Retrospective analysis of the upper airway anatomy and Sella turcica morphology across different skeletal malocclusions: a computerized technique

OBJECTIVE

This study aimed to investigate the normal volumetric space and variations in the measurements of different landmarks in adults with different skeletal relations of the maxilla and the mandible based on CBCT data. The study also analyses these landmarks to locate any correlations.

BACKGROUND

Numerous studies in orthodontics have found a relationship between orthodontic treatment and changes in the anatomy and function of the airway. Severe changes in airway morphology can cause breathing difficulties, lower quality of life, and even result in life-threatening conditions such as obstructive sleep apnoea. Consequently, orthodontic diagnosis and treatment planning require a thorough understanding of the airway space and its function.

METHODS

The present retrospective study was conducted using CBCT records of 120 adult patients, containing 40 samples of each skeletal class (20 males and 20 females). The boundaries were defined for the 3 major regions: the nasopharynx, the oropharynx, and the hypopharynx. Various measurements were recorded across these regions, as well as selective cephalometric landmarks. The obtained data was used to calculate average and standard deviation, while regression analysis was used to evaluate correlations and t-test was used to test statistical significance of gender differences.

RESULTS

The results demonstrate that skeletal Class III individuals exhibit a reduced airway volume in the nasopharynx compared to other groups, whereas skeletal Class II individuals displayed a diminished airway volume in the hypopharynx. A strong correlation was observed for Sella turcica parameters. There were no significant differences in skeletal parameters across genders. Nasopharynx cavity volume demonstrated significant differences between skeletal Class I-Class III as well as between skeletal Class II-Class III. Hypopharynx cavity volume also demonstrated significant differences between skeletal Class I-Class II and between skeletal Class II-Class III.

CONCLUSION

The major findings are the presence of a reduced nasopharyngeal volume in skeletal Class III malocclusions while skeletal Class II individuals displayed a diminished hypopharyngeal volume, making these critical areas to consider during the diagnostic and orthodontic treatment planning stages. This study also revealed a consistent correlation between Sella turcica parameters across various facial skeletal profiles, with skeletal Class II patients exhibiting a distinct pattern and skeletal Class I and Class III demonstrating an average relationship.

Development and validation of predictive models for skeletal malocclusion classification using airway and cephalometric landmarks

OBJECTIVE

This study aimed to develop a deep learning model to predict skeletal malocclusions with an acceptable level of accuracy using airway and cephalometric landmark values obtained from analyzing different CBCT images.

BACKGROUND

In orthodontics, multitudinous studies have reported the correlation between orthodontic treatment and changes in the anatomy as well as the functioning of the airway. Typically, the values obtained from various measurements of cephalometric landmarks are used to determine skeletal class based on the interpretation an orthodontist experiences, which sometimes may not be accurate.

METHODS

Samples of skeletal anatomical data were retrospectively obtained and recorded in Digital Imaging and Communications in Medicine (DICOM) file format. The DICOM files were used to reconstruct 3D models using 3DSlicer (slicer.org) by thresholding airway regions to build up 3D polygon models of airway regions for each sample. The 3D models were measured for different landmarks that included measurements across the nasopharynx, the oropharynx, and the hypopharynx. Male and female subjects were combined as one data set to develop supervised learning models. These measurements were utilized to build 7 artificial intelligence-based supervised learning models.

RESULTS

The supervised learning model with the best accuracy was Random Forest, with a value of 0.74. All the other models were lower in terms of their accuracy. The recall scores for Class I, II, and III malocclusions were 0.71, 0.69, and 0.77, respectively, which represented the total number of actual positive cases predicted correctly, making the sensitivity of the model high.

CONCLUSION

In this study, it is observed that the Random Forest model was the most accurate model for predicting the skeletal malocclusion based on various airway and cephalometric landmarks.

Postoperative Upper Airway Volume Measurements Among Children With Craniofacial Abnormalities

OBJECTIVE

To measure postoperative airway volumes among patients with craniofacial abnormalities and compare them to normative values.

STUDY DESIGN

Retrospective, comparative study.

SETTING

Academic Medical Center.

METHODS

Retrospective analysis of imaging of children with craniofacial abnormalities treated at NYU Langone Health from January 2013 to February 2021. Upper airway volumes postcraniofacial surgery were measured using 3D processing software (Dolphin 3D, version 11.95). These values were compared with published normative values.

RESULTS

Twenty-one subjects were identified and compared to normative values. The postoperative oropharyngeal volumes were on average 43.7% smaller than the normative values (P < .001), and the total upper airway volumes were 31.6% smaller (P = .003). No significant differences were observed in the nasopharyngeal or hypopharyngeal volumes of the study cohort compared to the normative data. Among children ages 12 to 17 years (n = 13), the mean oropharyngeal volumes were 47.6% smaller than normal (P < .001), and the mean total upper airway volumes were 34.6% smaller than normal (P < .001). Among children ages 7 to 11 years (n = 8), the mean oropharyngeal volumes were 35.1% smaller than normal (P = .049), but no difference in mean total upper airway volume was observed.

CONCLUSION

In children with craniofacial anomalies, postoperative airway volumes remain lower than normative values. However, even a slight increase in airway volume can yield a substantial increase in flow rate. 3D airway evaluations are a valuable tool for surgical planning and analysis and can help with optimizing airway dynamics.

Magnetic resonance thermometry for hyperthermia in the oropharynx region

Magnetic resonance thermometry (MRT) can measure in-vivo 3D-temperature changes in real-time and noninvasively. However, for the oropharynx region and the entire head and neck, motion potentially introduces large artifacts. Considering long treatment times of 60-90 min, this study aims to evaluate whether MRT around the oropharynx is clinically feasible for hyperthermia treatments and quantify the effects of breathing and swallowing on MRT performance. A 3D-ME-FGRE sequence was used in a phantom cooling down and around the oropharynx of five volunteers over ∼75 min. The imaging protocol consisted of imaging with acceleration (ARC = 2), number of image averages (NEX = 1,2 and 3). For volunteers, the acquisitions included a breath-hold scan and scans with deliberate swallowing. MRT performance was quantified in neck muscle, spinal cord and masseter muscle, using mean average error (MAE), mean error (ME) and spatial standard deviation (SD). In phantom, an increase in NEX leads to a significant decrease in SD, but MAE and ME were unchanged. No significant difference was found in volunteers between the different scans. There was a significant difference between the regions evaluated: neck muscle had the best MAE (=1.96 °C) and SD (=0.82 °C), followed by spinal cord (MAE = 3.17 °C, SD = 0.92 °C) and masseter muscle (MAE = 4.53 °C, SD = 1.16 °C). Concerning the ME, spinal cord did best, then neck muscle and masseter muscle, with values of -0.64 °C, 1.15 °C and -3.05 °C respectively. Breathing, swallowing, and different ways of imaging (acceleration and NEX) do not significantly influence the MRT performance in the oropharynx region. The ROI selected however, leads to significant differences.

Changes in the upper airway and its surrounding structures after bimaxillary surgery in patients with cleft-related Class III deformity

OBJECTIVES

To compare upper airway changes following bimaxillary surgery for correction of Class III deformity between patients with unilateral cleft lip and palate (UCLP) and bilateral cleft lip and palate (BCLP) and to compare the preoperative and postoperative upper airway among patients with UCLP and BCLP to healthy controls.

MATERIALS AND METHODS

Sixty adults with CLP-related skeletal Class III deformity (30 UCLP and 30 BCLP) who consecutively underwent bimaxillary surgery were studied retrospectively. Cone-beam computed tomography (CBCT) was performed before and after surgery to measure upper airway and movements of facial skeletal and surrounding structures. CBCT images from 30 noncleft skeletal Class I adults, matched by age, gender, and body mass index and without surgical intervention, served as controls.

RESULTS

After surgery, the volume of the nasopharynx increased in patients with CLP (both P < .001). Patients with CLP did not differ from controls in postoperative volume of the nasopharynx or oropharynx. However, the nasal cavity differed significantly between patients with CLP and controls (P < .001).

CONCLUSIONS

After bimaxillary surgery, the nasal cavity of patients with CLP differed significantly compared with the controls. Volumes of the nasopharynx and oropharynx did not differ between patients with CLP after surgery and controls.

Correlation between oral cavity volume and upper airway changes in skeletal Class III patients undergoing bimaxillary orthognathic surgery: a pilot cone-beam computed tomography study

OBJECTIVES

To evaluate changes of the upper airway and oral cavity volumes in patients with skeletal Class III malocclusion undergoing bimaxillary orthognathic surgery, and to analyze the correlation between postoperative upper airway decrease and the amount of jaw movement and oral cavity volume reduction.

MATERIALS AND METHODS

Thirty patients (16 males and 14 females) undergoing bimaxillary surgery were included. Three-dimensional reconstruction of the upper airway and oral cavity were performed using preoperative (T0) and postoperative (T1) (6 months) cone-beam computed tomography scans.

RESULTS

The volume, sagittal area and minimum cross-sectional area of the upper airway were diminished (P < .001). The decrease in volume and minimum cross-sectional area in the oropharyngeal region of the upper airway were weakly correlated with B-point posterior movement (P < .05). Total oral cavity volume was decreased, with maxillary oral volume increasing and mandibular oral volume decreasing (P < .001). Upper airway decrease was highly correlated with total oral volume reduction and mandibular oral volume reduction, with the most significant correlation being with total oral volume reduction (P < .001).

CONCLUSIONS

Class III bimaxillary surgery reduced the volume, sagittal area, and minimum cross-sectional area of the upper airway as well as oral cavity volume. Upper airway changes were weakly correlated with anterior-posterior mandibular movement but significantly correlated with oral cavity volume changes. Thus, oral cavity volume reduction is a crucial factor of upper airway decrease in patients with skeletal Class III malocclusion undergoing bimaxillary orthognathic surgery.

A mouse model of progressive lung fibrosis with cutaneous involvement induced by a combination of oropharyngeal and osmotic minipump bleomycin delivery

Systemic sclerosis (SSc) with interstitial lung disease (SSc-ILD) lacks curative pharmacological treatments, thus necessitating effective animal models for candidate drug discovery. Existing bleomycin (BLM)-induced SSc-ILD mouse models feature spatially limited pulmonary fibrosis, spontaneously resolving after 28 days. Here, we present an alternative BLM administration approach in female C57BL/6 mice, combining oropharyngeal aspiration (OA) and subcutaneous mini-pump delivery (pump) of BLM to induce a sustained and more persistent fibrosis, while retaining stable skin fibrosis. A dose-finding study was performed with BLM administered as 10 µg (OA) +80 mg/kg (pump) (10 + 80), 10 + 100, and 15 + 100. Forty-two days after OA, micro-computed tomography (micro-CT) imaging and histomorphometric analyses showed that the 10 + 100 and 15 + 100 treatments induced significant alterations in lung micro-CT-derived readouts, Ashcroft score, and more severe fibrosis grades compared with saline controls. In addition, a marked reduction in hypodermal thickness was observed in the 15 + 100 group. A time-course characterization of the BLM 15 + 100 treatment at days 28, 35, and 42, including longitudinal micro-CT imaging, revealed progressing alterations in lung parameters. Lung histology highlighted a sustained fibrosis accompanied by a reduction in hypodermis thickness throughout the explored time-window, with a time-dependent increase in fibrotic biomarkers detected by immunofluorescence analysis. BLM-induced alterations were partly mitigated by Nintedanib treatment. Our optimized BLM delivery approach leads to extensive and persistent lung fibrotic lesions coupled with cutaneous fibrotic alterations: it thus represents a significant advance compared with current preclinical models of BLM-induced SSc-ILD.NEW & NOTEWORTHY This study introduces an innovative approach to enhance the overall performance of the mouse bleomycin (BLM)-induced model for systemic sclerosis with interstitial lung disease (SSc-ILD). By combining oropharyngeal aspiration and subcutaneous mini-pump delivery of BLM, our improved model leads to sustained lung fibrosis and stable skin fibrosis in female C57BL/6 mice. The optimized 15 + 100 treatment results in extensive and persistent lung fibrotic lesions and thus represents a significant improvement over existing preclinical models of BLM-induced SSc-ILD.

State-Dependent Biomechanical Behavior of Oropharyngeal Structures in Apneic and Control Subjects: A Proof-of-Concept Study

Rationale: Apneic individuals have reduced airway caliber during sleep. The biomechanical changes in upper airway anatomy contributing to this airway narrowing are largely unknown. Objectives: We sought to investigate the state-dependent (wake vs. sleep) biomechanical behavior of the upper airway soft-tissue and craniofacial structures. Methods: Upper airway magnetic resonance imaging was performed in 15 sleep-deprived control subjects (apnea-hypopnea index, <5; 0.3 ± 0.5 events per hour) and 12 sleep-deprived apneic subjects (apnea-hypopnea index, ⩾5; 35.2 ± 18.1 events per hour) during wake and sleep and analyzed for airway measures and soft-tissue/mandibular movement. Results: In the retropalatal region, control subjects showed sleep-dependent reductions (P ⩽ 0.037) in average cross-sectional airway area (CSA), minimum CSA, and anteroposterior and lateral dimensions. Apneic subjects showed sleep-dependent reductions (P ⩽ 0.002) in average CSA, minimum CSA, and anteroposterior and lateral dimensions. In the retroglossal region, control subjects had no sleep-dependent airway reductions. However, apneic subjects had sleep-dependent reductions in minimal CSA (P = 0.001) and lateral dimensions (P = 0.014). Control subjects only showed sleep-dependent posterior movement of the anterior-inferior tongue octant (P = 0.039), whereas apneic subjects showed posterior movement of the soft palate (P = 0.006) and all tongue octants (P ⩽ 0.012). Sleep-dependent medial movement of the lateral walls was seen at the retropalatal minimum level (P = 0.013) in control subjects and at the retropalatal and retroglossal minimum levels (P ⩽ 0.017) in apneic subjects. There was posterior movement of the mandible in apneic subjects (P ⩽ 0.017). Conclusions: During sleep, control and apneic subjects showed reductions in retropalatal airway caliber, but only the apneic subjects showed retroglossal airway narrowing. Reductions in anteroposterior and lateral airway dimensions were primarily due to posterior soft palate, tongue and mandibular movement and to medial lateral wall movement. These data provide important initial insights into obstructive sleep apnea pathogenesis.

Measurement of Upper Airway Volume in Children with Craniofacial Abnormalities

OBJECTIVE(S)

Previous literature has established a high prevalence of upper airway obstruction in children with craniofacial abnormalities. This study aims to perform quantitative airway volume measurements in patients with craniofacial abnormalities and compare them to age and sex-matched controls.

METHODS

We performed a retrospective review of the records of all children with craniofacial abnormalities who underwent head-and-neck computed tomography (CT) imaging at a single tertiary-care center between 1/1/13 and 12/31/20 using the ICD-10 codes Q75.1, Q75.4, and Q87.0. These patients were then matched by age and sex to patients with isolated craniosynostosis (Q75.0). CT scans were imported into Dolphin Imaging software, and airway volumes were measured for the nasal cavity, nasopharynx, oropharynx, and hypopharynx. The primary outcome was the total airway volume, defined as the sum of these measurements.

RESULTS

Thirty subjects with craniofacial syndromes were matched to 30 patients with isolated craniosynostosis (controls). In both groups, 18 subjects (60%) were male (p = 0.99). The average ages for syndromic patients and controls were 12.1 and 12.9 months, respectively (p = 0.84). On average, the total airway volumes of syndromic patients were 25% lower than those of controls (p = 0.02). Syndromic patients had 39% smaller nasal cavity volumes (p < 0.001) and 32% smaller nasopharyngeal volumes (p < 0.01). Significant volume differences were not observed for the oropharynx or hypopharynx.

CONCLUSION

We present a unique technique to measure airway volumes in patients with craniofacial abnormalities. These findings will help practitioners to further understand the anatomy and pathophysiology of disturbed breathing in children with craniofacial syndromes.

LEVEL OF EVIDENCE

III Laryngoscope, 134:2915-2921, 2024.

Comparative cephalometric study of the airways between different ethnic groups with normal occlusion

OBJECTIVE

This study aimed to compare the nasopharynx and oropharynx airway dimensions of Caucasians, Blacks, Japanese, Japanese Brazilians, and Black Caucasians.

METHODS

A sample of 216 lateral radiographs of untreated young Brazilian subjects (mean age of 12.94 years; SD 0.88) were divided into five groups: Black Caucasian, Black, Caucasian, Japanese, and Japanese Brazilian. Lateral radiographs were used to measure the oropharynx (from the midpoint on the soft palate to the closest point on the anterior pharyngeal wall) and the nasopharynx (from the intersection of the posterior border of the tongue and the inferior border of the mandible to the closest point on the posterior pharyngeal wall). Analyses of variance (ANOVA) and Tukey's test were performed (p< 0.05).

RESULTS

The linear dimension of the oropharynx was similar among the different ethnic groups. Caucasian individuals presented a significantly greater linear dimension of the nasopharynx than Black Caucasian and Black individuals.

CONCLUSIONS

All the groups had similar buccopharyngeal values. However, Caucasian individuals had significantly higher values when compared to Black Caucasians and Black individuals.

Assessment of maximal inspiratory and expiratory pressures in skeletal Class II patients with different growth patterns

OBJECTIVES

To evaluate maximal inspiratory (MIP) and expiratory (MEP) pressures, which are reflective of respiratory muscle strength, in skeletal Class II patients with different growth patterns (horizontal, average, and vertical) and to correlate those with airway dimension.

MATERIALS AND METHODS

Patients with a Class II skeletal base seeking orthodontic treatment were assigned to the following groups: average, horizontal, and vertical growth pattern. The control group (n = 14) comprised patients with a Class I skeletal base and average growth pattern. Airway dimensions were obtained using cone-beam computed tomography scans, and a spirometer with a pressure transducer was used for assessment of MIP and MEP. Routine spirometry for assessment of lung function was also performed.

RESULTS

No significant differences were found in maximal inspiratory and expiratory pressures for the study groups in comparison with the control group. Class I patients had significantly greater oropharyngeal and nasopharyngeal airway volumes compared with the study groups. No significant difference in minimal cross-section area of the airway was observed among groups. A weak positive correlation between maximal inspiratory pressure and airway volume was observed.

CONCLUSIONS

Although Class I patients displayed significantly greater oropharyngeal and nasopharyngeal airway volumes, there was no significant difference in respiratory muscle strength or airway function between Class II patients with different growth patterns and the Class I control group. The findings underscore the significance of exploring factors beyond craniofacial growth patterns that may contribute to sleep-related breathing disorders.

Predictive value of local control by 4'-[methyl-11C]-thiotymidine PET volume parameters in p16-negative oropharyngeal, hypopharyngeal, and supraglottic squamous cell carcinoma

PURPOSE

We investigated the potential of baseline 4'-[methyl- 11 C]-thiothymidine ([ 11 C]4DST) PET for predicting loco-regional control of head and neck squamous cell carcinoma (HNSCC).

METHODS

A retrospective analysis was performed using volumetric parameters, such as SUVmax, proliferative tumor volume (PTV), and total lesion proliferation (TLP), of pretreatment [ 11 C]4DST PET for 91 patients with HNSCC with primary lesions in the oral cavity, hypopharynx, supraglottis, and oropharynx, which included p16-negative patients. PTV and TLP were calculated for primary lesions and metastatic lymph nodes combined. We examined the association among the parameters and relapse-free survival and whether case selection focused on biological characteristics improved the accuracy of prognosis prediction.

RESULTS

The area under the curves (AUCs) using PTV and TLP were high for the oropharyngeal/hypopharyngeal/supraglottis groups (0.91 and 0.87, respectively), whereas that of SUVmax was 0.66 ( P  < 0.01). On the other hand, the oral group had lower AUCs for PTV and TLP (0.72 and 0.77, respectively). When all cases were examined, the AUCs using PTV and TLP were 0.84 and 0.83, respectively.

CONCLUSION

Baseline [ 11 C]4DST PET/CT volume-based parameters can provide important prognostic information with p16-negative oropharyngeal, hypopharyngeal, and supraglottic cancer patients.

Delineation of the "Oropharyngeal Mucosa" and Limiting its Dose in Head and Neck Cancer Patients Spares the Oropharynx Without Compromising Target Coverage

OBJECTIVES

Radiation-induced oropharyngeal injury is a dose-limiting toxicity in head and neck cancer patients. Delineation of the "oropharyngeal mucosa" and limiting its dose to spare the oropharynx was investigated.

METHODS

In this retrospective study, computed tomography imaging from eight patients with previously untreated head and neck cancer was employed. An adaptive contouring brush within the planning software Monaco was used to create an air cavity within the oropharynx, and then the air cavity was expanded uniformly 2 mm to create the "oropharyngeal mucosa". Three plans were independently generated for each patient: Plan1: dose constraint was applied for the oropharynx; Plan2: dose constraints were applied for the oropharynx and the "oropharyngeal mucosa"; Plan3: dose constraint was applied for the "oropharyngeal mucosa". T-tests were used to compare the dosimetry variables.

RESULTS

All plans had adequate target coverage and there were no statistical differences among plans. The mean dose, D30%, D45%, D50%, D85%, D90%, D95%, D100%, V25 Gy, V30 Gy, V35 Gy, V40 Gy, and V45 Gy of the oropharynx and "oropharyngeal mucosa" in Plan1 were significantly higher than those in Plan2 and Plan3. There were no significant differences between Plan2 and Plan3. There were no significant differences in the dosimetric parameters of any other organs at risk.

CONCLUSION

Delineation of the "oropharyngeal mucosa" and limiting its dose should be an easy and effective method to spare the oropharynx.

Role of the tonsil-oropharynx ratio on lateral cephalograms in assessing tonsillar hypertrophy in children seeking orthodontic treatment

OBJECTIVES

To analyze the diagnostic value of the tonsil-oropharynx (T/O) ratio on lateral cephalograms for evaluating tonsillar hypertrophy (TH).

METHODS

A cross-sectional study was performed on 185 consecutive children (101 males, 84 females; mean age 7.3 ± 1.4 years) seeking orthodontic treatment. The T/O ratios on lateral cephalograms were calculated following Baroni et al.'s method. Tonsil sizes were clinically determined according to the Brodsky grading scale. Spearman correlation coefficients between the T/O ratio and clinical tonsil size were calculated with the total sample and subgroups and then compared between subgroups. Diagnostic value was analyzed using the receiver operating characteristic (ROC) curve, sensitivity, specificity, positive and negative predictive values, and accuracy.

RESULTS

There was a strong correlation between the T/O ratio and clinical tonsil size in children (ρ = 0.73; P < 0.001). A significantly higher correlation coefficient was found in the Class III children. The ROC curve revealed an area under the curve of 0.90 (95% CI, 0.86-0.94; P < 0.001). The optimal cutoff value of the T/O ratio for predicting TH was 0.58, with a sensitivity of 98.7% and specificity of 64.2%. Employing the cutoff value of 0.5, the sensitivity was 100% and the specificity was 45.9%.

CONCLUSIONS

Measurement of the T/O ratio on lateral cephalograms may be helpful to initial screening in children for TH. Practitioners may combine the clinical examination of tonsil size with the cephalometric findings for a more comprehensive evaluation.

CBCT Analysis of Oropharynx Airway Volume

OBJECTIVE

The study was performed to analyze the oropharynx airway and examine the influence of age and gender on the oropharynx volume configuration using cone beam computed tomography.

MATERIALS AND METHODS

This study examined the cone beam computed tomographic images of 51 patients 25 male and 26 females, group matched for age and gender. The oropharynx airway volume and area between the posterior nasal spine and top of the epiglottis were measured and compared.

RESULTS

The statistical measurements of 51 cone beam computed tomography images showed a nonsignificant difference found between male and female regarding the age (the mean age for female 40.15 y. and for male32.72 y). Male subjects had greater oropharynx volume, a high significant difference ( P =0.005) in oropharynx volume between the 3 age groups. A significant difference was found between the smallest age group with the larger age groups.

CONCLUSION

The study data revealed that the changes in measurements of oropharynx airway are age-dependent in addition to gender effect.

Short-term outcomes in the upper airway with tooth-bone-borne vs bone-borne rapid maxillary expanders

BACKGROUND

This study compared the area and minimal section of the nasal cavity, nasopharynx, oropharynx, and hypopharynx in cases treated with different methods of microimplant-assisted expansion.

METHODS

Based on a pilot study to calculate the sample size, 30 patients with transverse maxillary deficiency over 14 years of age were retrospectively selected. These patients had received two different types of microimplant-assisted maxillary expansion treatment (MARPE and BAME). The patient underwent Cone-Beam computed tomography (CBCT) before and after treatment (mean time 1.5 months) with MARPE or BAME and upper airway measurements (volume and minimum cross-sectional area) were taken to assess upper airways changes and compare changes between the groups. A paired sample t-test was performed to evaluate the T0-T1 change of airway measurements obtained with MARPE and BAME, and a student t-test to compare changes in airway measurements between MARPE and BAME.

RESULTS

This investigation shows a statistically significant increase in total nasopharyngeal airway volume (0.59 ± 1.42 cm3; p < 0.01), total oropharyngeal airway volume (3.83 ± 7.53 cm3; p < 0.01) and minimum oropharyngeal cross-section (53.23 ± 126.46 mm2; p < 0.05) in all cases treated with micro-screw assisted expansion. The minimal cross-sectional area of the oropharynx ((79.12 ± 142.28 mm2; p < 0.05) and hypopharynx (59.87 ± 89.79 mm2; p < 0.05) showed significant changes for cases treated with BAME. As for the comparison between cases treated with MARPE and BAME, no differences in upper airway changes have been observed, except for the minimum cross-sectional area of the nasal cavity, which increases for MARPE (52.05 ± 132.91 mm2) and decreases for BAME (-34.10 ± 90.85 mm2).

CONCLUSIONS

A significant increase in total area and minimal section at the level of nasopharynx and oropharynx was observed in cases treated with BAME. Regarding the comparison of MARPE and BAME treatments, no differences were found in the total airway volume and minimal section in upper airway except for the minimum cross section of the nasal cavity that increases for MARPE and decreases for BAME.

[Morphological changes of upper airway in patients with skeletal Class Ⅲ malocclusion after bimaxillary surgery and correlation analysis]

PURPOSE

To analyze the morphological changes of the upper airway and related influencing factors in patients with skeletal Class Ⅲ malocclusion after bimaxillary surgery.

METHODS

Twenty skeletal Class Ⅲ patients who underwent Le Fort I osteotomy and bilateral sagittal split ramus osteotomy(BSSRO) for maxillary advancement and mandibular setback were selected. The patients received CT scans before(T0) and 3-6 months after surgery, and the images were reconstructed three-dimensionally with Dolphin Imaging 11.9 software. Changes in the volume, cross-sectional area, and landmarks of each soft and hard tissue of the airway were measured. Statistical analysis of the data was performed using SPSS 25.0 software package.

RESULTS

The volume of nasopharyngeal airway increased after operation (P＜0.05), and the volume of oropharyngeal airway decreased significantly(P＜0.01). The cross-sectional area of the airway at the plane of the second cervical vertebra was significantly decreased (P＜0.01), and the coronal and sagittal diameters were decreased(P＜0.05). The change of nasopharyngeal airway volume was moderately positively correlated with the sagittal change of the posterior nasal spine (r=0.460, P＜0.05), and the change of oropharynx and laryngopharyngeal airway volume was positively correlated with the vertical change of the midpoint of the soft palate(r=0.496, 0.696, P＜0.05). The airway cross-sectional area in the second and third cervical vertebra planes and the sagittal diameter of the airway in the third cervical vertebra plane were positively correlated with the vertical changes of the midpoint of the soft palate(r=0.474, 0.629, 0.547, P＜0.05). The change of airway cross-sectional area at the third cervical vertebra plane was moderately negatively correlated with the change of mandibular plane angle(r=-0.536, P＜0.05).

CONCLUSIONS

The volume and cross-sectional area of oropharyngeal airway in skeletal Class Ⅲ patients after bimaxillary surgery will decrease. However, the total upper airway volume doesn't change significantly. The changes in the upper airway are correlated with the changes in some soft and hard tissue landmarks.

Multi-stage Unet segmentation and automatic measurement of pharyngeal airway based on lateral cephalograms

OBJECTIVES

Orthodontic treatment profoundly impact the pharyngeal airway (PA) of patients. Airway examination is an integral part of daily orthodontic diagnosis, and lateral cephalograms (LC) are reliable to reveal PA structures. This study attempted to develop a simple method to help clinicians make a preliminary judgement of patients' PA conditions and assess the impact of orthodontic treatment on their airways.

METHODS

LCs of 764 patients were used to train a multistage unit segmentation model. Another 130 images were used to validate the model and more 130 images were used to test the model.

RESULTS

Unet was used as the backbone, with a mean dice value of 0.8180, precision of 0.8393, and recall of 0.8188. Furthermore, we identified seven key points and measured related indices. The length of the line separating the nasopharynx and oropharynx and the line separating the oropharynx and hypopharynx were manually measured thrice and the average values was compared. The intraclass correlation coefficient (ICC) for the two lines was 0.599 and 0.855. Then, we performed a single linear regression analysis, which indicated a strong correlation between the predictions and measurements for the two lines.

CONCLUSIONS

This method is reliable for segmenting three regions (nasopharynx, oropharynx, and hypopharynx) of the PA and calculating related indices. However, the predictions obtained from this model still have errors, and it is necessary for clinical practitioners to assess and adjust the predictions.

CLINICAL SIGNIFICANCE

Our model can help orthodontists formulate personalised treatment plans and evaluate the risk of airway stenosis during orthodontic treatment. This method may mark the beginning of a new and simpler approach for PA obstruction detection, specifically tailored to orthodontic patients.

Are the severity of obstruction and the apnea-hypopnea index related to orofacial anatomy in children with obstructive sleep apnea? a kinetic MRI study

OBJECTIVES

The proportionality between anatomical characteristics and disease severity in children and adolescents with obstructive sleep apnea (OSA) has not been well characterized. The present study investigated the relationship between the dentoskeletal and oropharyngeal features of young patients with OSA and either the apnea-hypopnea index (AHI) or the amount of upper airway obstruction.

METHODS

MRI of 25 patients (8- to 18-year-old) with OSA (mean AHI = 4.3 events/h) was retrospectively analyzed. Sleep kinetic MRI (kMRI) was used to assess airway obstruction, and static MRI (sMRI) was used to assess dentoskeletal, soft tissue, and airway parameters. Factors related to AHI and obstruction severity were identified with multiple linear regression (significance level α = 0.05).

RESULTS

As evidenced by kMRI, circumferential obstruction was present in 44% of patients, while laterolateral and anteroposterior was present in 28%; as evidenced by kMRI, obstructions were retropalatal in 64% of cases and retroglossal in 36% (no nasopharyngeal obstructions); kMRI showed a higher prevalence of retroglossal obstructions compared to sMRI(p = 0.037); the main obstruction airway area was not related to AHI; the maxillary skeletal width was related to AHI (β = -0.512, p = 0.007) and obstruction severity (β = 0.625, p = 0.002); and the retropalatal width was related to AHI (β = -0.384, p = 0.024) and obstruction severity (β = 0.519, p = 0.006).

CONCLUSIONS

In children and adolescents, the severity of OSA and obstruction were inversely proportional to the maxillary basal width and retropalatal airway width. Further studies are needed to assess the benefits of targeted clinical treatments widening the transverse dimension of these structures.

Temporal measures of oropharyngeal swallowing events identified using ultrasound imaging in healthy young adults

Swallowing is a complex process that involves precise coordination among oral and pharyngeal structures, which is essential to smooth transition of bolus and adequate airway protection. Tongue base retraction and hyolaryngeal excursion are two significant swallowing movements, and their related events can be examined using ultrasound imaging, which is physically and radioactively non-invasive. The present study aimed to 1) establish the temporal sequences and timing of swallowing events identified using ultrasound imaging, and 2) investigate the variability of the above temporal sequences and 3) investigate the effect of bolus type on the variability of temporal sequences in non-dysphagic individuals. Forty-one non-dysphagic young adults of both genders (19 males and 22 females) participated in the study. Ultrasound images were acquired mid-saggitally at their submental region during swallowing of boluses with different volume (i.e. 5mL or 10mL) and consistencies (i.e. IDDSI Levels 0 and 4). Timing and sequence of six events 1) displacement onset (TBOn), 2) maximum displacement (TBMax) and 3) displacement offset of tongue base retraction (TBOff); and, 4) displacement onset (HBOn), 5) maximum displacement (HBMax) and 6) displacement offset of the hyoid bone excursion (HBOff) were extracted from the ultrasound images. Out of the 161 swallows, 85.7% follow a general sequence of HBOn < TBOn < HBMax < TBMax < HBOff < TBOff. Percentage adherence to six anticipated paired-event sequences was studied. Results suggested the presence of individual variability as adherence ranged from 75.8% to 98.1% in four of the anticipated sequences, leaving only two sequences (HBOn < TBMax and TBMax < HBOff) obligatory (i.e. 100% adherence). For non-obligatory sequences, it was found that bolus type may have an effect on the level of adherence. Findings of the present study lay the groundwork for future studies on swallowing using ultrasound imaging and also the clinical application of ultrasonography.

Imaging of the upper airway: which method is best for orthodontic assessment?

The objectives of the present study were to compare measurements of pharyngeal airway subregions on lateral cephalometric (LC) and cone beam computed tomographic (CBCT) images in relation to skeletal classes and discuss the advantages and disadvantages of these imaging formats for this type of assessment. The CBCT images were assessed via both multiplanar reconstruction (MPR) and 3-dimensional (3D) reconstruction. The LC and CBCT images from 107 patients were classified according to skeletal class: I, n = 35; II, n = 35; and III, n = 37. Linear measurements of the subdivisions of the upper airway were performed on the LC, MPR, and 3D images. In addition, area and volumetric measurements were performed on the MPR images. The relationships among imaging methods, skeletal class, and pharyngeal thirds were assessed by means of a 1-way analysis of variance (α = 0.05). No statistically significant differences in the linear, area, or volumetric measurements of the upper airway subregions were found among the skeletal classes (P > 0.05). For the linear measurements in the oropharynx and hypopharynx, greater values were observed for the LC images than for the MPR and 3D images (P ≤ 0.05). Based on the study findings, MPR images should be preferred for visualization of the pharyngeal airway subregions. However, LC imaging is preferable to 3D reconstruction.

Three-dimensional evaluation of upper airway changes following rapid maxillary expansion: A retrospective comparison with propensity score matched controls

BACKGROUND

The aim of this study is to evaluate upper airway changes three-dimensionally following rapid maxillary expansion (RME) and compare the changes with matched controls.

MATERIALS AND METHODS

Seventeen patients (mean age 12.6 ± 1.8 years) with maxillary transverse deficiency were treated with RME. Using the propensity score matching method, 17 patients (mean age 12.3 ± 1.5 years) were selected from a non-RME control group of 33. Case-control matching was performed based on 5 covariates: age, gender, CBCT scan interval, sagittal skeletal pattern, and tongue posture. Airway volumes of nasopharynx and oropharynx and minimum cross-sectional areas (MCA) of oropharynx were measured and compared between the case and control groups in CBCT scan images.

RESULTS

In the case group, significant increases from before to after RME were found in all measurements except MCA of the retroglossal segment of oropharynx. Before treatment, there were no significant differences between case group and control group. While comparing the case group with the control group after treatment showed overall greater increases in the case group. In particular, MCA of retropalatal segment showed statistically significant differences.

CONCLUSION

The results of this study indicate that RME causes an increase in upper airway dimensions.

Comparing different software packages for measuring the oropharynx and minimum cross-sectional area

INTRODUCTION

Several imaging software packages report the ability to measure the oropharynx and minimum cross-sectional area (MCA). This study aimed to compare 4 imaging software packages for measuring the oropharynx volume and MCA.

METHODS

Twenty-eight randomly selected cone-beam computed tomography scans had oropharynx volume and MCA calculated by 2 experienced operators using 4 different programs: Dolphin 3D (version 11.95.8.64; Dolphin Imaging & Management Solutions and Management Solutions, Chatsworth, Calif), InVivo Dental (version 6; Anatomage Inc, San Jose, Calif), OnDemand3D (version 1.0.10.7510; CyberMed, Seoul, South Korea), and ITK-SNAP (version 3.8.0; www.itksnap.org). The measurements were repeated after 2 weeks, and intraclass correlation coefficients were used for the reliability tests. Analysis of variance with the Tukey post-hoc test was used to compare the measurements of oropharynx and MCA with different software programs. Paired t tests were used to compare measurements of both investigators and software programs. Bland-Altman analysis was used to assess interexaminer reliability and agreement between the software programs.

RESULTS

The intraclass correlation coefficients revealed excellent repeatability for the 4 programs for both investigators. Analysis of variance showed no statistically significant difference between programs when comparing the oropharynx and MCA. There were no significant differences in software programs when measuring the airway. Bland-Altman showed the maximum difference as 4.1 cm³ for volume and 35 mm² for MCA. Those differences were below the standard deviations of 5.33 cm³ for volume and 73.75 mm² for MCA.

CONCLUSIONS

The use of 4 different software packages to measure the airway for oropharynx volume and MCA showed high intraoperator and interoperator reliability, no statistically significant difference when using analysis of variance, Tukey post-hoc, paired t tests, and variations within one standard deviation when using Bland-Altman.