Reliability and accuracy of a semi-automatic segmentation protocol of the nasal cavity using cone beam computed tomography in patients with sleep apnea.

OBJECTIVES: The objectives of this study included using the cone beam computed tomography (CBCT) technology to assess: (1) intra- and inter-observer reliability of the volume measurement of the nasal cavity; (2) the accuracy of the segmentation protocol for evaluation of the nasal cavity. MATERIALS AND METHODS: This study used test-retest reliability and accuracy methods within two different population sample groups, from Eastern Asia and North America. Thirty obstructive sleep apnea (OSA) patients were randomly selected from administrative and research oral health data archived at two dental faculties in China and Canada. To assess the reliability of the protocol, two observers performed nasal cavity volume measurement twice with a 10-day interval, using Amira software (v4.1, Visage Imaging Inc., Carlsbad, CA). The accuracy study used a computerized tomography (CT) scan of an OSA patient, who was not included in the study sample, to fabricate an anthropomorphic phantom of the nasal cavity volume with known dimensions (18.9 ml, gold standard). This phantom was scanned using one NewTom 5G (QR systems, Verona, Italy) CBCT scanner. The nasal cavity was segmented based on CBCT images and converted into standard tessellation language (STL) models. The volume of the nasal cavity was measured on the acquired STL models (18.99 ± 0.066 ml). RESULTS: The intra-observer and inter-observer intraclass correlation coefficients for the volume measurement of the nasal cavity were 0.980-0.997 and 0.948-0.992 consecutively. The nasal cavity volume measurement was overestimated by 1.1%-3.1%, compared to the gold standard. CONCLUSIONS: The semi-automatic segmentation protocol of the nasal cavity in patients with sleep apnea and by using cone beam computed tomography is reliable and accurate. CLINICAL RELEVANCE: This study provides a reliable and accurate protocol for segmentation of nasal cavity, which will facilitate the clinician to analyze the images within nasoethmoidal region.

Comparison of the upper airway morphology between Dutch and Chinese adults with obstructive sleep apnea.

PURPOSE: The pathogenesis of obstructive sleep apnea (OSA) is complex and may vary between different races. It has been suggested that the anatomical balance between skeletal tissues and soft tissues around the upper airway is a key pathophysiologic factor of OSA. Therefore, the aim of this study was to compare the anatomical balance of the upper airway between Dutch and Chinese patients with OSA based on cone beam computed tomography (CBCT) images. METHODS: This was a cross-sectional study performed in two centers and included Dutch and Chinese adults with OSA. CBCT scans in the supine position were obtained for both Dutch and Chinese OSA groups. The primary outcome variable was the anatomical balance of the upper airway, defined as the ratio of the tongue area and the maxillomandibular enclosure area. RESULTS: A total of 28 Dutch adults (mean age ± SD of 46.6 ± 14.1 years, body mass index [BMI] of 26.8 ± 3.5 kg/m2, and apnea-hypopnea index [AHI] of 15.7 ± 7.1 events/h) and 24 Chinese adults (age 41.0 ± 12.4 years, BMI 26.5 ± 3.3 kg/m2, and AHI 16.5 ± 7.8 events/h). There were no significant differences in AHI, age, BMI, and sex between the two groups (P = 0.14-0.76). The Dutch group had a significantly larger tongue area and tongue length compared to the Chinese group (P = 0.01 and P < 0.01). On the other hand, the Chinese group had a smaller maxilla length compared to the Dutch group (P < 0.01). However, the anatomical balance of the upper airway of both groups was not significantly different (P = 0.16). CONCLUSION: Within the limitations of this study, no significant difference was found in the anatomical balance of the upper airway between Dutch and Chinese patients with mild to moderate OSA. TRIAL REGISTRATION: The present study was registered at the ClinicalTrials.gov identifier NCT03463785.

Comparison of anatomic and aerodynamic characteristics of the upper airway among edentulous mild, moderate, and severe obstructive sleep apnea in older adults.

STUDY OBJECTIVES: First, to compare the upper airway's anatomic and aerodynamic characteristics of the edentulous older adults who experience mild, moderate, and severe obstructive sleep apnea (OSA). Second, to examine the correlation between the severity of OSA and the anatomic and aerodynamic characteristic(s) of the upper airway in these edentulous individuals. METHODS: NewTom5G cone beam computed tomography scans of 58 edentulous individuals with mild, moderate, and severe OSA were included in this analysis. 1) Computational models of the upper airway were reconstructed based on cone beam computed tomography images and the anatomical and aerodynamic characteristics of the upper airway were examined by an observer blind to OSA severity. 2) Pearson correlation analysis was used to determine the correlation between apnea-hypopnea index and the anatomic and aerodynamic characteristics of the upper airway. RESULTS: Compared with edentulous patients with mild and moderate OSA, those with severe OSA have a more hourglass-shaped upper airway. The severity of OSA, namely, apnea-hypopnea index, was significantly correlated with the length, shape, and minimum cross-sectional area of the upper airway. During inspiration, the mean velocity of the airflow within the upper airway of the edentulous patients with severe OSA was higher than that of patients with mild and moderate OSA. During both inspiration and expiration, apnea-hypopnea index was found to be significantly correlated with maximum velocity (P = .05) and airway resistance (P = .024, 0.038). CONCLUSIONS: The edentulous patients with severe OSA have a more hourglass-shaped upper airway. The findings also suggest that, during inspiration, the airflow travels faster in edentulous patients with severe OSA than in those with mild or moderate OSA. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: The Effect of Nocturnal Wear of Dentures on Sleep and Oral Health Related Quality of Life; URL: https://clinicaltrials.gov/ct2/show/NCT01868295; Identifier: NCT01868295. CITATION: Chen H, Elham E, Li Y, et al. Comparison of anatomic and aerodynamic characteristics of the upper airway among edentulous mild, moderate, and severe obstructive sleep apnea in older adults. J Clin Sleep Med. 2022;18(3):759-768.

Comparison of anterior and posterior trabecular bone microstructure of human mandible using cone-beam CT and micro CT.

BACKGROUND: The aim of this study was to compare the trabecular bone microstructures of anterior and posterior edentulous regions of human mandible using cone-beam computed tomography (CBCT) and micro computed tomography (µCT). METHODS: Twenty volumes of interests consisting of six anterior and fourteen posterior edentulous regions were obtained from human mandibular cadavers. A CBCT system with a resolution of 80 µm (3D Accuitomo 170, J. Morita, Kyoto, Japan) and a µCT system with a resolution of 35 µm (SkyScan 1173, Kontich, Belgium) were used to scan the mandibles. Three structural parameters namely, trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp) were analysed using CTAn software (v 1.11, SkyScan, Kontich, Belgium). For each system, the measurements obtained from anterior and posterior regions were tested using independent sample t-test. Subsequently, all measurements between systems were tested using paired t-test. RESULTS: In CBCT, all parameters of the anterior and posterior mandible showed no significant differences (p > 0.05). However, µCT showed a significant different of Tb.Th (p = 0.023) between anterior and posterior region. Regardless of regions, the measurements obtained using both imaging systems were significantly different (p ≤ 0.021) for Tb.Th and Tb.N. CONCLUSIONS: The current study demonstrated that only the variation of Tb.Th between anterior and posterior edentulous region of mandible can be detected using µCT. In addition, CBCT is less feasible than µCT in assessing trabecular bone microstructures at both regions.

Phenotypes of responders to mandibular advancement device therapy in obstructive sleep apnea patients: A systematic review and meta-analysis.

Mandibular advancement device (MAD) therapy is the most commonly used non-continuous positive airway pressure (CPAP) treatment for obstructive sleep apnea (OSA). Although OSA patients prefer MAD over CPAP, on average over one third have minimal or no major reduction in OSA severity with MAD therapy. Improved understanding of responder characteristics (or "phenotypes") to MAD may facilitate more efficient use of limited medical resources and optimize treatment efficacy. The aim of this review is to describe the baseline phenotypic characteristics of responders to MAD therapy in OSA patients. Pubmed, Web of Science, EMBASE, Scopus were searched for eligible studies published until Feb 2019. A total of 650 studies were identified. 41 studies were included in this review and meta-analysis. The quality of the studies was assessed using the risk of bias assessment tool for non-randomized studies (RoBANS). Based on meta-analysis, the responders to MAD therapy had certain clinical phenotypic characteristics: lower age (95% CI: -4.55 to -1.62, p < 0.00001), female (95% CI: 0.56 to 0.91, p = 0.006), lower body mass index (95% CI: -2.80 to -1.11, p < 0.00001), smaller neck circumference (95% CI: -1.57 to -0.52, p < 0.00001), lower apnea-hypopnea index (95% CI: -7.23 to -1.89, p < 0.00001), a retracted maxilla and mandible, a narrower airway and a shorter soft palate than non-responders. The above-mentioned phenotypic responder characteristics provides useful information for the clinician when considering prescribing MAD therapy for OSA patients.

Differences in three-dimensional craniofacial anatomy between responders and non-responders to mandibular advancement splint treatment in obstructive sleep apnoea patients.

AIM: The primary aim of this study was to assess the differences in the upper airway morphology between responders and non-responders to mandibular advancement splint (MAS) treatment in obstructive sleep apnoea (OSA) management. The secondary aim was to assess the correlation between the minimum cross-sectional area of the upper airway and the anatomical structures (i.e. mandibular external length, maxillary length, soft palate length, area of the tongue, maxillomandibular enclosure size, and anatomical balance ratio) surrounding the upper airway. The third aim was to assess the differences in the overall skeletal configuration between responders and non-responders to MAS treatment. METHODS: Data from 64 patients (23 females and 41 males) diagnosed with OSA by polysomnography (PSG) at baseline and provided with an adjustable MAS were analysed. All patients had NewTom3G cone beam computed tomography (CBCT) scans, performed in the supine position, at baseline. After acclimatization to MAS, follow-up PSG tests were performed to assess the apnoea-hypopnea index (AHI) with the MAS in situ. Responders were defined by a post-treatment AHI less than 10/hour and at least 50 per cent reduction in AHI, and non-responders by a post-treatment AHI at least 10/hour or less than 50 per cent reduction in AHI. Several upper airway and anatomical variables surrounding the upper airway based on CBCT images were measured to determine the differences between responders and non-responders to MAS. RESULTS: There were 36 responders (AHI = 24.8 ± 11.9 at baseline) and 28 non-responders (AHI = 31.2 ± 20.3 at baseline) to MAS. There were no significant differences in the upper airway morphology between responders and non-responders (P = 0.17-0.93) or in the anatomical structure surrounding the upper airway (P = 0.24-0.58). CONCLUSION: Within the limitations of this study, it can be concluded that there are no significant differences in upper airway morphology and in anatomical structures surrounding the upper airway between responders and non-responders to MAS treatment. These findings suggest that the craniofacial anatomical structures analyzed in this study cannot explain the response to MAS treatment.

CBCT assessment of gubernacular canals in relation to eruption disturbance and pathologic condition associated with impacted/unerupted teeth.

OBJECTIVES: The aim of this study was to demonstrate the imaging characteristics of gubernacular canals (GCs) in impacted/unerupted permanent teeth and to determine whether these characteristics differ as a result of the presence of eruption disturbances or pathologic conditions associated with impacted/unerupted teeth. STUDY DESIGN: GCs were retrospectively analyzed by using cone beam computed tomography in 250 patients with 753 impacted/unerupted permanent teeth (105 males, 145 females; mean age, 21.09 ± 14.45 years; range 6-70 years). RESULTS: The rate of detection of GCs was significantly lower in cases with eruption disturbances than in those without eruption disturbances. An inverse correlation was observed between age and detection of GCs. Similarly, root resorption of adjacent teeth and resorption of impacted/unerupted teeth were associated with lower rates of detection of GCs. However, no association was found for widening of the follicular space. Regression analysis determined disturbed eruption pattern as the most important factor for the absence of GCs. CONCLUSIONS: The absence of GC may indicate a disturbed eruption pattern of the tooth and may increase the risk of complications related to impaction resulting in a tooth that is more likely to remain unerupted.

The Effects of Noncontinuous Positive Airway Pressure Therapies on the Aerodynamic Characteristics of the Upper Airway of Obstructive Sleep Apnea Patients: A Systematic Review.

PURPOSE: The effects of noncontinuous positive airway pressure (non-CPAP) therapies on the airflow in the upper airway in obstructive sleep apnea (OSA) patients are not completely clear yet. Therefore, the primary aim of this systematic review was to determine the effects of various non-CPAP therapies on the aerodynamic characteristics of the upper airway in OSA patients. MATERIALS AND METHODS: A PICO (population or patient, intervention, comparison, outcome) search strategy, focusing on the effects of various non-CPAP therapies on the aerodynamic characteristics of the upper airway (ie, velocity, wall shear stress, wall static pressure, airway resistance, pressure drop, and pressure effort) of OSA patients, was conducted in the following databases: MEDLINE (PubMed), Embase (Excerpta Medica), and Web of Science. In this systematic review, the inclusion criteria were 1) adults diagnosed with OSA by polysomnography, 2) treatment outcome assessed by a second polysomnography, and 3) computational fluid dynamics (CFD) applied. RESULTS: Of 51 unique studies retrieved, 9 fulfilled the criteria for this systematic review. Seven studies were on maxillomandibular advancement (MMA) surgery, and 2 were on mandibular advancement device (MAD) therapy. The aerodynamic characteristics of the upper airway improved in OSA patients who underwent MMA surgery. However, the studies on MMA surgery included only responders to MMA surgery. In the responders to MAD therapy, the velocity, wall static pressure, and airway resistance of the upper airway decreased. In nonresponders to MAD therapy, the wall static pressure and airway resistance of the upper airway increased. CONCLUSIONS: This systematic review suggests that MMA surgery and MAD therapy may improve several aerodynamic characteristics of the upper airway in OSA patients by CFD analysis. However, because of limitations of the selected studies, there is not enough evidence yet to support CFD analysis as a routine tool to predict the treatment outcome in OSA patients.

Accuracy of MDCT and CBCT in three-dimensional evaluation of the oropharynx morphology.

Objective: To assess the accuracy of five different computed tomography (CT) scanners for the evaluation of the oropharynx morphology. Methods: An existing cone-beam computed tomography (CBCT) data set was used to fabricate an anthropomorphic phantom of the upper airway volume that extended from the uvula to the epiglottis (oropharynx) with known dimensions (gold standard). This phantom was scanned using two multi-detector row computed tomography (MDCT) scanners (GE Discovery CT750 HD, Siemens Somatom Sensation) and three CBCT scanners (NewTom 5G, 3D Accuitomo 170, Vatech PaX Zenith 3D). All CT images were segmented by two observers and converted into standard tessellation language (STL) models. The volume and the cross-sectional area of the oropharynx were measured on the acquired STL models. Finally, all STL models were registered and compared with the gold standard. Results: The intra- and inter-observer reliability of the oropharynx segmentation was fair to excellent. The most accurate volume measurements were acquired using the Siemens MDCT (98.4%; 14.3 cm3) and Vatech CBCT (98.9%; 14.4 cm3) scanners. The GE MDCT, NewTom 5G CBCT, and Accuitomo CBCT scanners resulted in smaller volumes, viz., 92.1% (13.4 cm3), 91.5% (13.3 cm3), and 94.6% (13.8 cm3), respectively. The most accurate cross-sectional area measurements were acquired using the Siemens MDCT (94.6%; 282.4 mm2), Accuitomo CBCT (95.1%; 283.8 mm2), and Vatech CBCT (95.3%; 284.5 mm2) scanners. The GE MDCT and NewTom 5G CBCT scanners resulted in smaller areas, viz., 89.3% (266.5 mm2) and 89.8% (268.0 mm2), respectively. Limitations: Images of the phantom were acquired using the vendor-supplied default airway scanning protocol for each scanner. Conclusion: Significant differences were observed in the volume and cross-sectional area measurements of the oropharynx acquired using different MDCT and CBCT scanners. The Siemens MDCT and the Vatech CBCT scanners were more accurate than the GE MDCT, NewTom 5G, and Accuitomo CBCT scanners. In clinical settings, CBCT scanners offer an alternative to MDCT scanners in the assessment of the oropharynx morphology.

Age of majority assessment in Dutch individuals based on Cameriere's third molar maturity index.

Radiological examination of the third molar is done in living individuals for estimation of chronological age, especially in the late adolescence. The aim of this study was to assess the application of Cameriere's third molar maturity index (I3M) to determine whether an individual is 18 years or older (adult) or younger than 18 years (minor) in a sample of Dutch individuals. The sample consisted of panoramic images of 360 individuals aged between 14 and 22 years old. Three observers performed the measurements. Gender was not statistically significant in discriminating adults and minors. The highest value of the Youden index of the receiver operating curve analysis was for the value of I3M<0.08 in discriminating individuals as minor or adult. The specificity (Sp) and sensitivity (Se) results for females were 96.3% and 72.7% respectively. The Sp and Se for males were 95.0% and 84.0% respectively. The probabilities of correctly classified individuals were 83.3% and 88.9%, and Bayes post-test probability was 96.3% and 95.7% in females and males respectively. Obtained results showed that the specific cut-off point of I3M<0.08 may be a useful and reliable method for adult age assessment in a Dutch population.

Analyses of aerodynamic characteristics of the oropharynx applying CBCT: obstructive sleep apnea patients versus control subjects.

OBJECTIVES: To determine the most relevant aerodynamic characteristic of the oropharynx related to the collapse of the upper airway in obstructive sleep apnea (OSA) patients; and to determine the correlation between the most relevant aerodynamic characteristic(s) of the oropharynx and anatomical characteristics of the oropharynx in OSA patients. METHODS: 31 mild to moderate OSA patients (mean ± SD age = 43.5 ± 9.7 years) and 13 control subjects (mean ± SD age = 48.5 ± 16.2 years) were included in this prospective study. The diagnosis of OSA patients was based on an overnight polysomnographic recording. To exclude the presence of OSA in the control subjects, they were asked to fill out a validated questionnaire to determine the risk of OSA. NewTom5G cone beam CT (CBCT) scans were obtained from both OSA patients and control subjects. Computational models of the oropharynx were reconstructed based on CBCT images. The aerodynamic characteristics of the oropharynx were calculated based on these computational models. Pearson correlation analysis was used to analyse the correlation between the most relevant aerodynamic characteristic(s) and anatomical characteristics of the oropharynx in OSA patients. RESULTS: Compared with controls, the airway resistance during expiration (Rex) of the OSA patients was significantly higher (p = 0.04). There was a significant negative correlation between Rex and the minimum cross-sectional area (CSAmin) of the oropharynx (r = -0.41, p = 0.02), and between Rex and the volume of the oropharynx (r = -0.48, p = 0.01) in OSA patients. After excluding an outlier, there is only significant correlation between Rex and the CSAmin of the oropharynx (r = -0.45, p = 0.01). CONCLUSIONS: Within the limitations of this study, we concluded that the most relevant aerodynamic characteristic of the oropharynx in the collapse of the upper airway in OSA patients is Rex. Therefore, the repetitive collapse of the upper airway in OSA patients may be explained by a high Rex, which is related to the CSAmin of the oropharynx.

A novel imaging technique to evaluate airflow characteristics in the upper airway of an obstructive sleep apnea patient.

We report about a novel imaging technique for airflow analysis, particle image velocimetry (PIV), used in a moderate obstructive sleep apnea (OSA) patient. By measuring the airflow characteristics in the upper airway at different protrusion positions, the effect of mandibular advancement device (MAD) on OSA was further understood.

Reliability and accuracy of three imaging software packages used for 3D analysis of the upper airway on cone beam computed tomography images.

OBJECTIVES: The aim of this study was to assess the reliability and accuracy of three different imaging software packages for three-dimensional analysis of the upper airway using CBCT images. METHODS: To assess the reliability of the software packages, 15 NewTom 5G® (QR Systems, Verona, Italy) CBCT data sets were randomly and retrospectively selected. Two observers measured the volume, minimum cross-sectional area and the length of the upper airway using Amira® (Visage Imaging Inc., Carlsbad, CA), 3Diagnosys® (3diemme, Cantu, Italy) and OnDemand3D® (CyberMed, Seoul, Republic of Korea) software packages. The intra- and inter-observer reliability of the upper airway measurements were determined using intraclass correlation coefficients and Bland & Altman agreement tests. To assess the accuracy of the software packages, one NewTom 5G® CBCT data set was used to print a three-dimensional anthropomorphic phantom with known dimensions to be used as the "gold standard". This phantom was subsequently scanned using a NewTom 5G® scanner. Based on the CBCT data set of the phantom, one observer measured the volume, minimum cross-sectional area, and length of the upper airway using Amira®, 3Diagnosys®, and OnDemand3D®, and compared these measurements with the gold standard. RESULTS: The intra- and inter-observer reliability of the measurements of the upper airway using the different software packages were excellent (intraclass correlation coefficient ≥0.75). There was excellent agreement between all three software packages in volume, minimum cross-sectional area and length measurements. All software packages underestimated the upper airway volume by -8.8% to -12.3%, the minimum cross-sectional area by -6.2% to -14.6%, and the length by -1.6% to -2.9%. CONCLUSIONS: All three software packages offered reliable volume, minimum cross-sectional area and length measurements of the upper airway. The length measurements of the upper airway were the most accurate results in all software packages. All software packages underestimated the upper airway dimensions of the anthropomorphic phantom.

Venous malformation with multiple phleboliths: A case report.

Venous malformations are congenital, abnormally formed vessels, present at birth. They do not undergo regression with the growth of the patient. Due to the stagnation of blood flow in venous malformations, thrombosis and phlebolith formation may occur. Phleboliths are calcified thrombi which radiographically must be differentiated from calcified lymph nodes, sialoliths, foreign bodies, and other radiopacities. We report an extensive venous malformation in a 19-year-old woman with panoramic radiography demonstrating multiple phleboliths. Magnetic resonance imaging revealed the extension of the lesion into the hard palate and the masseter muscles superiorly, extending from the oropharynx to the tongue, inferiorly reaching the right clavicula and spreading between the right sternocleidomastoid muscle and strap muscles of the neck. The article is presented because the presence of phleboliths demonstrated on panoramic radiography is rarely described in the literature.

Three-dimensional imaging of the upper airway anatomy in obstructive sleep apnea: a systematic review.

INTRODUCTION: The pathogenesis of upper airway collapse in people with obstructive sleep apnea (OSA) is not fully understood. The aim of this study was to systematically review the literature in order to assess the most relevant anatomical characteristics of the upper airway related to the pathogenesis of OSA by analyzing the three-dimensional upper airway anatomy. METHOD: A PICO (population/patient, intervention, comparison, outcome) search strategy, focusing on the upper airway anatomy of people with OSA, was conducted using the following databases: MEDLINE (PubMed), Excerpta Medica database (EMBASE), Web of Science, and Cochrane Library. The studies in which three-dimensional images were made from the participants who were awake and in the supine position during quiet breathing were selected in this systematic review. RESULTS: Of the 758 unique retrieved studies, eight fulfilled the criteria for this systematic review. The minimum cross-sectional area of the upper airways of people with OSA, which is influenced by many factors such as hard and soft tissues surrounding the upper airway, was significantly smaller than that of those without OSA. CONCLUSION: Within the limitation of the selected studies, this systematic review suggested that a small minimum cross-sectional area is the most relevant anatomical characteristic of the upper airway related to the pathogenesis of OSA.

Reliability of three-dimensional measurements of the upper airway on cone beam computed tomography images.

OBJECTIVES: The aim of this study was (1) to assess intra- and interobserver reliability of the localization of anatomic landmarks of the upper airway on cone beam computed tomography (CBCT) images; and (2) to assess intra- and interobserver reliability of the three-dimensional measurements of the upper airway based on these landmarks. STUDY DESIGN: Fifteen NewTom 5G (QR systems, Verona, Italy) CBCT data sets were randomly selected from the archives of the Department of Oral Radiology, Academic Centre for Dentistry (ACTA) at University of Amsterdam and VU University, Amsterdam, The Netherlands. Three observers localized six anatomic landmarks that are relevant for upper airway analysis twice, with a 10-day interval, using 3Diagnosys software (v5.3.1, 3diemme, Cantu, Italy). Subsequently, the observers performed upper airway volume measurement based on those landmarks twice as well, again with a 10-day interval, using Amira software (v4.1, Visage Imaging Inc., Carlsbad, CA). The upper airway measurements also included the minimum cross-sectional area (CSAmin), location of the CSAmin, and anteroposterior and lateral dimensions of the CSAmin. RESULTS: Both intraobserver reliability and interobserver reliability were excellent for the localization of the anatomic landmarks of the upper airway (intraclass correlation coefficients = 0.97-1.00) as well as for the three-dimensional upper airway measurements (intraclass correlation coefficients = 0.78-1.00). CONCLUSIONS: The methodology of landmark localization and upper airway measurements, as used in this study, showed an excellent reliability and can thus be recommended for upper airway analysis on CBCT images.

Extra- and intra-cranial arterial calcifications in adults depicted as incidental findings on cone beam CT images.

OBJECTIVE: The aim of this study was to evaluate, retrospectively, the gender- and age-related prevalence of incidentally found calcifications, depicted within the course of the extra- and intra-cranial portion of internal carotid artery (ICA), in cone beam computed tomography (CBCT) examinations in adults, and to assess their clinical significance. MATERIALS AND METHODS: Out of a pull of 700 CBCT examinations a total of 484 CBCT scans of adult patients were finally selected according to a set of pre-defined criteria. These were evaluated for arterial calcifications presence within the ICAs course according to gender and age criteria. RESULTS: In total, 492 calcifications were detected: 211 (42.88%) extra-cranial and 281 (57.11%) intra-cranial. Those were recorded in 150 scans (30.99%) and 161 scans (33.26%), respectively. Calcifications, with either extra- or intra-cranial allocation, were found more frequent in males than in females (all p-values < 0.05); also patients who presented with positive findings were older than those without findings (all p-values < 0.05). Furthermore, calcification presence with either extra- or intra-cranial allocation increases with age (all p-values < 0.05). CONCLUSION: Significant calcification frequencies were found within the ICA's course, in CBCT scans. Moreover, an increased incidence of either extra- or intra-cranial presence of these depictions and its relation to age and gender was documented.

Bone quality evaluation at dental implant site using multislice CT, micro-CT, and cone beam CT.

OBJECTIVES: The first purpose of this study was to analyze the correlation between bone volume fraction (BV/TV) and calibrated radiographic bone density Hounsfield units (HU) in human jaws, derived from micro-CT and multislice computed tomography (MSCT), respectively. The second aim was to assess the accuracy of cone beam computed tomography (CBCT) in evaluating trabecular bone density and microstructure using MSCT and micro-CT, respectively, as reference gold standards. MATERIAL AND METHODS: Twenty partially edentulous human mandibular cadavers were scanned by three types of CT modalities: MSCT (Philips, Best, the Netherlands), CBCT (3D Accuitomo 170, J Morita, Kyoto, Japan), and micro-CT (SkyScan 1173, Kontich, Belgium). Image analysis was performed using Amira (v4.1, Visage Imaging Inc., Carlsbad, CA, USA), 3Diagnosis (v5.3.1, 3diemme, Cantu, Italy), Geomagic (studio(®) 2012, Morrisville, NC, USA), and CTAn (v1.11, SkyScan). MSCT, CBCT, and micro-CT scans of each mandible were matched to select the exact region of interest (ROI). MSCT HU, micro-CT BV/TV, and CBCT gray value and bone volume fraction of each ROI were derived. Statistical analysis was performed to assess the correlations between corresponding measurement parameters. RESULTS: Strong correlations were observed between CBCT and MSCT density (r = 0.89) and between CBCT and micro-CT BV/TV measurements (r = 0.82). Excellent correlation was observed between MSCT HU and micro-CT BV/TV (r = 0.91). However, significant differences were found between all comparisons pairs (P < 0.001) except for mean measurement between CBCT BV/TV and micro-CT BV/TV (P = 0.147). CONCLUSIONS: An excellent correlation exists between bone volume fraction and bone density as assessed on micro-CT and MSCT, respectively. This suggests that bone density measurements could be used to estimate bone microstructural parameters. A strong correlation also was found between CBCT gray values and BV/TV and their gold standards, suggesting the potential of this modality in bone quality assessment at implant site.

Accuracy of trabecular bone microstructural measurement at planned dental implant sites using cone-beam CT datasets.

OBJECTIVE: Cone-beam CT (CBCT) images are infrequently utilized for trabecular bone microstructural measurement due to the system's limited resolution. The aim of this study was to determine the accuracy of CBCT for measuring trabecular bone microstructure in comparison with micro CT (µCT). MATERIALS AND METHODS: Twenty-four human mandibular cadavers were scanned using a CBCT system (80 µm) and a µCT system (35 µm). Three bone microstructural parameters trabecular number (Tb.N), thickness (Tb.Th) and separation (Tb.Sp) were assessed using CTAn imaging software. RESULTS: Intraclass correlation coefficients (ICC) showed a high intra-observer reliability (≥ 0.996) in all parameters for both systems. The Pearson correlation coefficients between the measurements of the two systems were for Tb.Th 0.82, for Tb.Sp 0.94 and for Tb.N 0.85 (all P's<0.001). The Bland and Altman plots showed strongest agreement in Tb.N (-0.37 µm) followed by Tb.Th (1.6 µm) and Tb.Sp (8.8 µm). CONCLUSIONS: Cone-beam CT datasets can be used to evaluate trabecular bone microstructure at dental implant sites. The accuracy for measuring Tb.N was the best followed by Tb.Th and Tb.Sp.

Precision of identifying cephalometric landmarks with cone beam computed tomography in vivo.

The study aims were to assess the precision and time required to conduct cephalometric analysis with cone-beam computed tomography (CBCT) in vivo on both three-dimensional (3D) surface models and multi-planar reformations (MPR) images. Datasets from 10 patients scanned with CBCT were used to create two types of images: 1. axial, coronal, and sagittal MPR images and 2. 3D surface models. Eleven observers identified 22 cephalometric landmarks on 3D surface models first and then using 3D in combination with MPR images twice independently. Tracing time was recorded in both methods. Precision was defined as the absolute difference between an observer's repeated measurements and the mean of all measurements per landmark. Inter- and intra-observer agreements were defined as the absolute difference of the observers' measurements from each other and from their repeated measurements averaged over all landmarks, respectively. The precision of measurements ranged between 0.29 ± 0.17 and 2.82 ± 7.53. Adding MPR alongside, 3D surfaces improved the precision of tracing for 15 of 22 of the landmark but it took on average twice as much time. Mean time required to trace one patient was 6:03 ± 2:48 and 10:41 ± 4:01 minutes for 3D and 3D + MPR, respectively (P = 0.0001).