Assessment of pneumatization of the paranasal sinuses: a comprehensive and validated metric

Intercarotid artery distance in the pediatric population: Implications for endoscopic transsphenoidal approaches to the skull base

OBJECTIVE

Comprehensive quantitative evaluation of the intercarotid artery distance (ICD) in the pediatric population has not been sufficiently explored. This study aims to measure the minimal ICDs at multiple levels of the skull base to assess changes in the ICD during development.

METHODS

Measurement of the ICDs between the paired paraclival, parasellar, and paraclinoid segments of the internal carotid artery (ICA) was performed on coronal MRI from 540 patients ranging from 0 to 17 years old (n = 30 for each age). Comparison of these indices in the very young (0-5 years, Group 1) and young (6-17 years, Group 2) patients, and assessment of the degree of sphenoid sinus pneumatization was employed.

RESULTS

The narrowest ICD was located at the paraclinoid ICAs in the vast majority of cases (89.44%). When comparing the ICDs in very young age patients with the ICDs of 17 years old subjects, a statistically significant difference was found at the paraclival (ages 0-5), parasellar (ages 0-2), and paraclinoid (ages 0-4) ICDs (p < 0.05). Comparison of the ICDs between the intergroups (Group 1 and 2) also demonstrated a statistically significant difference (p < 0.0001). Pneumatization of the sphenoid sinus was initially noted to start at 3 years of age, and there were no patients with a non-pneumatized sphenoid sinus identified after 7 years of age in our cohort.

CONCLUSION

Measurement of ICDs at multiple levels provides a valuable reference for EEA procedures in the pediatric population. While the ICD may be largely stable in the pediatric population after 5 years of age, additional anatomic factors may restrict transsphenoidal access in very young patients (0-5 years).

Variability of Paranasal Sinus Pneumatization in the Absence of Sinus Disease

Background: Paranasal sinus pneumatization is a complex process, and numerous computed tomography (CT) studies document developmental variations in the setting of underlying sinus disease. The purpose of this study was to investigate variation in paranasal sinus pneumatization in a population of nondiseased subjects using a metric validated for tracking individual anatomic variants as well as total sinus volume.

Methods: A total of 591 consecutive sinus and maxillofacial CT scans were considered for study inclusion. After patients with inflammatory sinus or respiratory disease were excluded, 323 CT scans were scored using the Assessment of Pneumatization of the Paranasal Sinuses (APPS) instrument, and relevant demographic data were recorded for each scan. APPS findings were compared according to demographic characteristics and laterality.

Results: Laterality and sex were associated with differences in paranasal sinus pneumatization in a nondiseased population. Based on APPS score, the left side (4.95) was more pneumatized than the right (4.74, P=0.006), and males (10.16) were more extensively pneumatized than females (9.18, P=0.005). We found no correlation of age with sinus pneumatization (ρ=0.025). The probability of perceptible asymmetry in any given individual's paranasal sinus pneumatization was 69%, and the probability of left-sided dominance was 53%.

Conclusion: Substantial anatomic variation exists in paranasal sinus anatomy, even among patients without sinus disease. Significant differences are found between males and females and between the left and right sides. Continued systematic research of paranasal sinus anatomy may facilitate a standard for CT sinus assessment that will aid clinician evaluation of anatomic variation and surgical decision making.

Volumetric assessment of paranasal sinus opacification on computed tomography can be automated using a convolutional neural network

BACKGROUND

Computed tomography (CT) plays a key role in evaluation of paranasal sinus inflammation, but improved, and standardized, objective assessment is needed. Computerized volumetric analysis has benefits over visual scoring, but typically relies on manual image segmentation, which is difficult and time-consuming, limiting practical applicability. We hypothesized that a convolutional neural network (CNN) algorithm could perform automatic, volumetric segmentation of the paranasal sinuses on CT, enabling efficient, objective measurement of sinus opacification. In this study we performed initial clinical testing of a CNN for fully automatic quantitation of paranasal sinus opacification in the diagnostic workup of patients with chronic upper and lower airway disease.

METHODS

Sinus CT scans were collected on 690 patients who underwent imaging as part of multidisciplinary clinical workup at a tertiary care respiratory hospital between April 2016 and November 2017. A CNN was trained to perform automatic segmentation using a subset of CTs (n = 180) that were segmented manually. A nonoverlapping set (n = 510) was used for testing. CNN opacification scores were compared with Lund-MacKay (LM) visual scores, pulmonary function test results, and other clinical variables using Spearman correlation and linear regression.

RESULTS

CNN scores were correlated with LM scores (rho = 0.82, p < 0.001) and with forced expiratory volume in 1 second (FEV₁ ) percent predicted (rho = -0.21, p < 0.001), FEV₁ /forced vital capacity ratio (rho = -0.27, p < 0.001), immunoglobulin E (rho = 0.20, p < 0.001), eosinophil count (rho = 0.28, p < 0.001), and exhaled nitric oxide (rho = 0.40, p < 0.001).

CONCLUSION

Segmentation of the paranasal sinuses on CT can be automated using a CNN, providing truly objective, volumetric quantitation of sinonasal inflammation.

The Unified Airway: Does Asthma Influence Paranasal Sinus Pneumatization?

Asthma has been implicated as a driving force in lower airway remodeling; however, its effect on upper airway development has not been studied. Clinical disease, particularly cystic fibrosis (CF), has been associated with anatomical paranasal sinus variation, although the mechanism for these variations remains unclear. The purpose of this study was to determine whether asthma is associated with altered sinus pneumatization. Five hundred ninety-one computed tomography scans, including 303 adolescents (age 13-18) and 288 adults (age > 18), were evaluated using the Assessment of Pneumatization of the Paranasal Sinuses (APPS) instrument. The APPS score is validated for assessing anatomical variation and total sinus volume. A diagnosis of asthma was ascertained from the medical record, and patients with CF were included as a positive control group. Patients with asthma had mean APPS score of 9.66, compared to 9.85 for participants without asthma (P = .585). Subgroup analysis demonstrated similar findings among adults (P = .817) and adolescents (P = .585). Patients with a diagnosis of CF had significant sinus hypoplasia according to a mean APPS scores of 3.50 (P < .001). Sinus hypoplasia persisted in both adults (P < .001) and adolescents (P < .001) with CF. The presence of asthma is not associated with altered paranasal sinus pneumatization. In contrast, CF is associated with significantly reduced sinus pneumatization. These findings suggest that aberrant sinus pneumatization may not be a feature of asthma and that chronic mucosal respiratory disease is not a generalizable cause for altered paranasal sinus pneumatization.

The Bifurcated Frontal Sinus

Objectives

Frontal sinus anatomy is complex, and multiple variations of ethmoid pneumatization have been described that affect the frontal outflow tract. In addition, the lumen proper of the frontal sinus may exist as 2 separate parallel cavities that share an ipsilateral outflow tract. This variant has not been previously described and may have implications for surgical management.

Study Design

Case series.

Setting

Tertiary rhinology practice.

Subjects and Methods

Cases with radiographic and intraoperative findings of separate parallel tracts within a unilateral frontal sinus were identified from a consecutive series of 186 patients who underwent endoscopic sinus surgery between May 2015 and July 2016. Data were recorded including sinusitis phenotype, coexisting frontal cells, and extent of surgery.

Results

Ten patients (5.4%) were identified with computed tomography scans demonstrating bifurcation of the frontal sinus into distinct medial and lateral lumens. All cases were treated with Draf 2a or 2b frontal sinusotomy with partial removal of the common wall to create a unified ipsilateral frontal ostium. Eleven sides had a coexisting ipsilateral agger nasi cell, 7 had a supra-agger cell, 8 had a suprabullar cell, and 1 had a frontal septal cell. There were no significant complications.

Conclusion

The bifurcated frontal sinus is an anatomic variant that the surgeon should recognize to optimize surgical outcomes. Failure to do so may result in incomplete clearance of the sinus and residual disease. The bifurcated sinus may occur with other types of frontal sinus cells and may be safely treated with endoscopic techniques.

Paranasal sinus opacification-to-pneumatization ratio applied as a rapid and validated clinician assessment

BACKGROUND

The utility of clinician-applied instruments, particularly the Lund-Mackay score, in the assessment of paranasal sinus computed tomography (CT) in chronic rhinosinusitis (CRS) remains incompletely defined. The purpose of this study was to determine if a new approach to the evaluation of sinus CT could accurately predict the extent of opacification while remaining simple for clinician use.

METHODS

Twenty-four sinus CT scans were measured for the percent of sinus opacification using three-dimensional (3D) volumetric analyses. The same scans were also evaluated using the Lund-Mackay score to measure opacification and the Assessment of Pneumatization of the Paranasal Sinuses (APPS) score to measure total sinus volume (TSV). Correlation analysis was performed for the Lund-Mackay to APPS score ratio as a predictor of percent opacification. Validation analysis was also performed to determine the optimal orientation for Lund-Mackay scoring, which has not previously been described.

RESULTS

The Lund-Mackay to APPS score ratio was very strongly correlated with the percentage of sinus opacification measured by 3D volumetric analysis (r = 0.862, r² = 0.743, p < 0.001). Lund-Mackay scoring was not statistically different between axial-only, coronal-only, or triplanar groups for interrater (p = 0.379) and intrarater reliability (p = 0.312).

CONCLUSION

The Lund-Mackay score is validated for rater reliability in multiple orientations. Using the APPS score as a measure of TSV, the Lund-Mackay-to-APPS ratio very strongly correlates with the percentage of sinus opacification by 3D volumetric analysis. Further study will be required to determine if this ratio is predictive of symptom severity.

Prevalence of bony septa, antral pathology, and dimensions of the maxillary sinus from a sinus augmentation perspective: A retrospective cone-beam computed tomography study

PURPOSE

Sinus elevation procedures have become a routine and reliable way to gain bone volume in the edentulous maxilla for dental implant placement. Presence of bony septations and pathology in the maxillary sinus often cause complications leading to graft or implant failure or both. The aim of this study was to retrospectively evaluate the prevalence of pathology, direction of the septa, and sinus width measured at 2 mm, 5 mm, and 10 mm from the sinus floor in maxillary sinuses using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Seventy-two sinuses from 36 random preoperative CBCT scans referred for implant therapy were retrospectively evaluated for the number, prevalence, and direction of bony septations and presence of pathology. Width of the sinus was also measured at 2 mm, 5 mm, and 10 mm from the sinus floor to account for the amount of bone available for implant placement.

RESULTS

Maxillary sinus septa were found in 59.7%. Presence of a single septum was noted in 20 sinuses (27.7%), followed by two septa in 17 sinuses. The most common direction of the septum was the transverse direction. Retention pseudocyst and mucosal thickening were the most commonly seen abnormality/pathology.

CONCLUSION

Based on the high prevalence of septa and sinus pathology in this sample, a preoperative CBCT scan might be helpful in minimizing complications during sinus augmentation procedures for dental implant therapy.