Using 3D printed sinonasal models to visualize and optimize personalized sinonasal sinus irrigation strategies

Abstract

Background: Topical sinus irrigations (neti-pot, squeeze bottles) play a critical role in the management of sinonasal disease. However, due to intricate nasal anatomy, penetration of topical irrigations to targeted sinus regions may be highly variable, and difficult to objectively predict. Variables, including head positions, injection angles, flow rates, etc. may vary significantly depending on the individual's anatomy.

Objective: The purpose of this study was to propose a novel idea: using a 3D printed model of sinonasal cavities to visualize and develop a patient-specific irrigation strategy.

Methods: As a proof of concept, 3D replicas of one patient's sinonasal cavities pre- and post-surgery were printed with a Form2 SLA 3D printer based on their CT scans. The setup included rubber/silicon seals attached to the model's nostrils to create a watertight seal with the irrigation device and food color dye added for better visualization of irrigation results.

Results: Irrigations were performed on the 3D models with various head positions, injection angles, and flow rates, and were successful to determine the optimal strategy to targeted sinuses. Significant differences were observed between different targeted sinuses and between pre and post-surgery models.

Conclusion: With more affordable 3D printing, this technology may potentially improve patient care and patient education, allowing clinicians and patients to develop a personalized irrigation strategy and have visual confirmation.

Figure 1.

a) a 3D printed nasal replica based on one patient’s specific CT scan. b) a cross-section of the 3D printed nasal replica. A wall of 3–4mm thickness is created to enclose the nasal air space. c-e) various attachment of water-tightly connection for common irrigation devices to the 3D printed nasal model. As examples, we have (c) rubber molds hot glued onto a squeeze bottle, (d) silicon deformable and detachable molds on a squeeze bottle, (e) similar silicon molds on a typical net-pot. They all serve the similar function of creating a water-tight connection between the irrigation device and the nasal replica so that irrigation trials can be easily performed over a sink, as shown in Figure 2,3 and Video 1.

Figure 2

displayed the snapshot of irrigation fluid level for the pre-surgery model at different head positions (see Video1 for full trials). a) specifically compared the irrigation outcome to the maxillary sinus, which showed that except for the 45° Head Tilt to Left, none of the other head positions resulted in any visible filling of the maxillary sinus. b) summarized the ethmoid sinus, in which 90° Head Tilt to the side demonstrated the best outcome. c) showed the frontal sinuses, where the 90° Head Tilt Forward demonstrated the best outcome. In brief conclusion, the optimal head positions for different sinuses can be very different.

Figure 3

showed the fluid filling level for the post-surgery model, which in general was much improved compared to the pre-surgery case, but still with significant variations for different head positions or different targeted sinuses. For example, a) both 45° Head Tilt to Left and 90° Head Tilt to Left received completely full filling of the contralateral maxillary sinus, whereas 45° Head Tilt Forward only received a light filling. But since 45° Head Tilt to Left even received half filling of the ipsilateral maxillary sinus, it is probably a better position than the 90° Head Tilt to Left for maxillary sinuses. b) only 90° Head Tilt to Left received moderate filling of ethmoid and sphenoid sinus, whereas none of the other head positions received any visible filling of ethmoid and sphenoid sinuses. c) while the 90° Head Tilt Forward received full frontal sinuses filling, none of the other sinuses received penetration; whereas the 90° Head Tilt to the side position actually received irrigation of the majority of frontal sinus as well as receiving irrigation of the contralateral maxillary and ethmoid sinuses. There could be a split of opinion, but based on overall performance, the 90° Head Tilt to the side position could be the optimal position for all sinuses for the post-surgery case.