Skull of a 5,300-year-old mummy: reproduction and investigation with CT-guided stereolithography

3D printed skulls in court - a benefit to stakeholders?

Forensic pathologists may use 3D prints as demonstrative aids when providing expert testimony in court of law, but the effects remain unclear despite many assumed benefits. In this qualitative study, the effects of using a 3D print, demonstrating a blunt force skull fracture, in court were explored by thematic analysis of interviews with judges, prosecutors, defence counsels, and forensic pathologists with the aim of improving the expert testimony. Five semi-structured focus groups and eight one-to-one interviews with a total of 29 stakeholders were transcribed ad verbatim and analysed using thematic analysis. The study found that a highly accurate 3D print of a skull demonstrated autopsy findings in detail and provided a quick overview, but sense of touch was of little benefit as the 3D print had different material characteristics than the human skull. Virtual 3D models were expected to provide all the benefits of 3D prints, be less emotionally confronting, and be logistically feasible. Both 3D prints and virtual 3D models were expected to be less emotionally confronting than autopsy photos. Regardless of fidelity, an expert witness was necessary to translate technical language and explain autopsy findings, and low-fidelity models may be equally suited as demonstrative aids. The court infrequently challenged the expert witnesses' conclusions and, therefore, rarely had a need for viewing autopsy findings in detail, therefore rarely needing a 3D print.

An Integrated Study of the Mesolithic Skeleton in Theopetra Cave, Greece: From the Skeleton Analysis to 3D Face Reconstruction

Skeletal evidence dating back to the Mesolithic period is scarce and should be studied under a multidisciplinary perspective. The primary objective of the study was to carefully assess the skeleton of a young woman from this era, named “Avgi,” to compile its bioarchaeological profile, analyze its paleopathology and dental pathology, and deploy a 3D reconstruction and modeling method in order to reveal her face. Both demographic and pathological information were drawn from macroscopically observing the bones, long bone X-rays, skull CT and X-rays, 3D modeling and printing of the skull, and panoramic dental X-rays. The Manchester method was used for the 3D facial reconstruction. On analysis, we determined that Avgi was a female adolescent, aged around 17–19 years at death, and likely suffering from iron deficiency anemia and Class III dental malocclusion. Notably, Harris lines and a hair-on-end pattern were identified in the long bones and skull radiographs, respectively. Various less significant skeletal lesions reflected potential minor pathologies. Our findings suggest that multidisciplinary collaborative approaches should be followed in the modern study of lesser-known past eras. Multiple scientific perspectives, as well as social structures, geographical aspects, settlements, population movements, and social networks should all be taken into account when assessing lifestyle characteristics and paleopathological signs in skeletal remains.

Microtomographic Analysis of a Palaeolithic Wooden Point from the Ljubljanica River

A rare and valuable Palaeolithic wooden point, presumably belonging to a hunting weapon, was found in the Ljubljanica River in Slovenia in 2008. In order to prevent complete decay, the waterlogged wooden artefact had to undergo conservation treatment, which usually involves some expected deformations of structure and shape. To investigate these changes, a series of surface-based 3D models of the artefact were created before, during and after the conservation process. Unfortunately, the surface-based 3D models were not sufficient to understand the internal processes inside the wooden artefact (cracks, cavities, fractures). Since some of the surface-based 3D models were taken with a microtomographic scanner, we decided to create a volumetric 3D model from the available 2D tomographic images. In order to have complete control and greater flexibility in creating the volumetric 3D model than is the case with commercial software, we decided to implement our own algorithm. In fact, two algorithms were implemented for the construction of surface-based 3D models and for the construction of volumetric 3D models, using (1) unsegmented 2D images CT and (2) segmented 2D images CT. The results were positive in comparison with commercial software and new information was obtained about the actual state and causes of the deformation of the artefact. Such models could be a valuable aid in the selection of appropriate conservation and restoration methods and techniques in cultural heritage research.

A three-dimensional reconstructive study of pelvic cavity in the red fox (Vulpes vulpes)

Three-dimensional (3D) reconstructive techniques are being used in many morphometric studies and clinical applications. The red fox is a wild animal localized in a wide geography. This study has been performed to determine morphometric properties of the pelvic cavity and reveal differences between sexes via 3D reconstruction obtained by multi-detector computed tomography images (MDCT) of the red fox. A total of 12 adult red foxes of both sexes were used in this study. Two-dimensional (2D) MDCT images of the pelvic cavity obtained and stored in DICOM format were used to reconstruct the 3D model. Mimics 13.1 program was used to perform the 3D reconstruction. A total of 24 dimensions were measured from the reconstructive model of the pelvic cavity. Twenty two dimensions were found to be significantly different (p < 0.05) between sexes. In conclusion, according to the pelvimetric data, it was determined that the red fox has sexual dimorphism and these data may be useful in wild animals morphological and gynaecological research. The authors hope to help in the diagnosis and treatment of the pelvic cavity-related orthopaedic and gynaecological disorders in the wild animals.

A Multidisciplinary Study of Egyptian Mummies from the Pushkin State Museum of Fine Arts (Methodical Aspects)

We present the results of a multidisciplinary study (the fi rst one in Russia) of nine Egyptian mummies owned by the Pushkin State Museum of Fine Arts (Moscow), carried out at the Kurchatov Institute. A detailed description of the methods is provided. X-ray computed tomography is shown to be a highly informative non-destructive technique for studying the 3D structures of mummies. On the basis of the results, plus the conclusions of forensic experts, a detailed anthropological analysis was conducted. Mummifi cation techniques, sex, and age of all individuals were assessed. In three cases, the sex differed from that indicated in the museum inventory. Morphologically, all crania represent varieties of the Mediterranean type. One individual, however, has typically sub-Saharan features. Pathological changes concern mostly the spine and are both age-related and traumatic. In two individuals, spinal pathologies might have caused death.

Applying 3D prints to reconstructing postmortem craniofacial features damaged by devastating head injuries

Postmortem facial identification is one of the most common techniques for establishing a deceased person's identity. In victims suffering from devastating cranial injuries, the feasibility of facial identification tasks can be compromised by damage to or disfigurement of the identifying cranial features. Although there are several reconstructive approaches, which help experts to restore the essence of person's physical appearance, thus enhancing the chances of recognition, only a few of them involve restoring the fractured cranial bones as the foundation for the reconstructed soft tissues. Here, we propose a technique based on replacement of heavily damaged hard tissues with generic prosthetics manufactured by 3D printing. Our approach does not require medical imaging technologies or other costly lab equipment. It is simple, affordable and relatively labor-efficient. The deceased's reconstructed craniofacial features can be subsequently assessed, photographed, drawn or otherwise reproduced in order to help determine his or her identity. In addition, the imagery can be displayed, published or broadcasted in media without concerns of being overly graphic.

Virtual anthropology - a brief review of the literature and history of computed tomography

Computed tomography (CT) has influenced numerous fields since its inception in the 1970s. The field of palaeoanthropology significantly benefited from this efficient and non-invasive medium in terms of the conservation, reconstruction and analysis of fossil human remains. Over the past decade, there has been a steady increase in the number of forensic anthropological studies incorporating virtual osteological analyses. Because of the increasing importance of these modern cross-sectional imaging techniques and the requirement for standardized parameters in forensic science, we deemed it important to outline the history and development of CT applications in these related academic areas. The present paper outlines the history of “virtual anthropology” and osteological multi-detector CT in the context of palaeoanthropology and forensic anthropology.

CT-scan vs. 3D surface scanning of a skull: first considerations regarding reproducibility issues

Three-dimensional surface scanning (3DSS) and multi-detector computed tomography (MDCT) are two techniques that are used in legal medicine for digitalizing objects, a body or body parts such as bones. While these techniques are more and more commonly employed, surprisingly little information is known about the quality rendering of digitalized three-dimensional (3D) models provided by each of them. This paper presents findings related to the measurement precision of 3D models obtained through observation of a study case, where a fractured skull reconstructed by an anthropologist was digitalized using both post-mortem imaging methods. Computed tomography (CT) scans were performed using an 8-row MDCT unit with two different slice thicknesses. The variability of 3D CT models superimposition allowed to assess the reproducibility and robustness of this digitalization technique. Furthermore, two 3D surface scans were done using a professional high resolution 3D digitizer. The comparison of 3D CT-scans with 3D surface scans by superimposition demonstrated several regions with significant differences in topology (average difference between +1.45 and -1.22 mm). When comparing the reproducibility between these two digitalizing techniques, it appeared that MDCT 3D models led in general to greater variability for measurement precision between scanned surfaces. Also, the reproducibility was better achieved with the 3D surface digitizer, showing 3D models with fewer and less pronounced differences (from +0.32 to -0.31 mm). These experiments suggest that MDCT provides less reproducible body models than 3D surface scanning. But further studies must be undertaken in order to corroborate this first impression, and possibly explain the reason for these findings.

Stereolithography for posterior fossa cranioplasty

Posterior fossa cranioplasty has been suggested for improvement of neurological symptoms following craniectomy. However, there is no particular recommendation in the literature about techniques for prosthesis manufacture and implantation. We report our experience using rapid prototyping technology and stereolithography for pre-surgical implant design and production of cranioplasties.

In what ways can human skeletal remains be used to understand health and disease from the past?

Disease and illness in previous generations can be investigated using palaeopathology. This article describes the commonly used techniques in palaeopathology, includes examples of how such techniques are able to formulate data on a variety of health issues that occurred in the past and suggests how these data can be relevant today.

VIRTOPSY: minimally invasive, imaging-guided virtual autopsy

Invasive "body-opening" autopsy represents the traditional means of postmortem investigation in humans. However, modern cross-sectional imaging techniques can supplement and may even partially replace traditional autopsy. Computed tomography (CT) is the imaging modality of choice for two- and three-dimensional documentation and analysis of autopsy findings including fracture systems, pathologic gas collections (eg, air embolism, subcutaneous emphysema after trauma, hyperbaric trauma, decomposition effects), and gross tissue injury. Various postprocessing techniques can provide strong forensic evidence for use in legal proceedings. Magnetic resonance (MR) imaging has had a greater impact in demonstrating soft-tissue injury, organ trauma, and nontraumatic conditions. However, the differences in morphologic features and signal intensity characteristics seen at antemortem versus postmortem MR imaging have not yet been studied systematically. The documentation and analysis of postmortem findings with CT and MR imaging and postprocessing techniques ("virtopsy") is investigator independent, objective, and noninvasive and will lead to qualitative improvements in forensic pathologic investigation. Future applications of this approach include the assessment of morbidity and mortality in the general population and, perhaps, routine screening of bodies prior to burial.

Multi-detector row CT scanning in Paleoanthropology at various tube current settings and scanning mode

The purpose of this study was to determine the optimal tube current setting and scanning mode for hominid fossil skull scanning, using multi-detector row computed tomography (CT). Four fossil skulls (La Ferrassie 1, Abri Pataud 1, CroMagnon 2 and Cro-Magnon 3) were examined by using the CT scanner LightSpeed 16 (General Electric Medical Systems) with varying dose per section (160, 250, and 300 mAs) and scanning mode (helical and conventional). Image quality of two-dimensional (2D) multiplanar reconstructions, three-dimensional (3D) reconstructions and native images was assessed by four reviewers using a four-point grading scale. An ANOVA (analysis of variance) model was used to compare the mean score for each sequence and the overall mean score according to the levels of the scanning parameters. Compared with helical CT (mean score=12.03), the conventional technique showed sustained poor image quality (mean score=4.17). With the helical mode, we observed a better image quality at 300 mAs than at 160 in the 3D sequences (P=0.03). Whereas in native images, a reduction in the effective tube current induced no degradation in image quality (P=0.05). Our study suggests a standardized protocol for fossil scanning with a 16 x 0.625 detector configuration, a 10 mm beam collimation, a 0.562:1 acquisition mode, a 0.625/0.4 mm slice thickness/reconstruction interval, a pitch of 5.62, 120 kV and 300 mAs especially when a 3D study is required.

Rapid prototyping in Maxillofacial Surgery and Traumatology

Review of the literature from 1991 to 2002 on the use of rapid prototyping in the biomedical area emphasizes the applicability of this technique to aid diagnosis and planning in Maxillofacial Surgery and Traumatology. A case report in which a TMJ ankylosis relapse was treated using rapid prototyping (selective laser sintering) for surgery planning is presented. After one year, the patient's buccal opening was 45 mm. Transitory paralysis of the facial nerve disappeared totally in six months.

Facial Reconstruction of a Wrapped Egyptian Mummy Using MDCT

OBJECTIVE

Facial reconstruction of mummies and corpses in general is important in anthropological, medical, and forensic studies. The purpose of our study was to evaluate the role of MDCT examination for 3D facial reconstruction and report the results of multidisciplinary work performed by radiologists, anthropologists, and forensic police in reconstructing the possible physiognomy of an ancient Egyptian mummy.

MATERIALS AND METHODS

Three-dimensional MDCT data were obtained from a well-preserved, completely wrapped Egyptian mummy from the collection of the Egyptian Museum in Torino, Italy, which dated from the XXII or XXIII dynasty (945-715 BC). Data were used as a model for the rapid prototyping stereolithographic technique, a method that allows the creation of a 3D model with digital data using synthetic materials such as a resin or nylon.

RESULTS

The physical creation of the face was accomplished with boosting techniques performed by the progressive layering of plasticine on the nylon model according to the anthropometric data, the conditions of the soft residual dehydrated tissues, and the most accepted scientific and anthropological criteria. CT is the only noninvasive method for obtaining fundamental data for 3D reconstructions of the skull and the body, especially with wrapped mummies.

CONCLUSION

Our multidisciplinary cooperative study produced a model of the face of an individual who lived nearly 3,000 years ago, which would not previously have been possible unless we unwrapped, destroyed, and altered the conservation of the bandages and the mummy.

[Rapid prototyping in planning reconstructive surgery of the head and neck. Review and evaluation of indications in clinical use]

PURPOSE

The aim was to define the indications for use of rapid prototyping models based on data of patients treated with this technique.

PATIENTS AND METHODS

Since 1987 our department has been developing methods of rapid prototyping in surgery planning. During the study, first the statistical and reproducible anatomical precision of rapid prototyping models was determined on pig skull measurements depending on CT parameters and method of rapid prototyping.

RESULTS

Measurements on stereolithography models and on selective laser sintered models confirmed an accuracy of +/-0.88 mm or 2.7% (maximum deviation: -3.0 mm to +3.2 mm) independently from CT parameters or method of rapid prototyping, respectively. With the same precision of models multilayer helical CT with a higher rate is the preferable method of data acquisition compared to conventional helical CT. From 1990 to 2002 in atotal of 122 patients, 127 rapid prototyping models were manufactured: in 112 patients stereolithography models, in 2 patients an additional stereolithography model, in 2 patients an additional selective laser sinter model, in 1 patient an additional milled model, and in 10 patients just a selective laser sinter model.

CONCLUSION

Reconstructive surgery, distraction osteogenesis including midface distraction, and dental implantology are proven to be the major indications for rapid prototyping as confirmed in a review of the literature. Surgery planning on rapid prototyping models should only be used in individual cases due to radiation dose and high costs. Routine use of this technique only seems to be indicated in skull reconstruction and distraction osteogenesis.

Radiologic evaluation of the Llullaillaco mummies

OBJECTIVE

Our purpose was to determine the imaging findings in three 500-year-old frozen mummies of sacrificial Inca children.

MATERIALS AND METHODS

CT, conventional radiography, and dental radiography of Inca mummies were reviewed. Different techniques, which were adjusted to the anatomic position of the bodies, were used for radiologic analyses. Working sessions were limited to 20 min because of the fragility of these mummies and to prevent thawing of the specimens.

RESULTS

Internal organs in good condition with a natural shrinkage caused by dehydration were shown on CT scans. Both white and gray matter were clearly observed in the brain and cerebellum. The white matter and the fatty tissue of the bodies were visibly white. This condition was possibly caused by the transformation of the fatty tissue into a waxlike substance and the deposition of calcium salts. The lungs were expanded in all three mummies. The ages of the three children at the time of their deaths were estimated by means of radiographs of the teeth and long bones. Bone mineralization, the muscular volume, and the thickness of the adipose panniculus indicated the good nutritional state of the three Inca children. The spleen was not visualized in any case.

CONCLUSION

Radiology helped us determine the state of the internal organs, the nutritional conditions, and the physical abnormalities of the naturally mummified children. These mummies can be considered among the best preserved mummies currently known.

The Application of Rapid Prototyping Techniques in Cranial Reconstruction and Preoperative Planning in Neurosurgery

The value of rapid prototype models of the skull in our craniofacial and neurosurgical practice was analyzed. Individual skull models of 52 patients were produced by means of rapid prototyping techniques and used in various procedures. Patients were divided into three groups as follows: group I (26 patients) requiring corrective cranioplasty 1) after resection of osseous tumors (15 patients) and 2) with congenital and posttraumatic craniofacial deformities (11 patients), group II (10 patients) requiring reconstructive cranioplasty, and group III (16 patients) requiring planning of difficult skull base approaches. The utility of the stereolithographic models was assessed using the Gillespie scoring system. The esthetic and clinical outcomes were assessed by means of the esthetic outcome score and the Glasgow Outcome Score, respectively. Simulation of osteotomies for advancement plasty and craniofacial reassembly in the model before surgery in group I reduced operating time and intraoperative errors. In group II, the usefulness of the models depended directly on the size and configuration of the cranial defect. The planning of approaches to uncommon and complex skull base tumors (group III) was significantly influenced by the stereolithographic models. The esthetic outcome was pleasing. The indications for the manufacture of individual three-dimensional models could be cases of craniofacial dysmorphism that require meticulous preoperative planning and skull base surgery with difficult anatomical and reconstructive problems. The stereolithographic models provide 1) better understanding of the anatomy, 2) presurgical simulation, 3) intraoperative accuracy in localization of lesions, 4) accurate fabrication of implants, and 5) improved education of trainees.

The iceman: discovery and imaging

The anatomic features of a 5,300-year-old mummy, the iceman, were documented with conventional radiographic, portable computed radiographic, and conventional and spiral computed tomographic images obtained between September 1991 and June 2001. A team of scientists and radiologists from Austria, Italy, and the United States supervised the examinations and interpreted the images. The images demonstrated excellent preservation of the mineralized skeleton with profound dehydration of the soft tissues. The skeleton exhibited several types of trauma, including (a) healed rib fractures, (b) hairline skull fractures and a compression deformity of the thorax, probably acquired while encased in the glacier, and (c) damage acquired during the effort to recover the corpse. Skeletal variants were present, as was evidence of degenerative arthritis, frostbite, vascular calcification, and adaptation to cultural and geographic influences. In terms of anatomy and apparent health-related conditions, the iceman was very similar to modern humans. An arrowhead lodged between the rib cage and the left scapula was the probable cause of the iceman's death. Study of the images also provided insight regarding postmortem processes that led to the iceman's mummification.

Whole-body three-dimensional multidetector CT of 13 Egyptian human mummies

OBJECTIVE

The purpose of this article is to assess the role of multidetector CT and three-dimensional (3D) reconstructions in noninvasive studies of Egyptian mummies.

MATERIALS AND METHODS

We studied 13 mummies from the Egyptian Museum in Torino, Italy, dating from Dynasty III to Dynasty IV (2650-2450 B.C.) and from the Ptolemaic period (332-30 B.C.) to the Roman period (30 B.C.-A.D. 395), using a multidetector CT unit with a single volumetric acquisition of the whole body, including lower extremities, followed by 3D reconstruction. All mummies were completely wrapped; preservation conditions of external wrappings were good in all.

RESULTS

The general setting, embalming techniques, sex and age assessment (from body and skeletal features), anthropometric measurements (cranial measurements and evaluation of stature), conditions of the skeleton and soft tissue, any abnormalities, and the presence of foreign objects were evaluated in each mummy, and a detailed report was drawn up. Virtual unwrapping permitted the identification of physiognomy of the whole dehydrated body placed beneath the wrappings; 3D reconstruction and virtual fly-through navigation allowed further evaluations of the internal parts of the body.

CONCLUSION

The results obtained with this protocol provided important anthropologic and paleopathologic information that would have been impossible to obtain by other noninvasive techniques. Moreover, this method has great potential for studies of conservation, anthropology, and paleopathology of other Egyptian and ancient human remains. Multidisciplinary cooperation among anthropologists, paleopathologists, Egyptologists, and radiologists is essential.

Three-dimensional craniofacial reconstruction imaging

This review article aims to describe and discuss the imaging techniques most commonly used in medicine and dentistry to obtain three-dimensional images of the craniofacial complex. Three-dimensional imaging techniques provide extensive possibilities for the detailed and precise analysis of the whole craniofacial complex, for virtual (on-screen) simulation and real simulation of orthognathic surgery cases on biomodels before treatment, as well as for the detailed evaluation of the effects of treatment. Laser scanning in combination with the stereolithographic biomodeling seems to be a very promising combination for three-dimensional imaging, although there is still considerable room for improvement. Constant efforts should be made in the direction of developing and enhancing the existing techniques as well as exploring the potential for developing new methods based on emerging sectors of technology.

Paleoradiology: advanced CT in the evaluation of nine Egyptian mummies

Axial thin-collimation state-of-the-art spiral computed tomography (CT) was combined with sagittal and coronal reformatting, three-dimensional (3D) reconstruction, and virtual "fly-through" techniques to nondestructively study nine Egyptian mummies. These techniques provided important paleopathologic and historical information about mummification techniques, depicted anatomy in the most informative imaging plane, illustrated the soft-tissue preservation and physical appearance of mummies in superb detail, and generated an intriguing virtual tour through hollow mummified remains without harming the specimens themselves. Images generated with these methods can help archaeologists and Egyptologists understand these fascinating members of mankind and can serve as adjunct visual aids for laypersons who are interested in mummies. CT has emerged as the imaging modality of choice for the examination of Egyptian mummies due to its noninvasive cross-sectional nature and inherently superior contrast and spatial resolution. As multi-detector row CT and postprocessing tools evolve, the capabilities and applications of CT will continue to proliferate, attesting to the expanded versatility and utility of CT as a noninvasive research tool in the multidisciplinary study of Egyptian mummies.

Virtual anthropology (VA): a call for glasnost in paleoanthropology

The adventurous scientist, with a hat protecting him from the fierce sun as he travels from one remote place to another, hunting for fossils of our ancestors, has been a part of the romantic imagination associated with anthropological research in the 20th Century. This picture of the paleoanthropologist still retains a grain of truth. Indeed, many new sites were discovered under troublesome conditions in the recent past and have added substantial information about our origins. But on another front, probably less sensational but no less important, are contributions stemming from the analysis of the already discovered fossils. With the latter, a rapid evolution in anthropologic research took place concurrently with advances in computer technology. After ambitious activities by a handful of researchers in some specialized laboratories, a methodologic inventory evolved to extract critical information about fossilized specimens, most of it preserved in the largely inaccessible interior as unrevealed anatomic structures. Many methodologies have become established but, for various reasons, access to both the actual and the digitized fossils is still limited. It is time for more transparency, for a glasnost in paleoanthropology. Herein are presented some answers to the question of how a high-tech approach to anthropology can be integrated into a predominantly conservative field of research, and what are the main challenges for development in the future.

Virtual anthropology: the digital evolution in anthropological sciences

The discovery and explanation of differences among organisms is a major concern for evolutionary and systematic biologists. In physical anthropology, the discrimination of taxa and the qualitative and quantitative description of ontogenetic or evolutionary change require, of course, the analysis of morphological features. Since the 1960s, a remarkable amount of fossil material was excavated, some of it still awaiting a detailed first analysis, some of it requiring re-examination by more developed methods. While the fossil record grew continuously, a revolution in anthropological research took place with advances in computer technology in the 1980s: a handful of innovative researchers working in specialized anthropology laboratories or medical departments developed the methodological inventory needed to extract critical information from subjects in vivo and from fossilized remains. A considerable part of this information is preserved in the physically heretofore inaccessible interior of anatomical structures. Virtual Anthropology (VA) is a means of making them visible and measurable. Thus, VA also allows access to 'hidden' landmarks; in addition, the large number of semilandmarks accessible on the form enhances the power of Geometric Morphometrics analysis. Furthermore, the density information in volume data allows manipulations such as segmentation, impossible with the real, physical object. Moreover, metric body measurements generally, and cranial measurements specifically, are also an important source of information for the analysis of the ontogenetic development of the skeletal system, and--last but not least--for clinical use (e.g., operation planning, operation simulation, prosthetics). Thus, there developed a fruitful interdisciplinary cooperation between statistics, medicine, and physical anthropology.

The potential role of stereolithography in the study of facial aging

The potential role of high-resolution stereolithography for the study of facial aging was evaluated. Stereolithography has been used extensively in the engineering sciences to create model replicas prior to full production. More recently, stereolithography has found a role in the preoperative planning of complex dentofacial anomalies. Previous work has suggested that continued differential growth of the maxilla may occur throughout life. To further evaluate this finding, computed tomography scans were collected from younger (mean, 20.2 years) and older (mean, 58.8 years) individuals (N = 20). Both men and women were included. An exact replica of the facial skeleton was made for each subject by the process of laser polymerization. The angles of the maxillary wall and piriform aperture, defined by specific points, were measured relative to sella-nasion. Height, width, and depth changes were also evaluated. Findings show that angular changes occurred with age. The mean angle of the maxilla relative to sella-nasion decreased from 69 degrees to 56.8 degrees with age (P =.015). The mean angle of the piriform likewise decreased from 65.1 degrees to 55.7 degrees (P =.019). This angular change with age suggests that differential growth may continue throughout life. This work highlights the potential role of 3-dimensional modeling for future research in the field of facial aging. Curve and contour analysis are 2 additional areas in which stereolithography may yield valuable insights into the mechanisms of facial growth.

Stereolithography: a potential new tool in forensic medicine

Stereolithography is a computer-mediated method that can be used to quickly create anatomically correct three-dimensional epoxy and acrylic resin models from various types of medical data. Multiple imaging modalities can be exploited, including computed tomography and magnetic resonance imaging. The technology was first developed and used in 1986 to overcome limitations in previous computer-aided manufacturing/milling techniques. Stereolithography is presently used to accurately reproduce both the external and internal anatomy of body structures. Current medical uses of stereolithography include preoperative planning of orthopedic and maxillofacial surgeries, the fabrication of custom prosthetic devices; and the assessment of the degree of bony and soft-tissue injury caused by trauma. We propose that there is a useful, as yet untapped, potential for this technology in forensic medicine.

Virtual reality and anthropology

Since the discovery of the Tyrolean Iceman in 1991 advanced imaging and post processing techniques were successfully applied in anthropology. Specific techniques include spiral computed tomography and 3-dimensional reconstructions including stereolithographic and fused deposition modeling of volume data sets. The Iceman's skull was the first to be reproduced using stereolithography, before this method was successfully applied in preoperative planning. With the advent of high-end graphics workstations and biomedical image processing software packages, 3-dimensional reconstructions were established as a routine tool for analyzing volume data sets. These techniques opened totally new insights in the field of physical anthropology. Computed tomography became the ideal research tool to access the internal structures of various precious fossils without damaging or even touching them. Many of the most precious specimens from the species Autralopithecus (1.8-3.5 Myears), Homo heidelbergensis (200-600 kyears) or Homo neanderthalensis (40-100 kyears) were scanned during the last 5 years. Often the fossils are filled with a stone matrix or other materials. During the postprocessing routines highly advanced algorithms were used to remove virtually these incrustations. Thus it was possible to visualize the morphological structures that lie beneath the matrix. Some specimen were partially destroyed, so the missing parts were reconstructed on computer screen in order to get estimations of the brain volume and endocranial morphology, both major fields of interest in physical anthropology. Moreover the computerized form of the data allows new descriptions of morphologic structures by the means of 'geometric morphometrics'. Some of the results may change aspects and interpretations in human evolution. The introduction of new imaging and post processing techniques created a new field of research: Virtual Anthropology.

A comparative study of stereolithographically modelled skulls of Petralona and Broken Hill: implications for future studies of middle Pleistocene hominid evolution

Computer generated three-dimensional stereolithographic models of middle Pleistocene skulls from Petralona and Broken Hill are described and compared. The anterior cranial fossae of these models are also compared with that of another middle Pleistocene skull, Arago 21. Stereolithographic modelling reproduces not only the outer surfaces of skulls, but also features within the substance of the bones, and details of the internal braincase. The skulls of Petralona and, to a somewhat lesser degree, Broken Hill are extremely pneumatized. Previously undescribed features associated with pneumatization are detailed, along with their possible functional significance, polarity, and potential for understanding hominid cranial variation. Petralona and Broken Hill also exhibit a dramatic suite of cerebral features that is probably related to extensive pneumatization of the skull, namely frontal lobes that are tilted and located behind rather than over the orbits, laterally flared temporal lobes, marked occipital projection, and basal location of the cerebellum. Comparison of the anterior cranial fossae of Petralona, Broken Hill, and Arago 21 suggests that external resemblance of skulls may not always correlate with endocranial similarity. We believe that stereolithographic reconstructions have the potential for helping to resolve difficult questions about the origins of Neanderthal and anatomically modern people.

3D image-guided surgery on the example of the 5,300-year-old Innsbruck Iceman

Interventional Video Tomography (IVT) is regularly used for computer-assisted 3D navigation in ear-, nose, throat, and head & neck surgery in our clinic. We present the technology and its application to collect biopsies of a 5,300 year old, completely conserved male cadaver, the Iceman. IVT links intraoperative live video with medical imaging data sets, realizing real-time surgical guidance in the live video and/or in the medical images. The IVT data contain the video images and the spatial sensor information; this has a large potential for documentation, training, teaching, and telepresence. IVT allowed us to sample the Iceman's mucosa by the minimally invasive endoscopic approach of the maxillary sinus, the nasal cavity, and the larynx, minimizing tissue damage. Visual inspection of the sinuses and the mucosa revealed the typical mucosa of a fresh cadaver, albeit originating from the stone-age.

Preliminary experience with medical applications of rapid prototyping by selective laser sintering

Rapid prototyping techniques, originally developed for building components from computer aided designs in the motor industry, are now being applied in medicine to build models of human anatomy from high resolution multiplanar imaging data such a computed tomography (CT). The established technique of stereolithography and the more recent selective laser sintering (SLS), both build up an object layer by layer. Models have applications in surgical planning, for the design of customised implants and for training. Preliminary experience of using the SLS technique for medical applications is described, addressing questions regarding image processing, data transfer and manufacture. Pilot models, built from nylon, included two skills (a child with craniosynoslosis and an adult with hypertetorism) and a normal femur which was modelled for use in a bioengineering test of an artificial hip. The dimensions of the models were found to be in good agreement with the CT data from which they were built-for the child's skull the difference between the model and the CT data was less than 1.0 +/- 0.5 mm in each direction. Our experience showed that, with care, a combination of existing software packages may be used for data conversion. Ideally, image data of high spatial resolution should be used. The pilot models generated sufficient clinical interest for the technique to be pursued in the orthopaedic field.