Automatic identification and characterization of radial files in light microscopy images of wood.

BACKGROUND AND AIMS: Analysis of anatomical sections of wood provides important information for understanding the secondary growth and development of plants. This study reports on a new method for the automatic detection and characterization of cell files in wood images obtained by light microscopy. To facilitate interpretation of the results, reliability coefficients have been determined, which characterize the files, their cells and their respective measurements. METHODS: Histological sections and blocks of the gymnosperms Pinus canariensis, P. nigra and Abies alba were used, together with histological sections of the angiosperm mahogany (Swietenia spp.). Samples were scanned microscopically and mosaic images were built up. After initial processing to reduce noise and enhance contrast, cells were identified using a 'watershed' algorithm and then cell files were built up by the successive aggregation of cells taken from progressively enlarged neighbouring regions. Cell characteristics such as thickness and size were calculated, and a method was developed to determine the reliability of the measurements relative to manual methods. KEY RESULTS: Image analysis using this method can be performed in less than 20 s, which compares with a time of approx. 40 min to produce the same results manually. The results are accompanied by a reliability indicator that can highlight specific configurations of cells and also potentially erroneous data. CONCLUSIONS: The method provides a fast, economical and reliable tool for the identification of cell files. The reliability indicator characterizing the files permits quick filtering of data for statistical analysis while also highlighting particular biological configurations present in the wood sections.

[Three-dimensional imaging and cephalometry of cranio-facial asymmetry]. / Imagerie et céphalométrie tridimensionnelles des asymétries cranio-faciales.

The 75th meeting of the French Orthodontics Society will be held in Biarritz May 8-9-10-11 2002. The main topic for discussion will be: "facial asymmetry". During the meeting, authors will present study of facial asymmetries using a new innovative three-dimensional cephalometry. The method combines CT scans data, anatomical landmarks and mathematical tools to create, using the "Cepha" software, a 3D model of the human face. Balance and symmetry of the model are stable enough to define normality for each individual even with different ethnic and cultural origins. Unbalance and asymmetry characterize pathologies. Follow up shape and size of models allows growth prediction and modeling. The model is in the process of becoming the indispensable reference for all those who are interested in studying the human face: Orthodontics, Surgery, Anatomy, Anthropology, Plastic surgery, Forensic Medicine.

[3-dimensional cephalometry in orthodontics. The current possibilities of Cepha 3DT software]. / Céphalométrie tridimensionnelle en orthopédie dento-faciale. Les possibilités actuelles du logiciel Cépha 3DT.

A 3D cephalometric analysis method from a scanner acquisition, has been developed thanks to a long collaboration between the CIRAD modeling Laboratory and Jacques Treil. The model of skeletal description is based on eight landmarks related to the neuromatrical axis of facial growth (heads of the mallei, supraorbital, suborbital, submental points); it has been abundantly described. The purpose of this work consists in presenting the dentoalveolar level of the analysis. The description and the marking of the arches and the teeth mainly rest on the systematic use of a mathematical tool, the calculation of the central matrix of inertia, and on three fundamental choices: the identification of the dental arches from their constituting teeth leaving aside any alveolar marking, the marking of each tooth relative to the arch, as it can be observed by the orthodontist's eye, and not relative to the craniofacial architecture, the definition of the position of each tooth by the orientation of its coronoradicular axis and not its sole buccal side, Their uses in orthodontics are numerous: diagnosis, choice of the mechanics, therapeutic simulation, therapeutic follow up, analysis of the findings... Clinical applications illustrate the theoretical presentation.