Cephalometric assessment regarding craniocervical posture in orthodontic patients.

A major factor that contributes to dental malocclusions is represented by the positioning of the mandible. Considering the existing interconnections between the craniocervical and craniomandibular systems it is interesting to assess how changes in one system can influence the other, thus establishing a pattern in terms of certain cephalometric landmarks that orthodontists could consider when diagnosing and evaluating an orthodontic case. Therefore, the aim of this study was to investigate the connections between cervical posture, head position, hyoid bone position in orthodontic patients with different skeletal patterns. 45 lateral cephalometric radiographs were analyzed. Skeletal class and vertical growth were the main elements that were considered when classifying patients. Craniofacial and Cervical landmarks were determined on the cephalograms, from which lines and angles resulted which were considered relevant in our study. Correlations between cephalometric variables of the patients were determined. there were some statistically significant changes identified concerning craniocervical posture and hyoid bone position between the patients in the following parameters: H-Rgn, OPT/HOR, CVT/HOR, OPT/SN, CVT/SN, H-SN. The results obtained allowed us to conclude that there were some differences at the skeletal level of the sample of patients studied. The findings are indicating that there is a close relationship between, mandible position, cervical- and head posture and the hyoid bone. The information obtained in this study could help to better understand the development of malocclusions, and to improve the orthodontic diagnostic and treatment plan.

A hydrodynamics assessment of the hammerhead shark cephalofoil.

Hammerhead sharks are characterized by a conspicuous lateral expansion of the head forming a structure known as a cephalofoil. Two theories regarding the function of this structure suggest that it may increase maneuverability as well as produce dynamic lift similar to a cambered airplane wing. Here we report on a family-wide computational fluid dynamics analysis of all eight hammerhead shark species and three sharks with typical head shape. Models cast of the heads of fresh and museum specimens of hammerhead and typical sharks were used to produce pressure surface maps and lift and drag polar diagrams at various angles of attack. These analyses suggested that the cephalofoil (1) provides greater maneuverability that may be important in prey capture efficacy, (2) does not provide significant dynamic lift when held parallel to flow, (3) is characterized by greater drag than typical sharks across all attack angles, and (4) was found to result in a 10-x increase in energetic cost over typical shark head morphologies.

Anthropometric, biochemical and clinical assessment of malnutrition among Egyptian children with chronic liver diseases: a single institutional cross-sectional study.

BACKGROUND: Malnutrition is a common problem among children with chronic liver diseases (CLD). We aimed to assess the nutritional status of children with CLD and to correlate the anthropometric indices with the severity of liver disease, liver function tests, insulin growth factor-1 (IGF-1) and 25-hydroxy vitamin D (25- OH D). METHODS: A total of 69 patients with CLD and 50 healthy controls (6 months - 6 years) were included in the study. Nutritional status was assessed by anthropometric indices expressed in standard deviation score (Z score), biochemical, hematological and clinical parameters. RESULTS: We found 52.2% of CLD patients underweight by weight for age (W/A); 50.2% were stunted by height for age/ length for age (HAZ or LAZ); and 39% exhibited wasting by weight/height or (length) for age (W/HZ or W/LZ) z scores analysis. The mean values of z scores for all anthropometric parameters were significantly correlated with unconjugated and conjugated bilirubin and INR (p < 0.05), except HAZ or LAZ. Also, a significant correlation to albumin was found, except for W/HZ or (W/LZ) (p = 0.157). The z scores < - 2 SD based on W/ H versus arm indicators showed significant differences in MUAC, UAA and AMA (p < 0.001). We found no correlation between anthropometric z-scores and the mean IGF-1 and (25- OH D) values (p > 0.05). Malnutrition was directly correlated with the severity of hepatic dysfunction, particularly, Child-Pugh C cases. The mean IGF-1 and (25- OH D) values were significantly correlated with the severity of liver disease (p < 0.001). CONCLUSIONS: Our results identified anthropometric arm indicators and MUAC/A measurements as an effective applied methods for assessing nutritional status in CLD children. Moreover, Integrating comprehensive clinical assessment, anthropometric measurements and objective biochemical analyses is essential for evaluation, follow-up and management of CLD children with variable degree of malnutrition.

Maternal health and birth outcomes in a South African birth cohort study.

BACKGROUND: Maternal physical and mental health during pregnancy are key determinants of birth outcomes. There are relatively few prospective data that integrate physical and mental maternal health measures with birth outcomes in low- and middle-income country settings. We aimed to investigate maternal health during pregnancy and the impact on birth outcomes in an African birth cohort study, the Drakenstein Child Health Study. METHODS: Pregnant women attending 2 public health clinics, Mbekweni (serving a predominantly black African population) and TC Newman (predominantly mixed ancestry) in a poor peri-urban area of South Africa were enrolled in their second trimester and followed through childbirth. All births occurred at a single public hospital. Maternal sociodemographic, physical and psychosocial characteristics were comprehensively assessed. Multivariable linear regression models were used to explore associations between maternal health and birth outcomes. RESULTS: Over 3 years, 1137 women (median age 25.8 years; 21% HIV-infected) gave birth to 1143 live babies. Most pregnancies were uncomplicated but gestational diabetes (1%), anaemia (22%) or pre-eclampsia (2%) occurred in a minority. Most households (87%) had a monthly income of less than USD 350; only 27% of moms were employed and food insecurity was common (37%). Most babies (80%) were born by vaginal delivery at full term; 17% were preterm, predominantly late preterm. Only 74 (7%) of babies required hospitalisation immediately after birth and only 2 babies were HIV-infected. Food insecurity, socioeconomic status, pregnancy-associated hypertension, pre-eclampsia, gestational diabetes and mixed ancestry were associated with lower infant gestational age while maternal BMI at enrolment was associated with higher infant gestational age. Primigravida or alcohol use during pregnancy were negatively associated with infant birth weight and head circumference. Maternal BMI at enrolment was positively associated with birth weight and gestational diabetes was positively associated with birth weight and head circumference for gestational age. Smoking during pregnancy was associated with lower infant birth weight. CONCLUSION: Several modifiable risk factors including food insecurity, smoking, and alcohol consumption during pregnancy were identified as associated with negative birth outcomes, all of which are amenable to public health interventions. Interventions to address key exposures influencing birth outcomes are needed to improve maternal and child health in low-middle income country settings.

Data-driven model optimization for optically pumped magnetometer sensor arrays.

Optically pumped magnetometers (OPMs) have reached sensitivity levels that make them viable portable alternatives to traditional superconducting technology for magnetoencephalography (MEG). OPMs do not require cryogenic cooling and can therefore be placed directly on the scalp surface. Unlike cryogenic systems, based on a well-characterised fixed arrays essentially linear in applied flux, OPM devices, based on different physical principles, present new modelling challenges. Here, we outline an empirical Bayesian framework that can be used to compare between and optimise sensor arrays. We perturb the sensor geometry (via simulation) and with analytic model comparison methods estimate the true sensor geometry. The width of these perturbation curves allows us to compare different MEG systems. We test this technique using simulated and real data from SQUID and OPM recordings using head-casts and scanner-casts. Finally, we show that given knowledge of underlying brain anatomy, it is possible to estimate the true sensor geometry from the OPM data themselves using a model comparison framework. This implies that the requirement for accurate knowledge of the sensor positions and orientations a priori may be relaxed. As this procedure uses the cortical manifold as spatial support there is no co-registration procedure or reliance on scalp landmarks.

Comparison of the INTERGROWTH-21st standard and a new reference for head circumference at birth among newborns in Southern China.

BACKGROUND: Previous studies proposed that there were racial or ethnic disparities in fetal growth, challenging the use of international standards in specific populations. This study was to evaluate the validity of applying the INTERGROWTH-21st standard to a Chinese population for identifying abnormal head circumference (HC), in comparison with a newly generated local reference. METHODS: There were 24,257 singletons delivered by low-risk mothers in four perinatal health-care centers in Southern China. New HC reference was constructed and comparison in distribution of HC categories was performed between the INTERGROWTH-21st standard and new reference after applying these two tools in study population. Logistic regression was used to examine the association between abnormal HC and adverse neonatal outcomes. RESULTS: There were 4.40% of the newborns identified with microcephaly (HC > 2 standard deviation below the mean) using the INTERGROWTH-21st standard, comparing to the proportion of 2.83% using new reference. The newborns identified with microcephaly only by the INTERGROWTH-21st standard were not at a higher risk of adverse neonatal outcome, compared with those identified as non-microcephaly by both tools (OR 0.73, 95% CI 0.47-1.13). CONCLUSION: The new HC reference may be more appropriate for newborn assessment in Chinese populations than the INTERGROWTH-21st standard.

Longitudinal Anthropometric Assessment of Rhesus Macaque (Macaca mulatta) Model of Huntington Disease.

The neurodegeneration associated with Huntington disease (HD) leads to the onset of motor and cognitive impairment and their advancement with increased age in humans. In children at risk for HD, body measurement growth abnormalities include a reduction in BMI, weight, height, and head circumference. The transgenic HD NHP model was first reported in 2008, and progressive decline in cognitive behaviors and motor impairment have been reported. This study focuses on longitudinal body measurements in HD macaques from infancy through adulthood. The growth of HD macaques was assessed through head circumference, sagittal and transverse head, and crown-to-rump ('height') measurements and BMI. The animals were measured monthly from 0 to 72 mo of age and every 3 mo from 72 mo of age onward. A mixed-effect model was used to assess subject-specific effects in our nonlinear serial data. Compared with WT controls, HD macaques displayed different developmental trajectories characterized by increased BMI, head circumference, and sagittal head measurements beginning around 40 mo of age. The physiologic comparability between NHP and humans underscores the translational utility of our HD macaques to evaluate growth and developmental patterns associated with HD.

Quality assessment of MEG-to-MRI coregistrations.

For high precision in source reconstruction of magnetoencephalography (MEG) or electroencephalography data, high accuracy of the coregistration of sources and sensors is mandatory. Usually, the source space is derived from magnetic resonance imaging (MRI). In most cases, however, no quality assessment is reported for sensor-to-MRI coregistrations. If any, typically root mean squares (RMS) of point residuals are provided. It has been shown, however, that RMS of residuals do not correlate with coregistration errors. We suggest using target registration error (TRE) as criterion for the quality of sensor-to-MRI coregistrations. TRE measures the effect of uncertainty in coregistrations at all points of interest. In total, 5544 data sets with sensor-to-head and 128 head-to-MRI coregistrations, from a single MEG laboratory, were analyzed. An adaptive Metropolis algorithm was used to estimate the optimal coregistration and to sample the coregistration parameters (rotation and translation). We found an average TRE between 1.3 and 2.3 mm at the head surface. Further, we observed a mean absolute difference in coregistration parameters between the Metropolis and iterative closest point algorithm of [Formula: see text] and [Formula: see text] m. A paired sample t-test indicated a significant improvement in goal function minimization by using the Metropolis algorithm. The sampled parameters allowed computation of TRE on the entire grid of the MRI volume. Hence, we recommend the Metropolis algorithm for head-to-MRI coregistrations.

Fit, stability and comfort assessment of custom-fitted bicycle helmet inner liner designs, based on 3D anthropometric data.

Research has demonstrated that a better-fitted bicycle helmet offers improved protection to the rider during an impact. Nowadays, bicycle helmets in the market that range in size from small/medium to medium/large might not fit the diverse range of human head shapes and dimensions. 3D scanning was used to create 3D head shape databases of 20 participants who volunteered for the study. We developed new custom-fitted helmet inner liners, based on the 3D head shape of two sub-groups of participants, to map their head sizes and contours closely to the conventional Medium (M) and Large (L) sizes as described in from AS/NZS 2512.1: 2009. The new custom-fitted helmet was compared with the helmet available in the market place in a dynamics stability test and from participants' subjective feedback. A significant reduction in the angle of helmet rotation on the headform in the lateral direction was recorded for the custom-fitted helmet. A Wilcoxon signed-rank test was conducted to evaluate participants' feedback on the helmets according to different area definitions. The overall fit and comfort and the top region of the new helmet were significantly improved. However, no difference was found at the significant level of 0.05 for the front and rear region of the new helmet.

Development of a paediatric head voxel model database for dosimetric applications.

OBJECTIVE: To develop a database of paediatric head voxel models intended for Monte Carlo (MC) dosimetric applications. METHODS: Seventeen head and neck CT image data sets were retrieved from the picture archiving and communicating system of our hospital and were reformed into voxel models. 22 organs were segmented at each data set. The segmented organ masses were compared to the respective age- and gender-specific ICRP reference mass value. Adjustments were made such that segmented and reference mass values coincide within a tolerance of 10%. A dental cone beam CT cleft palate simulation study was set up to demonstrate the applicability of our database to MC frameworks and to investigate the need for age- and gender-specific paediatric models. RESULTS: The designed database covers the age range from 2 months to 14 years old. Each model represents a reference head voxel phantom for its corresponding age and gender category. The simulation study revealed absorbed organ dose differences larger than 50% among the 5, 8 and 12 years old models when exposed to identical conditions. CONCLUSION: Children cannot be represented by one average phantom covering the entire age range like adults due to the fact that their organs change rapidly in size and shape. A database of paediatric head voxel models was designed to enable dose calculations via MC simulations. Advances in knowledge: The application of each model of the database to MC frameworks provides age- and gender-specific organ dose estimations from medical exposures in the head and neck region.

Preserving the Facial Nerve During Orbitozygomatic Craniotomy: Surgical Anatomy Assessment and Stepwise Illustration.

OBJECTIVE: Surgical safety and efficiency during an orbitozygomatic (OZ) osteotomy rely on thorough knowledge of the surgical anatomy of the facial nerve. Although the anatomy of the facial nerve and its relation to the pterional craniotomy are described, a thorough assessment of facial nerve preservation techniques during the OZ approach and its variations is lacking. We assessed the surgical anatomy of the facial nerve related to the OZ approach and provided a thorough stepwise description on how to preserve it. METHODS: The OZ approach was performed bilaterally in 15 cadaveric heads. The interfascial and subfascial techniques were performed to study their nuances in preserving the facial nerve. We compared the 2 techniques and provided a thorough description on how to preserve the facial nerve during each step of the OZ approach. RESULTS: At the zygomatic arch, the facial nerve was found between the galea and the superficial temporal fascia. A cut in the fascia at the posterior end of the zygomatic arch did not cross any facial nerve branches. The subfascial technique was simpler, more efficient, and provided more structural protection of the facial nerve branches than the interfascial technique. CONCLUSIONS: The frontal division of the facial nerve is related directly to dissection over the zygomatic bone and may be injured during fascial dissection or osteotomies. Both interfascial and subfascial techniques are feasible to use during the OZ craniotomy and provide ample exposure of the OZ unit. Regarding the preservation of the facial nerve branches, we favor the subfascial method.

Influence of voxelization on finite difference time domain simulations of head-related transfer functions.

The scattering around the human pinna that is captured by the Head-Related Transfer Functions (HRTFs) is a complex problem that creates uncertainties in both acoustical measurements and simulations. Within the simulation framework of Finite Difference Time Domain (FDTD) with axis-aligned staircase boundaries resulting from a voxelization process, the voxelization-based uncertainty propagating in the HRTF-captured sound field is quantified for one solid and two surface voxelization algorithms. Simulated results utilizing a laser-scanned mesh of Knowles Electronics Manikin for Acoustic Research (KEMAR) show that in the context of complex geometries with local topology comparable to grid spacing such as the human pinna, the voxelization-related uncertainties in simulations emerge at lower frequencies than the generally used accuracy bandwidths. Numerical simulations show that the voxelization process induces both random error and algorithm-dependent bias in the simulated HRTF spectral features. Frequencies fr below which the random error is bounded by various dB thresholds are estimated and predicted. Particular shortcomings of the used voxelization algorithms are identified and the influence of the surface impedance on the induced errors is studied. Simulations are also validated against measurements.

Assessment of diffusion tensor image quality across sites and vendors using the American College of Radiology head phantom.

The purpose of this study was to explore the feasibility of assessing quality of diffusion tensor imaging (DTI) from multiple sites and vendors using American College of Radiology (ACR) phantom. Participating sites (Siemens (n = 2), GE (n= 2), and Philips (n = 4)) reached consensus on parameters for DTI and used the widely available ACR phantom. Tensor data were processed at one site. B0 and eddy current distortions were assessed using grid line displacement on phantom Slice 5; signal-to-noise ratio (SNR) was measured at the center and periphery of the b = 0 image; fractional anisotropy (FA) and mean diffusivity (MD) were assessed using phantom Slice 7. Variations of acquisition parameters and deviations from specified sequence parameters were recorded. Nonlinear grid line distortion was higher with linear shimming and could be corrected using the 2nd order shimming. Following image registration, eddy current distortion was consistently smaller than acquisi-tion voxel size. SNR was consistently higher in the image periphery than center by a factor of 1.3-2.0. ROI-based FA ranged from 0.007 to 0.024. ROI-based MD ranged from 1.90 × 10-3 to 2.33 × 10-3 mm2/s (median = 2.04 × 10-3 mm2/s). Two sites had image void artifacts. The ACR phantom can be used to compare key qual-ity measures of diffusion images acquired from multiple vendors at multiple sites.

The Helmet Fit Index--An intelligent tool for fit assessment and design customisation.

Helmet safety benefits are reduced if the headgear is poorly fitted on the wearer's head. At present, there are no industry standards available to assess objectively how a specific protective helmet fits a particular person. A proper fit is typically defined as a small and uniform distance between the helmet liner and the wearer's head shape, with a broad coverage of the head area. This paper presents a novel method to investigate and compare fitting accuracy of helmets based on 3D anthropometry, reverse engineering techniques and computational analysis. The Helmet Fit Index (HFI) that provides a fit score on a scale from 0 (excessively poor fit) to 100 (perfect fit) was compared with subjective fit assessments of surveyed cyclists. Results in this study showed that quantitative (HFI) and qualitative (participants' feelings) data were related when comparing three commercially available bicycle helmets. Findings also demonstrated that females and Asian people have lower fit scores than males and Caucasians, respectively. The HFI could provide detailed understanding of helmet efficiency regarding fit and could be used during helmet design and development phases.

Associations between Domestic-Dog Morphology and Behaviour Scores in the Dog Mentality Assessment.

The domestic dog shows a wide range of morphologies, that humans have selected for in the process of creating unique breeds. Recent studies have revealed correlations between changes in morphology and behaviour as reported by owners. For example, as height and weight decrease, many undesirable behaviours (non-social fear, hyperactivity and attention seeking) become more apparent. The current study aimed to explore more of these correlations, but this time used reports from trained observers. Phenotypic measurements were recorded from a range of common dog breeds (n = 45) and included cephalic index (CI: the ratio of skull width to skull length), bodyweight, height and sex. These data were then correlated with results from the Dog Mentality Assessment (DMA), which involves trained observers scoring a dog's reaction to stimuli presented over 10 standardised subtests. Each subtest is designed to evoke a behavioural response. Backward elimination and weighted step-wise regression revealed that shorter dogs demonstrated more aggressive tendencies, reacting defensively toward both assistants dressed as ghosts (p = 0.045), and to a dummy (p = 0.008). Taller dogs were more affectionate when greeting and being handled by humans (p = 0.007, p = <0.001, respectively). Taller dogs were also more cooperative (p = <0.001), and playful (p = 0.001) with humans than shorter dogs. Heavier dogs were more inquisitive toward a dummy (p = 0.011), to the source of a metallic noise (p = 0.010) and to an assistant (p = 0.003). Heavier dogs were also more attentive to the ghosts (p = 0.013). In comparison, lighter dogs were cautious of a dummy (p = <0.001) and fearful of the sound of a gunshot (p = <0.001). Lighter dogs were also cautious of, and demonstrated prolonged fearfulness toward, the source of metallic noise (p = <0.001, p = <0.034, respectively). With a far larger sample and the advantage of third-party reporting (which overcomes potential owner bias), the current findings build on previous studies in this field, further supporting covariance between morphology and behaviour.

Low level arsenic contaminated water consumption and birth outcomes in Romania-An exploratory study.

Women are exposed to drinking water with low arsenic concentrations (<10.0µg/L) worldwide, yet little work has been done to assess the risk. To begin to address this data gap, we conducted an exploratory study of birth outcomes in Timis County, Romania. We prospectively followed 122 women with singleton deliveries, for whom we constructed individual exposure indicators using self-reported water consumption weighted by arsenic measured in drinking water sources. There were no overall confounder-adjusted effects for arsenic exposure on birth outcomes. Yet, higher average arsenic (10µg/L) was associated with a -2.45 lower birth weight Z-score (P=0.021) and a -1.17 shorter birth length Z-score (P=0.029) among smokers. Higher average iAs (10µg/L) was also associated with smaller ponderal index in boys (P=0.023). Our results suggest smoking may potentiate an otherwise benign arsenic exposure. A larger, more definitive biomarker-based study is needed to investigate the potential risks in conjunction with smoking.

Parallel Solver for Diffuse Optical Tomography on Realistic Head Models With Scattering and Clear Regions.

Diffuse optical tomography is an imaging technique, based on evaluation of how light propagates within the human head to obtain the functional information about the brain. Precision in reconstructing such an optical properties map is highly affected by the accuracy of the light propagation model implemented, which needs to take into account the presence of clear and scattering tissues. We present a numerical solver based on the radiosity-diffusion model, integrating the anatomical information provided by a structural MRI. The solver is designed to run on parallel heterogeneous platforms based on multiple GPUs and CPUs. We demonstrate how the solver provides a 7 times speed-up over an isotropic-scattered parallel Monte Carlo engine based on a radiative transport equation for a domain composed of 2 million voxels, along with a significant improvement in accuracy. The speed-up greatly increases for larger domains, allowing us to compute the light distribution of a full human head ( ≈ 3 million voxels) in 116 s for the platform used.

Virtual endoscopy--a new assessment tool in difficult airway management.

Preemptive mapping of the airway is a useful adjunct to conventional clinical assessments when airway management planning for patients with complex head and neck pathology. Nasendoscopy is frequently used for this purpose but is also invasive and poorly tolerated in a subset of patients and, even in expert hands, may not allow complete visualization of the glottis and subglottic structures. We present a novel tool for difficult airway management planning in the form of virtual endoscopy by applying free online OsiriX software to head and neck computed tomographic scans to generate a "fly-through" airway reconstruction. To highlight how well virtual endoscopy correlates to conventional fibreoscopy, we compare both of these assessment tools in 3 patients with glottic, subglottic, and multilevel airway pathologies. Virtual endoscopy represents a unique, noninvasive, safe, and accurate airway assessment and educational resource, which warrants further exploration.

MRI reconstruction of multi-image acquisitions using a rank regularizer with data reordering.

PURPOSE: To improve rank constrained reconstructions for undersampled multi-image MRI acquisitions. METHODS: Motivated by the recent developments in low-rank matrix completion theory and its applicability to rapid dynamic MRI, a new reordering-based rank constrained reconstruction of undersampled multi-image data that uses prior image information is proposed. Instead of directly minimizing the nuclear norm of a matrix of estimated images, the nuclear norm of reordered matrix values is minimized. The reordering is based on the prior image estimates. The method is tested on brain diffusion imaging data and dynamic contrast enhanced myocardial perfusion data. RESULTS: Good quality images from data undersampled by a factor of three for diffusion imaging and by a factor of 3.5 for dynamic cardiac perfusion imaging with respiratory motion were obtained. Reordering gave visually improved image quality over standard nuclear norm minimization reconstructions. Root mean squared errors with respect to ground truth images were improved by ∼18% and ∼16% with reordering for diffusion and perfusion applications, respectively. CONCLUSIONS: The reordered low-rank constraint is a way to inject prior image information that offers improvements over a standard low-rank constraint for undersampled multi-image MRI reconstructions.