Hervé Reychler

Selection and delineation of lymph node target volumes in head and neck conformal radiotherapy. Proposal for standardizing terminology and procedure based on the surgical experience

The increasing use of 3D treatment planning in head and neck radiation oncology has created an urgent need for new guidelines for the selection and the delineation of the neck node areas to be included in the clinical target volume. Surgical literature has provided us with valuable information on the extent of pathological nodal involvement in the neck as a function of the primary tumor site. In addition, few clinical series have also reported information on radiological nodal involvement in those areas not commonly included in radical neck dissection. Taking all these data together, guidelines for the selection of the node levels to be irradiated for the major head and neck sites could be proposed. To fill the missing link between these guidelines and the 3D treatment planning, recommendations for the delineation of these node levels (levels I-VI and retropharyngeal) on CT (or MRI) slices have been proposed using the guidelines outlined by the Committee for Head and Neck Surgery and Oncology of the American Academy for Otolarynology-Head and Neck Surgery. These guidelines were adapted to take into account specific radiological landmarks more easily identified on CT or MRI slices than in the operating field.

Oxygen isotope fractionation between human phosphate and water revisited

The oxygen isotope composition of human phosphatic tissues (delta18OP) has great potential for reconstructing climate and population migration, but this technique has not been applied to early human evolution. To facilitate this application we analyzed delta18OP values of modern human teeth collected at 12 sites located at latitudes ranging from 4 degrees N to 70 degrees N together with the corresponding oxygen composition of tap waters (delta18OW) from these areas. In addition, the delta18O of some raw and boiled foods were determined and simple mass balance calculations were performed to investigate the impact of solid food consumption on the oxygen isotope composition of the total ingested water (drinking water+solid food water). The results, along with those from three, smaller published data sets, can be considered as random estimates of a unique delta18OW/delta18OP linear relationship: delta18OW=1.54(+/-0.09)xdelta18OP-33.72(+/-1.51)(R2=0.87: p [H0:R2=0]=2x10(-19)). The delta18O of cooked food is higher than that of the drinking water. As a consequence, in a modern diet the delta18O of ingested water is +1.05 to 1.2 per thousand higher than that of drinking water in the area. In meat-dominated and cereal-free diets, which may have been the diets of some of our early ancestors, the shift is a little higher and the application of the regression equation would slightly overestimate delta18OW in these cases.

Positron Emission Tomography With [18F]Fluorodeoxyglucose Improves Staging and Patient Management in Patients With Head and Neck Squamous Cell Carcinoma: A Multicenter Prospective Study

PURPOSE To address the impact of positron emission tomography with [(18)F]fluorodeoxyglucose (PET-FDG) on the initial staging and management of patients with head and neck squamous cell carcinoma (HNSCC). PATIENTS AND METHODS This multicenter, prospective study included 233 patients with newly diagnosed and untreated HNSCC. TNM stage and therapeutic decision were first determined based on the conventional work-up (including physical examination, computed tomography [CT]/magnetic resonance imaging of the head and neck region, and thoracic CT) and sealed in envelope 1. Whole-body PET-FDG was then performed, and subsequent TNM stage and therapeutic decision were written in envelope 2. Changes in TNM stages and in patient management as a result of PET-FDG imaging were recorded. Clinical outcome and histopathology were used as gold standards to validate the TNM stage. Conventional and PET stages were compared using the McNemar test. Results Conventional and PET stage were discordant in 100 (43%) of 233 patients. PET proved to be accurate in 47 patients and inaccurate in 13 patients. TNM status was left unconfirmed in 40 patients because no therapeutic change was expected from the stage difference. Conventional + PET TNM classification (envelope 2) was significantly more accurate than conventional classification (envelope 1; P < .0001, McNemar test). PET-FDG altered the therapeutic plan in 32 (13.7%) of 233 patients. CONCLUSION Adding whole-body PET-FDG to the pretherapeutic conventional staging of HNSCC improved the TNM classification of the disease and altered the management of 13.7% of patients. These findings support the implementation of PET-FDG in the routine imaging work-up of HNSCC.

3D CT-based cephalometric analysis: 3D cephalometric theoretical concept and software.

IntroductionWe present an original three-dimensional cephalometric analysis based on a transformation of a classical two dimensional topological cephalometry.MethodsTo validate the three-dimensional cephalometric CT based concept we systematically compared the alignments of anatomic structures. We used digital lateral radiography to perform the classical two-dimensional cephalometry, and a three-dimensional CT surface model for the three-dimensional cephalometry.ResultsDiagnoses based on both two-dimensional and three-dimensional analyses were adequate, but the three-dimensional analysis gave more information such as the possibility of comparing the right and left side of the skull. Also the anatomic structures were not superimposed which improved the visibility of the reference landmarks.ConclusionWe demonstrated that three-dimensional analysis gives the same results as two-dimensional analysis using the same skull. We also present possible applications of the method.

Reproducibility of osseous landmarks used for computed tomography based three-dimensional cephalometric analyses

PURPOSE The aim of this paper was to measure the reproducibility of osseous landmark identification from two recently described three-dimensional (3D) cephalometric analyses: 3D-ACRO and 3D-Swennen analyses. The study population consisted of 13 patients examined with spiral 3D computed tomography (CT). We used a previously validated low-dose CT protocol. For each analysis, 22 cephalometric reference landmarks were identified on 3D CT surface renderings. Forty-four reference landmarks were identified per patient. Two series of identifications were performed by two independent observers. In total, 3432 imaging measurements were completed. The intra-observer reconstructed mean log was 1.210+/-1.042mm for the 3D-ACRO analysis, and 1.311+/-1.042mm for 3D-Swennen analysis (comparison: p=0.17 NS). The inter-observer reconstructed mean log was 1.799+/-1.037mm for the 3D-ACRO analysis, and 2.465+/-1.036mm for 3D-Swennen analysis (comparison: p=0.000000002). The difference between the intra- and inter-observer reconstructed mean logs were 1.486+/-1.057mm for 3D-ACRO and 1.880+/-1.056mm for 3D-Swennen analysis. In conclusions: 3D-ACRO analysis was significantly more reproducible than 3D-Swennen analysis (p=0.0027) due to the use of a majority of highly reproducible cephalometric landmarks. Finally, we propose a classification scheme and exclusion criteria for reference landmarks used in 3D cephalometrics, based on inter-observer reproducibility and anatomical reality.

Mandibular reconstruction with the free fibula osteocutaneous flap

Experience with 17 mandibular reconstructions by the free fibula flap is presented. The main advantages of this reconstruction method include the bicortical structure of the bone and its adaptability to conform to the mandibular contour. The only real disadvantage is the limited height of the bone graft, which does not allow alveolar ridge reconstruction. An implant-borne dental prosthesis can, however, generally be made for functional occlusal rehabilitation.

Innovative procedure for computer-assisted genioplasty : three-dimensional cephalometry, rapid-prototyping model and surgical splint

The authors present a new procedure of computer-assisted genioplasty. They determined the anterior, posterior and inferior limits of the chin in relation to the skull and face with the newly developed and validated three-dimensional cephalometric planar analysis (ACRO 3D). Virtual planning of the osteotomy lines was carried out with Mimics (Materialize) software. The authors built a three-dimensional rapid-prototyping multi-position model of the chin area from a medical low-dose CT scan. The transfer of virtual information to the operating room consisted of two elements. First, the titanium plates on the 3D RP model were pre-bent. Second, a surgical guide for the transfer of the osteotomy lines and the positions of the screws to the operating room was manufactured. The authors present the first case of the use of this model on a patient. The postoperative results are promising, and the technique is fast and easy-to-use. More patients are needed for a definitive clinical validation of this procedure.

Towards an integrated system for planning and assisting maxillofacial orthognathic surgery

Computer-assisted maxillofacial orthognathic surgery is an emerging and interdisciplinary field linking orthognathic surgery, remote signal engineering and three-dimensional (3D) medical imaging. Most of the computational solutions already developed make use of different specialized systems which introduce difficulties both in the information transfer from one stage to the others and in the use of such systems by surgeons. Trying to address such issue, in this work we present a common computer-based system that integrates proposed modules for planning and assisting the maxillofacial surgery. With that we propose to replace the current standard orthognathic preoperative planning, and to bring information from a virtual planning to the real operative field. The system prototype, including three-dimensional cephalometric analysis, static and dynamic virtual orthognathic planning, and mixed reality transfer of information to the operation room, is described and the first results obtained are presented.

Les limites de la chirurgie des modèles en chirurgie orthognathique: implications théoriques et pratiques

Orthognathic model surgery is a classical technique used to simulate orthognathic surgical cases. However, a detailed analysis of this technique demonstrates that theoretical errors and inaccuracies can occur in routine practice. 2D and 3D cephalometric analysis is the first source of inaccuracies. Then, during the occlusal plane transfer from the patient to the semi-adjustable dental articulator, errors can occur by inaccurate manipulation of the facial bow. Simulating the operation on the plaster cast is difficult due to the lack of a real link between the cephalometric analysis and the model surgery. Rotation and translation movements of the plaster casts are insufficiently controlled during the model surgery stage. Finally, the splint, which transfers the final relative position of maxilla to the mandible, summates all of the errors of the previous stages.

Distraction osteogenesis of a fibula free flap used for mandibular reconstruction: preliminary report

The authors report the first case of mandibular distraction osteogenesis applied to a fibula microvascularized flap used to reconstruct an almost entire mandible. The technique and complications are described. The literature is reviewed. The biological and physiological process of bone elongation by Ilizarovs method is explained according new studies on chondroid tissue. Preoperative planning of vectors of device placement and trajectory is essential for good results.