Purpose

State-of-the-art medical examination techniques (e.g., rhinomanometry and endoscopy) do not always lead to satisfactory postoperative outcome. A fully automatized optimization tool based on patient computer tomography (CT) data to calculate local pressure gradient regions to reshape pathological nasal cavity geometry is proposed.

Methods

Five anonymous pre- and postoperative CT datasets with nasal septum deviations were used to simulate the airflow through the nasal cavity with lattice Boltzmann (LB) simulations. Pressure gradient regions were detected by a streamline analysis. After shape optimization, the volumetric difference between the two shapes of the nasal cavity yields the estimated resection volume.

Results

At LB rhinomanometry boundary conditions (bilateral flow rate of 600 ml/s), the preliminary study shows a critical pressure gradient of −1.1 Pa/mm as optimization criterion. The maximum coronal airflow ΔA := cross-section ratio \(\frac{\mathrm{virtual surgery }}{\mathrm{post}-\mathrm{surgery}}\) found close to the nostrils is 1.15. For the patients a pressure drop ratio ΔΠ := (pre-surgery − virtual surgery)/(pre-surgery − post-surgery) between nostril and nasopharynx of 1.25, 1.72, −1.85, 0.79 and 1.02 is calculated.

Conclusions

LB fluid mechanics optimization of the nasal cavity can yield results similar to surgery for air-flow cross section and pressure drop between nostril and nasopharynx. The optimization is numerically stable in all five cases of the presented study. A limitation of this study is that anatomical constraints (e.g. mucosa) have not been considered.

中文翻译：

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基于晶格玻尔兹曼流体模拟的手术前计划工具，用于估计切除体积以改善鼻呼吸

目的

最先进的医学检查技术（例如，鼻压计和内窥镜检查）并不总能带来令人满意的术后结果。提出了一种基于患者计算机断层扫描（CT）数据的全自动优化工具，用于计算局部压力梯度区域以重塑病理性鼻腔几何形状。

方法

使用具有鼻中隔偏差的五个匿名术前和术后CT数据集，通过格子Boltzmann（LB）模拟来模拟流经鼻腔的气流。通过流线分析检测压力梯度区域。在形状优化之后，两种形状的鼻腔之间的体积差异会产生估计的切除体积。

结果

在LB鼻压测定法的边界条件（双向流速为600 ml / s）下，初步研究表明，临界压力梯度为-1.1 Pa / mm作为优化标准。最大冠状气流Δ甲：=横截面比\（\压裂{\ mathrm {虚拟手术}} {\ mathrm {交} - \ mathrm {手术}} \）发现接近鼻孔是1.15。对于患者，计算出鼻孔和鼻咽之间的压降比ΔΠ：=（术前-虚拟手术）/（术前-术后）1.25、1.72，-1.85、0.79和1.02。

结论

LB鼻腔的流体力学优化可产生与手术相似的结果，包括气流横截面和鼻孔与鼻咽之间的压降。在本研究的所有五种情况下，优化在数值上都是稳定的。该研究的局限性在于尚未考虑解剖学限制（例如粘膜）。