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Accuracy of registration methods in frameless stereotaxis
1Division of Neuroradiology, Johns Hopkins Hospital, Baltimore, Maryland 21287-2182, USA.
Summary
Fiducial marker registration for frameless stereotaxy is most accurate for surgical guidance. Adding surface points does not improve accuracy and can increase errors in image-guided surgery.
Area of Science:
- Neurosurgery
- Medical Imaging
- Surgical Navigation
Background:
- Accurate image-to-patient registration is crucial for intraoperative frameless stereotactic surgical guidance.
- Existing registration techniques require evaluation for optimal performance.
Purpose of the Study:
- To assess the accuracy of image-to-head phantom registration using standard techniques with a clinical frameless stereotactic instrument.
- To compare the accuracy of fiducial marker-based versus anatomic landmark-based registration.
Main Methods:
- Two radioopaque fiducial marker types were affixed to a plastic head phantom.
- Computed tomography scans were performed, followed by registration using fiducial markers, fiducial markers plus surface fit, anatomic landmarks, and anatomic landmarks plus surface fit.
- Linear inaccuracy measurements were taken for 32 markers per registration, repeated 10 times each.
Main Results:
- Fiducial registration alone yielded the smallest overall mean error (2.07 mm).
- Other techniques showed significantly increased error at posterior locations, unlike fiducial registration.
- Adding surface points to fiducial registration did not enhance accuracy and increased error.
Conclusions:
- Surface-applied fiducial markers provide measurably superior accuracy compared to surface anatomic landmarks for this hardware.
- Fiducial registration alone is the most accurate method; surface point augmentation is detrimental.