Resolving Reflection and Resolution in 3D Imaging of Fresh Bone

Structured light scanning is a noninvasive, accurate, and cost-effective 3D imaging technique, but due to reflection issues is yet to be utilized for tool mark analysis on fresh bone. During imaging, reflection from shiny surfaces, such as greasy bone, disrupts image formation. This study tested the David SLS-1 scanner's ability to image saw marks and explored six strategies to reduce reflection by [1] dulling the surface or [2] altering the projected light. The surface was dulled by freezing, talcum powder, dulling spray, or compressed air. The projected light was altered with a diffuser or limited to single pattern-coded. Results demonstrated that the resolution was insufficient for capturing minute details of striae. All six tests failed to reduce reflection sufficiently to produce complete images, but projecting vertical pattern-coded light showed the most promise. Future research is required concentrating on enhancing resolution and exploring the role of pattern-coded light in reducing reflection.     

Differentiation of Antemortem and Postmortem Appendicular Fractures Using Magnetic Resonance Imaging Signal Intensity Changes in Bone and Soft Tissues,

Intraosseous T1-weighted (T1W) and short-tau inversion recovery (STIR) magnetic resonance imaging (MRI) signal intensity changes—so-called bone marrow edema—may be able to differentiate antemortem and postmortem fractures in human forensic imaging. The primary objective of this study was to investigate this hypothesis using an animal model. Three juvenile Landrace pigs were anesthetized and underwent MRI of both tibiae and both radii using a 1.5 T magnet. T1W, T2-weighted (T2W), STIR, and T2* sequences were included. Antemortem fractures were induced in both tibiae and postmortem fractures in both radii, and MRI was repeated. Two board-certified radiologists blinded to fracture group jointly evaluated the images for intraosseous and soft tissue signal intensity changes. Sensitivity (Se) and specificity (Sp) in identifying antemortem fractures were calculated based on intraosseous, soft tissue, and combined intraosseous and soft tissue signal intensity changes. Intraosseous and soft tissue signal intensity changes, when present, were hyperintense in all sequences. Intraosseous hyperintensity in T1W and T2W sequences yielded Sp of 100% for antemortem fractures. Regardless of sequence, soft tissue hyperintensity was comparatively more sensitive than intraosseous hyperintensity. Sensitivity for each sequence could be maximized by assessment of soft tissue and intraosseous hyperintense signals together; for the T1W sequence, such assessment optimized diagnostic utility yielding a Se of 100% and Sp of 83%. In summary, MRI—particularly the T1W sequence—can differentiate antemortem and postmortem fractures and may be a useful adjunct to the forensic analyses of fractures.     

Perimortem or Postmortem Bone Fractures? An Experimental Study of Fracture Patterns in Deer Femora*

The determination of perimortem trauma is important for forensic anthropologists. Characteristics of bone fractures such as sharp edges, presence of fracture lines, the shape of the broken ends, fracture surface morphology, fracture angle on the Z-axis, and butterfly fractures are said to differentiate perimortem from postmortem trauma. A Drop Weight Impact Test Machine was used to break 76 deer femora of various ages since death. The results of this study suggest that the characteristics listed above are unreliable at differentiating a perimortem fracture from a postmortem fracture in a forensic case. There are, however, statistically significant differences between fresh bones broken less than 4 days old and dry bones broken 44 days or 1 year old after death.     

Ossification of laryngeal structures as indicators of age

As the role of forensic anthropologists expands to the medical examiner setting, their expertise is being applied beyond the traditional dry skeletal material. In such scenarios radiographic techniques can be applied when maceration is not appropriate. This study explores the use of radiographic analysis of laryngeal structures for age-at-death determination. Isolated human laryngeal structures (n = 104) from individuals between the ages of 15 and 89 were removed at autopsy and radiographically examined. The cricoid and individual regions of the thyroid cartilage were scored according to degree of ossification, and the relationship between age and degree of ossification statistically examined. A previously published study on age-determination from thyroid ossification by Cerny was assessed for accuracy. The results of the study indicate that although a consistent sequence in the ossification of laryngeal structures exists, variations in timing does not permit narrow age range estimates. Consequently the method presented by Cerny is inaccurate and should not be used in the forensic setting.     

14岁青少年骨发育的变化趋势

目的描述当前我国14岁青少年手腕骨发育特征,并初步评估14岁的青少年骨发育的变化趋势。方法以湖南娄底地区14岁青少年为对象(男53人,女56人),拍摄左手腕部X线片,参照顾氏图谱法描述各选定观察部位并分析发育特征,将统计结果与顾氏图谱法14岁骨龄标准进行比较分析。结果与顾氏法相比,男生组桡骨远端、第1掌骨近端和近节第4指骨骨骺发育程度较高,而女生组桡骨远端、第2～5掌骨、第1～5近节指骨和第2～5中节指骨骨骺发育程度较高。结论当前我国14岁青少年骨发育存在提前趋势,在女生组尤为显著。14岁是刑事责任年龄点之一,法医推断该年龄时应注意该特征对推断结果的影响。     

A Concentrated Hydrochloric Acid-based Method for Complete Recovery of DNA from Bone

The successful extraction of DNA from historical or ancient animal bone is important for the analysis of discriminating genetic markers. Methods used currently rely on the digestion of bone with EDTA and proteinase K, followed by purification with phenol/chloroform and silica bed binding. We have developed a simple concentrated hydrochloric acid-based method that precludes the use of phenol/chloroform purification and can lead to a several-fold increase in DNA yield when compared to other commonly used methods. Concentrated hydrochloric acid was shown to dissolve most of the undigested bone and allowed the efficient recovery of DNA fragments <100 bases in length. This method should prove useful for the recovery of DNAs from highly degraded animal bone, such as that found in historical or ancient samples.     

硝基苯致小鼠骨髓细胞的突变作用

为探讨硝基苯对哺乳动物的致突变性,将12周龄雄性昆明小鼠随机分为染毒组(26、52、104mg/kg)、空白对照组(生理盐水)、溶剂对照组(花生油)和阳性对照组(环磷酰胺),连续灌胃染毒7 d,检测骨髓细胞微核率、骨髓细胞染色体畸变率以及外周血网织红细胞数。结果显示,随着染毒剂量的增加,骨髓细胞微核率、染色体畸变率均有增加,外周血网织红细胞数减少,各组与对照组差异均极显著(P<0.01),并呈剂量-效应关系。表明,硝基苯可导致小鼠骨髓细胞发生突变。     

Neck markings and fractures in suicidal hangings

Over a 10-year period in which both a retrospective and prospective study of suicidal hangings was made, fractures of the thyroid cartilage alone, or the hyoid bone alone, or of both together were noted in 20% of the cases. In the prospective study, an incidence of 46% was found. This contrasts sharply with the incidence of 15% in the retrospective study. This wide discrepancy indicates the need for longer periods of a controlled prospective study by properly trained prosectors. Fractures were found in all age groups above 19 years of age and occurred whether suspension was complete or incomplete, whether the ligature was soft or hard, narrow or wide, and whether decedents did or did not jump from a platform. The higher incidence of fractures occurring among women is unexplained. The presence of reddish or pink bands or linear streaks (with or without superimposed abrasions) along one side of the neck, separated by bands of pale skin, canting upwards towards the back of the neck and revealing the imprint of a folded cloth permits the diagnosis of ante-mortem hanging in the absence of very strong proof to the contrary. As in any type of Medical Examiner's case, a knowledge of the circumstances and investigation of the scene are required before a final determination of the cause and manner of death can be considered.     

Introducing Computed Tomography Standards for Age Estimation of Modern Australian Subadults Using Postnatal Ossification Timings of Select Cranial and Cervical Sites,

Contemporary, population‐specific ossification timings of the cranium are lacking in current literature due to challenges in obtaining large repositories of documented subadult material, forcing Australian practitioners to rely on North American, arguably antiquated reference standards for age estimation. This study assessed the temporal pattern of ossification of the cranium and provides recalibrated probabilistic information for age estimation of modern Australian children. Fusion status of the occipital and frontal bones, atlas, and axis was scored using a modified two‐ to four‐tier system from cranial/cervical DICOM datasets of 585 children aged birth to 10 years. Transition analysis was applied to elucidate maximum‐likelihood estimates between consecutive fusion stages, in conjunction with Bayesian statistics to calculate credible intervals for age estimation. Results demonstrate significant sex differences in skeletal maturation (p < 0.05) and earlier timings in comparison with major literary sources, underscoring the requisite of updated standards for age estimation of modern individuals.     

Practical Considerations in Trace Element Analysis of Bone by Portable X‐ray Fluorescence

Forensic anthropologists are more often turning to nondestructive methods to assist with skeletal analyses, specifically for trace elemental analyses. Portable XRF (pXRF) instruments are versatile and are able to be used in diverse settings or for specimens of a shape and size that cannot be accommodated by laboratory‐based instruments. Use of XRF requires knowledge of analysis parameters such as X‐ray penetration and exit depth. Analysis depth was determined by examining pure elements through known thicknesses of equine bone slices. Correlation between the element's X‐ray emission energy and the depth of reading was observed. Bone surfaces from a small unknown historic cemetery were analyzed before and after sanding of the periosteal surface to observe possible changes in XRF readings based on potential diagenesis. Results validate the pXRF device as a powerful and convenient instrument for nondestructive analysis, while highlighting limitations and considerations for the analysis of osseous materials.