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Marcello Macellari
Nasal septal deviations commonly cause obstructions of the nasal airways; when severe, deviations are surgically corrected by ear-nose-throat (ENT) specialists. Septoplasty, however, has a low success rate when the actual post-surgical benefits are considered, owing to a lack of standardized clinical tools capable to properly assess type and severity of obstructions, which vary wildly in shape and location. Often fully restoring the septal wall is impossible, and sometimes it is not required.
This paper introduces a procedure, based on patient-specific Computational Fluid Dynamics (CFD) simulations, to support ENT surgeons in septoplasty planning. The method hinges upon the adjoint-based optimization theory; by minimizing a cost function that indirectly accounts for viscous losses, a sensitivity map is computed on the mucosal wall which shows if and how much the removal of each point would contribute to easing the obstruction. The optimization is applied to three real nasal anatomies reconstructed from CT images of patients affected by complex septal deviations.
The sensitivity map is consistently found to identify all the anomalies correctly; the surgical action suggested by the sensitivity map appears to be feasible. Improvements in the characteristics of the nasal airflow after optimization were proved performing a suitable morphing of the geometries.