PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Soft Computing”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,261 records · Page 70Linked to original sources
PubMed1985

[Technic and results of spinal computed tomography in the diagnosis of cervical disk disease].

We give a description of a technique of the patient's positioning with traction of the arms during the cervical spinal computed tomography which allows to draw the shoulders downwards by about one to three cervical segments. By this method the quality of the images can be improved in 96% in the cervical segment 6/7 and in 81% in the cervical/thoracal segment 7/1 to such a degree that a reliable judgement of the soft parts in the spinal canal becomes possible. The diagnostic reliability of the computed tomography of the cervical disc herniation is thus improved so that the necessity of a myelography is decreasing. The results of 396 cervical spinal computed tomographies are presented.

Cervical Vertebrae↗
PubMed1992

Locomotory characteristics of fibroblasts within a three-dimensional collagen lattice: modulation by a helium/neon soft laser.

It has been postulated that low energy (soft) lasers can enhance wound healing. Considering the importance of cell locomotion in the wound healing process, we have studied the effects of a helium/neon laser upon the locomotory behaviour of a population of fibroblasts migrating within a three-dimensional hydrated collagen lattice. Statistical methods were used to quantify cell three-dimensional trajectories obtained using a computer-assisted tracking system. A two-minute exposure of embryonic fibroblasts to soft laser light decreased the speed and increased the frequency and duration of stops compared to controls. The locomotory phenotype induced in embryonic fibroblasts by the laser light resembled that of the developmentally older c20 fibroblasts, which are known to express a more mature locomotory phenotype. The relevance of these results to wound healing is discussed.

Animals↗
PubMed2005

Inflammatory sternal metastasis heralding lung cancer: two cases.

Bone pain due to bone metastases is a frequent presenting symptom of lung cancer. However, sternal metastases are unusual. We report two patients with inflammatory sternal metastases mimicking osteitis and indicating lung cancer. Chest computed tomography scan showed lytic lesion of the sternal manubrium invading anterior soft tissue. Diagnosis relied on histological examination of sternal biopsy and negative bacteriologic cultures. Local radiotherapy resulted in resolution of local signs.

Adenocarcinoma↗
PubMed2001

Image guided surgical navigation for removal of foreign bodies in the head and neck.

INTRODUCTION: The removal of foreign bodies in the head and neck area is often a surgical challenge due to a combination of difficult access and a close anatomical relationship of the foreign body to vital structures. Recent developments in computer-assisted surgery (CAS) have brought major improvements to the operating rooms for maxillofacial surgeons. The purpose of this paper is to report our experience in computer assisted removal of foreign bodies from the head and neck area, based on various clinical cases. PATIENTS: Computer assisted removal of foreign bodies from the head and neck area was performed in 11 patients. Three patients sustained gun shot wounds with remaining projectiles or fragments in the soft tissue. In six cases, objects related to a preceding surgical intervention were removed. Two patients presented with dislocated teeth in the facial or cervical soft tissues after 3rd molar surgery. METHOD: For surgical planning and intra-operative navigation, a computer based image guided surgery system (VectorVision(2), BrainLab) was used. RESULTS: In 10 of 11 cases the foreign bodies could be removed without major complications by a minimal invasive manner. More than 40 % of surgery time could be saved compared to similar interventions operated upon using conventional methods. CONCLUSION: In our opinion, the use of a computer based image guided surgical system is of great benefit when removing foreign bodies from the head and neck area. The minimally invasive access helps to prevent major complications such as injury to vital structures and allows a quicker operation.

Adolescent↗
PubMed1990

CT and MR assessment of tumors of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space using ROC methodology.

Neoplastic disease of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space requires thorough assessment of location and extension in order to plan appropriate treatment. This study evaluates computer tomography and magnetic resonance imaging in the workup of malignant and non-malignant tumors of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space in 76 patients. An attempt is made to characterize histopathology on magnetic resonance images by analyzing the signal intensities on T1- and T2-weighted images relative to muscle and brain tissue. The test performance of computer tomography and magnetic resonance imaging in the assessment of tumor extension are compared with receiver operating characteristic methodology. Although no definitive conclusions can be made as to the histopathology on the basis of the signal intensities on magnetic resonance imaging, some tumors show characteristic images. Receiver operating characteristic analysis of the performance of computer tomography and magnetic resonance imaging in the assessment of extension of neoplastic disease of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space, demonstrates no statistically significant difference in overall test performance. However, in evaluating regions involving predominantly soft tissue structures and comparatively large bony structures magnetic resonance imaging is superior to computer tomography, whereas in evaluating regions involving thin bony structures, computer tomography performs better than magnetic resonance imaging.

Adenocarcinoma↗
PubMed1997

Virtual bronchoscopy with perfluoronated hydrocarbon enhancement.

RATIONALE AND OBJECTIVES: Bronchoscopic computed tomography (CT) is limited by machine resolution and air-soft-tissue contrast. The objective of this study was to determine whether improving the contrast by using the contrast agent perflubron (PFOB) in the lung would improve the bronchoscopic CT technique and permit visualization of small airways. MATERIALS AND METHODS: Bronchoscopic CT was performed in an anesthetized 8-week-old New Zealand white rabbit before and after the endotracheal administration of PFOB. RESULTS: Bronchoscopic CT performed with PFOB permitted navigation of bronchi as small as 0.8 mm in diameter, which are much smaller than those that can be navigated without PFOB. CONCLUSION: In this example, the use of perfluorochemicals with bronchoscopic CT enhanced the capabilities of virtual bronchoscopy.

Animals↗
PubMedDate not supplied

Two algorithms for the three-dimensional reconstruction of tomograms.

Three-dimensional (3-D) surface reconstructions provide a method to view complex anatomy contained in a set of computed tomography (CT), magnetic resonance imaging (MRI), or single photon emission computed tomography tomograms. Existing methods of 3-D display generate images based on the distance from an imaginary observation point to a patch on the surface and on the surface normal of the patch. We believe that the normalized gradient of the original values in the CT or MRI tomograms provides a better estimate for the surface normal and hence results in higher quality 3-D images. Then two algorithms that generate 3-D surface models are presented. The new methods use polygon and point primitives to interface with computer-aided design equipment. Finally, several 3-D images of both bony and soft tissue show the skull, spine, internal air cavities of the head and abdomen, and the abdominal aorta in detail.

Algorithms↗
PubMed2001

Extending positron emission tomography scan utility to high-risk neuroblastoma: fluorine-18 fluorodeoxyglucose positron emission tomography as sole imaging modality in follow-up of patients.

PURPOSE: Although positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose ((18)F-FDG) has a major impact on the treatment of adult cancer, the reported experience with extracranial tumors of childhood is limited. We describe a role for PET in patients with neuroblastoma (NB). PATIENTS AND METHODS: In 51 patients with high-risk NB, 92 PET scans were part of a staging evaluation that included iodine-123 or iodine-131 metaiodobenzylguanidine (MIBG) scan, bone scan, computed tomography (and/or magnetic resonance imaging), urine catecholamine measurements, and bone marrow (BM) examinations. The minimum number of tests sufficient to detect NB was determined. RESULTS: Of 40 patients who were not in complete remission, only 1 (2.5%) had NB that would have been missed had a staging evaluation been limited to PET and BM studies, and 13 (32.5%) had NB detected by PET but not by BM and urine tests. PET was equal or superior to MIBG scans for identifying NB in soft tissue and extracranial skeletal structures, for revealing small lesions, and for delineating the extent and localizing sites of disease. In 36 evaluations of 22 patients with NB in soft tissue, PET failed to identify only two long-standing MIBG-negative abdominal masses. PET and MIBG scans showed more skeletal lesions than bone scans, but the normally high physiologic brain uptake of FDG blocked PET visualization of cranial vault lesions. Similar to MIBG, FDG skeletal uptake was diffusely increased with extensive or progressing BM disease but faint or absent with minimal or nonprogressing BM disease. CONCLUSION: In the absence or after resolution of cranial vault lesions, and once the primary tumor is resected, PET and BM tests suffice for monitoring NB patients at high risk for progressive disease in soft tissue and bone/BM.

3-Iodobenzylguanidine↗
PubMed2003

Truth cube: establishing physical standards for soft tissue simulation.

Accurate real-time models of soft tissue behavior are key elements in medical simulation systems. The need for fast computation in these simulations, however, often requires simplifications that limit deformation accuracy. Validation of these simplified models remains a challenge. Currently, real-time modeling is at best validated against finite element models that have their own intrinsic limitations. This study develops a physical standard to validate real-time soft tissue deformation models. We took CT images of a cube of silicone rubber with a pattern of embedded Teflon spheres that underwent uniaxial compression and spherical indentation tests. The known material properties, geometry and controlled boundary conditions resulted in a complete set of volumetric displacement data. The results were compared to a finite element model analysis of identical situations. This work has served as a proof of concept for a robust physical standard for use in validating soft tissue models. A web site has been created to provide access to our database: http://biorobotics.harvard.edu/truthcube/ (soon to be http://www.truthcube.org).

Animals↗
PubMed1997

[Imaging of the middle ear. CT and MRI].

High-resolution computed tomography (HRCT) provides excellent contrast between osseous structures, air and soft tissue in conjunction with high spatial resolution. Therefore, thin-section HRCT with bone window setting is the method of choice for the examination of the middle ear structures. The indications are acute and chronic inflammatory changes, cholesteatoma and tumor, the "postoperative middle ear", and malformations. In most cases, HRCT enables differentiation between inflammatory changes, cholesteatoma, and tumor. The excellent depiction of subtle osseous details enables the identification of erosions of the ossicles or of the bony walls of the mastoid cells, of osseous defects of the tegmen, of the bony labyrinth, and of the tympanic course of the facial canal. In addition, HRCT enables excellent depiction of reconstructions of the ossicles or prosthesis of the ossicles. Although HRCT is the first method of choice, magnetic resonance imaging (MRI) may provide additional information and lead to a more accurate diagnosis in some cases. This is explained by the excellent soft tissue contrast provided by MRI. In addition, MRI offers the possibility of using various pulse sequences and the administration of i.v. contrast material. Therefore, MRI may allow the differentiation between inflammatory changes, cholesteatoma, and tumor in those cases in which accurate diagnosis cannot be made by HRCT. The differentiation between a meningocele or meningoencephalocele and other entities such as tumors or cholesteatoma can be established by MRI. Furthermore, MRI can accurately depict cases of labyrinthitis or of neuritis of the facial nerve or of intracranial disease caused by middle ear processes, while this is not always possible by HRCT. In summary, HRCT of the middle ear is the method of choice, but MRI may provide supplementary information in those cases in which accurate diagnosis cannot be established by HRCT.

Ear Diseases↗
PubMed1995

Orthodontic camouflage versus orthognathic surgery in the treatment of mandibular deficiency.

Clearly, there are postpubertal patients with Class II malocclusions for whom orthognathic surgery combined with orthodontics is the "best" option, but epidemiologic information suggests they are a relatively small percentage of the potential patient pool. The majority of patients fall into either an orthodontic treatment group or a borderline category. Many of these can be treated successfully with orthodontic camouflage. Research has shown psychosocial factors play a major role in determining the patient's selection of a treatment option. This emphasizes the need for careful attention to global psychologic factors, with special emphasis on patient concerns regarding body image. Morphometric criteria have been offered describing appropriate candidates for orthodontic camouflage. These are supported by a combination of research and clinical experience. Patients who do not fit these criteria should not automatically be considered candidates for surgery. Psychosocial research suggests a percentage of these individuals place less importance on facial change and are content to improve dental esthetics and function to the degree possible. To assist in the decision-making process, patients should be given the best information available regarding potential outcome. Currently this may involve treatment simulation using a combination of computer images and dental models. Caution has been suggested, given the variability associated with predicting soft tissue change. There are additional legal concerns regarding the implied guarantee of treatment outcome. Correspondingly, the influence of this technology must be kept in perspective. Recent research on the decision-making process found computer imaging to be an important factor in only 24% of the patients studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Decision Making↗
PubMed2007

A theoretical framework to analyze bend testing of soft tissue.

It has been hypothesized that repetitive flexural stresses contribute to the fatigue-induced failure of bioprosthetic heart valves. Although experimental apparatuses capable of measuring the bending properties of biomaterials have been described, a theoretical framework to analyze the resulting data is lacking. Given the large displacements present in these bending experiments and the nonlinear constitutive behavior of most biomaterials, such a formulation must be based on finite elasticity theory. We present such a theory in this work, which is capable of fitting bending moment versus radius of curvature experimental data to an arbitrary strain energy function. A simple finite element model was constructed to study the validity of the proposed method. To demonstrate the application of the proposed approach, bend testing data from the literature for gluteraldehyde-fixed bovine pericardium were fit to a nonlinear strain energy function, which showed good agreement to the data. This method may be used to integrate bending behavior in constitutive models for soft tissue.

Animals↗
PubMed1989

Computed tomography of chest wall masses.

The authors argue that CT is superior to other imaging techniques for the examination of the bones and soft tissues of the chest wall. They also note the importance of CT in planning therapy for lesions involving these structures. In support of these theses they present computed tomograms showing 26 different types of lesion involving the chest wall ranging from sternal fracture to malignant fibrous histiocytoma. Malignant neoplasms involving the chest wall by metastasis or direct extension from the breast, lung or mediastinum are emphasized.

Humans↗
PubMed1990

Magnetic resonance imaging evaluation of congenital dislocation of the hips.

Magnetic resonance (MR) images were obtained preoperatively and postoperatively for 12 pediatric patients with congenital dislocation of the hip (CDH). The images were compared with arthrograms and computed tomography scans. The MR images were more accurate in defining soft-tissue anatomy, hip position, and obstructive factors to relocation. MR imaging is an efficient diagnostic tool in CDH.

Arthrography↗
PubMed1993

[Influence of various impression procedures for removable partial denture on displacement of soft mucosal tissue].

In the impression-taking procedure for the distal extension removable partial denture, the pressure produced at the interface of the soft mucosal tissue and the impression material is the most important factor for the stability of the saddle under functional load. However, a review of the literature revealed little information about the displacement of the soft tissue caused by the impression pressure. In the present study, to investigate the influence of various impression procedures on the magnitude of the soft tissue displacement more precisely, a new three-dimensional deformation measurement system was devised. Compared to the previous studies, the greatest advantage of the system is that the hardened impression material can be surveyed directly without substituting a dental stone. It was found that, in the investigation using a partially edentulous simulated model, the amount of the subsidence in the soft tissue was increased as the thickness of the spacer of the impression tray was reduced or the seating speed of the tray was fast. Especially in the buccal area, a large amount of vertical displacement was present compared to the midridge and lingual area. Thus it was suggested that many factors are associated with the form of soft tissue under impression loading.

Computer Simulation↗
PubMed2005

Orbital and maxillofacial computer aided surgery: patient-specific finite element models to predict surgical outcomes.

This paper addresses an important issue raised for the clinical relevance of Computer-Assisted Surgical applications, namely the methodology used to automatically build patient-specific finite element (FE) models of anatomical structures. From this perspective, a method is proposed, based on a technique called the mesh-matching method, followed by a process that corrects mesh irregularities. The mesh-matching algorithm generates patient-specific volume meshes from an existing generic model. The mesh regularization process is based on the Jacobian matrix transform related to the FE reference element and the current element. This method for generating patient-specific FE models is first applied to computer-assisted maxillofacial surgery, and more precisely, to the FE elastic modelling of patient facial soft tissues. For each patient, the planned bone osteotomies (mandible, maxilla, chin) are used as boundary conditions to deform the FE face model, in order to predict the aesthetic outcome of the surgery. Seven FE patient-specific models were successfully generated by our method. For one patient, the prediction of the FE model is qualitatively compared with the patient's post-operative appearance, measured from a computer tomography scan. Then, our methodology is applied to computer-assisted orbital surgery. It is, therefore, evaluated for the generation of 11 patient-specific FE poroelastic models of the orbital soft tissues. These models are used to predict the consequences of the surgical decompression of the orbit. More precisely, an average law is extrapolated from the simulations carried out for each patient model. This law links the size of the osteotomy (i.e. the surgical gesture) and the backward displacement of the eyeball (the consequence of the surgical gesture).

Algorithms↗