Search results for "geometry."

The number of contacts in random fibre networks

2012

There is a wide range of materials that can be considered as nonwoven random networks of fibres. Such materials include glass-fibre mats, filters, various paper products and structural components of cells and tissues. The mechanical properties of these kinds of networks have been studied extensively for many decades. As many of such networks form more or less two-dimensional structures, they can, to a good approximation, be considered to consist of randomly distributed fibres or filaments connected at their crossings points. Recent development of the resolution of X-ray computed tomography have enabled imaging of the three dimensional structure of such materials with a resolution sufficient…

Characterization of normal regional myocardial function by MRI cardiac tagging

2013

Purpose The aim of this study was to establish reference values for segmental myocardial strain measured by magnetic resonance (MR) cardiac tagging in order to characterize the regional function of the heart. Material and Methods We characterized the left ventricular (LV) systolic deformation in 39 subjects (26 women and 13 men, age 58.8 ± 11.6 years) whose cardiological study had not revealed any significant abnormality. The deformation was measured from MR-tagged (Siemens 1.5T MR) images using an algorithm based on sine wave modeling. Circumferential and radial peak systolic strain values along with the torsion angle and circumferential-longitudinal (CL) shear were determined in 16 LV seg…

Real and simulated endoscopy of neurosurgical approaches in an anatomical model

1997

Endoscopy simulation is a new visualisation technique which can be used to visualise patient anatomy as seen through endoscopes. In the following, we describe the application of simulated endoscopy to neurosurgical endoscopic approaches. We assess different aspects of virtual images and their influence on the final result, as judged by clinicians. One of these aspects is the projective geometry which is used to render the 3D images. Rendering using stereographic projection leads to more realistic endoscopic views than perspective projection.

Alveolar ridge reconstruction with titanium meshes: A systematic review of the literature

2014

Alveolar bone regeneration by means of titanium meshes is a widespread procedure, however to date, only few relevant studies were reported in literature concerning this technique. Consequently, the aim of the present systematic review was to analyze the reliability of the titanium mesh as a barrier, in conjunction with horizontal and vertical ridge reconstruction for implant placement purposes. A total of 17 articles complying with the inclusion and exclusion criteria were reviewed. Three outcome variables were defined: a) horizontal and vertical bone regeneration obtained, b) complication rate, defined as the percentage of membrane exposures and c) evaluation of implant survival, success a…

A practical MRI-based reconstruction method for a new endocavitary and interstitial gynaecological template

2015

Purpose: There are perineal templates for interstitial implants such as MUPIT and Syed applicators. Their limitations are the intracavitary component deficit and the necessity to use computed tomography (CT) for treatment planning since both applicators are non-magnetic resonance imaging (MRI) compatibles. To overcome these problems, a new template named Template Benidorm (TB) has been recently developed. Titanium needles are usually reconstructed based on their own artifacts, mainly in T1-weighted sequence, using the void on the tip as the needle tip position. Nevertheless, patient tissues surrounding the needles present heterogeneities that complicate the accurate identification of these …

A new technique for the treatment of nasal telangiectasia using atmospheric plasma (voltaic arc dermabrasion): Postoperative pain assessment by therm…

2020

Background Nasal telangiectasias are superficial, small vessels in the ala nasi and nasolabial crease with a varying origin. They represent an unaesthetic condition, frustrating patients who frequently request their removal. Microsclerotherapy, electrosurgery, different types of laser therapy, needle-assisted electrocoagulation, and TRASER therapy have been described for treating this condition. Aims The aim of this study is to describe a novel technique that removes nasal telengectiasias using voltaic arc dermabrasion (VAD). Patients/methods Voltaic arc dermabrasion treatment was used to remove nasal telangiectasia in 23 patients. The post-treatment condition was monitored by means of phot…

Assessment of paradoxical anterior translation in a CR total knee prosthesis coupling dynamic RSA and FE techniques

2021

Purpose: The study aims were to assess the kinematic data, Internal-External (IE) rotation, and Antero-Posterior (AP) translation of the contact points between the femoral condyles and polyethylene insert and to develop a combined dynamic RSA-FE (Radiostereometric – Finite Element) model that gives results congruent with the literature. Methods: A cohort of 15 patients who underwent cemented cruciate-retaining highly congruent mobile-bearing total knee arthroplasty were analyzed during a sit-to-stand motor task. The kinematical data from Dynamic RSA were used as input for a patient-specific FE model to calculate condylar contact points between the femoral component and polyethylene insert. …

Red Flag for Cauda Equina Syndrome in Symptomatic Lumbar Disc Herniation

2020

Puncture of every mass lesion in the pancreas?

2004

3D virtual histopathology of cardiac tissue from Covid-19 patients based on phase-contrast X-ray tomography

2021

eLife 10, e71359 (2021). doi:10.7554/eLife.71359