Visual Asymmetry Research Articles

Theta burst stimulation in adults with symmetric and asymmetric visual acuity.

Theta Burst Stimulation can influence adult neuro-visual response in imbalanced visual pathways, possibly by influencing cortical excitability. Our objective was to compare suppressive imbalance (SI) and visual acuity (VA) after applying repetitive Transcranial Magnetic Stimulation between groups of subjects with normal binocular vision, visual asymmetry, and amblyopia. Thirty-five volunteers between 19 and 51years of age were split into three groups: 6 volunteers with asymmetric VA (group A); 19 amblyopes (group B); and 10 subjects with normal binocular vision (group C). VA and SI of all groups were evaluated before and after a single session of continuous Theta Burst Stimulation (cTBS) or placebo stimulation over the right occipital cortex. In both groups A and B, we found a significant VA improvement in the non-dominant eye after cTBS (p = 0.04 and p = 0.01, respectively). In SI evaluation, group A and group B also revealed a significant improvement after the cTBS session (p = 0.03 and p = 0.01, respectively). Finally, in the group of volunteers with normal binocular vision and for placebo groups A and B, there were no significant differences in VA and SI after cTBS. Amblyopic and visually asymmetric individuals improved VA and SI of the non-dominant eye after cTBS when compared to baseline and to placebo stimulation. These enhancements were not found in the group of volunteers with normal binocular vision. We can therefore reasonably assume that cTBS may interfere with the visual system of subjects that present some kind of asymmetry, possibly by improving neuronal imbalances.

The effect of art expertise on visual symmetry and asymmetry preference

The main differences between artists and non-artists can be discovered in information processing, drawing performance and aesthetical preferences. Aesthetical preference is influenced by stimulus complexity and by the symmetry-asymmetry dimension of the presented stimulus. Although the differences between artists and non-artists are clear regarding aesthetical evaluation, there are evidence supporting the assumption that symmetry is preferred over asymmetry regardless of domain specific knowledge. In the current study we investigated the role of expertise in visual art on aesthetical evaluation of symmetrical and asymmetrical, simple, and complex geometrical forms, using visual stimuli based on Jacobsen and Höfel (2001). Participants from art high- school and university have been gathered (N = 56) and were distributed into three separate groups by their visual art and art history experience (experts, novice, and medium experience). Our main result shows a significant effect of experience in visual art on aesthetical preference, participants in the expert group preferred complex asymmetrical stimuli more compared to participants in art novice group. Asymmetrical simple and complex forms were aesthetically preferred more by expert group than the two other groups. We also found that symmetrical forms are preferred over asymmetrical ones regardless of level of expertise in art, however preference of art experts tends to be more unified over stimulus complexity. Our results are in line with results from previous studies regarding symmetry- asymmetry preference. We can conclude that beside the general preference for symmetrical forms, experience in art alters asymmetry preference and it regulates the preference over simple- complex symmetrical and asymmetrical stimuli.

Linear Discriminant Analysis for Investigating Differences in Upper Body Movement Symmetry in Horses before/after Diagnostic Analgesia in Relation to Expert Judgement.

Simple SummaryIdentifying the anatomical structures involved in causing pain and an associated lameness in a horse typically requires assessment in straight lines and circles and using regional administration of local anesthetic drugs (diagnostic analgesia). Visual assessment of changes in movement are affected by bias, i.e., expected changes influence decisions. Quantitative measurements with inertial sensors aim at removing this bias. The current study is aimed at investigating how a specific data-driven method, linear discriminant analysis (LDA), may be useful for aiding veterinary decision making about perceived changes in lameness. Changes in movement data after diagnostic analgesia and expert judgements from 53 lame horses were used to study (a) the accuracy of LDA-based decision making, (b) differences between straight-line and circular movement and (c) which commonly used movement features are most useful in this context. Accuracy was comparatively low and varied considerably between 36% and 57%, indicating considerable overlap between movement symmetry data of the diagnostic analgesia categories. The best data-driven separation between categories was observed when the limb in which perineural anaesthesia had been performed was on the inside of the circle (on hard ground for forelimb and on soft ground for hindlimb diagnostic analgesia). Movement features of all three landmarks (head, withers, pelvis) were important for data-driven classification, emphasizing the complexity of the movement pattern changes after diagnostic analgesia observed in lame horses.Diagnostic analgesia and lunging are parts of the equine lameness examination, aiding veterinarians in localizing the anatomical region(s) causing pain-related movement deficits. Expectation bias of visual assessment and complex movement asymmetry changes in lame horses on the lunge highlight the need to investigate data-driven approaches for optimally integrating quantitative gait data into veterinary decision-making to remove bias. A retrospective analysis was conducted with inertial sensor movement symmetry data before/after diagnostic analgesia relative to subjective judgement of efficacy of diagnostic analgesia in 53 horses. Horses were trotted on the straight and on the lunge. Linear discriminant analysis (LDA) applied to ten movement asymmetry features quantified the accuracy of classifying negative, partial and complete responses to diagnostic analgesia and investigated the influence of movement direction and surface type on the quality of the data-driven separation between diagnostic analgesia categories. The contribution of movement asymmetry features to decision-making was also studied. Leave-one-out classification accuracy varied considerably (38.3–57.4% for forelimb and 36.1–56.1% for hindlimb diagnostic analgesia). The highest inter-category distances (best separation) were found with the blocked limb on the inside of the circle, on hard ground for forelimb diagnostic analgesia and on soft ground for hindlimb diagnostic analgesia. These exercises deserve special attention when consulting quantitative gait data in lame horses. Head and pelvic upward movement and withers minimum differences were the features with the highest weighting within the first canonical LDA function across exercises and forelimb and hindlimb diagnostic analgesia. This highlights that movement changes after diagnostic analgesia affect the whole upper body. Classification accuracies based on quantitative movement asymmetry changes indicate considerable overlap between subjective diagnostic analgesia categories.

Morphological Evaluation of the Thyroid Lobes and Isthmus in Asymptomatic Indian Young Adults using Ultrasonography: A Cross-sectional Study

Introduction: Studies on morphological variations of the thyroid gland have been published from various parts of the world. Awareness of these variations becomes critical for diagnosing pathologies involving the gland and for surgeons dealing with head and neck surgery. Aim: To observe and document asymmetry in thyroid morphology using ultrasonography (visual inspection followed by size estimation) in asymptomatic subjects. Materials and Methods: It was a descriptive cross-sectional study, which included 100 volunteer first year students (50 males and 50 females), who attended classes from April 2019-March 2020 in the Department of Anatomy, King George’s Medical University, Lucknow, Uttar Pradesh, India. Ultrasonography of the thyroid gland was performed and the image showing the thyroid isthmus along with both the lobes at their greatest depth and width was captured. The thickness of isthmus was also observed at this stage. Any visual asymmetry observed was noted; thereafter, in these subjects displaying asymmetry on close examination, the maximal width (mediolateral), maximal depth (anteroposterior), and greatest length (craniocaudal) of each lobe was taken. The statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 24. The values were represented in number (%) and mean±Standard Deviation (SD). Results: During sonographic assessment of the thyroid gland, visual asymmetry was observed on the coronal scan images in 24 out of 100 individuals (14 females and 10 males). These 24 cases were subjected to assessment of actual size measurements on ultrasound. In 23 of these subjects (13 females, 10 males), this asymmetry on close examination was correctly validated during measurements. However, in 1 female subject, the apparent asymmetry of lobe visualised via the transverse scan, did not translate into a difference in measurements, i.e., both the lobes measured almost similar. An asymmetry in thickness of isthmus was also uniquely observed in 10 subjects (8 females and 2 males). Conclusion: Visual assessment of thyroid lobes using ultrasonographic examination revealed asymmetry in lobe size, which was congruent with the measurement of dimensions of the lobes and also asymmetric isthmus thickness was seen. Hence, ultrasonographic examination proved to be a useful tool in routine diagnosis and treatment planning procedures.

The Role of Stimuli Complexity and Handedness on Visual Symmetry and Asymmetry Preference

Previous research results indicate visual information processing asymmetry in case of visual verbal stimuli. However, other studies that investigate nonverbal stimuli processing show inconsistent effect of laterality. Although differences between left- and right-handers can be found in tasks that involve letters, spatial attention stimuli and visuomotor control performance, the differences between the two groups almost disappear in several directional preference tasks, suggesting that direction preference is influenced mainly by writing and reading habits. Perceiving visual art involves visual attention, that is driven by the bottom-up aspects of the visual stimuli, therefore perception of nonverbal images, that contain geometrical forms might be influenced by handedness. To assess the possible differences in visual symmetry- asymmetry preference, university students (N = 65) were divided into two groups based on handedness, and as a measurement we used simple- complex- symmetrical and asymmetrical geometrical forms. Our main result shows a significant effect of stimuli complexity on symmetry-asymmetry preference. The interaction effect between handedness and symmetry-asymmetry type was not significant. After conducting a pairwise comparison our results show that right-handers evaluate simple and complex symmetrical forms as more preferable than simple and complex asymmetrical forms. We also found that there is a preference for symmetry over asymmetry in both groups, however these differences are significant only in the right-handed group. We conclude that preference for symmetrical geometrical forms is not influenced by handedness, however preference for complexity is affected by right-handedness. To extend these results, further investigations are needed.

EFFECT OF CEREBRAL LATERALIZATION ON VISUAL AND AUDITORY SIMPLE REACTION TIME AND REACTION ASYMMETRIES

The aim of the study is to examine the effect of cerebral lateralization on visual and auditory simple reaction time and reaction asymmetry in young adults. For this purpose, 52 individuals were divided into 3 groups according to hand preference and their audio-visual reaction times were measured and compared in both hands. The obtained data were analyzed in SPSS 22.0 program. After testing for normality and homogeneity, one-way analysis of variance and LSD correction were performed for multiple groups. According to the data obtained, it was determined that hand preference had no effect on reaction time and reaction asymmetry (p>0.05). As a result, it can be said that lateralization has no effect on reaction time and reaction asymmetry.
 
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Visual Search Asymmetry Due to the Relative Magnitude Represented by Number Symbols.

In visual search tasks, physically large target stimuli are more easily identified among small distractors than are small targets among large distractors. The present study extends this finding by presenting preliminary evidence of a new search asymmetry: stimuli that symbolically represent larger magnitude are identified more easily among featurally equivalent distractors that represent smaller magnitude. Participants performed a visual search task using line-segment digits representing the numbers 2 and 5, and the numbers 6 and 9, as well as comparable non-numeric control stimuli. In three experiments, we found that search times are faster when the target is a digit that represents a larger magnitude than the distractor, although this pattern was not evident in one additional experiment. The results provide suggestive evidence that the magnitude of a number symbol can affect perceptual comparisons between number symbols, and that the semantic meaning of a target stimulus can systematically affect visual search.

Act Like a Radiologist: Towards Reliable Multi-View Correspondence Reasoning for Mammogram Mass Detection.

Mammogram mass detection is crucial for diagnosing and preventing the breast cancers in clinical practice. The complementary effect of multi-view mammogram images provides valuable information about the breast anatomical prior structure and is of great significance in digital mammography interpretation. However, unlike radiologists who can utilize the natural reasoning ability to identify masses based on multiple mammographic views, how to endow the existing object detection models with the capability of multi-view reasoning is vital for decision-making in clinical diagnosis but remains the boundary to explore. In this paper, we propose an anatomy-aware graph convolutional network (AGN), which is tailored for mammogram mass detection and endows existing detection methods with multi-view reasoning ability. The proposed AGN consists of three steps. First, we introduce a bipartite graph convolutional network (BGN) to model the intrinsic geometric and semantic relations of ipsilateral views. Second, considering that the visual asymmetry of bilateral views is widely adopted in clinical practice to assist the diagnosis of breast lesions, we propose an inception graph convolutional network (IGN) to model the structural similarities of bilateral views. Finally, based on the constructed graphs, the multi-view information is propagated through nodes methodically, which equips the features learned from the examined view with multi-view reasoning ability. Experiments on two standard benchmarks reveal that AGN significantly exceeds the state-of-the-art performance. Visualization results show that AGN provides interpretable visual cues for clinical diagnosis.

Does hemispheric vascular regulation differ significantly in glaucoma patients with altitudinal visual field asymmetry? A single-center, prospective study

PurposeVascular risk factors and ocular perfusion are heatedly discussed in the pathogenesis of glaucoma. The retinal vessel analyzer (RVA, IMEDOS Systems, Germany) allows noninvasive measurement of retinal vessel regulation. Significant differences especially in the veins between healthy subjects and patients suffering from glaucoma were previously reported. In this pilot-study we investigated if localized vascular regulation is altered in glaucoma patients with altitudinal visual field defect asymmetry.Methods15 eyes of 12 glaucoma patients with advanced altitudinal visual field defect asymmetry were included. The mean defect was calculated for each hemisphere separately (−20.99 ± 10.49 profound hemispheric visual field defect vs −7.36 ± 3.97 dB less profound hemisphere). After pupil dilation, RVA measurements of retinal arteries and veins were conducted using the standard protocol. The superior and inferior retinal vessel reactivity were measured consecutively in each eye.ResultsSignificant differences were recorded in venous vessel constriction after flicker light stimulation and overall amplitude of the reaction (p < 0.04 and p < 0.02 respectively) in-between the hemispheres. Vessel reaction was higher in the hemisphere corresponding to the more advanced visual field defect. Arterial diameters reacted similarly, failing to reach statistical significance.ConclusionLocalized retinal vessel regulation is significantly altered in glaucoma patients with asymmetric altitudinal visual field defects. Veins supplying the hemisphere concordant to a less profound visual field defect show diminished diameter changes. Vascular dysregulation might be particularly important in early glaucoma stages prior to a significant visual field defect.

Ocular Dominance and Functional Asymmetry in Visual Attention Networks.

PurposeThe dorsal attention network (DAN) and the ventral attention network (VAN) are known to support visual attention, but the influences of ocular dominance on the attention networks are unclear. We aimed to explore how visual cortical asymmetry of the attention networks correlate with neurophysiological oscillation and connectivity markers of attentional processes.MethodsAn oddball task with concentric circle stimuli of three different sizes (i.e., spot size of 5°, 20°, or 30° of visual angle) was used to vary task difficulty. Event-related oscillations and interareal communication were tested with an electroencephalogram-based visual evoked components as a function of ocular dominance in 30 healthy subjects.ResultsAccuracy rates were higher in the dominant eyes compared with the nondominant eyes. Compared with the nondominant eyes, the dominant eyes had higher theta, low-alpha, and low-beta powers and lower high-alpha powers within the nodes of VAN and DAN. Furthermore, visual information processed by the dominant and nondominant eye had different fates, that is, the dominant eyes mainly relied on theta and low-alpha connectivity within both the VAN and the DAN, whereas the nondominant eyes mainly relied on theta connectivity within the VAN and high-alpha connectivity within the DAN. The difference in accuracy rate between the two eyes was correlated with the low-alpha oscillations in the anterior DAN area and low-alpha connectivity of the left DAN.ConclusionsThe ocular dominance processing and interareal communication reveal a cortical asymmetry underlying attention, and this reflects a two-way modulatory mechanism within attention networks in the human brain.

Assessment of localization accuracy and postsurgical prediction of simultaneous 18F-FDG PET/MRI in refractory epilepsy patients.

To evaluate the accuracies of simultaneous 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging ([18F]-FDG PET/MRI) in preoperative localization and the postsurgical prediction. This retrospective study was performed on ninety-eight patients diagnosed with refractory epilepsy whose presurgical evaluation included [18F]-FDG PET/MRI, with 1-year post-surgery follow-up between August 2016 and December 2018. PET/MRI images were interpreted by two radiologists and a nuclear medicine physician to localize the EOZ using standard visual analysis and asymmetry index based on standard uptake value (SUV). The localization accuracy and predictive performance of simultaneous 18F-FDG PET/MRI based on the surgial pathology and postsurgical outcome were evaluated. A total of 41.8% (41/98) patients were found to have a definitely structural abnormality on the MR portion of PET/MRI; 93.9% (92/98) were shown hypometabolism on the PET portion of the hybrid PET/MRI. PET/MRI identified 18 cases with subtle structural abnormalities on MRI re-read. Six percent (6/98) of patients PET/MRI were negative. A total of 65.3% (64/98) patients showed seizure-free at 1-year follow-up after epilepsy surgery. The sensitivity, specificity, and accuracy of [18F]-FDG PET/MRI was 95.3%, 8.8%, and 65.3% for seizure onset localization based on surgical pathology and postsurgical outcome, respectively. Multivariate regression analysis indicated that concordant of EOZ localization between PET/MRI and surgical resection range, which was a good positive predictor of seizure freedom (Engel I) (OR = 14.741, 95% CI 3.934-55.033, p < 0.001). [18F]-FDG PET/MRI used as two combined modalities providing additional sensitivity when detecting possible epileptic foci and will probably improve the surgical outcome. • Sensitivity, specificity, and accuracy of [18F]-FDG PET/MRI were 95.3%, 8.8%, and 65.3% for seizure onset localization based on surgical pathology and postsurgical outcome, respectively. • Concordance of EOZ localization between PET/MRI and surgical resection range was a good positive predictor of seizure freedom; presurgical [18F]-FDG PET/MRI will probably improve the surgical outcome.

The effect of acute, moderate intensity indoor cycling on the temporal resolution of human vision system, measured by critical fusion frequency.

Critical fusion frequency (CFF) reflects the basic temporal function of the visual system and therefore is a good measure of its performance. CFF has been implemented in psychological and pharmacological studies to evaluate cognitive functions. The influence of abnormal environmental conditions, such as physical exercise, has been recently explored. Previous studies have presented alterations of cognitive processes due to acute exercise. However, the duration of the effect after the end of exercise has not been investigated. This evaluation is important especially in reference to long‐term conclusions on the effect of training on CFF as an improvement of cognition. The main goal of this study was to check whether a stimulatory effect of acute submaximal physical exercise on CFF among non‐experienced cyclists persists over time. Moreover, we asked whether this effect differs between areas of visual field. CFF thresholds from 15 volunteers were measured by means of an automated medical perimeter PTS 910 (Bogdani) before, immediately after the end, and 30 min after the end of two sessions (training and rest). During rest, CFF did not change significantly, but we observed an increased CFF immediately after training. Interestingly, this increase was maintained 30 min after the end of exercise in fovea. A greater decrease of CFF during rest was observed for lower than for upper hemifield. Our results suggest that an acute, moderate‐intensity cycling improved CFF in non‐experienced cyclists, with the duration of the effect depending on eccentricity. The possible visual hemifield asymmetries of CFF changes over time will be further investigated.

Effect of Global and Local Processing on Visual Search Asymmetry

Effect of Global and Local Processing on Visual Search Asymmetry

PSYCHOPHYSIOLOGICAL FEATURES OF VOLLEYBALL PLAYERS WITH HEARING IMPAIRMENT

Aim. The paper aims to reveal the features of the central nervous system and interhemispheric asymmetry in volleyball players with hearing impairment. Materials and methods. The study involved 14 athletes of various sports experience with varying degrees of hearing impairment aged from 20 to 35 years (average age 29.20 ± 1.3 years). Simple visual reaction was studied in terms of the reaction time, reaction stability, and functional capabilities of the nervous system. To establish the manual asymmetry, the M. Annette questionnaire and motor tests (dynamometry, tests for intertwined fingers, the applause test) were used, the coefficient of the right hand was calculated. When detecting visual asymmetry, the Rosenbach test and the telescope test were used. The coefficient of the right eye was also calculated. Results. It was established that a third of the examined athletes had a symmetric distribution of signs in both the visual and manual spheres. The reliable dependence between symmetric distribution and sports titles was not found. The reaction time in volleyball players with hearing impairment was reduced. The reaction stability and the level of functional capabilities were within the normal range and had a significant dependence on the sports rank and category. Conclusion. It was revealed that volleyball players with hearing impairment formed a special type of interhemispheric interaction characterized by a more uniform distribution between the right and left hemispheres, which resulted in low values of manual and visual asymmetry.

Cognitive and Affective Assessment of Navigation and Mobility Tasks for the Visually Impaired via Electroencephalography and Behavioral Signals.

This paper presented the assessment of cognitive load (as an effective real-time index of task difficulty) and the level of brain activation during an experiment in which eight visually impaired subjects performed two types of tasks while using the white cane and the Sound of Vision assistive device with three types of sensory input—audio, haptic, and multimodal (audio and haptic simultaneously). The first task was to identify object properties and the second to navigate and avoid obstacles in both the virtual environment and real-world settings. The results showed that the haptic stimuli were less intuitive than the audio ones and that the navigation with the Sound of Vision device increased cognitive load and working memory. Visual cortex asymmetry was lower in the case of multimodal stimulation than in the case of separate stimulation (audio or haptic). There was no correlation between visual cortical activity and the number of collisions during navigation, regardless of the type of navigation or sensory input. The visual cortex was activated when using the device, but only for the late-blind users. For all the subjects, the navigation with the Sound of Vision device induced a low negative valence, in contrast with the white cane navigation.

Asymmetric visual representation of sex from human body shape

We efficiently infer others' states and traits from their appearance, and these inferences powerfully shape our social behaviour. One key trait is sex, which is strongly cued by the appearance of the body. What are the visual representations that link body shape to sex? Previous studies of visual sex judgment tasks find observers have a bias to report “male”, particularly for ambiguous stimuli. This finding implies a representational asymmetry – that for the processes that generate a sex percept, the default output is “male”, and “female” is determined by the presence of additional perceptual evidence. That is, female body shapes are positively coded by reference to a male default shape. This perspective makes a novel prediction in line with Treisman's studies of visual search asymmetries: female body targets should be more readily detected amongst male distractors than vice versa. Across 10 experiments (N = 32 each) we confirmed this prediction and ruled out alternative low-level explanations. The asymmetry was found with profile and frontal body silhouettes, frontal photographs, and schematised icons. Low-level confounds were controlled by balancing silhouette images for size and homogeneity, and by matching physical properties of photographs. The female advantage was nulled for inverted icons, but intact for inverted photographs, suggesting reliance on distinct cues to sex for different body depictions. Together, these findings demonstrate a principle of the perceptual coding that links bodily appearance with a significant social trait: the female body shape is coded as an extension of a male default. We conclude by offering a visual experience account of how these asymmetric representations arise in the first place.

Intraindividual relative deficits in visual memory to lateralize seizure onset in temporal lobe epilepsy

It is well established that presurgical neuropsychological assessment can assist in lateralizing and localizing focal epileptogenic regions. However, unlike verbal memory impairment, which is a robust and reliable finding in patients with left temporal lobe epilepsy (LTLE), nonverbal memory deficits are less consistently found among patients with right TLE (RTLE). This study aimed to determine whether memory assessment for spatial location in addition to visual content would differentiate patients with RTLE and LTLE. We compared performances between patients with 25 RTLE and 37 patients with LTLE on the Wechsler Advanced Clinical Solutions-Faces (ACS-F) subscales (Faces I, Faces II, Content, and Spatial), verbal–visual memory asymmetry scores, and intelligence quotient (IQ)–visual memory difference scores. Results revealed no significant differences between patients with RTLE and LTLE for any ACS-F memory score. By contrast, groups demonstrated significant differences in memory asymmetry scores (p = .007) and IQ difference scores (p = .006). Thus, visual memory scores in isolation failed to differentiate groups with RTLE and LTLE; however, within-patient differences between visual memory and other cognitive abilities successfully differentiated the groups. These results highlight the importance of using an intraindividual model of neuropsychological assessment to identify relative weaknesses potentially associated with the epileptogenic region.

Birth prevalence of achondroplasia: A systematic literature review and meta-analysis.

Achondroplasia is a genetic disorder that results in disproportionate short stature. The true prevalence of achondroplasia is unknown as estimates vary widely. This systematic literature review and meta‐analysis was conducted to better estimate worldwide achondroplasia birth prevalence. PubMed, Embase, Scielo, and Google Scholar were searched, complemented by manual searching, for peer‐reviewed articles published between 1950 and 2019. Eligible articles were identified by two independent researchers using predefined selection criteria. Birth prevalence estimates were extracted for analysis, and the quality of evidence was assessed. A meta‐analysis using a quality effects approach based on the inverse variance fixed effect model was conducted. The search identified 955 unique articles, of which 52 were eligible and included. Based on the meta‐analysis, the worldwide birth prevalence of achondroplasia was estimated to be 4.6 per 100,000. Substantial regional variation was observed with a considerably higher birth prevalence reported in North Africa and the Middle East compared to other regions, particularly Europe and the Americas. Higher birth prevalence was also reported in specialized care settings. Significant heterogeneity (Higgins I 2 of 84.3) was present and some indication of publication bias was detected, based on visual asymmetry of the Doi plot with a Furuya‐Kanamori index of 2.73. Analysis of pooled data from the current literature yields a worldwide achondroplasia birth prevalence of approximately 4.6 per 100,000, with considerable regional variation. Careful interpretation of these findings is advised as included studies are of broadly varying methodological quality.

Visual Breast Asymmetry Assessment with Optical-Flow Algorithm.

Breast surgery is one of the most important procedures in cosmetic and reconstructive surgery. However, there is no ideal method to assess results. One of the greatest difficulties is the subjective aspect of evaluation. In recent years, several objective computer systems have been proposed and validated as assessment methods, such as BCCT®, OBCS®, GBAI©, etc. In this study, we propose a novel system named VIBA©, that uses an Optical Flow (OF) algorithm which objectively classifies results into symmetrical and asymmetrical categories, with a numerical score. Software was developed in MATLAB (MATLAB and Statistics Toolbox Release 2018b, The MathWorks, Inc., Natick, Massachusetts, USA) called VIBA-Calc© (VIBA stands for VIsual Breast Asymmetry). We compared our OF score with the well-established asymmetry scoring system called Objective Breast Cosmesis Scale (OBCS®). In order to do so, we studied 100 frontal photographs of patients who underwent aesthetic breast surgery between 2017 and 2018, from the senior author's private practice. VIBA-Calc© allows the user to load an image and then draw a rectangle containing both breasts. By simply clicking on a button, the program finds the midline of the rectangle and calculates the final score, as well as the color map of asymmetric regions. Classification into symmetric or asymmetric categories using OBCS and VIBA scores agreed in most cases. Concordance between both classification systems was almost perfect in the group of postoperative cases (k = 0.84; p < 0.001), and substantial in preoperative cases (k = 0.76; p < 0.001). Global Cohen's kappa coefficient was 0.80 (p < 0.001). VIBA© is a useful tool for pre- and post-operative evaluation of breasts, that could be used both in reconstructive and aesthetic surgery.

Quantification of cerebral veins in patients with acute migraine with aura: A fully automated quantification algorithm using susceptibility-weighted imaging.

IntroductionSusceptibility weighted imaging (SWI) is a very sensitive technique that often depicts prominent focal veins (PFV) in patients with acute migraine with aura (MwA). Interpretation of visual venous asymmetry (VVA) between brain hemispheres on SWI may help support the clinical diagnosis of MwA. Our goal was to develop an automated algorithm for segmentation and quantification of cerebral veins using SWI.Materials and methodsExpert readers visually evaluated SWI of patients with acute MwA for VVA. Subsequently a fully automated algorithm based on 3D normalization and 2D imaging processing using SPM and MATLAB image processing software including top-hat transform was used to quantify cerebral veins and to calculate volumetric differences between hemispheres.ResultsFifty patients with MwA were examined with SWI. VVA was present in 20 of 50 patients (40%). In 95% of patients with VVA, the fully automated calculation agreed with the side that visually harboured more PFV. Our algorithm showed a sensitivity of 95%, specificity of 90% and accuracy of 92% for detecting VVA. Patients with VVA had significantly larger vein volume on the hemisphere with more PFV compared to patients without (15.90 ± 5.38 ml vs 11.93 ± 5.31 ml; p = 0.013). The mean difference in venous volume between hemispheres in patients with VVA was larger compared to patients without VVA (16.34 ± 7.76% vs 4.31 ± 3.26% p < 1E-10). The average time between aura onset and SWI correlated negatively with venous volume of the dominant brain hemisphere (r = -0.348; p = 0.038).ConclusionA fully automated algorithm can accurately identify and quantify cerebral venous distribution on SWI. Absolute quantification may be useful for the future assessment of patients with suspected diseases, which may be associated with a unilateral abnormal degree of venous oxygenation.