manipulation of the sinuses as they move to the target area," he adds.
Dr. Shah enjoys being able to reference an MRI-CT fusion image dur-
ing an advanced tumor case or a skull base procedure, such as
transsphenoidal surgery. She says the combined images provide valu-
able information about bone anatomy, soft tissue landmarks and the
tumor she's targeting.
3. Better instrumentation
The 2 main ways instruments communicate with image-guidance plat-
forms have remained consistent:
• Electromagnetic guidance. Surgeons don't need to maintain a
direct line of sight between instruments and the image processor.
They typically must use proprietary instruments, however, and the
surgical team must keep metal items away from the patient in order
to avoid interfering with the system's electromagnetic field.
The tips of proprietary suction devices, which are used frequently,
can bend slightly over time, making navigation more difficult, accord-
ing to Dr. Shah. She says the manufacturers of image-guided technolo-
gy are responding to that concern and producing hardier instruments.
She also points out that some systems have developed disposable suc-
tion devices, so the wear and tear on the instruments doesn't impact
how well they perform in practice.
• Infrared guidance. Passive infrared systems have fiducial markers
placed on the patient and instruments that reflect infrared light back
to the system camera. Active systems have infrared emitting diodes
on operating instruments that are actively tracked by an overhanging
camera. With both types of technology, you must maintain a clear line
of sight between instruments and the imaging unit. These systems are
highly accurate and especially helpful and convenient during routine
sinus cases, because the small markers placed on the distal ends of
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