Abstract:Purpose
The goal of this study was to develop a complete workflow allowing for conducting computational fluid dynamics (CFD) simulation of airflow through the upper airways based on computed tomography (CT) and cone-beam computed tomography (CBCT) studies of individual adult patients.
Methods
This study is based on CT images of 16 patients. Image processing and model generation of the human nasal cavity and paranasal sinuses were performed using open-source and freeware software. 3-D Slicer was used primaril… Show more
“…An example of air movement visualization was shown in Fig. 4 after about 30 s. This visualization combines the infected air volume fraction α (yellow) and vortices reconstructed utilizing the Q-criterion ( Tretiakow et al, 2020 ). The qualitative difference between the case without a face shield (bottom) and when the infected person has a face shield (top) is clearly visible.…”
Section: Resultsmentioning
confidence: 99%
“…1 inhales and exhales infected air, and the model on the right exhales and inhales clean air. The volumetric flow rate is defined by the following relationship ( Tretiakow et al, 2020 ): Fig. 1 Flow domain (inlet and outlet surfaced indicated).…”
We aimed to develop a model to quantitatively assess the potential effectiveness of face shield (visor) in reducing airborne transmission risk of the novel coronavirus SARS-CoV-2 during the current COVID-19 pandemic using the computational fluid dynamics (CFD) method. The studies with and without face shield in both an infected and healthy person have been considered in indoor environment simulation. In addition to the influence of the face shield and the synchronization of the breathing process while using the device, we also simulated the effect of small air movements on the SARS-CoV-2 infection rate (outdoor environment simulation). The contact with infectious particles in the case without a face shield was 12–20 s (s), in the presence of at least one person who was positive for SARS-CoV-2. If the infected person wore a face shield, no contact with contaminated air was observed during the entire simulation time (80 s). The time of contact with contaminated air (infection time) decreases to about 11 s when the surrounding air is still and begins to move at a low speed. Qualitative differences between simulations performed on the patients with and without the face shield are clearly visible. The maximum prevention of contagion is probably a consequence of wearing a face shield by an infected person. Our results suggest that it is possible to determine contact with air contaminated by SARS-CoV-2 using the CFD method under realistic conditions for virtually any situation and configuration. The proposed method is probably the fastest and most reliable among those based on CFD-based techniques.
“…An example of air movement visualization was shown in Fig. 4 after about 30 s. This visualization combines the infected air volume fraction α (yellow) and vortices reconstructed utilizing the Q-criterion ( Tretiakow et al, 2020 ). The qualitative difference between the case without a face shield (bottom) and when the infected person has a face shield (top) is clearly visible.…”
Section: Resultsmentioning
confidence: 99%
“…1 inhales and exhales infected air, and the model on the right exhales and inhales clean air. The volumetric flow rate is defined by the following relationship ( Tretiakow et al, 2020 ): Fig. 1 Flow domain (inlet and outlet surfaced indicated).…”
We aimed to develop a model to quantitatively assess the potential effectiveness of face shield (visor) in reducing airborne transmission risk of the novel coronavirus SARS-CoV-2 during the current COVID-19 pandemic using the computational fluid dynamics (CFD) method. The studies with and without face shield in both an infected and healthy person have been considered in indoor environment simulation. In addition to the influence of the face shield and the synchronization of the breathing process while using the device, we also simulated the effect of small air movements on the SARS-CoV-2 infection rate (outdoor environment simulation). The contact with infectious particles in the case without a face shield was 12–20 s (s), in the presence of at least one person who was positive for SARS-CoV-2. If the infected person wore a face shield, no contact with contaminated air was observed during the entire simulation time (80 s). The time of contact with contaminated air (infection time) decreases to about 11 s when the surrounding air is still and begins to move at a low speed. Qualitative differences between simulations performed on the patients with and without the face shield are clearly visible. The maximum prevention of contagion is probably a consequence of wearing a face shield by an infected person. Our results suggest that it is possible to determine contact with air contaminated by SARS-CoV-2 using the CFD method under realistic conditions for virtually any situation and configuration. The proposed method is probably the fastest and most reliable among those based on CFD-based techniques.
“…In the present study the method used by Tretiakow et al has been employed for volume calculation. 9 After image acquisition, axial, coronal, and sagittal planes were generated by the software and the segmentation process was navigated and inspected. The "threshold", "scissors", "islands", "level" and "smoothing" tools were used respectively and paranasal sinus volumes were calculated.…”
Introduction: The anatomy of the paranasal sinuses is important for many
surgeon groups. The precise knowledge of such structures with variable
anatomy will be important for the preservation of these structures and
the management of complications in surgeries such as endoscopic sinus
surgery and osteotomies involving the maxilla. Objective: The purpose of
the present study is to investigate volumetric differences between
ethmoid, sphenoid and maxillary sinus volumes in patients with maxillary
deficiency requiring Le Fort osteotomy and healthy patients, by
employing computed tomography imaging. Methods: Computed tomography
scans of 120 patients (59 maxillary deficiency patients and 61 control
patients) were included in the study. Images were processed, the
paranasal sinuses were sculpted out from 3D images and measured. All
measurements were taken twice by the same observers. The observers
performed the study twice with an interval of 2 weeks to detect
intra-observer variability. Results: Ethmoid and left and right
maxillary sinus volumes were smaller in the Le Fort group, although no
differences were observed for sphenoid sinus volumes. Conclusion:
Paranasal sinus volumes varied between maxillary deficiency patients and
control patients. This condition may be crucial for the surgeon
operating in these areas and should be taken into consideration during
surgeries.
“…We are not aware of any other 3DSlicer-based surgically oriented studies of the middle turbinate’s anatomy. However, diverse workgroups already reported on this software’s feasibility to analyze the paranasal sinuses and the skull base for anatomical 17 , 18 , biophysical 19 , 20 or forensic 21 purposes. Raappana et al described a 3DSlicer-based planning workflow for transnasal pituitary surgery, focusing on the relevant parasellar anatomy 22 .…”
The middle turbinate’s basal lamella (3BL) is a variable landmark which needs to be understood in endoscopic transnasal skull base surgery. It comprises an anterior frontal and a posterior horizontal part and appears in its simplest depiction to be “L”-shaped, when viewed laterally. In this study we analyzed its 3D morphology and variations focusing on a precise and systematic description of the anatomy. CBCTs of 25 adults, 19 cadavers and 6 skulls (total: 100 sides) were investigated with the 3DSlicer software, creating 3D models of the 3BL. We introduced a novel geometrical classification of the 3BL’s shape, based on segments. We analyzed their parameters and relationship to neighboring structures. When viewed laterally, there was no consistent “L”-shaped appearance of the 3BL, as it is frequently quoted. A classification of 9 segment types was used to describe the 3BL. The 3BLs had in average of 2.95 ± 0.70 segments (median: 3), the most frequent was the horizontal plate (23.05% of all segments), next a concave/convex plate (22.71%), then a sigma plate (22.37%). Further types were rare. We identified a horizontal plate in 68% of all lateral views whilst 32% of the 3BLs were vertical. A sigma–concave/convex–horizontal trisegmental 3BL was the most common phenotype (27%). Globally, the sigma–concave/convex pattern was present in 42%. The 3BL adhered the ethmoidal bulla in 87%. The segmenting method is eligible to describe the 3BL’s sophisticated morphology.
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