Article
Low-tech method for craniotomy planning of convexity targets
Low-tech Methode zur Kraniotomieplanung an der Schädelkonvexität
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Authors
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Max Jägersberg
- Universitätsmedizin Mainz, Neurochirurgische Klinik und Poliklinik, Mainz, Deutschland
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Florian Ringel
- Universitätsmedizin Mainz, Neurochirurgische Klinik und Poliklinik, Mainz, Deutschland
| Published: | June 26, 2020 |
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Outline
Text
Objective: Computer navigation for precise craniotomy planning is widely available. Nonetheless, in case of navigation breakdown or limited resources, for educational purposes and surgeon’s confidence, every neurosurgeon should be able to hark back to a conventional technique to locate a target on the convexity with acceptable precision.
We present here a method to localize a target based on fundamental geometry with inexpensive and globally available tools (conventional 2D imaging in one single plane, calculator, divider).
Methods: The distances of a defined target from two distinct landmarks (eg. nasion, porion) are assessed in a CT or MR data set with a conventional image viewer within one single plane and by means of Pythagoras' theorem. The two distances from the landmarks are marked as circles onto the head of the patient with the help of a divider. The intersection defines the target. The congress presentation will include illustration and proof of the geometrical background and a step-by-step video of the procedure.
Results: In a first step, 20 radio-opaque targets were placed on a saw bone skull prior to CT scanning. Targets were then assessed with the here described method and with navigation as gold standard. The mean offset between the measured target and the real target was 3.2 ± 2.4 mm in this series. The mean offset between computer-navigated target and real target was 1.8 ± 1.1. mm in this series (BrainLab Colibri Cart 1.1, p<0.05).
With regard to this successful saw bone model a clinical study was executed. In 15 patients undergoing navigated cranial procedures, 100 targets were set randomly over the convexity in a navigation tool and localized with the here presented method and then with navigation. The mean offset was 10.9 ± 5.2 mm, with a confidence interval of 9.9 – 11.9 mm (a= 0.05).
Conclusion: This is a low-tech procedure for localization of a radiological target on the convexity of the patient’s head in short time and with inexpensive and globally available tools, with satisfying precision for many procedures.
Figure 1 [Fig. 1]
