Department of Neurosurgery, University Medical Center Mainz, Johannes Gutenberg University, Mainz, Germany.
PLoS One. 2021 May 20;16(5):e0251023. doi: 10.1371/journal.pone.0251023. eCollection 2021.
A technique to localize a radiological target on the head convexity fast and with acceptable precision is sufficient for surgeries of superficial intracranial lesions, and of help in the setting of emergency surgery, computer navigation breakdown, limited resources and education. We present a caliper technique based on fundamental geometry, with inexpensive and globally available tools (conventional CT or MRI image viewer, calculator, caliper).
The distances of the radiological target from two landmarks (nasion and porus acusticus externus) are assessed with an image viewer and Pythagoras' theorem. The two distances are then marked around the landmarks onto the head of the patient with help of a caliper. The intersection defines the target. We tested the technique in a saw bone skull model and afterwards in the operating room. Convexity targets were localized with the caliper navigation technique and then with computer navigation as ground truth.
In the saw bone model, the mean offset between the caliper navigated target and the real target was 2.9 ± 2.8 mm, 95% CI (1.6 mm; 4.2 mm). The mean offset between computer navigated target and real target was 1.6 ± 0.9 mm, 95% CI (1.2 mm; 2 mm) (ns). In 15 patients undergoing navigated cranial procedures, 100 targets were assessed in reference to computer navigation. The mean offset of the caliper navigation was 11 ± 5.2 mm, 95% CI (9.9 mm; 12 mm).
This is a low-tech approach for translation of a radiological target to the patient's head in short time and with globally available inexpensive tools, with satisfying precision for many procedures.
对于浅表性颅内病变手术和紧急手术、计算机导航故障、资源有限和教育程度有限的情况下，一种能够快速且具有可接受精度将放射学目标定位到头部凸面的技术就足够了。我们提出了一种基于基本几何原理的卡尺技术，使用廉价且全球可用的工具（常规 CT 或 MRI 图像查看器、计算器、卡尺）。
使用图像查看器和毕达哥拉斯定理评估放射学目标与两个标志物（鼻根和外听道孔）之间的距离。然后，使用卡尺在患者头部周围标记两个标志物周围的两个距离。交点定义目标。我们在一个锯骨颅骨模型中测试了该技术，然后在手术室中进行了测试。使用卡尺导航技术和计算机导航定位凸面目标作为基准。
在锯骨模型中，卡尺导航目标与真实目标之间的平均偏差为 2.9 ± 2.8 毫米，95%置信区间（1.6 毫米；4.2 毫米）。计算机导航目标与真实目标之间的平均偏差为 1.6 ± 0.9 毫米，95%置信区间（1.2 毫米；2 毫米）（无统计学差异）。在 15 名接受导航颅骨手术的患者中，对 100 个目标进行了评估。卡尺导航的平均偏差为 11 ± 5.2 毫米，95%置信区间（9.9 毫米；12 毫米）。
这是一种将放射学目标快速且具有可接受精度转换到患者头部的低成本方法，使用廉价且全球可用的工具，对于许多手术具有令人满意的精度。
