The application accuracy of a skull-mounted trajectory guide system for image-guided functional neurosurgery

Figures & data

Figure 1. The plastic skull phantom used in this study attached to a Leksell frame for stability. The first generation NeXframe device is mounted over the right-sided entry point and the stainless steel mandrel localizes the target. A cranial reference arc is indicated by the asterisk(*).

Figure 2. The target disc. Radial markings are 1 mm apart.

Figure 3. The mandrel at target, demonstrating a 0.5 mm error in the anterolateral direction.

Figure 4. Histogram plot of localization errors in 560 trials, showing quasinormal distribution around the mean of 1.25 mm.

Table I.  The application accuracy of two stereotactic frame systems as compared to the frameless device.

	CRW [4] (mm)	Leksell [4] (mm)	Frameless (mm)
Mean	1.8	1.7	1.25
99% CI for mean	1.69 to 1.91	1.60 to 1.80	1.19 to 1.31
Std. Dev.	1.1	1.0	0.6
Min. value	0.0	0.2	0.0
Max. value	4.9	4.9	4.0
95% CI	3.6	3.4	2.7
99.9% CI	5.2	4.8	4.0

CRW—Cosman-Roberts-Wells; Min—minimum; Max—maximum; CI—confidence interval.

Table II.  A comparison of laboratory studies investigating the mean localization accuracy of framed and frameless stereotactic systems

Study	Mean localization accuracy (mm)	System	Fiducials
Maciunas et al. (1994)	1.8	CRW	N-bar
Maciunas et al. (1994)	1.7	Leksell	N-bar
Steinmeier et al. (2000)	1.59	Zeiss MKM	Adhesive “doughnut”
Steinmeier et al. (2000)	1.59	Stealth	Adhesive “doughnut”
Helm & Eckel (1998)	2.07	Viewing Wand	Adhesive “doughnut”
Dorward et al. (1999)	1.3	EasyGuide Neuro	Adhesive “doughnut”
Bernardete et al. (2001)	1.90	Cygnus	Adhesive “doughnut”
Bernardete et al. (2001)	1.67	Viewing Wand	Adhesive “doughnut”
Bernardete et al. (2001)	2.61	Zeiss SMN	Adhesive “doughnut”
Present study	1.25	Stealth	Bone fiducials

Maciunas R J, Galloway R L, Latimer J W. The application accuracy of stereotactic frames. Neurosurgery 1994; 35: 682–94

 PubMed Web of Science ®Google Scholar