Chronic invasive fungal rhinosinusitis vs sinonasal squamous cell carcinoma: the differentiating value of MRI.

OBJECTIVES: To investigate MRI features in discriminating chronic invasive fungal rhinosinusitis (CIFRS) from sinonasal squamous cell carcinomas (SNSCC). METHODS: MRI findings of 33 patients with CIFRS and 47 patients with SNSCC were retrospectively reviewed and compared. Multivariate logistic regression analysis was performed to identify significant imaging features in distinguishing between CIFRS and SNSCC. The ROC curves and the AUC were used to evaluate diagnostic performance. RESULTS: There were significant differences in cavernous sinus involvement (p < 0.001), sphenoid sinus involvement (p < 0.001), meningeal involvement (p = 0.024), T2 signal intensity (p = 0.006), and enhancement pattern (p < 0.001) between CIFRS and SNSCC. Multivariate logistic regression analysis identified cavernous sinus involvement (odds ratio [OR] = 0.06, 95% confidence interval [95% CI] = 0.02-0.20) and sphenoid sinus involvement (OR = 0.14, 95% CI = 0.05-0.45) as significant indicators for CIFRS and T2 isointensity to gray matter (OR = 4.44, 95% CI = 1.22-16.22) was a significant indicator for SNSCC. ROC curve analysis showed the AUC from a combination of three imaging features was 0.95 in differentiating CIFRS and SNSCC. CONCLUSIONS: MRI showed significant differences between CIFRS and SNSCC features. In immunocompromised patients, a sinonasal hypointense mass on T2WI with septal enhancement or loss of contrast enhancement, and involvement of cavernous sinus, sphenoid sinus, and meninges strongly suggest CIFRS. KEY POINTS: • Chronic invasive fungal rhinosinusitis (CIFRS) is often difficult to distinguish from sinonasal squamous cell carcinomas (SNSCC) in clinical practice. • Cavernous sinus and sphenoid sinus involvement appear to be significant indicators for CIFRS. T2 isointensity to gray matter appears to be a significant indicator for SNSCC. • Loss of contrast enhancement and septal enhancement can be used to distinguish CIFRS from SNSCC with a high degree of specificity.

Comparison between effects of various partial inferior turbinectomy options on nasal airflow: a computer simulation study.

Partial inferior turbinectomy is typically performed on patients suffering from chronic nasal obstruction due to hypertrophy of inferior turbinates and is refractory to other more conservative treatments. The effects of the various options of incision performed on the inferior turbinate in terms of the resulting nasal airflow pattern are examined using computational fluid mechanics. The pressure drops across the severely blocked nose and healthy nose models were found to be 32.3 and 12.3 Pa, respectively, whereas the pressure drops across the nasal cavity following one-third turbinate resection, total turbinate resection and front-end resection were obtained as 5.8, 6.1 and 30.5 Pa correspondingly. Based on the total pressure drop results, the one-third resection option seems to be better than the front-end surgery and the total turbinate resection.

Aerodynamic characteristics inside the rhino-sinonasal cavity after functional endoscopic sinus surgery.

BACKGROUND: The aim of this study was to evaluate effects of functional endoscopic sinus surgery (FESS) on transient nasal aerodynamic flow patterns using computational fluid dynamics (CFD) simulations. METHODS: A three-dimensional model of the nasal cavity was constructed from CT scans of a patient with FESS interventions on the right side of the nasal cavity. CFD simulations were then performed for unsteady aerodynamic flow modeling inside the nasal cavity as well as the sinuses. RESULTS: Comparisons of the local velocity magnitude and streamline distributions inside the left and right nasal cavity and maxillary sinus regions were presented. Because of the FESS procedures in the right nasal cavity, existences and distributions of local circulations (vortexes) were found to be significantly different for the same nasal airflow rate but at different acceleration, deceleration, or quiet phases in the maxillary sinus region on the FESS side. Because of inertia effects, local internal airflow with circulation existences was continuous throughout the whole respiration cycle. With a larger peak inspiration flow rate, the airflow intensity inside the enlarged maxillary sinus increased significantly. Possible outcomes on functional performances of the nose were also examined and discussed. CONCLUSION: Surgical enlargements of natural ostium of the maxillary sinus will change the aerodynamic patterns inside the main nasal cavity and maxillary sinus regions, which may affect normal nasal physiological functions. Local inertia effects play more important roles for the internal nasal airflow pattern changes and thus such conventional FESS procedures should be carefully planned.

Assessments of nasal bone fracture effects on nasal airflow: A computational fluid dynamics study.

BACKGROUND: The aim of this study was to evaluate effects of nasal bone fractures on nasal aerodynamic flow patterns using computational fluid dynamics (CFD) simulations. METHODS: A three-dimensional model of nasal cavity with a nasal bone fracture was constructed from computerized tomography (CT) scans of a patient with use of software Mimics 13.0 (The Materilize Group, Leuven, Belgium). CFD simulations were performed using Fluent 6.3 (ANSYS, Inc., Canonsburg, PA) with a turbulent flow model. Numerical results were presented with velocity, streamline, and pressure contour distributions in left and right nasal cavities and were compared with those of a healthy one. Possible outcomes on functional performances or patencies of the nose were also examined and discussed. RESULTS: For the nose with a nasal bone fracture, distributions of velocity contours showed there was more airflow in the right nasal cavity than in the left one, especially for inspiration status. In the left cavity, the airflow was redirected irregularly and there were also more circulations with larger sizes, higher pressure jumps, and greater wall shear stresses. Flow partitioning in the right and left cavities was noticeable with a larger nasal resistance compared with the healthy one. When the inspirational flow rate was increased, pressure jump from the nostril to the nasopharynx increased faster. CONCLUSION: The aerodynamic flow was redistributed greatly for the nose with a nasal bone fracture compared with the healthy one, which might affect local normal nasal functions. Such physical assessments of nasal airflow based on a model from the patients' CT scans may help clinicians determine the best treatment in advance.

A computational fluid dynamics model for drug delivery in a nasal cavity with inferior turbinate hypertrophy.

BACKGROUND: Intranasal medications are commonly used in treating nasal diseases. However, technical details of the correct usage of these medications for nasal cavity with obstruction are unclear. METHODS: A three-dimensional model of nasal cavity was constructed from MRI scans of a healthy human subject. Nasal cavities corresponding to healthy, moderate, and severe nasal obstruction (NO) were simulated by enlarging the inferior turbinate geometrically, which was documented by approximately one-third reduction of the minimum cross-sectional area for the moderate and two-thirds for the severe obstruction. The discrete phase model based on steady-state computational fluid dynamics was used to study the gas-particle flow. The results were presented with drug particle (from 7 x 10⁻5 to 10⁻7 m) deposition distribution along the lateral walls inside these three nasal cavities, and comparisons of the particle ratio escaping from the cavity were also presented and discussed. RESULTS: Nasal patency is an essential condition that had the most impact on particle deposition of the factors studied; the particle percentage escaping the nasal cavity decreased to less than a half and one-tenth for the moderately and severely blocked noses. Decreasing of flow rate and particle diameter increased the escaping ratio; however, zero escaping percentage was detected with the absence of air flow and the effect was less noticeable when the particle diameter was very small (<10⁻6 m). The existence of inspiratory flow and head tilt angle helped to improve the particle escaping ratio for the healthy nose; however, such changes were not significant for the moderately and severely blocked noses. CONCLUSION: When using an intranasal medication, it is advisable to have a moderate inspiratory air-flow rate and small size particles to improve particle escaping ratio. Various head positions suggested by clinicians do not seem to improve the drug escaping ratio significantly for the nasal cavities with inferior turbinate hypertrophy.

Impact of inferior turbinate hypertrophy on the aerodynamic pattern and physiological functions of the turbulent airflow - a CFD simulation model.

INTRODUCTION: The aim of this study was to investigate the effects of nasal obstruction with enlargement of inferior turbinates on the aerodynamic flow pattern using Computational Fluid Dynamics (CFD) tools including the effects of turbulence. METHODS: A high-resolution 3-dimensional model of the nasal cavity was constructed from MRI scans of a healthy human subject using MIMICS 12.0 software. Nasal cavities corresponding to healthy, moderate and severe nasal obstructions were simulated by enlarging the inferior turbinate geometrically. Numerical simulations with turbulent flow models were implemented using FLUENTS for CFD simulations. RESULTS: In the healthy nose, the main respiratory air stream occurs mainly in the middle of the airway, accompanied by a diffused pattern of turbulent flow on the surface of the nasal mucosa. The peak value of turbulent flow is found in the functional nasal valve region. However, this aerodynamic flow pattern has partially or completely changed in the models with enlarged inferior turbinate. An inhalation flow rate of 34.8 L/min with a maximum velocity of 5.69 m/s, 7.39 m/s and 11.01 m/s are detected, respectively, in the healthy, moderately and severely obstructed noses. Both total negative pressure and maximum shear stress have increased by more than three and two times, respectively, in severely blocked noses compared to the healthy one. CONCLUSION: Data of this study provide quantitative and quantitative information of the impact of inferior turbinate hypertrophy on the aerodynamic pattern and physiological functions of nasal airflow. By including the model of turbulent airflow, the results of this experimental study will be more meaningful and useful in predicting the aerodynamic effects of surgical correction of inferior turbinate hypertrophy.

The glossopharyngeal, vagus and spinal accessory nerves.

The glossopharyngeal, vagus and spinal accessory nerves are closely related anatomically, and to a certain extent, functionally. We present an overview of their anatomy, highlighting the important clinical and imaging implications. The main pathologic lesions arising from these nerves are also discussed and the imaging features reviewed.

Numerical simulation of the effects of inferior turbinate surgery on nasal airway heating capacity.

BACKGROUND: The aim of this study was to evaluate the effects of inferior turbinate surgery on nasal airway heating capacity using computational fluid dynamics (CFD) simulations. METHODS: Heat transfer simulations were performed for a normal nasal cavity and others with severely enlarged inferior turbinates, before and after three simulated surgical procedures: (1) resection of the lower third free edge of the inferior turbinate, (2) excision of the head of the inferior turbinate, and (3) radical inferior turbinate resection. The models were run with three different environmental temperatures. RESULTS: The changes of airflow pattern with the reduction of inferior turbinate affected heat transfer greatly. However, the distribution of wall heat flux showed that the main location for heat exchange was still the anterior region. Under the cold environment, the nasal cavities with the head of inferior turbinate reduction were capable of heating the inspired air to 98.40% of that of the healthy one; however, for the case with lower third of inferior turbinate excised, the temperature was 11.65% lower and for the case with radical inferior turbinate resection, 18.27% lower temperature compared with the healthy nasal cavity. CONCLUSION: The healthy nasal cavity is able to warm up or cool down the inspiratory airflow under different environmental temperature conditions; for the nasal cavities with turbinate surgeries, partial inferior turbinate reduction can still sustain such heating capacity. However, too much or total turbinate resection may impair the normal function of temperature adjustment by nasal mucosa.

Assessment of septal deviation effects on nasal air flow: a computational fluid dynamics model.

OBJECTIVES/HYPOTHESIS: The purpose of this article is to analyze the effects of septal deviation on the aerodynamic air flow pattern compared with that of a normal nose by computational fluid dynamics (CFD) tools. METHODS: Two 3-dimensional (3-D) models of nasal cavities were constructed from the magnetic resonance imaging and computed tomography scans of a healthy human nose and a nose with septal deviation, with the use of the software MIMICS 12.1 (The Materialise Group, Leuven, Belgium). Thereafter high-resolution 3-D volume meshes comprising boundary layer effect and computational domain exterior to the nose were constructed. Numerical simulations were carried out using FLUENT (ANSYS, Canonsburg, PA) for CFD simulations. The Reynolds-averaged Navier-Stokes equations were solved for the turbulence flow with the shear stress transport k - omega model. RESULTS: In the nose model with septal deviation, major changes in the pattern of inspiratory airflow (e.g., flow partitioning and nasal resistance, velocity and pressure distributions, intensity and location of turbulence), wall shear stress, and increasing of total negative pressure through the nasal cavity were demonstrated qualitatively and quantitatively. In the healthy nose, the area with the highest intensity of turbulent flow was found in the functional nasal valve region, but it became less apparent or even disappeared in the septal deviation one. CONCLUSIONS: This CFD study provides detailed information of the aerodynamic effects of nasal septal deviation on nasal airflow patterns and their associated physiological functions.

CT and MR imaging of solitary extramedullary plasmacytoma of the nasal tract.

BACKGROUND AND PURPOSE: Solitary extramedullary plasmacytoma (SEP) is rare. The purpose of this study was to determine the CT and MR imaging features of SEP of the nasal tract. METHODS: We retrospectively reviewed three CT and two MR images of three histologically proved cases in two men and one woman aged 43-66 years. RESULTS: The plasmacytomas predominantly involved the nasopharynx in two cases and the nasal cavity in one. Two of the tumors were bulky solid masses, whereas the third showed infiltrative features. They were predominantly masses or infiltrative lesions with soft-tissue attenuation on CT scans. The lesions were isointense and hyperintense on T1- and T2-weighted MR images, respectively. The tumors revealed moderate-to-marked contrast enhancement and may have been associated with lytic bone destruction. CONCLUSION: The imaging features of SEP are nonspecific. However, this entity should be included in the differential diagnosis of tumors in the nasopharynx and nasal cavity.