Research Progress of Age Estimation in the Living by Knee Joint MRI / 法医学杂志

Bone development shows certain regularity with age. The regularity can be used to infer age and serve many fields such as justice, medicine, archaeology, etc. As a non-invasive evaluation method of the epiphyseal development stage, MRI is widely used in living age estimation. In recent years, the rapid development of machine learning has significantly improved the effectiveness and reliability of living age estimation, which is one of the main development directions of current research. This paper summarizes the analysis methods of age estimation by knee joint MRI, introduces the current research trends, and future application trend.

Value of ocular trauma score and ocular structural parameters in the assessment of healing visual acuity from ocular trauma / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To explore the value of ocular trauma score(OTS), initial visual acuity, and ocular structural parameters in the assessment of healing visual acuity from ocular trauma.METHOD: A total of 302 cases(302 eyes)of ocular trauma were selected as subjects, which were accepted and issued clear appraisal opinions by the Academy of Forensic Science from June 2015 to June 2021. The subjects were grouped according to the healing best corrected visual acuity(BCVA)from ocular trauma. Group Ⅰ included 63 cases(63 eyes)with BCVA <3.7; Group Ⅱ included 70 cases(70 eyes)with 3.7≤ BCVA <4.5; Group Ⅲ included 78 cases(78 eyes)with 4.5≤ BCVA <4.9; Group Ⅳ included 91 cases(91 eyes)with BCVA≥4.9. In addition, 77 cases(77 healthy eyes)of ocular trauma were selected as the control group, namely Group Ⅴ. The healing BCVA and ocular structural parameters from ocular trauma and theirs correlation were analyzed, and the random forest(RF)and support vector machine(SVM)model of healing visual acuity was established by the IBM SPSS Modeler 18.0.RESULTS: The initial visual acuity, OTS, the grading of corneas, lenses, and fundus, and the thickness of the retinal never fiber layer of ocular trauma patients were correlated with the healing BCVA(P<0.01). There were significant differences in ocular structural parameters among groups, except the central subfield thickness(P<0.001). The SVM model had higher accuracy of predicting healing visual acuity than the RF model, and the accuracy rate was over 80% when the error was within 0.15.CONCLUSION:OTS and ocular structural examination can provide effective information for the clinical forensic medicine appraisal of visual dysfunction after ocular trauma, and they are valuable in discriminating camouflage of visual dysfunction.

Correlation between Elbow Flexor Muscle Strength and Needle Electromyography Parameters after Musculocutaneous Nerve Injury / 法医学杂志

OBJECTIVES@#To explore the changes of elbow flexor muscle strength after musculocutaneous nerve injury and its correlation with needle electromyography (nEMG) parameters.@*METHODS@#Thirty cases of elbow flexor weakness caused by unilateral brachial plexus injury (involving musculocutaneous nerve) were collected. The elbow flexor muscle strength was evaluated by manual muscle test (MMT) based on Lovett Scale. All subjects were divided into Group A (grade 1 and grade 2, 16 cases) and Group B (grade 3 and grade 4, 14 cases) according to their elbow flexor muscle strength of injured side. The biceps brachii of the injured side and the healthy side were examined by nEMG. The latency and amplitude of the compound muscle action potential (CMAP) were recorded. The type of recruitment response, the mean number of turns and the mean amplitude of recruitment potential were recorded when the subjects performed maximal voluntary contraction. The quantitative elbow flexor muscle strength was measured by portable microFET 2 Manual Muscle Tester. The percentage of residual elbow flexor muscle strength (the ratio of quantitative muscle strength of the injured side to the healthy side) was calculated. The differences of nEMG parameters, quantitative muscle strength and residual elbow flexor muscle strength between the two groups and between the injured side and the healthy side were compared. The correlation between elbow flexor manual muscle strength classification, quantitative muscle strength and nEMG parameters was analyzed.@*RESULTS@#After musculocutaneous nerve injury, the percentage of residual elbow flexor muscle strength in Group B was 23.43% and that in Group A was 4.13%. Elbow flexor manual muscle strength classification was significantly correlated with the type of recruitment response, and the correlation coefficient was 0.886 (P<0.05). The quantitative elbow flexor muscle strength was correlated with the latency and amplitude of CMAP, the mean number of turns and the mean amplitude of recruitment potential, and the correlation coefficients were -0.528, 0.588, 0.465 and 0.426 (P<0.05), respectively.@*CONCLUSIONS@#The percentage of residual elbow flexor muscle strength can be used as the basis of muscle strength classification, and the comprehensive application of nEMG parameters can be used to infer quantitative elbow flexor muscle strength.

Pelvic Injury Discriminative Model Based on Data Mining Algorithm / 法医学杂志

OBJECTIVES@#To reduce the dimension of characteristic information extracted from pelvic CT images by using principal component analysis (PCA) and partial least squares (PLS) methods. To establish a support vector machine (SVM) classification and identification model to identify if there is pelvic injury by the reduced dimension data and evaluate the feasibility of its application.@*METHODS@#Eighty percent of 146 normal and injured pelvic CT images were randomly selected as training set for model fitting, and the remaining 20% was used as testing set to verify the accuracy of the test, respectively. Through CT image input, preprocessing, feature extraction, feature information dimension reduction, feature selection, parameter selection, model establishment and model comparison, a discriminative model of pelvic injury was established.@*RESULTS@#The PLS dimension reduction method was better than the PCA method and the SVM model was better than the naive Bayesian classifier (NBC) model. The accuracy of the modeling set, leave-one-out cross validation and testing set of the SVM classification model based on 12 PLS factors was 100%, 100% and 93.33%, respectively.@*CONCLUSIONS@#In the evaluation of pelvic injury, the pelvic injury data mining model based on CT images reaches high accuracy, which lays a foundation for automatic and rapid identification of pelvic injuries.

Application of the Virtual Reality-Pattern Visual Evoked Potential in Forensic Visual Acuity Evaluation / 法医学杂志

Objective To explore a kind of visual evoked potential test equipment and method that is more suitable for the application of forensic clinical visual acuity evaluation. Methods Thirty-four volunteers （68 eyes） were selected, including 15 males and 19 females, aged between 20 and 40 years. Test lenses were placed before the tested eyes of volunteers to induce refractive myopia with insert method, and the diopter lenses were adjusted so that the visual acuity level of one eye of volunteers was above 0.8, and the visual acuity of the other eye was at moderate damage level （<0.3 and ≥0.1）. The tests were carried out under the binocular simultaneous asynchronous stimulation mode （hereinafter referred to as "binocular mode"） and monocular separate stimulation mode （hereinafter referred to as "monocular mode"） of virtual reality-pattern visual evoked potential （VR-PVEP）, and the amplitude of PVEP of volunteers under the two modes was compared at four spatial frequencies of 8×8, 16×16, 24×24 and 32×32. Results The differences in the amplitude of P100 wave between monocular and binocular modes at 8×8 spatial frequency had no statistical significance and the differences in amplitude of P100 wave between monocular and binocular modes at 16×16, 24×24, and 32×32 spatial frequencies had statistical significance （P<0.05）. The amplitude of the same eye in monocular mode was higher than that in binocular mode. Through correlation analysis, it was found that the amplitude of P100 wave in monocular mode was moderately correlated with amplitude of P100 wave in binocular mode. Conclusion In forensic identification practice, VR-PVEP is helpful for overcoming the disturbance of poor fixation, and to increase the reliability of PVEP evaluation results. It can greatly shorten the detection time of PVEP and improve work efficiency.

Application of Convolutional Neural Network in Identifying Different Levels of Isokinetic Exercise Efforts / 法医学杂志

Objective To develop a convolutional neural network （CNN） that can identify isokinetic knee exercises moment of force-time diagrams under different levels of efforts. Methods The 200 healthy young volunteers performed concentric isokinetic right knee flexion-extension reciprocating exercises with maximal effort as well as half the effort at angular velocities of 30°/s and 60°/s twice, respectively, with an interval of 45 min. The moment of force-time diagrams were collected. The 200 subjects were randomly divided into the training set （140 subjects） and the testing set （60 subjects）. The moment of force-time diagrams from subjects in the training set were used to train CNN model, and then the fully trained model was used to predict types of curves from the testing set. Random sampling of subjects along with subsequent development of models were performed 3 times. Results Under the circumstances of isokinetic knee exercises with maximal effort and half the effort, 2 400 moment of force-time diagrams were produced, respectively. Classification accuracy rates of the CNN models after the 3 trainings were 91.11%, 90.49% and 92.08%, respectively, and the average accuracy rate was 91.23%. Conclusion The CNN models developed in this study have a good effect on differentiating isokinetic moment of force-time diagrams of maximal effort exercises from those made with half the effort, which can contribute to identifying levels of efforts exerted by subjects during isokinetic knee exercises.

Comparative Analysis of Visual System Disability Evaluation Criteria between China and the United States / 法医学杂志

Gradation of Disability in Human Body Injuries （hereinafter referred to as Gradation） has been released and used since January 2017, and has become the most widely used standard in forensic science practice. This paper calculates and rates the visual system evaluation provisions of the current domestic disability evaluation criteria represented by the Gradation which used the methods of Guides to the Evaluation of Permanent Impairment （hereinafter referred to as GEPI） issued by American Medical Association （AMA）. Through comparing, a good correlation between the provisions in Gradation and whole person impairment rating index in GEPI was shown. On the basis of this, suggestions are put forward to amend some provisions of Gradation, in order to provide reference for the revision and further improvement of domestic standards and provisions.

Application of PRVEP Waveform Amplitude Ratio to Evaluate Visual Acuity and Its Forensic Significance / 法医学杂志

Objective To research the correlation between the visual acuity ratio and pattern reversal visual evoked potential （PRVEP） P100 waveform amplitude ratio of both eyes. Methods Forty-seven volunteers were selected, and the visual chart visual acuity of both eyes was measured. The visual acuity ratio of the eye with poor vision to the eye with better vision was calculated by five grade notation method. The amplitudes of P100 waveforms of both eyes were recorded respectively by using black-and-white checkerboard PRVEP and chosing 1°, 15' stimulating visual angle, and the ratio of amplitudes between the two eyes was also calculated. SPSS 20.0 software was used to analyze the correlation between the visual acuity ratio and the ratio of P100 waveform amplitudes between the two eyes. Return test and linear regression analysis with the binocular ratio of P100 waveform amplitudes as the independent variable （x） and the binocular visual acuity ratio as the dependent variable （y） were made. Results There was a positive correlation between the binocular visual acuity ratio and the ratio of P100 waveform amplitudes under 15' stimulating visual angle （Pearson correlation coefficient was 0.62, P=0.000）. The fitting linear regression equation was y=0.090 x+0.846 （F=20.954, P=0.000）. There was no significant correlation between the binocular ratio of visual acuity and the binocular ratio of P100 waveform amplitudes under 1° stimulating visual angle （P>0.05）. Results of return test showed that there was no statistical significance in the difference between visual acuity estimated by equation and actual detected visual acuity. Conclusion In forensic appraisal of monocular injury, fitting linear regression equation of binocular visual acuity ratio and the binocular ratio of P100 waveform amplitudes under 15' stimulating visual angle, is helpful for visual acuity level estimation of the injured eye to some extent.

Research Progress of the Effects of Monocular Visual Impairment on Binocular Vision / 法医学杂志

Binocular vision refers to a progress of analysing and integrating the binocular visual signals into a whole and three-dimensional sensory perception by higher nerve centre. In this process, the interac-tion between the two eyes results in the changes of output signal, which is called binocular interaction. Through a series of subjective and objective experiments, it can be concluded that binocular interaction can be divided into three types: facilitation, summation and suppression, and the forms of binocular in-teraction in different visual states are different. In general, the visual signal is processed by binocular in-teraction, so that there are some differences between binocular vision and monocular vision. The extent of the difference can be affected by the damage of monocular vision and then affects the binocular vision. Thus, it is necessary for forensic scientists to further study the effects of the monocular visual impairment on visual function. Based on relevant data, this paper reviews the mechanism of the monocular visual impairment in binocular vision, the research methods and the application prospect in forensic science.

Progress on the Muscle Function Evaluation and Its Forensic Application / 法医学杂志

Accurate evaluation of muscle function helps to understand the recovery of muscle, bone, nervous system diseases or injuries, especially for muscle dysfunction caused by peripheral nerve injury.Therefore, the methods of muscle function evaluation have been the focus of researchers, with new methods having been constantly proposed.Muscle strength testing is an important part of muscle function evaluation.Besides hand muscle strength assessment, currently used muscle function assessments include simple instrumental test, isokinetic muscle test, electrophysiological test, etc.In addition, the application of needle electromyography, motor unit number estimation, motion unit index in muscle function evaluation has also been reported for several times.This paper reviews the research progress and practical application of these methods.

Assessment of the Original Height of L1~2 after Vertebral Compression Fracture / 法医学杂志

OBJECTIVES@#To explore the assessment method of original height of L1-2 after vertebral compression fracture and its application value in forensic clinical practice.@*METHODS@#A total of 154 normal thoracic and lumbar X-ray films were collected, and 140 cases were used as experimental group while 14 cases as validation group. The heights of anterior （Ha） and posterior （Hp） vertebral body of T₁₂-L₃ vertebrae in each X-ray image were measured. In the experimental group, the correlation analysis between HaL₁ and HaT₁₂, HpT₁₂, HpL₁, HaL₂ and HpL₂ was carried out, and regression equation was established via fitting. The correlation analysis between HaL₂ and HaL₁, HpL₁, HpL₂, HaL₃, HpL₃ was performed, and the regression equation was also established via fitting. The difference between the predicted and measured values of HaL₁ and HaL₂ in validation group was compared.@*RESULTS@#In the 140 normal subjects, HaL₁ （y₁） was well correlated with HaT₁₂ （x₁） and HaL₂（x₂）, and the multiple linear regression equation was y₁=2.545+0.423 x₁+0.486 x₂ （determining coefficient R²=0.712, P<0.05; F=169.206, P<0.05）. There was no significant difference between the predicted and actual measured values of HaL₁ in the validation group （ P>0.05）. HaL₂ （y₂） was well correlated with HaL₁ （x₃） and HaL₃ （x₄）, and the multiple linear regression equation was y₂=4.354+0.530 x₃+0.349 x₄ （determining coefficient R²=0.689, P<0.05; F=151.575, P<0.05）. There was no significant difference between the predicted and actual measured values of HaL₂ in the validation group （ P>0.05）.@*CONCLUSIONS@#It is more appropriate to evaluate the original height of L₁ or L₂ single vertebrae by comparing with the height of the anterior edge of the upper and lower adjacent vertebral bodies.

Range of Hip Joint Motion and Weight of Lower Limb Function under 3D Dy-namic Marker / 法医学杂志

Objective To explore the range of reasonable weight coefficient of hip joint in lower limb function. Methods When the hip joints of healthy volunteers under normal conditions or fixed at three different positions including functional, flexed and extension positions, the movements of lower limbs were recorded by LUKOtronic motion capture and analysis system. The degree of lower limb function loss was calculated using Fugl-Meyer lower limb function assessment form when the hip joints were fixed at the aforementioned positions. One-way analysis of variance and Tamhane's T2 method were used to proceed statistics analysis and calculate the range of reasonable weight coefficient of hip joint. Results There were significant differences between the degree of lower limb function loss when the hip joints fixed at flexed and extension positions and at functional position. While the differences between the degree of lower limb function loss when the hip joints fixed at flexed position and extension posi-tion had no statistical significance. In 95％ confidence interval, the reasonable weight coefficient of hip joint in lower limb function was between 61.05％ and 73.34％. Conclusion Expect confirming the rea-sonable weight coefficient, the effects of functional and non-functional positions on the degree of lower limb function loss should also be considered for the assessment of hip joint function loss.

Contrast Visual Evoked Potentials under Pattern Stimulus in Ocular Trauma / 法医学杂志

OBJECTIVES@#To study the characteristic of contrast visual evoked potentials （CVEP） in patients with ocular trauma.@*METHODS@#Sixty patients defined as ocular trauma by forensic clinical examination in our center were selected, and split into 0.2-0.3 （Group A）, 0.3-0.5 （Group B） and ≥0.5 （Group C） according to the best corrected visual acuity. The variation characteristics of wave amplitude and latency of CVEP under 100%, 25% and 10% contrast were observed and analyzed statistically.@*RESULTS@#（1） Under the same contrast, the wave amplitude of P₁₀₀ decreased with the decrease of stimulus perspective. （2） Under the same stimulus perspective, the wave amplitude of P₁₀₀ decreased with the decrease of contrast （P<0.05）. （3） Under the contrast of 100% and 25% with the same stimulus perspective （except 100% 7' perspective stimulus）, the difference between group A and group B had no statistical significance （P>0.05）. Between group A and group C, group B and group C, the wave amplitude of P₁₀₀ gradually increased with the increase of vision （P<0.05）. Under the contrast of 10% with 15' stimulus perspective, the wave amplitude of P₁₀₀ increased with the increase of vision （P<0.05）. （4） Under the same contrast with the same stimulation perspective, the latency of P₁₀₀ wave shortened with the increase of vision, while the difference had no statistical significance （P>0.05）. Under the same stimulus perspective, the latency of P₁₀₀ wave was prolonged with the decrease of contrast （P>0.05）.@*CONCLUSIONS@#CVEP may become one of the possible methods for the evaluation of contrast visual acuity.

Distribution of Formic Acid after Methanol Intoxication in Rats / 法医学杂志

OBJECTIVE@#To investigate concentration and distribution in blood and tissues of formic acid after methanol intoxication in rats.@*METHODS@#The Sprague-Dawley rats were divided into groups for control group and 3-day and 7-day intoxication treatment groups. The experimental groups were administered methanol by gavage with the initial dose of 8 mL/kg and followed with 4 mL/kg supplemental dose 24 h later. After 3 days and 7 days later, rats were killed by decapitation. Then samples of cardiac blood, liver, kidney, brain, heart and stomach of each group were collected. Formic acid concentrations were detected by high performance liquid chromatography.@*RESULTS@#Formic acid concentrations in tissues were higher than in blood. Compared with 3-day intoxication group, there was an increase formic acid of concentration in brain and stomach in 7-day intoxication group, while a decrease in liver and kidney (P < 0.05).@*CONCLUSION@#High performance liquid chromatography could be used to accurately detect formic acid. As the metabolite of methanol, formic acid accumulates in rat blood and tissues after intoxication and the concentrations in organs and tissues are obviously higher than in blood.

Forensic Application of Microperimetry and Visual Evoked Potential in Macular Disease / 法医学杂志

OBJECTIV@#e To find the correlation between real best corrected visual acuity (BCVA) and testing results of microperimetry and visual evoked potential (VEP) and to explore a new method in recording BCVA in macular disease.@*METHODS@#Sixty-two patients with macular disease (macular disease group, 62 eyes) and eighteen healthy volunteers (control group, 36 eyes) had BCVA, microperimetry and VEP recorded.@*RESULTS@#(1) By microperimetry, the values of retinal mean sensitivity and fixation percentage in macular disease group were lower than that in control group. The bicurve ellipse area in macular disease group was higher than that in control group. By VEP, P100 amplitude under 0.5 cpd and 2 cpd in macular disease group were significantly higher than that in control group and the latency was prolonged (P < 0.05). (2) In macular disease group, BCVA had significant positive correlation with retinal mean sensitivity, bicurve ellipse area, macular central 2 degrees and 4 degrees fixation percentage, respectively (P < 0.05). There was a significant correlation between retinal mean sensitivity and P100 amplitude (P < 0.05). (3) Multiple linear regression equation was y = 0.053 x1+0.008 x3+3.897 (y was BCVA, while x1 was retinal mean sensitivity and x3 was P100 amplitude under 2 cpd).@*CONCLUSION@#Combined use of microperimetry and VEP is useful in the assessment of BCVA in macular disease.

Correlation between contrast vision and sweep visual evoked potential acuity / 法医学杂志

OBJECTIVE@#To compare the correlation between contrast vision (LV) and sweep visual evoked potential acuity (SVEP-A) among people with emmetropia, mild myopia, and moderate myopia.@*METHODS@#The CV and SVEP-A were tested individually in 96 eyes from healthy young volunteers, including 37 eyes of emmetropia, 27 eyes of mild myopia, and 32 eyes of moderate myopia. The statistic analysis was done by ANOVA analysis and rank sum test.@*RESULTS@#(1) With the decrease of contrast, CV and SVEP-A decreased in every group. (2) At 100% contrast, the difference of CV between emmetropia and mild myopia had statistical significance (P<0.05). At 100%, 25% and 10% contrast, the difference of CV between emmetropia and moderate myopia had statistical significance (P<0.05). (3) In the same group, the difference of 100% and 25% contrast had statistical significance (P < 0.05). So was between 100% and 10% contrast. (4) At 100% and 10% contrast, the difference of CV and SVEP-A had statistical significance (P < 0.05).@*CONCLUSION@#The CV of myopia relates to many factors including ametropia and fundus lesions. The correction of ametropia is important to the values of CV and SVEP-A.

Expression and mechanism of alphaB-crystallin in retina and extraocular tissues and organs / 法医学杂志

alphaB-crystallin is the structural protein of vertebrate lens, which is widely expressed in non-lens tissue. As one of the heat shock protein family members, alphaB-crystallin possesses biological properties of molecular chaperones and anti-apoptotic effects. Multi-factor injuries, such as retinopathy, inflammation and nervous system diseases, have a closely relationship with alphaB-crystallin. This paper reviews the research progress of the expression and mechanism of alphaB-crystallin in retina and extraocular tissues and organs.

Comparison of anterior chamber angle examination by UBM, SL-OCT and gonioscopy / 法医学杂志

OBJECTIVE@#To compare the agreement of anterior chamber angle examination by ultrasound biomicroscope (UBM), slit lamp optical coherence tomography (SL-OCT), and gonioscopy in angle recession and angle closure.@*METHODS@#The anterior chamber angle was measured with UBM, SL-OCT and gonioscopy in turns for temporal, nasal, superior and inferior quadrant in the same dark room. The results were compared with the agreement of the three methods in angle recession and angle closure by χ2 test and Kappa test.@*RESULTS@#There were no statistically significant differences of the three methods in testing angle closure and angle recession (P>0.05). The consistency of UBM and gonioscopy was better (Kappa value of 0.882) than that of SL-OCT and gonioscopy (Kappa value of 0.624).@*CONCLUSION@#When testing angle recession, UBM is better than SL-OCT with gonioscopy as the standard. When testing angle closure, UBM, SL-OCT and gonioscopy have good agreement.

Changes of oscillatory potentials of electroretinogram after methanol intoxication in rats / 法医学杂志

OBJECTIVE@#To study the characters of oscillatory potentials (OPs) of electroretinogram (ERG) after methanol intoxication in rats.@*METHOD@#The SD rat models of methanol intoxication were established and divided into control group, 3-day intoxication group, 7-day intoxication group. The changes of OPs of ERG were recorded in a dark room.@*RESULTS@#The total amplitudes of 3-day and 7-day intoxication groups decreased approximately 50% compared with that of the control group, while the schedule delayed approximately 16% and 61%, respectively.@*CONCLUSION@#The characters of methanol intoxication in rats included delay in schedule and decline in the total amplitude of OPs.

Application of MSCT's coronary artery calcification score in evaluation of sudden death caused by coronary artery disease / 法医学杂志

OBJECTIVE@#To access application value of multi-slice spiral computed tomography (MSCT) and coronary artery calcium scoring (CACS) in investigation the coronary artery disease (CAD), and to explore the effective way of virtual autopsy to evaluate the sudden death due to CAD.@*METHODS@#Nine cases of sudden cardiac death were collected to analyze MSCT before the autopsy. The quantitative analysis of the degree of coronary artery calcium was made by Agatston's method. The CACS of all the subjects were calculated based on the diagnostic criteria for CAD, in which calcium scoring was more than 400. The results of CACS were compared with that of the autopsy.@*RESULTS@#Only 2 cases got the high calcium scoring which were more than 400 in the 9 cases died of CAD confirmed by the autopsy. The prediction rate of CACS for CAD was only 22.2%. Pulmonary edema of different severity was found in both autopsy and MSCT. There was a higher morbidity rate in the left anterior descending of coronary artery than the other branches.@*CONCLUSION@#Obvious calcification of coronary artery can be detected by MSCT and calculating CACS. To detect subtle calcification needs other technologies such as postmortem angiography.