of scoliosis or the integrity of spinal fusion. 

Spinal X-rays provide the attending physician with an opportunity to evaluate the relationship between spinal pathology (disease) and spinal biomechanics (movement).