Region Of Skull Research Articles

Trifold origin of the reptilian ear ossicle and its relation to the evolutionary modification of the temporal skull region.

Whereas mammals are characterized by the presence of three middle ear ossicles, reptiles have only one, the columella (stapes). Nevertheless, there is a great diversity of columellar anatomy among sauropsids, especially in the unique and cartilaginous "extracolumella"-portion. Molecular studies revealed the "columella" of chicken and quails to be formed within the second pharyngeal arch, although conflicting evidence exists for the columellar footplate and distal parts of the columella in these birds. We studied columellar development in four turtles, one lizard, and one caiman species and argue, using early blastematous stages, that, distally, the so-called "extracolumella" in turtles is mainly of quadrate, that is, first pharyngeal arch origin. Differently, the dorsal aspect of the "extracolumella" of the lizard and a part of the "dorsal columella process" of the caiman are likely quadrate-derived. This indicates only a partial homology of the distal columellar compartments among reptiles. Moreover, we observed in most species that, at early stages, the footplate differentiates from the otic capsule, which confirms widespread experimental findings of mesodermal cells contributing to the proximal part of the columella. We provide a hypothetical framework for the changes in the columella and quadrate morphology in reptilian evolution. Originally, as evidenced by the fossil record, the columella served as a stabilizing brace between the quadrate and braincase. Associated with changes in the feeding mode of late Permian taxa, the quadrate was integrated along the stress flows from biting, and in early development part of the quadrate differentiated to differently contribute to the distal part of the "columella-complex," which now contacts the tympanic membrane. In addition, part of the original otic capsule contributes to the footplate of the mobile columella, providing a connection with the inner ear.

Noninvasive Monitoring of Changes in Cerebral Hemodynamics During Prolonged Field Care for Hemorrhagic Shock and Hypoxia-Induced Injuries With Portable Diffuse Optical Sensors.

Achieving simultaneous cerebral blood flow (CBF) and oxygenation measures, specifically for point-of-care injury monitoring in prolonged field care, requires the implementation of appropriate methodologies and advanced medical device design, development, and evaluation. The near-infrared spectroscopy (NIRS) method measures the absorbance of light whose attenuation is related to cerebral blood volume and oxygenation. By contrast, diffuse correlation spectroscopy (DCS) allows continuous noninvasive monitoring of microvascular blood flow by directly measuring the degree of light scattering because of red blood cell (RBC) movement in tissue capillaries. Hence, this study utilizes these two optical approaches (DCS-NIRS) to obtain a more complete hemodynamic monitoring by providing cerebral microvascular blood flow, hemoglobin oxygenation and deoxygenation in hemorrhage, and hypoxia-induced injuries. Piglet models of hemorrhage and hypoxia-induced brain injury were used with DCS and NIRS sensors placed over the preorbital to temporal skull regions. To induce hemorrhagic shock, up to 70% of the animal's total blood volume was withdrawn through graded hemorrhage serially via a syringe from a femoral artery cannula in 10 mL/kg aliquots over 1 minute every 10 minutes. A second group of animals was subjected to hypoxia for ∼1 hour through graded hypoxia by serial titration from normoxic fraction inspired oxygen of 21% to hypoxic fraction inspired oxygen of 6%. A subset of animals served as sham-controls undergoing anesthesia, instrumentation, and ventilation as the injury groups, yet experiencing no blood loss or hypoxia. We first investigated the relationship between hemorrhagic shock and no shock by using measured biomarkers, including blood flow index from DCS associated with CBF and oxygenated (HbO) and de-oxygenated hemoglobin from NIRS. The statistical analysis revealed a significant difference between no shock and hemorrhagic shock (P < .01). The HbO decreased with each blood loss as expected, yet the de-oxygenated hemoglobin was slightly changed. During hypoxia-induced global hypoxic-ischemic injury tests, the CBF results from graded hypoxia were consistent with the response previously measured during hemorrhagic shock. Moreover, HbO decreased when the animal was hypoxic, as expected. A statistical analysis was also conducted to compare the results with those of the sham controls. There is a consistency in blood flow measures in both injury mechanisms (hemorrhagic shock and hypoxia), which is significant as the new prototype system provides similar measures and trends for each brain injury type, suggesting that the optical system can be used in response to different injury mechanisms. Notably, the results support the idea that this optical system can probe the hemodynamic status of local cerebral cortical tissue and provide insight into the underlying changes of cerebral tissue perfusion at the microvascular level. These measurement capabilities can improve shock identification and monitoring of medical management of injuries, particularly hemorrhagic shock, in prolonged field care.

New evidence from high-resolution computed microtomography of Triassic stem-mammal skulls from South America enhances discussions on turbinates before the origin of Mammaliaformes

The nasal cavity of living mammals is a unique structural complex among tetrapods, acquired along a series of major morphological transformations that occurred mainly during the Mesozoic Era, within the Synapsida clade. Particularly, non-mammaliaform cynodonts document several morphological changes in the skull, during the Triassic Period, that represent the first steps of the mammalian bauplan. We here explore the nasal cavity of five cynodont taxa, namely Thrinaxodon, Chiniquodon, Prozostrodon, Riograndia, and Brasilodon, in order to discuss the main changes within this skull region. We did not identify ossified turbinals in the nasal cavity of these taxa and if present, as non-ossified structures, they would not necessarily be associated with temperature control or the development of endothermy. We do, however, notice a complexification of the cartilage anchoring structures that divide the nasal cavity and separate it from the brain region in these forerunners of mammals.

A novel approach to craniofacial analysis using automated 3D landmarking of the skull

Automatic dense 3D surface registration is a powerful technique for comprehensive 3D shape analysis that has found a successful application in human craniofacial morphology research, particularly within the mandibular and cranial vault regions. However, a notable gap exists when exploring the frontal aspect of the human skull, largely due to the intricate and unique nature of its cranial anatomy. To better examine this region, this study introduces a simplified single-surface craniofacial bone mask comprising of 6707 quasi-landmarks, which can aid in the classification and quantification of variation over human facial bone surfaces. Automatic craniofacial bone phenotyping was conducted on a dataset of 31 skull scans obtained through cone-beam computed tomography (CBCT) imaging. The MeshMonk framework facilitated the non-rigid alignment of the constructed craniofacial bone mask with each individual target mesh. To gauge the accuracy and reliability of this automated process, 20 anatomical facial landmarks were manually placed three times by three independent observers on the same set of images. Intra- and inter-observer error assessments were performed using root mean square (RMS) distances, revealing consistently low scores. Subsequently, the corresponding automatic landmarks were computed and juxtaposed with the manually placed landmarks. The average Euclidean distance between these two landmark sets was 1.5 mm, while centroid sizes exhibited noteworthy similarity. Intraclass coefficients (ICC) demonstrated a high level of concordance (> 0.988), with automatic landmarking showing significantly lower errors and variation. These results underscore the utility of this newly developed single-surface craniofacial bone mask, in conjunction with the MeshMonk framework, as a highly accurate and reliable method for automated phenotyping of the facial region of human skulls from CBCT and CT imagery. This craniofacial template bone mask expansion of the MeshMonk toolbox not only enhances our capacity to study craniofacial bone variation but also holds significant potential for shedding light on the genetic, developmental, and evolutionary underpinnings of the overall human craniofacial structure.

Lipid removal in deuterium metabolic imaging (DMI) using spatial prior knowledge

Abstract. Deuterium metabolic imaging (DMI) is a novel method to generate spatial maps depicting dynamic metabolism of deuterated substrates, such as [6,6′-2H2]-glucose, and their metabolic products, like 2H-lactate. While DMI acquisition methods are simple and robust, DMI processing still requires expert user interaction, e.g., in the removal of extracranial natural abundance 2H lipid signals that interfere with metabolism-linked 2H-lactate formation. Here we pursue the use of MRI-based spatial prior knowledge on brain and non-brain/skull locations to provide robust and objective lipid removal. Magnetic field heterogeneity was accounted for using DMI-derived surrogate B0 and B1 maps, as well as through subdivision of the skull region into smaller compartments. Adequate lipid removal with an average suppression of 90.5 ± 11.4 % is achieved on human brain in vivo without perturbation of the metabolic profile in brain voxels, thereby allowing for the generation of distinct and reliable metabolic maps for patients with brain tumors.

Detection of Brain Tumour Via Reversing Hexagonal Feature Pattern for Classifying Double-Modal Brain Images

The diagnosis of brain tumours (BT) is time-consuming and heavily dependent on the radiologists' abilities. Multiple algorithms have been developed for detecting and classifying BT that are both accurate and fast. Recent years have seen an increase in the popularity of deep learning, especially when it comes to developing automated systems that can diagnose and segment BT more accurately and with less time. In this paper, a novel Brain Hexagonal Pattern Network (BHPN) has been proposed to classify the MEG and PET images into normal, benign and malignant tumours. For pre-processing, a bilateral filter is employed to remove noise artifacts from the collected MEG and PET images. To remove the outer cortical and skull region, skull stripping is used, to be implemented to raise the volume of the training datasets. The pre-processed images are segmented using the Otsu threshold algorithm to segment the BT. These segmented tumours are taken as input to the Reversing Hexagonal algorithm to generate the hexagonal feature sets with and without a segmentation mask. In order to categorize tumours into normal, benign and malignant cases, a Spiking Dilated Convolutional Neural Network (SDCNN) classifier system is implemented. The classification accuracy of the Proposed BHPN approach is 99.54%. The Proposed BHPN approach improves the overall accuracy by 1.49%, 2.52%, and 3.93% better than hybrid deep autoencoder (DAE) and Bayesian Fuzzy Clustering (BFC), Deep CNN, and Neutrosophy and Convolutional Neural Network (NS-CNN) respectively.

Evolution of the temporal skull openings in land vertebrates: A hypothetical framework on the basis of biomechanics.

The complex constructions of land vertebrate skulls have inspired a number of functional analyses. In the present study, we provide a basic view on skull biomechanics and offer a framework for more general observations using advanced modeling approaches in the future. We concentrate our discussion on the cranial openings in the temporal skull region and work out two major, feeding-related factors that largely influence the shape of the skull. We argue that (1) the place where the most forceful biting is conducted and (2) the handling of resisting food (sideward movements) constitute the formation and shaping of either one or two temporal arcades surrounding these openings. Diversity in temporal skull anatomy among amniotes can be explained by specific modulations of these factors with different amounts of acting forces which inevitably lead to deposition or reduction of bone material. For example, forceful anterior bite favors an infratemporal bar, whereas forceful posterior bite favors formation of an upper temporal arcade. Transverse forces (inertia and resistance of seized objects) as well as neck posture also influence the shaping of the temporal region. Considering their individual skull morphotypes, we finally provide hypotheses on the feeding adaptation in a variety of major tetrapod groups. We did not consider ligaments, internal bone structure, or cranial kinesis in our considerations. Involving those in quantitative tests of our hypotheses, such as finite element system synthesis, will provide a comprehensive picture on cranial mechanics and evolution in the future.

MRI-based brain tumor detection and types of classification using CEHJB-RI and JMST

The Brain Tumor (BT), which forms in the brain cells and spreads to the whole brain, may lead to death. Hence, early diagnosis of BT is significant. Still, the detection of BT between the skull and brain region is not concentrated, which results in misclassification outcomes. Thus, this article proposes Magnetic Resonance Imaging (MRI)-based BT detection and types’ classification utilizing Carlitz Exponential Hamilton Jacobi Bellman-based Reinforcement Learning (CEHJB-RL) and JenSorensen similarity-based Minimum Spanning Tree (JMST). Primarily, raw MRI images are taken and then pre-processed. Then, with skull and without skull regions are extracted from the pre-processed image and are subjected to the graph construction. Conversely, the edges are detected from the pre-processed image that can be patch-extracted and subjected to graph construction. By utilizing JMST and Morphological Operations (MO), the graphs are constructed. Thereafter, the features are extracted and fed to the classifier. Then, the type of BT is classified by the classifier using CEHJB-RL. Concerning the performance metrics, the outcomes illustrated that the proposed technique attained a higher accuracy (99.27%), which is better than other existing techniques.

Full-wave Image Reconstruction in Transcranial Photoacoustic Computed Tomography using a Finite Element Method.

Transcranial photoacoustic computed tomography presents challenges in human brain imaging due to skull-induced acoustic aberration. Existing full-wave image reconstruction methods rely on a unified elastic wave equation for skull shear and longitudinal wave propagation, therefore demanding substantial computational resources. We propose an efficient discrete imaging model based on finite element discretization. The elastic wave equation for solids is solely applied to the hard-tissue skull region, while the soft-tissue or coupling-medium region that dominates the simulation domain is modeled with the simpler acoustic wave equation for liquids. The solid-liquid interfaces are explicitly modeled with elastic-acoustic coupling. Furthermore, finite element discretization allows coarser, irregular meshes to conform to object geometry. These factors significantly reduce the linear system size by 20 times to facilitate accurate whole-brain simulations with improved speed. We derive a matched forward-adjoint operator pair based on the model to enable integration with various optimization algorithms. We validate the reconstruction framework through numerical simulations and phantom experiments.

Automated Alzheimer's disease diagnosis using radiomics feature extraction on magnetic resonance images

The current study investigates automated Alzheimer disease diagnosis using radiomic feature extraction on magnetic resonance images. Alzheimer’s disease (AD) is a progressive, incurable neurological brain disorder. Early diagnosis of AD might prevent brain tissue damage and assist with proper treatment. Researchers examine numerous statistical and machine learning (ML) techniques for the detection of AD. Analyzing magnetic resonance imaging (MRI) is a traditional way of analyzing for AD in clinical examination. Diagnosis of AD is challenging because of the similarity in MRI statistics and standard healthy MRI information for elderly people. The application of DL to earlier diagnosis and automatic classification of AD is gaining immense popularity in recent times, as rapid development in neuroimaging techniques has generated large-scale multimodal neuroimaging datasets. This study develops a new Automated Alzheimer's Disease Diagnosis using Deep Learning Model (AADD-DLM) on MRI images. The presented AADD-DLM technique examines the MRI images to assist in the AD diagnostic process. In the presented AADD-DLM technique, three major processes are involved, namely skull stripping, segmentation, and feature extraction. Initially, the AADD-DLM technique uses the U-Net model for the skull stripping process, which enables the removal of the skull regions in the brain MRI. Next, the QuickNAT model is utilized for an effective brain MRI segmentation process. Moreover, the radiomics feature extraction approach is used to generate a useful set of feature vectors. For exhibiting the promising performance of the AADD-DLM technique, widespread experimentation analysis is made on the ADNI database. The optimized model achieves 99.6% accuracy in the ADNI database. The simulation outcomes revealed the improved effectiveness of the AADD-DLM technique over other recent approaches.

Differentiating fatal one-punch assaults from standing height falls based on skeletal trauma: a pilot study

ABSTRACTA fatal one-punch assault is defined as a single punch to a person’s head or neck resulting in death. In some of these assaults, it may be important to understand which injuries stemmed from the punch, the resulting fall, or both. The aim of this study was to identify if there were differences in skull and cervical fractures between deaths from a one-punch, one-punch with fall, and fall from standing height. Relevant cases were extracted from the Victorian Institute of Forensic Medicine’s database, and case circumstances and biological variables were recorded from coronial documentation. Fracture patterns and types were documented from post-mortem computed tomography scans. Trauma was analysed in the context of the variables using descriptive and bivariate models. Six one-punch, 15 one-punch with fall, and 30 standing height fall deaths were included. There were subtle fracture differences. All skull regions fractured in the three events; however, the frequency of fractures varied, and cervical vertebrae fractures did not occur in the isolated one-punch deaths. Variations of linear fractures resulted from falls while linear, diastatic and blowout fractures resulted from a punch. The findings augment the evidence base for trauma interpretations in one-punch assaults and provide the foundation for a large-scale study.

Automatic analysis of skull thickness, scalp‐to‐cortex distance and association with age and sex in cognitively normal elderly

AbstractBackgroundTranscranial brain stimulation has been a potential treatment for many brain diseases. The skull compartment exerts a strong influence on the delivery of stimulation, implying the need to accurately examine its geometry and alterations in the population. In addition, personalized neurostimulation requires better understanding of skull geometry and scalp‐to‐cortex distance for optimization.MethodHere, we developed an open source efficient pipeline BrainCalculator based on BrainSuite Skullfinder for automatically computing the skull thickness map to locate the position of minimum thickness, SCD, and brain volume based on structural T1‐weighted MRI 3T data. We examined the influence of age and sex cross‐sectionally in 407 cognitively normal older adults (71.93±7.98 years, 60.2% female) from the ADNI on the minimum skull thickness, SCD and brain volume of the whole‐head MR data. We demonstrated the compatibility of BrainCalculator with available preprocessing toolboxes, including FSL Brain Extraction Tool (BET) 2 and Statistical Parametric Mapping (SPM)12‐based unified segmentation, and compared their performance.ResultOur pipeline was able to compute automatically the skull thinkness, SCD and brain volume using T1 MR data in 8 minutes. We found that the sphenoid bone and temporal bone were thinnest among the skull regions. There was no increase in minimum skull thickness at different regions with increasing age except in the female sphenoid bone. No sex difference in minimum skull thickness or SCD in different age groups was observed. Positive correlations between age and SCD in both males and females were observed, and the slope was higher in the temporal cortex SCD in females (0.307%/y) than in males (0.216%/y) but comparable in other regions. A negative correlation between age and whole brain volume computed based on brain surface in both males and females was observed, and the slope was slightly higher in females (‐1.031%/y) than in males (‐0.998%/y).ConclusionWe developed a pipeline for MR‐based skull thickness and SCD brain volume automatic analysis and demonstrated the sex‐dependent association between minimum regional skull thickness, SCD and brain volume with age. This pipeline is potentially useful for personalized neurostimulation.

Comparison of the Effective Radiation Dose in the Region of the Facial Skull Between Multidetector CT, Dental Conebeam CT and Intraoperative 3D C-Arms

Study Design Experimental single-centre study of X-ray absorption using a phantom skull. Objective This experimental study aimed to compare the radiation doses of different 3D imaging devices used in maxillofacial surgery, including one Multidetector CT (MDCT), two Conebeam CT (CBCT) and four intraoperative 3D C-arms. Methods Thermoluminescent dosimeters (TLD) were used to determine the absorbed radiation in an Alderson-Rando phantom skull. The phantom skull was positioned in the before mentioned seven devices and a defined 3D facial skull image was acquired. Subsequently, the TLD’S were read out and the effective doses (ED) and the organ doses (OD) were calculated and compared. Results OD varied significantly between tissues as well as between the 3D X-ray devices. The OD of the 3D C-arms were significantly lower than those of all other devices. The OD of the CT, especially in the standard setting, was the highest. Only by special adjustments of the scan protocol regarding CMF requirements for traumatology, the MDCT could achieve almost equivalent doses as the two tested CBCT-scanners. The calculated effective doses were also lowest for the 3D C-arm devices (11.2 to 129.9 μSv). The ED of the MDCT were significant higher (284.52–844.97 μSv) than in all other devices. The ED of the CBCTs (173.7–184.9) were lower than for MDCT but still higher than those of the 3D C-arms. Conclusions Intraoperative imaging using 3D C-arm devices is an effective method to verify reduction results in maxillofacial surgery intraoperatively with significantly lower ED than postoperatively CBCT and MDCT imaging.

A taxonomic revision and cranial description of Terrestrisuchus gracilis (Archosauria, Crocodylomorpha) from the Upper Triassic of Pant‐y‐Ffynnon Quarry (southern Wales)

AbstractNon‐crocodyliform crocodylomorphs, formerly referred to the informal group ‘Sphenosuchia’, are the earliest known crocodylomorph precursors of extant crocodylians. They are therefore crucial for our understanding of early crocodylian evolution and the origin of typical crocodylian characteristics, such as the formation of a secondary palate, complex cranial pneumaticity, and a reinforced braincase. Terrestrisuchus gracilis, known from the Upper Triassic fissure fill deposits of Pant‐y‐Ffynnon in southern Wales, is represented by almost 200 specimens, comprising articulated, partially associated, and isolated remains. In this contribution we provide a taxonomic revision of Terrestrisuchus gracilis and redescribe its cranial anatomy in detail, based in part on novel micro‐computed tomography data. The posterior skull region is extensively pneumatized as indicated, among other features, by large pre‐ and postcarotid recesses on the parabasisphenoid, and a large pneumatic cavity in the articular of the mandible. In contrast, the quadrate forms only a small, unfused contact with the prootic, suggesting that complex pneumatization of the postorbital region pre‐dated the co‐ossification of the quadrate and braincase in Crocodylomorpha. Terrestrisuchus gracilis preserves an ossified basihyal, which represents the first occurrence of this bone in non‐avemetatarsalian archosaurs. Finally, we show that Terrestrisuchus gracilis was probably cathemeral (i.e. active in a range of light levels), based on a phylogenetic flexible discriminant analysis of the relative dimensions of the sclerotic ring and orbit.

The assessment of the relationship between the traits of temporal muscle and the massiveness of the supraorbital region of the Homo sapiens crania including the influence of the neurocranial shape and size of the occlusal surface of the upper molars – preliminary study

The knowledge about the pattern of the relationship between the morphological variability of the supraorbital region of human skulls and the features of the temporal muscle is far from complete. The main aim of this study was to determine the relationships between the traits of human temporal muscle (i.e., its relative height and length) and the relative massiveness of the supraorbital region of the frontal bone with taking into account the potential influence of the neurocranial shape and the relative area of the occlusal surface of the upper molars. Skulls of African and Australian males (n = 44) exhibiting high variability in the massiveness of the supraorbital region, the presence of two types of the upper molars (first and second, n = 88) and a good state of the preservation of the braincase with the clearly visible inferior temporal line were examined. The qualitative scales were used to assess the degrees of the massiveness of the supraorbital regions. Metric traits of temporal muscle and that used to calculate the index of the neurocranial shape, size of the braincase and the facial skeleton were collected. Values of the occlusal areas of the molars were obtained using the ImageJ software. Spearman’s rank correlation and partial rank correlation analyses were performed. The results of our study showed the relationships between the traits of the temporal muscle and only the degree of the robusticity of most lateral part of the supraorbital area (trigonum). However, when the influences of the neurocranial shape and the relative occlusal area of molars were excluded, these relationships disappeared. The greatest importance of the neurocranial shape for the formation of the morphology of the trigonum was indicated. The results of the study were discussed from the perspective of the potential role of the temporal muscle as the part of the mastication apparatus for the development of the robusticity of the cranial supraorbital region.

Ecological correlates of cranial evolution in the megaradiation of dipsadine snakes

BackgroundDipsadine snakes represent one of the most spectacular vertebrate radiations that have occurred in any continental setting, with over 800 species in South and Central America. Their species richness is paralleled by stunning ecological diversity, ranging from arboreal snail-eating and aquatic eel-eating specialists to terrestrial generalists. Despite the ecological importance of this clade, little is known about the extent to which ecological specialization shapes broader patterns of phenotypic diversity within the group. Here, we test how habitat use and diet have influenced morphological diversification in skull shape across 160 dipsadine species using micro-CT and 3-D geometric morphometrics, and we use a phylogenetic comparative approach to test the contributions of habitat use and diet composition to variation in skull shape among species.ResultsWe demonstrate that while both habitat use and diet are significant predictors of shape in many regions of the skull, habitat use significantly predicts shape in a greater number of skull regions when compared to diet. We also find that across ecological groupings, fossorial and aquatic behaviors result in the strongest deviations in morphospace for several skull regions. We use simulations to address the robustness of our results and describe statistical anomalies that can arise from the application of phylogenetic generalized least squares to complex shape data.ConclusionsBoth habitat and dietary ecology are significantly correlated with skull shape in dipsadines; the strongest relationships involved skull shape in snakes with aquatic and fossorial lifestyles. This association between skull morphology and multiple ecological axes is consistent with a classic model of adaptive radiation and suggests that ecological factors were an important component in driving morphological diversification in the dipsadine megaradiation.

Ambient light exposure of photostimulable phosphor plates: is there a safe limit for acceptable image quality?

To subjectively assess radiographs obtained with photostimulable phosphor (PSP) plates exposed to clinical levels of ambient light prior to read-out to potentially set a safe limit for acceptable image quality. Six dental regions of a dry human skull were X-rayed using PSP plates from VistaScan and Express under four exposure times: 0.1, 0.2, 0.32, and 0.4 s. Before read-out, the PSP plates were exposed to ambient light for 0, 5, 10, 30, 60, and 90 s. Six observers were asked to classify the 288 resulting radiographs as acceptable or unacceptable based on the identification of anatomical structures and global image quality. The number of answers classifying radiographs as unacceptable was used to calculate a rejection rate; a pairwise comparison for better image quality was further conducted among radiographs considered acceptable. Reproducibility was tested by having 25% of all experimental groups reassessed. Intra- and interobserver agreement ranged from 0.87 to 1.00 and from 0.81 to 0.92, respectively. Exposure of PSP plates to ambient light increased rejection rates mostly as of 10 s. In the pairwise comparison, subtle differences were observed between radiographs obtained with PSP plates not exposed and those exposed to ambient light for 5 s. Ambient light exposure of PSP plates impairs the image quality of radiographs. A safe limit of ambient light exposure of 5 s for VistaScan and Express should be considered. Ambient light exposure of PSP plates within safe limits can avoid retakes and reduce unnecessary patient exposure to X-rays.

Deep Learning-Based Magnetic Resonance Image Segmentation and Classification for Alzheimer’s Disease Diagnosis

Accurate and rapid detection of Alzheimer’s disease (AD) using magnetic resonance imaging (MRI) gained considerable attention among research workers because of an increased number of current researches being driven by deep learning (DL) methods that have accomplished outstanding outcomes in variety of domains involving medical image analysis. Especially, convolution neural network (CNN) is primarily applied for the analyses of image datasets according to the capability of handling massive unstructured datasets and automatically extracting significant features. Earlier detection is dominant to the success and development interferences, and neuroimaging characterizes the potential regions for earlier diagnosis of AD. The study presents and develops a novel Deep Learning-based Magnetic Resonance Image Segmentation and Classification for AD Diagnosis (DLMRISC-ADD) model. The presented DLMRISC-ADD model mainly focuses on the segmentation of MRI images to detect AD. To accomplish this, the presented DLMRISC-ADD model follows a two-stage process, namely, skull stripping and image segmentation. At the preliminary stage, the presented DLMRISC-ADD model employs U-Net-based skull stripping approach to remove skull regions from the input MRIs. Next, in the second stage, the DLMRISC-ADD model applies QuickNAT model for MRI image segmentation, which identifies distinct parts such as white matter, gray matter, hippocampus, amygdala, and ventricles. Moreover, densely connected network (DenseNet201) feature extractor with sparse autoencoder (SAE) classifier is used for AD detection process. A brief set of simulations is implemented on ADNI dataset to demonstrate the improved performance of the DLMRISC-ADD method, and the outcomes are examined extensively. The experimental results exhibit the effectual segmentation results of the DLMRISC-ADD technique.

MRI sequence optimisation methods to identify cranial nerve course for radiotherapy planning.

Magnetic resonance imaging (MRI) is being increasingly used to improve radiation therapy planning by allowing visualisation of organs at risk that cannot be well-defined on computed tomography (CT). Diagnostic sequences are increasingly being adapted for radiation therapy planning, such as the use of heavily T2-weighted 3D SPACE (Sampling Perfection with Application optimised Contrasts using different flip angle Evolution) sequence for cranial nerve identification in head and neck tumour treatment planning. A 3D isotropic T2 SPACE sequence used for cranial nerve identification was adapted for radiation therapy purposes. Distortion was minimised using a spin-echo-based sequence, 3D distortion correction, isocentre scanning and an increased readout bandwidth. Radiation therapy positioning was accounted for by utilising two small flex, 4-channel coils. The protocol was validated for cranial nerve identification in clinical applications and distortion minimisation using an MRI QA phantom. Normal anatomy of the cranial nerves CI-CIX, were presented, along with a selection of clinical applications and abnormal anatomy. The usefulness of cranial nerve identification is discussed for several case studies, particularly in proximity to tumours extending into the base of skull region. In-house testing validated that higher bandwidths of 600 Hz resulted in minimal displacement well below 1 mm. The use of MRI for radiation therapy planning allows for greater individualisation and prediction of patient outcomes. Dose reduction to cranial nerves can decrease late side effects such as cranial neuropathy. In addition to current applications, future directions include further applications of this technology for radiation therapy treatments.

Craniogenetic studies in Sus scrofa: With emphasis on the 'orbitosphenoid' problem.

The orbitosphenoid is a skeletal element of the endocranium of extant mammals. However, it has also been described in many of their fossil ancestors. Craniogenetic studies show that it is composed of two types of bone: first, the cartilaginous ala orbitalis and parts of the trabecular plate are transformed by endochondral ossification; second, so-called 'appositional bone' ('Zuwachsknochen') arises directly from the perichondrium of the two optic pilae and spreads in all directions and overlays the remaining cartilage and the endochondral ossifications. For some time, both bone types can be distinguished microscopically, but later in craniogenesis they fuse completely to become the presphenoid sensu lato of the osteocranium. We interpret the 'appositional bone' as neomorphic mode to reinforce the endocranial bone structures, which are the ossification of the delicate cartilaginous template of the chondrocranium. We studied the ossifications of the presphenoidal skull region in a series of ontogenetic stages of the pig Sus scrofa. We applied conventional histology as well as stained and unstained μCT scans. We can show the above-mentioned modes of ossification, and we can demonstrate the contribution of 'appositional bone' well into neonatal and infantile stages. The ossifications of the presphenoid (including the orbitosphenoid) are very slender in therapsids and early mammaliaforms as previously described by other authors. In mammaliaforms, they tend to become thicker and closely connected with the frontal bone, which may be due to the contribution of neomorphic appositional bone. We assume that thereby the presphenoid sensu lato becomes an enforcement of the orbital pillars.