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At least 127 records · Page 7Linked to original sources
PubMed1994

[Computed tomography in malignant primary soft tissue tumors].

The results of CT examinations in 36 patients suffering from histologically confirmed malignant primary tumours of the soft tissues are presented (6 rhabdomyosarcomas, 4 leiomyosarcomas, 6 liposarcomas, 4 malignant schwannomas, 5 malignant fibrous histiocytomas, 4 malignant haemangiopericytomas, 3 angiosarcomas, 1 fibrosarcoma, 1 renal sarcoma, 2 malignant mesenchymal tumours without histologically clear classification). The CT image alone will not yield information on the type of tumour or on the tumour status. However, CT continues to rank in the diagnosis of tumours of the soft tissues and is even superior to MR especially in the identification of gas accumulations due to infection in a tumour of the soft tissues that is otherwise unclear. Comparing the literature conclude that MR is now the imaging method of choice in the diagnosis of soft tissue tumours.

Adolescent↗
PubMed2003

Virtual reality simulator for vitreoretinal surgery.

AIM: To develop computer simulation of steps in vitreoretinal surgery using virtual reality technology. MATERIAL AND METHODS: A workstation with three-dimensional position tracking stylus was attached to a Pentium II desktop PC with a graphic accelerator. Computer algorithms were developed using Open GL and Microsoft Visual C++ languages to control the interaction and update the visual feedback tracking the instruments. Soft tissue computer modelling was carried out to mimic the removal of a vitreous opacity. Lens touch with the instruments was also detected. Mathematical modelling to allow for lens distortion was taken into account. RESULTS: A virtual reality computer model has been developed that can simulate initial steps of vitreoretinal surgery. Soft tissue modelling of the vitreous opacity and its removal by the vitrector was successfully simulated. The movements of the active and passive instruments in the dummy eye corresponded to the movements on the computer screen. On evaluation of the system, there was a minimal but discernable time lag between the stylus movement and the visual feedback. There was no tactile feedback when the lens touch was simulated. No further complex vitreoretinal surgery simulation was possible at this stage.

Algorithms↗
PubMed2002

The effect of perfusion on soft tissue mechanical properties: a computational model.

Some simple finite element models were constructed to investigate the magnitude and character of changes in mechanical properties of very soft tissues due to the loss of perfusion. Changes in the apparent stress-strain curve were used to characterise the effect of simulated blood perfusion pressure on the engineering stress-strain curve. The results indicated that the blood to tissue volume ratio and the perfusion pressure have the strongest effect on the effective stress-strain response of a representative tissue cell. Tissue viscoelasticity increased the sensitivity of the system to perfusion pressure changes.

Brain↗
PubMedDate not supplied

Magnetic resonance imaging versus computed tomography scan: accurate diagnosis of soft tissue lesions.

Due to their cost effectiveness and accessibility, computed tomography (CT) scans are being utilized when magnetic resonance imaging (MRI) appears to be the diagnostic technique of choice. Because of their availability, CT scans are still used for diagnosis of disc herniations. MRI may, however, be superior in its specificity. In taking into account the subjective complaint and orthopedic and neurological findings, a disk herniation can often be diagnosed without a CT scan or MRI. However, should the patient fail to respond to conservative care or show unusual symptoms, an MRI is indicated. This article discusses a case where MRI would be the imaging procedure of choice.

Adult↗
PubMed2001

A method for three-projection infant cephalometry.

OBJECTIVE: To assess morphology and growth in infants and children with craniofacial anomalies based on comprehensive digitization of radiographic films in three, mutually orthogonal projections. METHOD: The method consists of (1) acquisition of radiographic films in a highly standardized three-projection (lateral, frontal, and axial) cephalometer, (2) marking and digitization of a total of 279 anatomical landmarks in the three projections, and (3) computation and presentation (tabular and graphical) of 356 linear and angular variables describing the craniofacial morphology, including soft tissue. Computation of statistical entities describing a patient, a group of patients, the differences between patients or groups of patients was carried out. Error assessment of the method involved investigation of error distribution among a number of error sources. Duplicate digitization of radiographic films from 30 randomly selected patients, and from 10 dry skulls, was carried out to determine the errors contributed by the procedure of landmark digitization and the distribution of error among landmarks and variables, as well as between projections. RESULTS: The average error due to landmark digitization, s(i), determined by duplicate digitization and calculated by use of Dahlberg's formula was 0.8 mm for linear variables and 1.6 degrees for angular variables. CONCLUSION: This method of infant cephalometry has been shown to be highly accurate and reproducible, and it adds significant new potential for, e.g., asymmetry detection, population comparison, and growth measurements compared to other cephalometric techniques due to its standardized acquisition and digitization protocol, inclusion of an axial projection, and the large number of well-defined landmarks and variables involved.

Cephalometry↗
PubMed2002

Quantitative immunohistochemical evaluation of MIB-1 labeling index in adult soft-tissue sarcomas by computer-assisted image analysis.

We have found that the MIB-1 grade, based on tumor differentiation/histological type, necrosis and Ki-67 (MIB-1) score, is a valid and reproducible prognostic system for adult soft-tissue sarcomas. However, there are limited data available on Ki-67 labeling indices (LI) from adult soft-tissue sarcomas for testing the validity of quantitative image analysis. In this study, the records of 146 adult patients with soft-tissue sarcomas of the extremities and trunk were retrieved, and MIB-1 immunostaining was carried out for the grading. The counted MIB-1 LI values and the scores estimated from microscopic observation were defined as the gold standard. The correlation between MIB-1 LI as assessed by computer-assisted image analysis and by microscopic observation was determined. The image analysis -based MIB-1 LI was highly correlated with the microscopic observation-based MIB-1 LI (r = 0.87, 95% confidence interval (CI) = 0.82-0.92). In addition, agreement between the MIB-1 scores was very high (kappa statistic = 0.83, 95% CI = 0.75-0.91), as was the percentage agreement (89%, 95% CI = 82.8-93.6%) between the results from image analysis and microscopic observation. We conclude that quantitative immunohistochemical evaluation of MIB-1 LI by image analysis enables pathologists to improve interobserver agreement in the assessment of MIB-1 score, and can help to objectively assign the correct histological grade to cases of adult soft-tissue sarcoma, resulting in optimal clinical management.

Adult↗
PubMed1992

Microanatomy of the orbital apex. Computed tomography and microcryoplaning of soft and hard tissue.

PURPOSE: The anatomy of the orbital apex is characterized by a complex interplay between critical bony and neural structures. Traditional methods used to study this region include dissection, static sections, and computed tomography (CT). Tomographic techniques are very useful in understanding these complex relationships, but the resolution of conventional CT and magnetic resonance imaging (MRI) is not sufficient to recognize the intricate details of the optic nerve canal and associated structures. The purpose of this study is to determine the value of microcryoplaning and computer reconstruction in visualizing the orbital apex in detail not previously possible, at any orientation in three-dimensional space. METHODS: Microcryotomy of the orbital apex area was performed on cadaver specimens, and images of each cryosection were digitized. Subsequently, the lesser wing of sphenoid bone and optic nerve were outlined to allow for spatial manipulation and three-dimensional visualization of the orbital apex. RESULTS: The authors present reconstructed computer images of the orbital apex in coronal and axial planes with CT correlation. Clinically important anatomic points and landmarks as well as potential pitfalls are demonstrated. CONCLUSION: Microcryoplaning and computer reconstruction are useful techniques in viewing the detailed anatomy of the orbital apex. Although microcryoplaning has the limitation of poor soft tissue detail, the resolution of captured images is much greater than those obtained from CT or MRI scans; the improved resolution allows for accurate CT correlations. The technique has utility in education, surgical planning, and quantitative analysis of orbital apical anatomy.

Computer Simulation↗
PubMed2001

Detection of subtle pulmonary disease on CR chest images: monochromatic CRT monitor vs color CRT monitor.

To clarify the diagnostic efficacy of color soft-copy computed radiographic (CR) images of the chest in the detection of subtle pulmonary abnormalities. Twenty observers compared 87 soft-copy CR images on four types of CRT monitor (nonmagnified monochromatic CRT, magnified monochromatic CRT, nonmagnified color CRT, and magnified color CRT). Of 87 test images, 45 (including two identical sets of 12 images to test intraobserver variability) were abnormal and 42 (including two identical sets of 12 images) were normal. Of the 45 abnormal images, 15 showed subtle abnormalities, 15 showed mild abnormalities, and 15 showed obvious abnormalities. In the receiver operating characteristic (ROC) analyses, there were no statistically significant differences among the four types of CRT display formats in the detection of subtle abnormalities. Color CRT monitors can replace monochromatic CRT monitors without any loss in the ability to detect subtle interstitial lung disease.

Adult↗
PubMed1993

Visibility of foreign bodies in soft tissue in plain radiographs, computed tomography, magnetic resonance imaging, and ultrasound. An in vitro study.

We compared conventional plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) with respect to their suitability for detecting foreign bodies in soft tissue in an in vitro model using a cow tongue to simulate orofacial soft tissues. Four samples of different sizes of fractured tooth crown, pieces of amalgam, glass, asphalt, composite, dry wood, and stone were each embedded under a 2-cm-thick flap on the caudal surface of the tongue. Plain radiographs revealed all the materials except wood, and there was some variation in the subjectively evaluated radiopacity of the materials which indicated the nature of the foreign bodies concerned. MRI proved to be the least suitable imaging method, as particles with a metallic content gave rise to powerful interference artifacts. CT and especially US proved to be suitable imaging methods for foreign-body detection in soft tissue. Amalgam produced a metallic streaking artifact in CT, which visualized wood as gas density, and depicted all the other materials as similar hyperdense masses. Ultrasound was both sensitive and specific in detecting foreign bodies in soft tissue. The particles were better defined in form and size with CT and US than with MRI or plain radiography. We conclude that when plain radiographs, history, and clinical examination fail to reveal the presence of superficial foreign bodies, US or CT can serve as an alternative method.

Animals↗
PubMed2007

The computer-assisted sequential lateral soft-tissue release in total knee arthroplasty for valgus knees.

Soft-tissue management is a critical factor in total knee arthroplasty, especially in valgus knees. The stepwise release has been based upon surgeon's experience. Computer-assisted surgery has gained increasing scientific interest in recent times and allows the intraoperative measurement of leg axis and gap size in extension and flexion. We therefore aimed to analyse the effect of sequential lateral soft-tissue release and the resulting change in the a.p. limb axis on the one hand and the tibiofemoral gaps on the other hand in extension as well as in flexion in eight cadaveric knees. Measurements were obtained using a CT-free navigation system. In extension the highest increase compared to the previous release step was found for the first (iliotibial band, P = 0.002), second (popliteus muscle, P = 0.0003), third (LCL, 0.007) and the sixth (entire PCL, P = 0.001) release step. In 90 degrees flexion all differences of the lateral release steps were statistically significant (P < 0.004). Massive progression of the lateral gap in flexion was found after the second (popliteus muscle, P = 0.004) and third (LCL, 0.007) release step. Computer-assisted surgery allows measurement of the effect of each release step of the sequential lateral release sequence and helps the surgeon to better assess the result.

Arthroplasty, Replacement, Knee↗
PubMed1995

The accuracy of video imaging in orthognathic surgery.

Video imaging is an important emerging technology in planning orthognathic surgery and educating patients about the esthetic effects of treatment. The presurgical cephalograms of 56 patients, 41 with mandibular advancement alone and 15 with mandibular advancement plus genioplasty, were digitized, and the computer-generated soft tissue "line drawing" predictions were compared with the actual posttreatment cephalograms. Video images of the patients' presurgical lateral view were obtained, and two experienced clinicians compared the computer generated video image predictions with the actual posttreatment profile. Video images judged very good or excellent were considered acceptable for treatment planning; 60% to 83% met this criterion, depending on the profile area viewed. The percentage of acceptable images in the lower lip, labiomental fold, and chin area decreased with the addition of a genioplasty. The predicted and actual posttreatment soft tissue line drawings were quite similar for all areas except for the lower lip region, where statistically significant differences were noted, with the predicted lower lip more retrusive and thinner than the actual contours. For the lower lip and chin, a 2 mm or more discrepancy was observed in 20% of the patients. In all cases, the actual image was judged more esthetic than the predicted image, allaying fears of unrealistically optimistic computer generated predictions.

Adult↗
PubMed1989

[Single exposure energy subtraction chest radiography--clinical survey on utility of bone image].

The authors undertook a clinical study to determine the values and limitations of soft tissue subtracted image by dual-energy digital radiography. 573 patients were examined by dual-energy subtraction with a single exposure using computed radiography. Soft tissue subtracted image were found informative in 37 patients (6.5%) compared with non-subtraction image. It provided useful information about demonstrating calcification in pulmonary nodules, assessing the presence or absence of rib lesions, and excluding the possibility of pulmonary nodules.

Humans↗
PubMed2000

Three-dimensional magnetic resonance imaging of the orbit in craniofacial malformations and trauma.

Craniofacial malformations and trauma often lead to changes in orbital soft tissues, requiring surgical correction of both hard and soft tissues. Computed tomographic scans and 3-dimensional reconstructions are the optimal tools for evaluation of the bony structures. However, there is no equivalent method for the orbital soft tissues. The aim of this study was to establish a 3-dimensional magnetic resonance imaging (3-D MRI) technique that allows a differentiated visualization of the different types of soft tissue in the orbit. A total of 8 patients with different pathologic conditions of the orbit was examined. Five of these patients underwent secondary correction after trauma, and 3 had craniofacial malformations. The 3-D reconstruction was performed in the volume-rendering technique after acquisition of 3-mm axial slices. It was shown that a differentiated visualization of the orbital soft tissues is possible. Although the thin bony structures have a weak signal and, therefore, the imaging is poor, reliable reconstruction of the globe was achieved by different radiologists because of its circular delimitation from the bone. This technique is an additional support in the planning of orbital surgery.

Craniofacial Abnormalities↗
PubMed2000

Computer-assisted three-dimensional surgical planing and simulation. 3D soft tissue planning and prediction.

The purpose of this paper is to report a new technique for three-dimensional facial soft-tissue-change prediction after simulated orthognathic surgical planning. A scheme for soft tissue deformation, "Computer-assisted three-dimensional virtual reality soft tissue planning and prediction for orthognathic surgery (CASP)", is presented. The surgical planning was based on three-dimensional reconstructed CT visualization. Soft tissue changes were predicted by two newly devised algorithms: Surface Normal-based Model Deformation Algorithm and Ray Projection-based Model Deformation Algorithm. A three-dimensional color facial texture-mapping technique was also used for generating the color photo-realistic facial model. As a final result, a predicted and simulated patient's color facial model can be visualized from arbitrary viewing points.

Algorithms↗
PubMed2005

Computational simulation of penetrating trauma in biological soft tissues using the material point method.

The objective of this research was to develop realistic computational models for soft tissues subjected to finite deformation and failure, and to test these models in the context of numerical simulations of penetrating trauma injuries. A transversely isotropic hyperelastic model with strain-based failure criteria was used to represent the behavior of anisotropic soft tissue. The constitutive model was implemented into an existing numerical code based on the Material Point Method (MPM). The penetration of a low-speed bullet through a myocardium material slab was simulated and several wounding scenarios were analyzed and compared. The material symmetry, the type of contact modeled between the bullet and the soft tissue and the bullet speed were shown to have a significant influence on the wound profile.

Computer Simulation↗
PubMed1996

Phase-contrast X-ray computed tomography for observing biological soft tissues.

Biological soft tissues are almost transparent to hard X rays and therefore cannot be investigated without enhancement with a contrast medium, such as iodine. On the other hand, phase-contrast X-ray imaging is sensitive to light elements (1-8). This is because the X-ray phase shift cross section is almost thousand times larger than the X-ray absorption cross section for light elements such as hydrogen, carbon, nitrogen and oxygen (4,5). Hence, phase-contrast X-ray imaging is a promising technique for observing the structure inside biological soft tissues without the need for staining and without serious radiation exposure. We have devised a means of observing biological tissues in three dimensions using a novel X-ray computed tomography (CT) by modifying the phase-contrast technique. To generate appropriate CT input data, we used phase-mapping images obtained using an X-ray interferometer (6) and computer analysis of interference patterns (9). Now, we present a three-dimensional observation result of a nonstained sample of a cancerous rabbit liver, using a synchrotron X-ray source. Phase-contrast X-ray CT was able to clearly differentiate the cancer lesion from the normal tissue. Moreover, fine structures corresponding to cancerous degeneration and fibrous tissues were clearly depicted.

Animals↗