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Biomedical subjects

David Mitton

Publications and source records attributed to David Mitton.

9 recordsLinked to original sources
PubMed2006

External and internal geometry of European adults.

The primary objective of the study was to bring a deeper knowledge of the human anthropometry, investigating the external and internal body geometry of small women, mid-sized men and tall men. Sixty-four healthy European adults were recruited. External measurements were performed using classical anthropometric instruments. Internal measurements of the trunk bones were performed using a stereo-radiographic 3D reconstruction technique. Besides the original procedure presented in this paper for performing in vivo geometrical data acquisition on numerous volunteers, this study provides an extensive description of both external and internal (trunk skeleton) human body geometry for three morphotypes. Moreover, this study proposes a global external and internal geometrical description of 5th female 50th male and 95th male percentile subjects. This study resulted in a unique geometrical database enabling improvement for numerical models of the human body for crash test simulation and offering numerous possibilities in the anthropometry field.

Adult↗
PubMed2006

Assessment of femoral neck strength by 3-dimensional X-ray absorptiometry.

Hip fractures due to osteoporosis are accompanied with increased mortality and morbidity. Bone mineral density (BMD [g/cm(2)]) measured by dual-energy X-ray absorptiometry (DXA) is the most important risk factor. However, an overlap exists between results of fractured and nonfractured populations. Macro-architectural parameters of the femur are independent risk factors of fracture. They have been evaluated in two dimensions using X-ray films or DXA scans; therefore, they are highly dependent on patient positioning and interindividual anatomical variations. To overcome this problem, we have previously shown the possibility to reconstruct human femurs using two perpendicular DXA scans and to calculate 3-dimensional (3D) geometric parameters from these reconstructions by a method called 3-dimensional X-ray absorptiometry (3D-XA). The aim of this article is to assess whether the combination of areal BMD and 3D geometric parameters calculated from 3D-XA improves failure load prediction of human proximal femurs in stance phase configuration. Twelve femurs (11 women, 1 man; aged 88+/-9 yr; range: 72-103 yr) were included in this study. The BMD was measured using a Hologic Delphi-W device (Hologic, Waltham, MA) and 3D reconstruction of the femurs was done using two perpendicular DXA scans as previously published. The calculated 3D geometric parameters included femoral neck axis length (FNAL), mid-femoral neck cross-sectional area (mid-FN CSA), neck shaft angle (NSA), and femoral head diameter (FHD). Mechanical testing was performed using stance phase configuration, which resulted in subcapital fractures. The FHD was correlated to mid-FN CSA and FNAL (r=0.68 and 0.76, respectively; p<0.001). Failure load was correlated to age, FHD, NSA, and BMD measurements. Multiple regression analysis showed that femoral neck BMD, FHD, and mid-FN CSA gave the best statistical model for failure load prediction (r(2)=0.84; p<0.002). This is the first study suggesting that combining areal BMD to 3D geometric parameters obtained by 3D-XA improve failure load prediction in human femurs.

Absorptiometry, Photon↗
PubMed2005

Static mechanical properties of custom-made aortic endografts.

Several cases of delayed aortic rupture after endovascular aneurysm repair have been attributed to in vivo endograft fatigue. Such complications could involve damage to structural components during introduction. The purpose of this study was to compare forces applied during introduction to forces needed to damage the endograft. Testing was carried out on the custom-made endograft (CMEG) that has been in almost exclusive use at our center since 1996. Findings showed that the force applied during introduction was less than the force necessary to damage the endograft. No alteration in the mechanical properties of the CMEG was observed immediately after implantation.

Aorta↗
PubMed2005

Personalized body segment parameters from biplanar low-dose radiography.

Body segment parameters are essential data in biomechanics. They are usually computed with population-specific predictive equations from literature. Recently, medical imaging and video-based methods were also reported for personalized computation. However, these methods present limitations: some of them provide only two-dimensional measurements or external measurements, others require a lot of tomographic images for a three-dimensional (3-D) reconstruction. Therefore, an original method is proposed to compute personalized body segment parameters from biplanar radiography. Simultaneous low-dose frontal and sagittal radiographs were obtained with EOS system. The upper leg segments of eight young males and eight young females were studied. The personalized parameters computed from the biplanar radiographic 3-D reconstructions were compared to literature. The biplanar radiographic method was consistent with predictive equations based on gamma-ray scan and dual energy X-ray absorptiometry.

Algorithms↗
PubMed2004

Photodynamic therapy in oesophageal carcinoma: an overview.

Over the last five years, photodynamic therapy has become increasingly regarded as a viable option for palliative treatment of advanced oesophageal carcinoma, alongside more established modalities such as chemotherapy and radiotherapy. A large number of reports on the efficacy of photodynamic therapy as both a palliative and curative treatment for malignancy of the oesophagus have appeared in the 20 years since the first report on the use of this technique to treat oesophageal carcinoma, and this review aims to draw them all together to provide an overview of the current state of the field.

Clinical Trials as Topic↗
PubMed2004

Surgical correction of scoliosis by in situ contouring: a detorsion analysis.

STUDY DESIGN: A detorsion analysis of the scoliosis surgical correction by means of in situ contouring technique (ISC). OBJECTIVE: To describe the technique of ISC. To measure the vertebral and intervertebral axial rotation in thoracic and lumbar curves and their correction obtained by ISC. SUMMARY AND BACKGROUND DATA: The vertebral and intervertebral axial rotation allows to evaluate the severity of the curves. However, the intervertebral axial rotation is barely studied and the vertebral axial rotation is a controversial point of the surgical correction. METHODS: Twenty patients with thoracic and lumbar scoliosis were operated on with ISC. Vertebral axial rotation at the apex and the sum of intervertebral axial rotations all along the curve were computed before and after surgery from the three-dimensional stereoradiographic reconstruction of the spine and the pelvis. All the measurements were made in the standing position. RESULTS: Correction of the axial rotation was obtained at the apex of both thoracic and lumbar curves of idiopathic and degenerative scoliosis. The mean values of correction (in terms of axial rotation) were 8 degrees to 19 degrees (62%-67%). The percentage of correction of the sum of intervertebral axial rotations all along the curve, proposed as a "detorsion index" (preoperative - postoperative/preoperative), was found at 57% to 92%. No significant differences were found for the correction (in terms of axial rotation and detorsion) between idiopathic and degenerative curves. CONCLUSIONS: The axial rotation was measured in clinics on standing patients with scoliosis from three-dimensional stereoradiographic reconstruction and demonstrated a reliable detorsion obtained by ISC.

Adolescent↗
PubMed2004

Fast accurate stereoradiographic 3D-reconstruction of the spine using a combined geometric and statistic model.

OBJECTIVE: To describe and evaluate a fast accurate stereoradiographic 3D-reconstruction method of the spine. BACKGROUND: Stereoradiographic methods based on anatomical landmarks identification are the only ones providing information on 3D-deformities of the spine in a standing position, but require 2-4 h for the whole spine, making the method inadequate for clinical routine. METHODS: The proposed semi-automated method is based on (1) vertebral body volume reconstruction, (2) definition of a local referential associated to this volume, (3) reliable a priori knowledge of the vertebral shape using eight morphologic descriptors of the vertebral body to estimate, from a multiple linear regression, 21 3D-point coordinates per vertebra, (4) kriging of a 2000 points model with regard to the 21 points. The method was evaluated for vertebral orientation and shape accuracy. RESULTS: 3D models of the whole spine are obtained within 15 min. Manual vs. semi-automated reconstruction comparison yield similar accuracy regarding the CT-scan references. For vertebrae orientation, results were slightly different from the manual reconstruction method (however an absolute reference is lacking). CONCLUSION: The stereoradiographic 3D-reconstruction method allows for a significant reduction of the whole reconstruction time, with regard to previously described methods. Moreover, the accuracy was evaluated and was found to be comparable to the accuracy of previous methods. The results of this study show that stereoradiography could now be employed in routine clinical environment. RELEVANCE: 3D spine reconstruction from biplanar radiographs in standing position can be obtained using a fast and accurate method.

Algorithms↗
PubMed2003

Three-dimensional quantitative segmental analysis of scoliosis corrected by the in situ contouring technique.

STUDY DESIGN: A three-dimensional analysis of right thoracic scoliosis before and after surgical correction was performed. OBJECTIVE: To compare the orientations of the vertebrae in apical and junctional zones before and after surgery. SUMMARY AND BACKGROUND DATA: Three-dimensional segmental analysis considering the lateral, sagittal, and axial (vertebral and intervertebral) rotations that can define apical and junctional zones has been described previously. Modern surgical techniques have been designed to correct scoliosis three-dimensionally. Therefore, the effect of the surgery must be evaluated in three dimensions. METHODS: The three-dimensional reconstruction of the spine and pelvis of 10 patients with right thoracic scoliosis was obtained by a stereoradiographic method before and after surgery. The orientations of all vertebrae were computed, and the apical and junctional zones were defined. The correction of these characteristic vertebrae obtained by the in situ contouring technique was evaluated. RESULTS: The mean three-dimensional pattern for the 10 patients was 20 degrees of vertebral axial rotation with 6 degrees of intervertebral extension in the thoracic apex and 30 degrees of vertebral lateral rotation with 10 degrees of intervertebral axial rotation in the junctional zones of the thoracic curve. The correction obtained by in situ contouring was 52% to 79% for all these three-dimensional vertebral orientations. CONCLUSIONS: Three-dimensional reconstruction of the spine allows quantitative segmental analysis of the deformity. This could be used as a reliable tool to evaluate both the severity of the scoliosis and the effects of the surgical correction.

Adolescent↗