Validation study of skull three-dimensional computerized tomography measurements

Recent advances in imaging have led to high-resolution computerized tomography (CT) scanning with exquisitely detailed slice images of the skull and three-dimensional (3-D) surface reconstructions using computer software. It is possible to use CT scans to acquire morphologic information about the skull in a convenient digital form and to derive 3-D measurements from surface reconstruction images. Unfortunately, no effort has been made to date to test the validity of these measurements on laboratory specimens, and no compelling evidence is available from phantom studies to indicate the nature and magnitude of the errors inherent in the measurement technique. We have performed a pilot study to quantify the morphology of the skull based on surface features that can be found in CT scans and 3-D reconstructions. Comparative measurements were obtained from five skulls (two normal and three with dysmorphology) with calipers and a 3-D electromagnetic digitizer. These measurements were statistically compared with those based on original CT scan slices and reformatted 3-D images. It is concluded that 3D-CT measurement techniques are superior to those in which measurements are obtained directly from the original CT slices; 3-D CT methods, however, must be significantly improved before measurements based on these techniques can be used in studies that require a high degree of precision. The results are used to indicate the most fruitful areas of future study.     

现代人头骨面部某些特征的投影栅相位法测量研究

用投影栅相位法 ,定量测量现代人面颅骨的一些项目 ,分析比较了中国南方、北方面骨的特点及中国与欧洲现代人面骨的差异 ,并探讨该方法在人类学研究领域应用的可行性和实用性。发现 :1 不论云南、欧洲头骨 ,性别差异主要集中在线距项目上 ,男性测量值大于女性。 2 华北头骨的中面宽、上面高及其指数、颧上颌高和内侧两眶宽指数大于云南头骨 ,中面部的扁平度小于云南头骨 ,颧骨额蝶突的前外侧面比云南头骨的要朝向前方。 3 中国云南、华北现代人头骨上面部的宽度小于欧洲现代人头骨 ,上面部扁平程度大于欧洲现代人头骨; 颧骨额蝶突的前外侧面比欧洲头骨更朝向前方。华北头骨上面部高度及其指数大于欧洲头骨; 云南头骨上面高及男性的上面高指数与欧洲头骨无差异 ,云南女性上面高指数大于欧洲头骨。我们认为投影栅相位法可作为传统测量方法的有益补充。     

Craniometry of cranial vault bones in newborn infants

10 craniometric measurements of the skull bones' fornix have been performed on 89 dried infant skulls. The authors have shown that the craniometric variability of the skull bone's fornix is connected with the skull length rather than with its height. The skull length is determined mostly by the squama of the temporal bone and occipital squama. The shape of the skull vault is determined mainly by parietal bone and squama of the frontal bone. Parietal bones shut unpaired fontanelle, but the remaining bones, under investigation, contribute to the closure of anterolateral and postero-lateral fontanelle.     

An evaluation of the systematic value of skull morphology in the Trimeresurus radiation (Serpentes: Viperidae: Crotalinae) of Asian pitvipers

Trimeresurus (in its widest sense) is a very diverse and widespread radiation of Asian pitvipers, which has been subject to numerous taxonomic revisions, some of which have been based on characteristics of the skull. In order to evaluate the taxonomic utility of such characters, we conducted a comparison of the skulls of 57 specimens representing nine genera, and two currently unassigned species that are very closely related to each other. A canonical variate analysis reveals three distinct phenetic groups: the Protobothrops group, a group containing Ovophis monticola , ' Ovophis ' okinavensis , and ' Trimeresurus ' gracilis , and finally a group comprising the remaining species and characterized by considerable overlap between most genera with the exception of the monotypic Peltopelor and Himalayophis . Agreement between phenetic similarity based on skull characteristics and phylogenetic relationships based on molecular evidence varies between different groups: the morphological similarity of the skull of Protobothrops sieversorum to the other Protobothrops species is congruent with their recent synonymization while the phenetic similarity among the species within the second group does not reflect current molecular phylogenetic relationships and indicates that convergent or parallel evolution may be responsible for at least some of the phenetic similarity detected among skulls of the Asian pit vipers examined. A test of phylogenetic independence, however, indicates that there is still a significant phylogenetic signal that can be recovered from several skull characteristics. Thus, we conclude that skull morphology can contribute to an overall understanding of pitviper taxonomy, but that it would be unwise to rely on skull characteristics alone.     

Extensive and complex defects of the scalp, middle third of the face, and palate: the role of microsurgical reconstruction

Twenty-one patients with gigantic defects of the scalp and middle third of the face and palate following excision of neglected or recurrent tumors, burns, and infections have undergone microsurgical reconstruction. Wide resection of the middle third of the face, orbit, and palate requires "complex" three-dimensional volume reconstruction, whereas extensive defects of the scalp and skull (exceeding 80 cm2) require coverage of the larger surface area soft-tissue defect and the exposed brain and dura. The latissimus dorsi free-muscle flap and split-thickness skin graft have become our methods of choice for extensive scalp and skull defects. The latissimus dorsi musculocutaneous free flap is preferable for reconstruction of complex palatal and external skin and orbital defects of the middle third of the face. Microsurgical free-tissue transfer reliably frees the oncologic surgeon from the constraints imposed by conventional reconstructive techniques and may therefore allow improved curative or at least palliative resection of these extensive tumors.     

Computerized restoration of nonhomogeneous deformation of a fossil cranium based on bilateral symmetry

We developed a computerized method of correcting plastic deformation of a fossil skull, based on bilateral symmetry with respect to the midsagittal plane, and applied this method to reconstruction of a fossilized Proconsul heseloni cranium (KNM-RU-7290A). A three-dimensional (3D) model of the fossil was generated using consecutive cross-sectional images retrieved from computed tomography. 3D coordinates of anatomical landmarks that should be located on the midsagittal plane and pairs of landmarks that should be symmetrical with respect to this plane were acquired. These landmarks were then repositioned so that geometrical constraints were satisfied, while translated distances of landmarks were minimized. We adopted a thin-plate spline function to mathematically describe the 3D nonlinear volumetric transformation between acquired and repositioned landmarks. Using this function, the entire fossil shape was transformed, and the effect of reversing the deformation could be visualized. The results indicated that the proposed method was effective in eliminating nonhomogeneous deformation of the fossil skull. The antemortem appearance of the skull cannot be completely restored by this method alone, due to methodological limitations. However, the presented method has a role as an adjunct in complementing conventional restoration techniques on account of its objective nature.     

Morphometrical considerations on occipital condyles

From the study of the surface area of the occipital condyles and of skull volume resulted that the surface area is not proportional to skull volume. The measurements were conducted on a collection of 424 male and 317 female skulls. It was observed that the two condyles are rarely symmetrical and that also flat condyles appear. Bi-partitioned condyles can be divided into three types: roof-like bipartitions, simple bipartitions and total bipartitions.     

Changes in the skull morphology of the Arctic wolf, Canis lupus arctos, during the twentieth century

Measurements of a large series of skulls of the Arctic wolf, Canis lupus arctos . have shown that since 1930 there has been an overall reduction in the size of the skulls, together with widening of the cranium, shortening of the facial region, and reduction in size of the teeth. This suggests that hybridization and subsequent introgression occurred with huskies ( Canis familiaris ) during the 1930s, which is consistent with historical accounts. Since 1950 there has been a reversion in skull morphology to a more 'wolf-like' form, suggesting that hybridization is no longer occurring.
The skull of a wolf/dog hybrid is intermediate in size between the skulls of wolves and huskies but its shape is allometrically dissimilar. Skulls of wolves from the period 1930–50 are moi-e similar to the skull of this hybrid than in the other time periods.
The skull of a male canid from a carcass collected on Ellesmere Island and presented to the Natural History Museum. London, in 1986 was at first thought to be from a wolf/dog hybrid but analyses of the measurements show that it is more likely to be from an Arctic wolf with severe abnormalities to the jaws.     

中国古人类颅内模及脑演化研究进展

颅内模保存有脑表面的形态结构,是脑演化研究的直接证据。中国最早复原和研究的颅内模来自20世纪20年代北京周口店遗址发现的3号猿人头骨;此后虽然中国境内也相继发现了一些古人类的头骨化石,但由于古人类标本非常珍贵,不允许对其进行实体解剖,加上多数头骨破碎或者内部附有地层胶结物,导致颅内模无法成功复原。受技术水平及研究手段的限制,研究者一般只是侧重于化石外表形态结构的研究。高分辨率工业CT和3D软件的应用,可以在不损坏标本的情况下,虚拟复原出化石的内部解剖结构,使得一些重要的古人类化石标本的颅内模被复原出来,促进了脑演化的研究。近年来,本文第一作者采用新技术、新方法复原了南京直立人、柳江人等一些重要的中国古人类头骨的颅内模,通过对其颅容量、脑沟回特征、脑不对称性、脑表面的动、静脉血管压迹、各脑叶的大小、形状及比例的研究,获取了中国古人类脑形态特征变化的数据,为探讨东亚地区古人类的演化提供了参考信息。     

Size factor as one of the problems in the sex estimation of skulls: upper palaeolithic sample from Predmostí (Czech Republic) as an example

In this study we estimate sex and population affinity of Gravettian Predmostí (P) skulls using linear and geometric discriminant analysis (DA), and compare them with results of 2D geometric morphometrics (GM). We used the measurements of P3 and P9 males, P4 and P10 females, as originally estimated by Matiegka (1934), as well as two databases--the recent skull database of Howells and the fossil data of Henke. DA classifies the P skulls as robust and belonging to the "male" region, loosing the sensitivity of inter-population differences influenced by size factor. That is why this approach could not be applied. The geographic inter-population differences according to DA do not define P skull shapes as extreme. The influence of geographic variability could be stronger than the inter-sexual differences. Despite the chronological differences between databases and Gravettian skulls, these differences are a component of regional inter-population variability. According to our results, GM is more successful methodological approach than DA. Our previous sex estimation of P skulls with help of GM is completely in accordance with the classical morphoscopic estimation. However, an appropriate reference database is necessary in both the GM and DA approaches. For the sexing of skull with unknown population affinity, and with absence of appropriate reference database, we suggest to use the application of more subjective visual scoring methods.     

A multivariate study of the Petralona skull

The Petralona skull from Greece has been generally accepted as an Upper Pleistocene variant of Neanderthal Man. It was included in a series of multivariate analyses performed by the author on cranial measurements of Pleistocene hominids. The results of the Mahalanobis D² analyses suggest that Petralona is cranially similar to the Neanderthals, but facially is distinct. Overall it resembles the Broken Hill and Djebel Ighoud skulls most closely but there are features of resemblance to Homo erectus material. The results of these analyses support recent suggestions that the Petralona material is of greater antiquity than the Upper Pleistocence.     

中国古人类进化连续性新辩

本文通过对一些形态特征的分析说明研究人类起源和进化应该注意的一些思维方法的问题,并且为多地区进化说增添了新的证据:1)中国更新世头骨共同具有的眼眶及其外侧下缘形状等特征在近代头骨中已有所改变,在考虑其意义时不应该忽略时间和基因交流起过的作用;2)中国更新世头骨的共同特征并不因为它们也可见于其他地区而丧失其意义,因为证明连续性的共同特征不需要是地区独有的;3)铲形门齿的结构在近代人中变弱,不削弱它作为连续进化证据的价值,这种弱化的现象是人类进化过程中形态纤巧化的一种表现;4)在辩论时不要对有关形态作不正确的观察和曲解对方的观点和论据;5)头骨正中矢状突隆、下颌圆枕、夹紧状鼻梁和第三臼齿先天性缺失等四项特征在近代非洲人中阙如,却存在于东亚近代人,本文的分析认为这种现象增强多地区进化说的说服力。     

The versatility of pericranial flaps

The pericranium is the source of multiple, dependable, well-vascularized flaps which are of use to the plastic and reconstructive surgeon for multiple defects of the face and skull. Based anteriorly, the flap can cover the entire central third of the face or be transposed intracranially to correct abnormalities of the cribriform plate and dura. Based laterally on the temporalis muscle, the flap can be turned to multiple arcs for reconstruction of the face, ear, and intracranial defects. Donor-site morbidity and complications have been minimal.     

Skull allometry in the marine toad,Bufo marinus

Scaling predictions pioneered by A.V. Hill state that isometric changes in kinematics result from isometric changes in size. These predictions have been difficult to support because few animals display truly isometric growth. An exception to this rule is said to be the toads in the genus Bufo, which can grow over three orders of magnitude. To determine whether skull shape increases isometrically, I used linear measurements and geometric morphometrics to quantify shape variation in a size series of 69 skulls from the marine toad, B. marinus. Toads ranged in body mass from 1.8 gm to a calculated 1,558.9 gm. Of all linear measurements (S/V length, skull width, skull length, levator mass, depressor mass, adductor foramen area), only the area of the adductor foramen increased faster than body mass; the remaining variables increased more slowly. In addition, modeling the lower jaw as a lever‐arm system showed that the lengths of the closing in‐ and out‐levers scaled isometrically with body mass despite the fact that the skull itself is changing allometrically. Geometric morphometrics discerned areas of greatest variability with increasing body mass at the rear of the skull in the area of the squamosal bone and the adductor foramen. This increase in area of the adductor foramen may allow more muscle to move the relatively greater mass of the lower jaw in larger toads, although adductor mass scales with body mass. If B. marinus feeds in a similar manner to other Bufo, these results imply that morphological allometry may still result in kinematic isometry. J. Morphol. 241:115–126, 1999. © 1999 Wiley‐Liss, Inc.     

山顶洞101号男性头骨的三维颅面复原

山顶洞101号头骨化石是东亚地区保存最为完整的化石之一,是探讨东亚地区现代人起源的重要研究材料。本文依据数据集中现生人的面部软组织平均分布,提出了计算机三维颅面复原方法,实现了101号头骨生前面貌的预测复原。主要包括三个步骤：首先使用CT完成了101号男性头骨和下颌骨仿制模型的三维重建。然后,利用计算机技术将现生人的面部软组织分布作为101号头骨的面部软组织分布,实现了颅面虚拟复原,并采用手工绘画技巧再现了复原面貌的形态特征。最后,提出了一种基于面部软组织分布和面貌统计形状模型的形态分析方法,实现了颅面复原结果的评估。山顶洞101号头骨的复原面貌具有头部较长、额头前倾、眉弓粗壮等特征,与101号头骨的几何形态基本一致。该技术再现了更新世晚期人类的脑颅及面部的形态特征,为古人类颅面复原的研究提供了技术支持和参考资料。     

The skull of Combe Capelle

Since the end of World War II two of the most important anthropological artefacts of the Museum für Vor- und Frühgeschichte in Berlin, the skulls and skeletons of Le Moustier and Combe Capelle, were believed to be missing or destroyed, respectively. The postcrania were severely damaged during a fire after the museum was bombed in February 1945, while the skulls were brought to the Soviet Union in 1945. In 1965, the skull of the Neanderthal man from Le Moustier and the chain of the grave of Combe Capelle were found amongst the art objects returned by the Soviet Union into the German Democratic Republic in 1958. However, the Combe Capelle skull was still missing. In the end of 2001 this skull could be found and identified in a store-house of the museum. Now, one the oldest known representatives of Homo sapiens sapiens is again available for scientific research and public exhibitions.     

中国古人类颅容量的推算方法比较

古人类的体质特征和现代人不同,依据现代人头骨测量数据计算出来的公式往往不适于古人类颅容量的推算。获取古人类颅容量最准确的方法是复原出其内部的颅内模;然而,由于颅内模的复原工艺复杂,加上古人类头骨化石数量稀少且多数残破,如何准确地推算其颅容量,成为古人学者研究的难点问题之一。本文通过对中国境内发现的不同演化阶段的古人类颅容量推算方法的对比和验证,试图找出推算古人类颅容量的最适合的公式法。研究结果显示：1）早期现代人解剖特征同现代人基本接近,依据现代人头骨推算出来的回归方程可以用来推算其颅容量;2）直立人头骨厚重、脑颅低矮,体质特征不同于现代人,其颅容量的推算不能使用现代人公式法。依据本文中国直立人头骨测量数据推导出来的回程方程（C=-1301.944+60606L+0.718b+9.936h）适合其颅容量的推算。采用此直立人公式法,推算出蓝田直立人的颅容量为918 mL;3）古老型智人的体质特征位于直立人和现代人之间,对其颅容量的推算不能一概而论：体质特征接近直立人的,如大荔人、华龙洞6号,可采用直立人公式法;体质特征接近早期现代人的,如许昌1号,可采用现代人公式法;体质特征位于直立人和早期现代人中间位置的,如马坝人、金牛山人,其颅容量约等于采用现代人公式法和采用直立人公式法获得的颅容量的平均值。     

中国和欧洲早期智人的比较研究

中国与欧洲的早期智人头骨在颧骨额蝶突前外侧面的朝向、颧颌角、上颌骨颧突、鼻区、上面部高度、额鼻额颌缝形状、眉间区、矢状脊、印加骨和铲形门齿诸特征的形态或出现率等方面有明显差异。那时此两大地区存在相对独立的人类进化线,其间还有一定程度的基因交流。当时此两地区的人类居群分属于不同的人种。这一假说还可从古文化和古环境的资料得到支持。     

Transcranial Near-Infrared Laser Transmission (NILT) Profiles (800 nm): Systematic Comparison in Four Common Research Species

Background and Purpose

Transcranial near-infrared laser therapy (TLT) is a promising and novel method to promote neuroprotection and clinical improvement in both acute and chronic neurodegenerative diseases such as acute ischemic stroke (AIS), traumatic brain injury (TBI), and Alzheimer’s disease (AD) patients based upon efficacy in translational animal models. However, there is limited information in the peer-reviewed literature pertaining to transcranial near-infrared laser transmission (NILT) profiles in various species. Thus, in the present study we systematically evaluated NILT characteristics through the skull of 4 different species: mouse, rat, rabbit and human.

Results

Using dehydrated skulls from 3 animal species, using a wavelength of 800nm and a surface power density of 700 mW/cm2, NILT decreased from 40.10% (mouse) to 21.24% (rat) to 11.36% (rabbit) as skull thickness measured at bregma increased from 0.44 mm in mouse to 0.83 mm in rat and then 2.11 mm in rabbit. NILT also significantly increased (p<0.05) when animal skulls were hydrated (i.e. compared to dehydrated); but there was no measurable change in thickness due to hydration.In human calvaria, where mean thickness ranged from 7.19 mm at bregma to 5.91 mm in the parietal skull, only 4.18% and 4.24% of applied near-infrared light was transmitted through the skull. There was a slight (9.2-13.4%), but insignificant effect of hydration state on NILT transmission of human skulls, but there was a significant positive correlation between NILT and thickness at bregma and parietal skull, in both hydrated and dehydrated states.

Conclusion

This is the first systematic study to demonstrate differential NILT through the skulls of 4 different species; with an inverse relationship between NILT and skull thickness. With animal skulls, transmission profiles are dependent upon the hydration state of the skull, with significantly greater penetration through hydrated skulls compared to dehydrated skulls. Using human skulls, we demonstrate a significant correlation between thickness and penetration, but there was no correlation with skull density. The results suggest that TLT should be optimized in animals using novel approaches incorporating human skull characteristics, because of significant variance of NILT profiles directly related to skull thickness.