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OBJECTIVES: The various types of cone beam CT (CBCT) differ in several technical characteristics, notably their spatial resolution, which is defined by the acquisition voxel size. However, data are still lacking on the effects of voxel size on the metric accuracy of three-dimensional (3D) reconstructions. This study was designed to assess the effect of isotropic voxel size on the 3D reconstruction accuracy and reproducibility of CBCT data. METHODS: The study sample comprised 70 teeth (from the Institut d'Anatomie Normale, Strasbourg, France). The teeth were scanned with a KODAK 9500 3D® CBCT (Carestream Health, Inc., Marne-la-Vallée, France), which has two voxel sizes: 200 µm (CBCT 200 µm group) and 300 µm (CBCT 300 µm group). These teeth had also been scanned with the KODAK 9000 3D® CBCT (Carestream Health, Inc.) (CBCT 76 µm group) and the SCANCO Medical micro-CT XtremeCT (SCANCO Medical, Brüttisellen, Switzerland) (micro-CT 41 µm group) considered as references. After semi-automatic segmentation with AMIRA® software (Visualization Sciences Group, Burlington, MA), tooth volumetric measurements were obtained. RESULTS: The Bland-Altman method showed no difference in tooth volumes despite a slight underestimation for the CBCT 200 µm and 300 µm groups compared with the two reference groups. The underestimation was statistically significant for the volumetric measurements of the CBCT 300 µm group relative to the two reference groups (Passing-Bablok method). CONCLUSIONS: CBCT is not only a tool that helps in diagnosis and detection but it has the complementary advantage of being a measuring instrument, the accuracy of which appears connected to the size of the voxels. Future applications of such measurements with CBCT are discussed.

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Three-dimensional imaging of teeth will increase its impact in clinical practice if reconstructions are metrically accurate. We hypothesized that, with cone beam computed tomography (CBCT) data, three-dimensional images of teeth can be reconstructed with the same accuracy and precision as with in vitro micro-computed tomography (micro-CT) data acquisition, the current reference standard. We used a sample of CBCT and micro-CT data taken of tooth germs. Volumes obtained with CBCT and micro-CT devices were statistically similar (n = 120, Passing-Bablok regression). Geometric deviations between CBCT and micro-CT three-dimensional surface reconstructions did not show any areas of important and systematic errors. Future investigations with the use of larger samples may also demonstrate that CBCT data will be helpful for a more in-depth study of other aspects of dental morphology--for example, assessing tooth development. With sufficient accuracy for clinical situations, potential future medical applications of such measurements with CBCT are envisaged.

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We used micro-computed tomography and virtual tools to study metric and morphological features at the enamel-dentine junction and on the outer enamel surface in the postcanine dentition of an exceptionally well-preserved maxilla and mandible of an early hominin. The fossil, Sts 52 from Sterkfontein, South Africa, is attributed to Australopithecus africanus and is about 2.5 million years old. For comparative purposes in this exploratory study, we also used micro-computed tomography to analyse the dentition of a common chimpanzee (Pan troglodytes), a pygmy chimpanzee (Pan paniscus) and three extant humans. Metameric variation of the 3D enamel-dentine junction in the two chimpanzee mandibles was much smaller than in extant humans. Variation in metameric shape was high and complex. Notably, the mandibular metameric variation in extant humans can be greater within individuals, as compared with variation between individuals, with differences in shape appearing greater for M2 compared with M1. We recommend the use of a new approach in which individual metameric variation is systematically assessed before making inferences about differences between fossil hominin species. The fossil hominin examined in this study showed a metameric pattern of mandibular variation in shape that was comparable to the pattern seen in two chimpanzees. This degree of metameric variation appeared relatively small compared with the much larger patterns of variation observed within and between extant humans.

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Imaging has always been a part of dental implant procedures from its beginning. Initially, imaging was performed by dentists. The introduction of CT scan at the end of the seventies was revolutionary. Radiologists then played a major role in image generation and distribution. For the last two years, a revolution is occurring with the availability of "cone beam" CT machines in dental offices with implant planning software. The dentist can sometimes administer the entire delivery of care: choice of imaging technique, generation and distribution of imaging data, implant planning and treatment. The radiologist's role is now only conceivable as a specialist in dental imaging, attuned to the evolution of dental implant techniques.

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Three D Modeling of the human face. The method combines the use of DICOM CT scan or cone beam data, anatomical informations and a mathematical tool, the axes of inertia, in order to create a 3D model for cephalometric analysis of the human face. The balance and symmetry of the model are stable enough to define normality for each individual, even when there are differences in ethnic and cultural origins. Imbalance and asymmetry characterize pathologies. Follow up shape and size of models allow growth prediction and modeling. An original statistical study of the 3D model variability using the "geometry morphometrics method" (GMM) is introduced. This 3D model is in the process of becoming an indispensable reference for all of those who are interested in studying the human face such as Orthodontists, Surgeons, Anatomists, Anthropologists and Forensic Medical Practitioners.

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Late Miocene fossils from the Lukeino Formation in Kenya's Tugen Hills are assigned to Orrorin tugenensis. Of 20 fossils recovered there to date, 3 are proximal femurs. One of these, BAR 1002'00, preserves an intact head connected to the proximal shaft by an elongated neck. Although this fossil is comparable in size to Pan troglodytes, computerized tomography scans of the neck-shaft junction of BAR 1002'00 reveal that the cortex is markedly thinner superiorly than inferiorly, differing from the approximately equal cortical thicknesses observed in extant African apes, approaching the condition in later hominids, and indicating that O. tugenensis was bipedal.

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The Cepha3DT software is used to generate a 3D model of the human face.

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The use of the c2000 software led us to develop a new 3D cephalometric construction, based on the selection on the axial CT Scans of 8 anatomical landmarks and of teeth, all of which were situated along the trigeminal neuro matriciel facial growth axes. The analysis of this construction is based on the use of an original mathematical tool in biology: the axes of inertia. Using the selection of both mental foramen, both infra and supra orbital foramen and the head of both malleus, the C 2000 software creates a geometrical construction called: "the maxillo-facial frame", as well as, a 3D cephalometric analysis: angles, distances, areas, volumes center of gravity and axes of inertia. Using the selection of teeth, the C 2000 software calculates the axes of inertia of each tooth or of groups of teeth. The use of the axes of inertia allow us to create of a hierarchy of anatomical levels the teeth, the half arches, the arches, both arches and the maxillo-facial frame. In addition, for each of these anatomical levels, the axes of inertia create a 3D landmark which allows the calculation of the orientation of each of these elements in relation to the others. The study of 28 orthomorphic people using this analysis revealed the existence of a maxillo-facial balance that is unique for each individual.

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The authors propose a biomensurativ 3 D method based on the plotting of 8 anatomical landmarks situated on the trigeminal axis and the selection of teeth. In the analysis of this construction, we have employed mathematical tools unusual in developmental biology, the axis of inertia. The 3 D analysis allows to evidence the architectural, structural and functional balance of the dentomaxillofacial complex. This balance must be substituted to the normality concept to directly linked to cultural criterias and to the selection of mean parameters among culturally and ethnically homogeneous populations. Therapy does not have to lead to the normality of mean parameters but to the return or to the discovery of a real balance.

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Cerebral venous angiomas (CVAs) are made up of veins with abnormal structure: thick walls, lumens dilated of irregular calibre that converge radially towards a wide draining vein. The arteries are normal. The veins are separated by a normal nervous tissue. The malformation is thought to develop as a compensatory venous drainage consecutive to the occlusion, or lack of development, of one or several transcerebral veins during the formation of the mature venous system. Together with arteriovenous angiomas, capillary telangiectasias and cavernous angiomas, CVAs belong to the vascular angiomatous malformations, also called hamartomas. The present study is based on 12 cases collected between 1984 and 1989, all explored by CT and angiography, and by MRI in 2 cases. The diagnosis therefore was neuroradiological, except in 1 case where it was obtained by neuropathological examination. The malformation was supratentorial in 10 cases and cerebellar in 2 cases. Most CVAs were discovered in patients whose symptoms could hardly be attributed to these malformations and consequently were termed asymptomatic (6 cases). Two cases were found in subjects with generalized epileptic seizures without clear-cut relationship with the angioma; 4 cases were revealed by haemorrhages: subarachnoidal haemorrhage in 2 cases and supratentorial intraparenchymatous haematoma in 1 case. These 3 cases had a spontaneously favourable outcome after a follow-up of several years. One patient with a cerebellar hematoma died postoperatively of edematous infarction of the cerebellum. One of these patients had two symmetrical CVAs, one in each cerebral hemisphere (multiple venous angiomas), and in another patient the CVA was probably associated with a cavernous angioma.(ABSTRACT TRUNCATED AT 250 WORDS)

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The authors report their experience with 240 cases with lumbar phlebography in the diagnosis of lumbar disc herniations. The normal radiological anatomy and the radiological signs of disc herniations are described. Indications for phlebography are given, and the reliability of this test is compared with that of myelography performed with water-soluble agents.

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Metrizamide is a new hydrosoluble contrast medium of an entirely original conception which for first time makes it possible to explore the whole cord and its spaces. The technique of latero-cervical puncture between C1 and C2 was used in 45 cases of cervical cord compression, cervico-brachial neuralgia or brachial plexus paralysis. This technique of myelography has proved to be simple and reliable. It has a number of advantages: it is far more rapid, less painful and offers good visualisation of the nerve roots as compared with air myelography; unlike myelography with iodine-based oils, it is not necessary to remove the contrast medium after the examination since Metrizamide is spontaneously resorbable. Tolerance in general is remarkably good.

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We review 258 cases of craniofacial vascular lesion treated by endovascular occlusion in the past 7 years in the Neuroradiology Departments of Nancy, Nantes, and Toulouse. Dural fistulas very often need both embolization and surgery. Craniofacial angiomas are not straightforward indications for therapy: the age of the patient, the unpredictability of evolution, and possible sequelae have to be taken into account; embolization is very successful in counteracting hemorrhage. Angiomatoses such as Rendu-Osler disease can respond well to repeated embolizations over several years. Lesions such as hemolymphangiomas are also excellent indications for embolization, either alone or with surgery. Occlusion by detachable balloon is ideally the most elegant method, but it is not always technically feasible, nor free from complications.

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Two cases of cervical spondylolisthesis, due to a congenital defect in the pars interarticularis of C6, associated with spina bifida and elongation of the contralateral pars interarticularis, are reported. Tomography showed an abnormal direction of the articular facets of C6 and demonstrated a narrow frontal diameter of the cervical spinal canal at the level of the malformation. Gas myelography showed a slight compression of the cord. Unlike previously reported cases the patients had neurological findings which, in one case at least, were certainly referable to the spinal cord.

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