Noura A. Alsufyani

Three-dimensional segmentation of the upper airway using cone beam CT: a systematic review

The objectives of this study were to systematically review the literature for studies that used cone beam CT (CBCT) to automatically or semi-automatically model the upper airway (including the pharyngeal, nasal and paranasal airways), and to assess their validity and reliability. Several electronic databases (MEDLINE®, MEDLINE In-Process & Other Non-Indexed Citations, all evidence-based medicine reviews including the Cochrane database, and Scopus) were searched. Abstracts that appeared to meet the initial selection criteria were selected by consensus. The original articles were then retrieved and their references were searched manually for potentially suitable articles that were missed during the electronic search. Final articles that met all the selection criteria were evaluated using a customized evaluation checklist. 16 articles were finally selected. From these, five scored more than 50% based on their methodology. Although eight articles reported the reliability of the airway model generated, only three used intraclass correlation (ICC). Two articles tested the accuracy/validity of airway models against the gold standard, manual segmentation, using volumetric measurements; however, neither used ICC. Only three articles properly tested the reliability of the three-dimensional (3D) upper airway model generated from CBCT and only one article had sufficiently sound methodology to test the airway models accuracy/validity. The literature lacks proper scientific justification of a solid and optimized CBCT protocol for airway imaging. Owing to the limited number of adequate studies, it is difficult to generate a strong conclusion regarding the current validity and reliability of CBCT-generated 3D models.

The frequency and nature of incidental findings in large-field cone beam computed tomography scans of an orthodontic sample

BackgroundThe aim of this study is to evaluate the nature and frequency of incidental findings in large-field maxillofacial cone beam computed tomography (CBCT).MethodsA total of 427 consecutive CBCT radiologic reports obtained for orthodontic purposes were retrospectively reviewed. Findings were summarized and categorized into six anatomic categories.ResultsA total of 842 incidental findings were reported in the 427 CBCT scans (1.97 findings/scan). The most prevalent findings were those located in the airway (42.3%), followed by the paranasal sinuses (30.9%), dentoalveolar (14.7%), surrounding hard/soft tissues (4.0%), temporomandibular joint (TMJ) (6.4%), and cervical vertebrae (1.3%) regions. Non-odontogenic findings, defined as those located outside the dentition and associated alveolus, represented 718 of the 842 (85.3%) findings.ConclusionsThis study confirms the high occurrence of incidental findings in large-field maxillofacial CBCT scans in a sample of orthodontically referred cases. The majority are extragnathic findings, which can be normally considered outside the regions of interest of many dental clinicians. Specifically, incidental findings in the naso-oropharyngeal and paranasal air sinuses are the most frequent. This underscores the need for comprehensive review of the entire data volume and the requisite to properly document all findings, regardless of the region of interest.

Reliability of anatomic structures as landmarks in three-dimensional cephalometric analysis using CBCT.

OBJECTIVE To identify anatomic structures in three dimensions and examine their reliability to be used as landmarks in a three-dimensional coordinate cephalometric analysis, using cone-beam computerized tomography (CBCT). MATERIALS AND METHODS Thirty CBCT images were randomly selected for landmark location. Forty-two anatomic landmarks, which are not included in the traditional cephalometric landmarks, were chosen based on radiographic characteristics that make them pragmatic to mark in the CBCT image slices. The principal investigator marked the full set of landmarks on the software by navigating in the X, Y, and Z axes for every image three times, with each measurement trial being at least 1 week apart. One other investigator also located the landmarks once for each image for reliability purposes. Intraclass correlation coefficients (ICCs) were used to analyze the mean differences in landmark location in all axes. RESULTS Intra- and interexaminer reliability for x, y, and z coordinates for all landmarks had ICC greater than 0.95 with confidence interval of 0.88-0.99. Mean measurement differences found were <1.4 mm for all landmarks in all three coordinates. Mean measurement error differences obtained in the principal investigators trials were primarily <0.5 mm. CONCLUSION The most reliable and reproducible landmarks tested for use in CBCT are mental foramina, infraorbital foramina, inferior hamulus, dens axis, foramina transversarium of atlas, medial and lateral condyles of the mandible, superior clinoid processes, and mid-clinoid.

Correlations Between Acoustic Rhinometry, Subjective Symptoms, and Endoscopic Findings in Symptomatic Children With Nasal Obstruction

IMPORTANCE Nasal obstruction is common in children and difficult to quantify objectively. Symptom quantification is paramount for surgical and medical decision making. Acoustic rhinometry is a relatively new technique aimed at the objective assessment of nasal obstruction. There is no standardized method for the objective assessment of the pediatric nasal airway. OBJECTIVE To explore the correlations between acoustic rhinometry (AR), subjective symptoms, and endoscopic findings in children presenting with nasal obstruction. DESIGN, SETTING, AND PARTICIPANTS A cross-sectional, exploratory, diagnostic study of prospectively collected data from a multidisciplinary airway clinic (pulmonology, orthodontics, and otolaryngology) database at a tertiary academic referral center. Data were collected over a 2-year period (2010-2012) from 65 nonsyndromic children (38 boys) 7 years and older (mean [SD] age, 10.3 [2.5] years [range, 7-14 years]), presenting with persistent nasal obstructive symptoms for at least 1 year, without signs and symptoms of sinus disease. INTERVENTIONS We collected patient demographics and medical history information including allergy, asthma, and sleep-disordered breathing. Subjective nasal obstruction was scored using a visual analog scale (VAS). Sleep-disordered breathing was assessed using overnight pulse oximetry. The adenoid size, septal position, and visual severity of chronic rhinitis (endoscopic rhinitis score [ERS]) were rated on nasal endoscopy by 2 independent reviewers and validated by agreement. Acoustic rhinometry (AR) was undertaken before and after use of a decongestant. MAIN OUTCOMES AND MEASURES Correlation and multiple regression analyses were performed to explore interrelationships between subjective nasal obstruction VAS, AR, and nasal endoscopy. RESULTS Among the 65 patients, 28 (43%) had symptoms of sleep-disordered breathing, 14 (22%) had allergic rhinitis, 10 (15%) had asthma, 27 (41%) had grade 3 or 4 adenoidal obstruction, 28 (43%) had an ERS of 2, 6 (9%) had an ERS of 3, and 19 (29%) had septal deviation. Significant correlations were found between subjective nasal obstruction VAS score and ERS (r = -0.364, P = .003), ERS and minimal cross-sectional area before decongestion (r = -0.278, P = .03), and adenoid size and calculated nasal resistance after decongestion (r = 0.430, P < .001). Multiple regression analysis showed that the ERS was the only significant predictor of VAS score (β of -22.089; 95% CI, -35.56 to -8.61 [P = .002]). No predictors were identified for AR variables. CONCLUSIONS AND RELEVANCE Among the evaluated tools, endoscopy appears to be the most reliable tool to estimate the degree of subjective nasal symptoms.

Assessing the reliability of MRI-CBCT image registration to visualize temporomandibular joints

OBJECTIVES To evaluate image quality of two methods of registering MRI and CBCT images of the temporomandibular joint (TMJ), particularly regarding TMJ articular disc-condyle relationship and osseous abnormality. METHODS MR and CBCT images for 10 patients (20 TMJs) were obtained and co-registered using two methods (non-guided and marker guided) using Mirada XD software (Mirada Medical Ltd, Oxford, UK). Three radiologists independently and blindly evaluated three types of images (MRI, CBCT and registered MRI-CBCT) at two times (T1 and T2) on two criteria: (1) quality of MRI-CBCT registrations (excellent, fair or poor) and (2) TMJ disc-condylar position and articular osseous abnormalities (osteophytes, erosions and subcortical cyst, surface flattening, sclerosis). RESULTS 75% of the non-guided registered images showed excellent quality, and 95% of the marker-guided registered images showed poor quality. Significant difference was found between the non-guided and marker-guided registration (χ(2) = 108.5; p < 0.01). The interexaminer variability of the disc position in MRI [intraclass correlation coefficient (ICC) = 0.50 at T1, 0.56 at T2] was lower than that in MRI-CBCT registered images [ICC = 0.80 (0.52-0.92) at T1, 0.84 (0.62-0.93) at T2]. Erosions and subcortical cysts were noticed less frequently in the MRI-CBCT images than in CBCT images. CONCLUSIONS Non-guided registration proved superior to marker-guided registration. Although MRI-CBCT fused images were slightly more limited than CBCT alone to detect osseous abnormalities, use of the fused images improved the consistency among examiners in detecting disc position in relation to the condyle.

Does drug-induced sleep endoscopy change the surgical decision in surgically naïve non-syndromic children with snoring/sleep disordered breathing from the standard adenotonsillectomy? A retrospective cohort study

BackgroundAdenotonsillectomy is the most commonly performed operation for pediatric snoring/sleep disordered breathing (S/SDB). However, 20–40% of patients will fail to improve. Drug-induced sleep endoscopy (DISE) may provide a more individualized surgical plan and limit unsuccessful surgeries. The aim of this study was to assess the impact of DISE on surgical decision-making in surgically naïve children with S/SDB.MethodsA retrospective observational cohort study was undertaken at the Stollery Children’s Hospital. Patients 3–17 years of age who underwent DISE-directed surgery for S/SDB between January 2009 and December 2015 were eligible. We excluded other indications for tonsillectomy and syndromic children. The primary outcome was the level of agreement between a DISE-based surgical decision and the reference standard based on the American Academy of Pediatrics (AAP) guidelines via un-weighted Cohen’s kappa. Secondary outcomes included the frequency and type of alternate surgical targets identified by DISE. The agreement on tonsil size between in-office physical assessment and DISE was also calculated. The effectiveness of DISE-directed surgery on postoperative S/SDB was not investigated.ResultsFive hundred fifty-eight patients were included. DISE changed the surgical plan in 35% of patients. Agreement between DISE-based and AAP clinical practice guidelines-based management was low (κ = 0.354 +/- 0.021 [95% CI 0.312–0.395]). An alternate diagnosis or surgical target was identified by DISE in 54% of patients. There was moderate agreement on tonsil size (κ = 0.44 [0.33–0.55]) between DISE and in-office clinical assessment.ConclusionsThis is a first phase diagnostic study, which demonstrates that DISE affects decision-making in surgically naïve children with S/SDB in up to 35% of patients. It has utility in individualizing first stage surgical treatments as well as identifying alternate targets for further surgical or medical therapy, while potentially limiting unsuccessful surgeries. Further studies to examine the effect of DISE on surgical outcomes are required.

Upper airway imaging in sleep-disordered breathing: role of cone-beam computed tomography

ObjectiveTo review recent use of three-dimensional (3D) imaging, specifically cone-beam computed tomography (CBCT), in the analysis of the upper airway for diagnosis or treatment outcomes in patients with sleep-disordered breathing (SDB).Types of studies reviewedLiterature review of relevant medical and dental studies utilizing 3D imaging to assess the upper airway.ResultsImaging of the upper airway provided insight into potential areas of obstruction. Accessibility of CBCT to dentists is reflected in several applications of upper airway diagnosis, treatment planning, and different treatment outcomes, as well as association with craniofacial development. However, multiple deficiencies in image acquisition, 3D reconstruction, and analysis are evident.Practical implicationsThe role of CBCT in the analysis of the upper airway is growing; however, critical limitations remain. An understanding of these limitations, clarification of misconceptions, and improvements in analysis methods are required to ensure proper use and development of CBCT.

Changes in temporomandibular joint morphology in class II patients treated with fixed mandibular repositioning and evaluated through 3D imaging: a systematic review

To estimate the effects of skeletal class II malocclusion treatment using fixed mandibular repositioning appliances on the position and morphology of the temporomandibular joint (TMJ). Two independent reviewers performed comprehensive electronic searches of MEDLINE, EMBASE, EBM reviews and Scopus (until May 5, 2015). The references of the identified articles were also manually searched. All studies investigating morphological changes of the TMJ articular disc, condyle and glenoid fossa with 3D imaging following non-surgical fixed mandibular repositioning appliances in growing individuals with class II malocclusions were included in the analysis. Of the 269 articles initially reviewed, only 12 articles used magnetic resonance imaging and two articles used computed tomography (CT) or cone-beam CT images. Treatment effect on condyle and glenoid fossa was discussed in eight articles. Treatment effect on TMJ articular disc position and morphology was discussed in seven articles. All articles showed a high risk of bias due to deficient methodology: inadequate consideration of confounding variables, blinding of image assessment, selection or absence of control group and outcome measurement. Reported changes in osseous remodelling, condylar and disc position were contradictory. The selected articles failed to establish conclusive evidence of the exact nature of TMJ tissue response to fixed mandibular repositioning appliances.

Ground truth delineation for medical image segmentation based on Local Consistency and Distribution Map analysis.

Computer-aided detection (CAD) systems are being increasingly deployed for medical applications in recent years with the goal to speed up tedious tasks and improve precision. Among others, segmentation is an important component in CAD systems as a preprocessing step to help recognize patterns in medical images. In order to assess the accuracy of a CAD segmentation algorithm, comparison with ground truth data is necessary. To-date, ground truth delineation relies mainly on contours that are either manually defined by clinical experts or automatically generated by software. In this paper, we propose a systematic ground truth delineation method based on a Local Consistency Set Analysis approach, which can be used to establish an accurate ground truth representation, or if ground truth is available, to assess the accuracy of a CAD generated segmentation algorithm. We validate our computational model using medical data. Experimental results demonstrate the robustness of our approach. In contrast to current methods, our model also provides consistency information at distributed boundary pixel level, and thus is invariant to global compensation error.

Correlation between gonial angle and dynamic tongue collapse in children with snoring/sleep disordered breathing – an exploratory pilot study

BackgroundDrug induced sleep endoscopy (DISE) is hoped to identify reasons of failure of adenotonsillectomy (AT) in treating pediatric sleep disordered breathing (SDB). Maxillomandibular disproportion has been studied as another association which may explain alternative pathogenesis of SDB. We aimed to explore the relation between the size of the gonial angle and inclination of the epiglottis measured from cone beam CT (CBCT) and tongue base collapse based on DISE in children with SDB.MethodA retrospective chart review was conducted at a tertiary pediatric center. Children (6-17 years old) assessed at a multi-disciplinary Upper Airway Clinic, diagnosed with SDB and maxillo-mandibular disproportion (MMD), and who underwent DISE were eligible. Variables obtained from the electronic medical records of the clinic and prospective database included demographics, comorbidities, surgeries performed, investigations, DISE findings and CBCT findings. The gonial angle of subjects with and without tongue base collapse (TBC) on SNP were compared.ResultsIn total 29 patients (13 male, 8 female) age 6-17 (median= 9) were eligible for the study from January 2009 – July 2016. We included 11 subjects, and 10 comparators. The mean gonial angle of the TBC group was 139.3°± 7.6°, while that of the comparison group was 129.4°±3.5 (mean difference -9.937, 95% CI of -15.454 to - 4.421, P = 0.001, power of test 0.95). Additionally, the mean inclination of the epiglottis had a mild positive correlation (r=0.32, p<0.05) with the gonial angle, in the whole cohort.ConclusionsThis pilot study suggests that TBC may be mediated by a wider gonial angle in children with SDB patients. The posterior tilt of the epiglottis on CBCT may be a surrogate sign of TBC.