Correlation analysis between texture features and elasticity of skin hyperspectral images in the near-infrared band.

BACKGROUND/PURPOSE: Skin elasticity was used to evaluate healthy and diseased skin. Correlation analysis between image texture characteristics and skin elasticity was performed to study the feasibility of assessing skin elasticity using a non-contact method. MATERIALS AND METHODS: Skin images in the near-infrared band were acquired using a hyperspectral camera, and skin elasticity was obtained using a skin elastimeter. Texture features of the mean, standard deviation, entropy, contrast, correlation, homogeneity, and energy were extracted from the acquired skin images, and a correlation analysis with skin elasticity was performed. RESULTS: The texture features, and skin elasticity of skin images in the near-infrared band had the highest correlation on the side of eye and under of arm, and the mean and correlation were features of texture suitable for distinguishing skin elasticity according to the body part. CONCLUSION: In this study, we performed elasticity and correlation analyses for various body parts using the texture characteristics of skin hyperspectral images in the near-infrared band, confirming a significant correlation in some body parts. It is expected that this will be used as a cornerstone of skin elasticity evaluation research using non-contact methods.

Hyperspectral imaging-based erythema classification in atopic dermatitis.

BACKGROUND/PURPOSE: Among the characteristics that appear in the epidermis of the skin, erythema is primarily evaluated through qualitative scales, such as visual assessment (VA). However, VA is not ideal because it relies on the experience and skill of dermatologists. In this study, we propose a new evaluation method based on hyperspectral imaging (HSI) to improve the accuracy of erythema diagnosis in clinical settings and investigate the applicability of HSI to skin evaluation. METHODS: For this study, 23 subjects diagnosed with atopic dermatitis were recruited. The inside of the right arm is selected as the target area and photographed using a hyperspectral camera (HS). Subsequently, based on the erythema severity visually assessed by a dermatologist, the severity classification performance of the RGB and HS images is compared. RESULTS: Erythema severity is classified as high when using (i) all reflectances of the entire HSI band and (ii) a combination of color features (R of RGB, a* of CIEL*a*b*) and five selected bands through band selection. However, as the number of features increases, the amount of calculation increases and becomes inefficient; therefore, (ii), which uses only seven features, is considered to perform classification more efficiently than (i), which uses 150 features. CONCLUSION: In conclusion, we demonstrate that HSI can be applied to erythema severity classification, which can further increase the accuracy and reliability of diagnosis when combined with other features observed in erythema. Additionally, the scope of its application can be expanded to various studies related to skin pigmentation.

Single fiber curvature for muscle impairment assessment: Phase contrast imaging of stroke-induced animals.

There are technical challenges in imaging studies that can three-dimensionally (3D) analyze a single fiber (SF) to observe the functionality of the entire muscle after stroke. This study proposes a 3D assessment technique that only segments the SF of the right stroke-induced soleus muscle of a gerbil using synchrotron radiation x-ray microcomputed tomography (SR-µCT), which is capable of muscle structure analysis. Curvature damage in the SF of the left soleus muscle (impaired) progressed at 7-day intervals after the stroke in the control; particularly on the 7 days (1 week) and 14 days (2 weeks), as observed through visualization analysis. At 2 weeks, the SF volume was significantly reduced in the control impaired group (p = .033), and was significantly less than that in the non-impaired group (p = .009). We expect that animal post-stroke studies will improve the basic field of rehabilitation therapy by diagnosing the degree of SF curvature. RESEARCH HIGHLIGHTS: Muscle evaluation after ischemic stroke using synchrotron radiation x-ray microcomputed tomography (SR-µCT). Curvature is measured by segmenting a single fiber (SF) in the muscle. Structural changes in the SF of impaired gerbils at 7-day intervals were assessed.

Simultaneous visualization of micro-damage in cortical bone, trabecular bone, and intracortical vasculature for diagnosing osteoporosis: An animal model synchrotron imaging.

Osteoporosis (OP) is difficult to diagnose through the three-dimensional visualization of micro-damage. In this study, aimed to make an objective diagnosis by visualizing micro-damage caused by OP using synchrotron radiation-based µCT (SR-µCT). Female mice (n = 12) were randomly divided into an ovariectomized group (OVX, n = 6) in which both ovaries were excised and OP occurred, and a sham-operated group (SHAM, n = 6). After six weeks, all femurs (left and right) were excised from both groups (n = 12 per group). Thereafter, femurs were randomly divided into SR-µCT (OVX group, n = 6; SHAM group, n = 6) and µCT (OVX group, n = 6; SHAM group, n = 6) groups. In the SR-µCT group, micro-damage was visualized by manually segmenting the cortical bone, trabecular bone, and intracortical vasculature using a water-shedding algorithm. In addition, trabecular bone was obtained by automatic segmentation using µCT. Cortical bone volume/total volume was greater (p = .015), and cortical thickness was greater in the SHAM group than in the OVX group (p = .007). Among the trabecular bone parameters, the bone volume/total volume (TV) in OVX was significantly lower than that in the SHAM group (p = .012). The canal volume was greater (p = .021) and lacuna volume was greater (p < .001) in the SHAM group than in the OVX group. We expect that it will be possible to analyze damage and recovery mechanisms in the field of rehabilitation. SR-µCT has been proposed as an objective method for OP diagnosis as it allows the visualization of microstructures. RESEARCH HIGHLIGHTS: Damage mechanism for diagnosis and evaluation in an osteoporosis model. Synchrotron radiation can objectively diagnose osteoporosis. Visualization is possible by segmenting microdamage caused by osteoporosis.

4D dynamic system for visual-motor integration analysis.

It is very important to evaluate visual-motor integration (VMI), as it is used as an index to evaluate cognitive abilities. However, it is difficult to use the existing paper-based tests to evaluate the dynamic process, including spatial and depth perception abilities. Therefore, this study aims to extract kinematic and dynamic features for dynamic assessment for VMI. We propose a 4D dynamic analysis system that implements a VMI test in a virtual space using Leap motion controller and Unity3D and acquires the time-series data of hand joints and traces. We selected three categories of features: postural control ability, spatial and depth perception ability, and 4D analysis. The degree and patterns of postural maintenance differed between subjects in the VMI and MC tests. In addition, the personal patterns were identified with dynamic features, including their fluency and hesitation in relation to the task figures of the VMI test tool. As such, this system enables dynamic feature extraction and analysis which were previously impossible and presents performance results for healthy adults.

Robust skin microrelief depth estimation using a mobile stereo system.

BACKGROUND: The skin surface becomes wrinkled and rough due to various internal and external factors. A three-dimensional (3D) analysis of the skin is required to improve skin conditions. Stereophotogrammetry, a noninvasive 3D analysis method, is easy to install and use, but most stereo systems have a fixed baseline and scale. Previous stereo systems are not suitable for observing micro-range skin features. Therefore, we suggest the optimal conditions and methods for the 3D analysis of skin microrelief using a multi-conditioned stereo system. METHODS: We constructed a nonconvergence model using a mobile device and acquired stereo images under multiscale and multi-baseline conditions. We extracted 3D information of the skin through our process: preprocessing, skin feature extraction, feature matching, and actual depth mapping. We improved the accuracy of the 3D analysis of the skin by using disparity values instead of disparity maps. We compared and analyzed the performances of six local feature detector and descriptor algorithms. In addition, we suggested depth-mapping formulas to estimate the actual depth of the skin microrelief. RESULTS: We confirmed that stereo images with a working distance of 70-75 mm and a baseline of 4-8 mm are effective for the 3D analysis of skin microrelief. In addition, accelerated KAZE exhibited the best performance for features extraction and stereo matching. Finally, the extracted 3D information was converted to the actual depth, and the performance of the 3D analysis was verified. CONCLUSION: The proposed system and method that provide texture information are effective for 3D skin disease analysis and evaluation.

Skin color classification of Koreans using clustering.

BACKGROUND/PURPOSE: Skin color is used as an index for diagnosing and predicting skin irritation, dermatitis, and skin conditions because skin color changes based on various factors. Therefore, a new method for consistently and accurately evaluating skin color while overcoming the limitations of the existing skin color evaluation method was proposed, and its usefulness was demonstrated. METHODS: Skin color was quantified using the RGB (Red, Green, Blue), HSV (Hue Saturation Value), CIELab, and YCbCr color spaces in the acquired Korean skin images, which were classified through clustering. In addition, the classification performances of the existing visual scoring method and the proposed skin color classification method were compared and analyzed using multinomial logistic regression, support vector machine, K-nearest neighbor, and random forest. RESULTS: After quantifying the skin color through the color space conversion of the skin image, the skin color classification performance according to the number of quantified features and the classifier was verified. In addition, the usefulness of the proposed classification method was confirmed by comparing its classification performance with that of the existing skin color classification method. CONCLUSION: In this study, a method was proposed to objectively classify skin color values quantified from skin images of Koreans acquired using a digital camera through clustering. To verify the proposed method, its classification performance was compared with that of the existing classification method, and an optimized classification method was presented for the classification of Korean skin color. Thus, the proposed method can objectively classify skin color and can be used as a cornerstone in research to quantify skin color and establish objective classification criteria.

Automatic analysis system for abnormal red blood cells in peripheral blood smears.

The type and ratio of abnormal red blood cells (RBCs) in blood can be identified through peripheral blood smear test. Accurate classification is important because the accompanying diseases indicated by abnormal RBCs vary. In clinical practice, this task is time-consuming because the RBCs are manually classified. In addition, because the classification depends on the subjective criteria of pathologists, objective classification is difficult to achieve. In this paper, an automatic classification method that is solely based on images of RBCs captured under a microscope and processed using machine learning (ML) is proposed. The size and hemoglobin abnormalities of RBCs were classified by optimizing the criteria used in clinical practice. For morphologically abnormal RBCs classification, used seven geometric features information (major axis, minor axis, ratio of major and minor axis, perimeter, circularity, number of convex hulls, difference between area and convex area) and five types of multiple classifiers (Support Vector Machine, Decision Tree, K-Nearest Neighbor, Random Forest, and Adaboost models). Among was categorized using SVM, highly accurate results (99.9%) were obtained. The classification is performed simultaneously, and results are provided to the user through a graphical user interface (GUI).

Analysis of type I osteoporosis animal models using synchrotron radiation.

Preclinical experiments to analyze the trabecular space of spongy bones using small animals are required for the evaluation and treatment of patients with osteoporosis (OP). We performed ovariectomy to create OP models. A total of four mice were used. Ovariectomized group (OVX, n = 2) in which both ovaries were resected at random, and the sham operated group (SHAM, n = 2) performed surgery without resecting the ovaries. We propose a study that enables OP analysis by analyzing tibia microstructures of OVX and SHAM using synchrotron radiation (SR). SR imaging is a technology capable of irradiating an extremely small object in the order of several tens of nanometers using a nondestructive method at the microscopic level. Unlike previous imaging diagnoses (staining, micro-CT [Computed Tomography]) it was possible to preserve the real shape and analyze bone microstructures in real-time and analyze and evaluate spongy bones to secure data and increase the reliability of OP analysis. We were able to confirm the possibility of OP diagnosis through experimental animals for spongy bone damage related to bone mineral density. Therefore, we aimed to provide a rehabilitation and medicine therapy intervention method through basic research on the evaluation of OP diagnosis through human-based segmentation of challenging spongy bones while supplementing the limitations of existing imaging methods. RESEARCH HIGHLIGHTS: We present an analysis of osteoporosis through spongy bone using phase-contrast X-ray source. Unlike existing methods, it is possible to analyze the internal microstructure of the tibia with this method. This is an objective mechanism for OP and a basis for rehabilitation.

Optimization of psoriasis assessment system based on patch images.

Psoriasis is a chronic inflammatory skin disease that occurs in various forms throughout the body and is associated with certain conditions such as heart disease, diabetes, and depression. The psoriasis area severity index (PASI) score, a tool used to evaluate the severity of psoriasis, is currently used in clinical trials and clinical research. The determination of severity is based on the subjective judgment of the clinician. Thus, the disease evaluation deviations are induced. Therefore, we propose optimal algorithms that can effectively segment the lesion area and classify the severity. In addition, a new dataset on psoriasis was built, including patch images of erythema and scaling. We performed psoriasis lesion segmentation and classified the disease severity. In addition, we evaluated the best-performing segmentation method and classifier and analyzed features that are highly related to the severity of psoriasis. In conclusion, we presented the optimal techniques for evaluating the severity of psoriasis. Our newly constructed dataset improved the generalization performance of psoriasis diagnosis and evaluation. It proposed an optimal system for specific evaluation indicators of the disease and a quantitative PASI scoring method. The proposed system can help to evaluate the severity of localized psoriasis more accurately.

Micro- and nano-tomography analysis of mouse soleus muscle using radiation.

In this study, we analyze radiation images of muscle structure of mice soleus muscles using radiation source-based microtomography and nanotomography. Soleus muscle samples were collected for analysis from 8-week-old male Institute of Cancer Research mice. First, phase-contrast X-ray microtomography was employed in these experiments. Then to obtain images with excellent contrast, imaging was performed using monochromatic light with excellent transmission power. To analyze additional muscle structures in higher magnification images than these images, nanotomography was performed, which facilitated obtaining high-magnification and high-resolution images. Muscle tissue microstructures were confirmed through three-dimensional images obtained from phase-contrast X-ray microtomography. Thus, the muscle tissue's overall shape at microscopic level can be captured. Additionally, a single muscle fiber was examined using hard X-ray nano-imaging, through which we could observe the alignment of countless myofibrils, that is, actin and myosin filaments in the muscle fibers. Thus, the methodology adopted here proved to be advantageous in analyzing the muscle tissue's overall structure with microtomography and in observing the myofibrils in detail using nanotomography.

Three-dimensional structure analysis of mouse nails using synchrotron radiation.

Until now, studies on nail diseases have been performed through microscopic diagnosis and microscopic computed tomography (micro-CT). However, these kinds of conventional methods have some limitations. Firstly, the microscopic method is considered the gold standard for medical diagnosis. However, due to the use of fluorescent materials, the sample is damaged and it takes a long time to get results. Secondly, while micro-CT is a noninvasive method to get inner structure images of the sample with high resolution, the penetration and spatial resolution are insufficient for studying the microstructures of the sample, such as the sponge bone and the muscle fibers. In contrast, synchrotron radiation (SR) X-ray imaging technology has the advantage of very vividly demonstrating the anatomic structure of the sample with high penetration, sensitivity and resolution. In this study, we compared the optical microscopic method using hematoxylin and eosin staining and SR imaging to analyze the nail tissue in a mouse model. The results showed that SR could depict the inner structures of a mouse nail without any physical damage. Additionally, we could divide the important anatomical structures of the nail unit into three parts with three-dimensional (3D) images: the nail bed, nail matrix and hyponychium. The images showed that SR could be used for analyzing nails by visualizing the relatively clear and medically semantic structures in a 3D section. We expect that the results of this study will be applied to study nail diseases and conduct pharmaceutical research on their treatment.

Upper Limb Rehabilitation Tools in Virtual Reality Based on Haptic and 3D Spatial Recognition Analysis: A Pilot Study.

With aging, cerebrovascular diseases can occur more often. Stroke cases involve hemiplegia, which causes difficulties in performing activities of daily living. Existing rehabilitation treatments are based on the subjective evaluation of the therapist as the need for non-contact care arises; it is necessary to develop a system that can self-rehabilitate and offer objective analysis. Therefore, we developed rehabilitation tools that enable self-rehabilitation exercises in a virtual space based on haptics. Thirty adults without neurological damage were trained five times in a virtual environment, and the time, number of collisions, and coordinates were digitized and stored in real time. An analysis of variance (ANOVA) of the time and distance similarity changes revealed that as the number of rounds increased, no changes or increases occurred (p ≥ 0.05), and the collisions and paths were stable as the training progressed (p < 0.05). ANOVA showed a high correlation (0.90) with a decrease in the number of crashes and time required. It was meaningful to users when performing rehabilitation training more than four times and significantly impacted the analysis. This study analyzed the upper limb and cognitive rehabilitation of able-boded people in three-dimensional space in a virtual environment; the performance difficulty could be controlled through variations in rehabilitation models.

Three-dimensional analysis of injury conditions of single muscle fibers in small animals using phase-contrast X-ray imaging.

Muscle damage can reduces the biological functions and lead to ultimately a disease state. For the reason, it is important to accurately check the state of an injury such as atrophy, and it is required to identify the state of fibers constituting the muscle. This study describes a novel method of analyzing single muscle fibers with injury conditions in three-dimensions. The muscle fibers of the mice were visualized using phase-contrast X-ray projection the microstructure. In additions, it was possible to confirm the status by quantitatively analyzing the injury severity of muscle fibers. Significantly, the muscle conditions of multiple individuals were individually determined. This study could contributes to areas where it is very important to identify microdetailed and quantitative changes of state, such as new drug development.

Development of a Diagnosis and Evaluation System for Hemiplegic Patients Post-Stroke Based on Motion Recognition Tracking and Analysis of Wrist Joint Kinematics.

An inexperienced therapist lacks the analysis of a patient's movement. In addition, the patient does not receive objective feedback from the therapist due to the visual subjective judgment. The aim is to provide a guide for in-depth rehabilitation therapy in virtual space by continuously tracking the user's wrist joint during Leap Motion Controller (LMC) activities and present the basic data to confirm steady therapy results in real-time. The conventional Box and Block Test (BBT) is commonly used in upper extremity rehabilitation therapy. It was modeled in proportion to the actual size and Auto Desk Inventor was used to perform the 3D modeling work. The created 3D object was then implemented in C # through Unity5.6.2p4 based on LMC. After obtaining a wrist joint motion value, the motion was analyzed by 3D graph. Healthy subjects (23 males and 25 females, n = 48) were enrolled in this study. There was no statistically significant counting difference between conventional BBT and system BBT. This indicates the possibility of effective diagnosis and evaluation of hemiplegic patients post-stroke. We can keep track of wrist joints, check real-time continuous feedback in the implemented virtual space, and provide the basic data for an LMC-based quantitative rehabilitation therapy guide.

Adaptive Fine Distortion Correction Method for Stereo Images of Skin Acquired with a Mobile Phone.

With the development of the mobile phone, we can acquire high-resolution images of the skin to observe its detailed features using a mobile camera. We acquire stereo images using a mobile camera to enable a three-dimensional (3D) analysis of the skin surface. However, geometric changes in the observed skin structure caused by the lens distortion of the mobile phone result in a low accuracy of the 3D information extracted through stereo matching. Therefore, our study proposes a Distortion Correction Matrix (DCM) to correct the fine distortion of close-up mobile images, pixel by pixel. We verified the correction performance by analyzing the results of correspondence point matching in the stereo image corrected using the DCM. We also confirmed the correction results of the image taken at the five different working distances and derived a linear regression model for the relationship between the angle of the image and the distortion ratio. The proposed DCM considers the distortion degree, which appears to be different in the left and right regions of the image. Finally, we performed a fine distortion correction, which is difficult to check with the naked eye. The results of this study can enable the accurate and precise 3D analysis of the skin surface using corrected mobile images.

Synchrotron radiation imaging analysis of neural damage in mouse soleus muscle.

Damage to lower limb muscles requires accurate analysis of the muscular condition via objective microscopic diagnosis. However, microscopic tissue analysis may cause deformation of the tissue structure due to injury induced by external factors during tissue sectioning. To substantiate these muscle injuries, we used synchrotron X-ray imaging technology to project extremely small objects, provide three-dimensional microstructural analysis as extracted samples. In this study, we used mice as experimental animals to create soleus muscle models with various nerve injuries. We morphologically analyzed and quantified the damaged Section and Crush muscles, respectively, via three-dimensional visualization using synchrotron radiation X-ray imaging to diagnose muscle injury. Results of this study can also be used as basic data in the medical imaging field.

Synchrotron radiation-based analysis of fatigue in dental restorative materials.

Few studies performed a microstructural analysis of dental restorations to evaluate fatigue impact under various tensions, because of a lack of analytical equipment. In this study, the fatigue of restorative materials was evaluated using the force tester's fatigue method at 0.30, 0.3, 0.40, and 0.45 N. The fatigue effect analysis of tooth restorations was performed with each sample by randomly dividing the sequence into grades 0-4 and the evaluators were blinded to the test results. The evaluation methods involved visual and stereoscopic approaches, and used synchrotron radiation (SR). The evaluation facilitated the observation of microscopic cracks in the material using SR. The initiation of cracks was attributed to air bubbles, invisible to the naked eye or under the microscope. The fatigue effect analysis using SR enabled closer observations compared with other types of evaluation. We expect that this strategy will provide a basis for the study of physical and mechanical properties of dental materials.

Three-dimensional reconstruction of skin disease using multi-view mobile images.

BACKGROUND/PURPOSE: In skin beauty area, interest in diagnosis and management methods for acne is increasing. However, it is difficult to diagnose protruding skin disease by two-dimensional (2D) image. Three-dimensional (3D) approach is needed. The purpose of this study was to propose a system for reconstructing 3D model (visual hull) of 2D images obtained using mobile devices. METHODS: Acne images were acquired using a 3D printing mobile image acquisition system. Using two attached mirrors, five multi-view acne silhouette images were obtained. They were then, reconstructed to 3D. To measure the volume of the formed 3D model (visual hull), post-processing, calculation, and texture mapping were performed. The volume of acne samples designed with 3D printing was compared with the volume calculated in the produced system using statistical analysis program. RESULTS: The 3D modeling program demonstrated its superiority by showing high correlation (r = 0.783) between the actual volume of acne and the volume calculated by the system. The 3D model (visual hull) was successfully reconstructed by capturing 2D images of actual acne. CONCLUSION: In this study, we created a system to reconstruct small sized protruding skin disease images such as acne obtained with mobile devices. The 3D printing system was used to obtain images from mobile camera and reconstructed to 3D. To verify the volume of the reconstructed model, 3D printing samples were produced and compared with the calculated actual volume. It can be used, for initial diagnosis by receiving information about the protruding skin disease without space-time constraints using a mobile device.

Usefulness of synchrotron radiation for three-dimensional microstructure analysis of the mouse tibia.

This study was to construct a quantitative analysis for the diagnosis and evaluation of osteoporosis by using synchrotron radiation based X-ray, which can analyze the three-dimensional microstructure of white mouse tibia. The anatomical structure and microstructure of the white mouse tibia was obtained through synchrotron radiation, and to achieve this, three-dimensional structural analysis was performed. Then, we visualized the quantified analysis and microstructure information with high-resolution imagery through the image data obtained by synchrotron radiation. In addition, it was confirmed that synchrotron radiation can obtain more reliable results through accurate observation than analysis by the mechanical method. The present invention can provide the diagnosis and evaluation associated with osteoporosis. It is expected that this will provide a basis for the evaluation and prevention of evidence-based skeletal diseases.