[Problems of computer-oriented acquisition of "soft" medical data].
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Computers↗
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An improved video-based computer tracking system for soft biomaterials testing.
We present an improved video-based computer system for on-line tracking of small markers moving in a plane. The system consists of a CCD camera, a video monitor, a dedicated 80386/20 microcomputer, a video frame grabber, and custom software. Up to four markers can be tracked at the 30-Hz video frame rate using a two-step, correlation-based search procedure. We discuss the requisite hardware and software requirements and illustrate how this tracking system can be used to collect strain data during biaxial stretching tests on planar soft tissues. Operating at 30 Hz, this system is an improvement over those previously reported, which are either slower or yield less information.
Algorithms↗
Pre-operative assessment of soft tissue sarcomas by computed tomography.
The current trend towards limb-sparing surgery in patients with soft tissue sarcomas has increased the need for accurate pre-operative assessment of the primary tumour. Tumour site, extent and relationship to bone and neurovascular structures determine whether adequate radical surgery is feasible or whether more limited excision as a part of multimodality treatment is appropriate. Pre-operative computed tomography (CT) was compared with operative findings in 38 patients with soft tissue sarcomas. CT prediction of muscle group involvement by tumour was correct in 95 per cent and prediction of major artery or vein invasion was correct in 92 per cent and 97 per cent respectively. Assessment of tumour relationship to major peripheral nerve was accurate for thigh sarcomas but was not possible in upper limb tumours. While CT confirmed frank bony involvement in two patients, it failed to distinguish between tumours closely adjacent to periosteum and those with periosteal invasion. Detection of residual or recurrent tumour nodules is less reliable; CT is most accurate before any surgical intervention.
Adolescent↗
Detection of pulmonary edema in pigs: storage phosphor versus amorphous selenium-based flat-panel-detector radiography.
PURPOSE: To compare diagnostic accuracy of soft-copy selenium-based digital radiographic images and soft-copy computed radiographic images obtained for detection of pulmonary edema in pigs. MATERIALS AND METHODS: Oleic acid was injected intraatrially into three pigs (weight, 20-25 kg) at doses of 0.04, 0.05, and 0.06 mL/kg to induce pulmonary edema. Thirty-seven sets of computed radiographic, digital radiographic, and thin-section computed tomographic (CT) scans were obtained every 20-30 minutes in three pigs over 4-6 hours. Images were masked for identity, randomly sorted, and displayed on a monitor. Four radiologists rated each image for presence of parenchymal opacities by using a dichotomous scoring system in two sessions. Presence of pulmonary edema was determined with thin-section CT and a severity scale. Intra- and interobserver variations were determined with the kappa statistic and the Z test and with the Cochran Q test and the McNemar test, respectively. True-positive, true-negative, false-positive, and false-negative rates were determined. McNemar test was used to determine statistical significance of differences in detection between computed and digital radiographic images. RESULTS: There was no significant intra- or interobserver variation, except for one pair of observers during the first interpretative session with computed radiographic images (P =.016, McNemar test). Overall sensitivity (92.1%) and diagnostic accuracy (90.2%) of digital radiography were significantly higher than those of computed radiography (79.6% and 83.4%, respectively) (P <.001 for sensitivity, P =.01 for diagnostic accuracy, McNemar test). In detection of minimal and mild pulmonary edema, sensitivity of digital radiography (84%) was significantly higher than that of computed radiography (58%) (P <.001). CONCLUSION: Soft-copy digital radiographic images are superior to soft-copy computed radiographic images obtained for detection of mild pulmonary edema in pigs.
Animals↗
Patient specific finite element model of the face soft tissues for computer-assisted maxillofacial surgery.
This paper addresses the prediction of face soft tissue deformations resulting from bone repositioning in maxillofacial surgery. A generic 3D Finite Element model of the face soft tissues was developed. Face muscles are defined in the mesh as embedded structures, with different mechanical properties (transverse isotropy, stiffness depending on muscle contraction). Simulations of face deformations under muscle actions can thus be performed. In the context of maxillofacial surgery, this generic soft-tissue model is automatically conformed to patient morphology by elastic registration, using skin and skull surfaces segmented from a CT scan. Some elements of the patient mesh could be geometrically distorted during the registration, which disables Finite Element analysis. Irregular elements are thus detected and automatically regularized. This semi-automatic patient model generation is robust, fast and easy to use. Therefore it seems compatible with clinical use. Six patient models were successfully built, and simulations of soft tissue deformations resulting from bone displacements performed on two patient models. Both the adequation of the models to the patient morphologies and the simulations of post-operative aspects were qualitatively validated by five surgeons. Their conclusions are that the models fit the morphologies of the patients, and that the predicted soft tissue modifications are coherent with what they would expect.
Biomechanical Phenomena↗
[Computed tomography of the soft tissue of the neck. Lymph node metastases and their differential diagnosis].
Computed tomography is considered as the method of choice concerning N-staging in patients with known malignant tumours of the head and neck region. The application of an intravenous contrast medium (50 ml as a bolus, 100 ml as a fast infusion) is obligatory. In lesions of the neck with unknown histology the plain CT scan is important followed by the application of contrast medium, optional in form of a dynamic sequential CT. Calcifications, the densities pre and post contrast medium application, the curve of enhancement and the structure of the lesion are the important criteria of differential diagnosis.
Diagnosis, Differential↗
High resolution computed tomography, Part 1: Soft tissues of the neck.
Normal and pathologic anatomy of the soft tissues of the neck is clearly delineated with high resolution computed tomography (CT). The CT densities of soft tissues, fat, and enhanced blood vessels are strikingly different from each other and, therefore, mass lesions are clearly discernable. Often, a histologic diagnosis may be suggested with a high level of confidence based on the location and tissue characteristics.
Adult↗
[Role of x-ray computed tomography in infections of soft tissue].
The authors relate their own experience in 64 cases of soft tissue infection investigated by computed tomography: 25 lesions only located in soft tissue of the extremities and 39 associated with bone and/or joint lesions, including the spine. The describe CT findings of abscesses, "solid" infections and cellulitis. Advantages and bounds of the CT in this field are defined.
Abscess↗
Comparison of film, hard copy computed radiography (CR) and soft copy picture archiving and communication (PACS) systems using a contrast detail test object.
This paper describes two experiments where a widely available test object (FAXIL TO20) was used to compare film, hard copy computed radiography (CR) and soft copy picture archiving and communication systems (PACS) images. Baseline images were produced with a fixed mAs. All images were scored by four experienced medical physicists. Contrast detail curves for the three types of images were almost identical. A second series of images was produced with the mAs varying from 1 mAs to 250 mAs. The contrast detail curves were plotted for each mAs value and the wider exposure latitude of CR compared with film was demonstrated. Use of PACS provided no further increase in exposure latitude. The density of the film images increased with mAs but the density of the CR hard copy images remained constant. It is of concern that the wider latitude of the CR images extends to exposures that are much higher than those used for film with no noticeable change in CR image density but with better images at higher exposures, because the potential exists for patient doses to increase. Hard copy CR images provide information about the exposure index which relates to the input dose to the plate and hence approximately to the dose to the patient. However, since such information is currently not available on default soft copy images, the authors suggest that all manufacturers of PACS should provide an indication of dose as a mandatory default setting.
Evaluation Studies as Topic↗
Measurement of human tumour cell growth in soft-agar cultures using computer-assisted volume analysis.
Growth in soft-agar bilayer cultures of human tumour cells derived from 4 in vitro continuous cell lines, from 21 xenografts carried in athymic mice, and from 197 samples of fresh human solid tumours of various histologic types was analyzed by computer-assisted image analysis. Replicate cultures for each specimen were assessed on successive days of incubation for the number and volume of growth units within multiple size categories. Our results confirm the recent finding of others that there is an upper limit of approximately 10(9) microns 3 to the cumulative growth unit volume obtainable in a 2 ml bilayer soft agar culture system. Since this upper limit to the carrying capacity of the closed culture system exists, the extent of growth within the cultures is determined in a fundamental way by the cumulative volume of growth units initially inoculated into cultures. A growth index of greater than or equal to 16-fold was only seen when initial cumulative growth unit volume was less than 10(7) microns 3 per culture dish. Computer-assisted volume analysis (CAVA) appears to be a useful quantitative method to study the growth of human tumour cells in soft agar cultures.
Agar↗
Extracalvarial soft tissues in cranial computed tomography. Normal anatomy and pathology.
Computed tomography has emerged as the modality of choice for imaging soft tissues of the face and neck. However, the extracalvarial soft tissue anatomy has not been delineated. The CT appearance of normal anatomy and variants, including the cutaneous and subcutaneous tissues, muscle layers, and subgaleal space is described. A pathologic spectrum that includes congenital, inflammatory, traumatic, and neoplastic lesions is presented. When appropriate CT windows for viewing the extracalvarial soft tissues are utilized, significant clinical information may be provided.
Adolescent↗
Subcutaneous soft tissue densities: a computed tomography indicator of severe pancreatitis.
Twenty patients with known acute pancreatitis had 50 computed tomography studies. Those with severe pancreatitis showed streaky and fluffy soft tissue densities in the flanks and some in the gluteal regions. The appearance and disappearance of this finding correlates with the extravascular movement of fluid due to severe pancreatic inflammation.
Acute Disease↗
Ipsilateral irradiation for carcinomas of tonsillar region and soft palate based on computed tomographic simulation.
PURPOSE: To reduce xerostomia in selected patients with carcinomas of the tonsillar region and soft palate. METHODS AND MATERIALS: We evaluated the treatment results of 32 patients with tonsillar region and soft palate carcinoma treated by radical radiotherapy between May 1989 and December 1996. They have a unilateral tumor that did not cross midline and have no contralateral neck lymphnode metastasis and treated with an ipsilateral technique (an anterior oblique and a posterior oblique field). All patients were planned with computed tomographic (CT) simulation and given 65 Gy in 26 fractions in 6.5 weeks with or without 5-15 Gy boost irradiation. The median follow-up was 44 months (4-86 months). RESULTS: Five-year overall, cause-specific survival, local control, and regional control rate was 64, 79, 74 and 81%. No failure at the contralateral neck occurred. Moderate or severe symptomatic xerostomia was seen in 3 (9%) patients and ostero-radionecrosis requiring surgery occurred in one (3.3%) of 32 patients. CONCLUSION: It is suggested that the ipsilateral technique is indicated in patients who had an unilateral tonsillar region or soft palate carcinoma that did not cross midline and have no contralateral neck lymphnode metastasis.
Adult↗
Adhesion Probability of Colloidal Particles with Repulsive Soft Interaction.
Computer simulations of the irreversible adhesion of charged colloidal particles at a solid/liquid interface are performed to determine whether the distribution of particles in the vicinity of a preadsorbed (also charged) one follows the Boltzmann law applied to an a priori uniform adhesion probability, as first assumed by Adamczyk et al. (J. Colloid Interface Sci. 140, 123 (1990)). If true, this would indicate that the whole information on the deposition process is contained in the potential energy distribution on the adsorbing surface. In general, diffusion in a field of force and the irreversibility of the process induce significant deviations from the Boltzmann-weighted uniform adhesion density. Nevertheless, it is shown that for particles characterized by a small gravitational energy this procedure leads to a reasonable first approximation of the distribution of the particles over the adsorbing surface. This observation thus demonstrates the validity of Adamczyk's assumption and extends its range of applicability to the case of a weak gravitational field. Copyright 1999 Academic Press.
Journal Article↗
Soft-hard tissue correlations and computer drawings for the frontal view.
Hard and soft tissue measurements were obtained for nine Caucasian women. Based on these measurements, regression formulas were derived to approximate the soft tissue covering based on hard tissue data. The results are presented iconically by computer drawings. The preliminary data presented would suggest a definite predictable influence exerted by the facial skeleton on the position of landmarks in the overlying soft tissue.
Adult↗
The effectiveness of sequential medial soft tissue release on coronal alignment in total knee arthroplasty: using a computer navigation model.
Soft tissue management is a major step in total knee arthroplasty. We aimed to analyze the relationship between sequential medial soft tissue release and the resulting change in the anteroposterior limb axis and the tibiofemoral gaps. Measurements were obtained using a CT-free navigation system (Ci navigation system, DePuy I-Orthopaedics, Munich, Germany). Concerning leg axis, each release step led to significant (P < .001) effects. The highest effect was seen for the 6-cm release in extension and the release of medial collateral ligament in 90 degrees flexion. The medial gap difference was significant for each release step except the 4-cm release in extension. The highest increase resulted when sacrificing the entire posterior cruciate ligament in extension and in 90 degrees flexion. Implementation of computer-assisted surgery allows this first navigation-controlled study, elucidating the effect of soft tissue release in total knee arthroplasty.
Adolescent↗
Magnetic resonance imaging of soft-tissue tumors: comparison with computed tomography.
Twenty-seven patients with soft-tissue tumors were examined with a Picker 0.15-tesla resistive magnet and by computed tomography (CT). In all but one patient, MRI was better than or equal to CT in defining the anatomic extent of the tumor. We could determine whether major vascular structures were engulfed by the tumor in 80% of the MRI examinations but only in 62% of the CT scans. MRI and CT were equally effective in determining the presence or absence of bony invasion. The MRI images of all the tumors showed increased signal intensity relative to normal muscle when spin-echo (SE) pulse sequences with long repeat times were used (SE: echo time [TE], 60 ms; repetition time [TR], 2,000 ms). When T1 weighted pulse sequences were used (SE: TE, 30 ms; TR, 500 ms or inversion recovery: inversion time, 500 ms; TE, 40 ms; TR, 2,000 ms) the malignant tumors showed decreased signal intensity compared to normal muscle. Only lipomas showed high signal intensity on both T1 and T2 weighted pulse sequences.
Adolescent↗
Computed tomography analysis of bone tumors: patterns of cortical destruction and soft tissue extension.
Computed tomography was used to identify three different ways in which primary bone tumors may transgress a bony cortex. Analysis of the pattern of cortical transgression was used in conjunction with the presence or absence of matrix mineralization to classify correctly the lesion into one of four different diagnostic categories in 84% of 72 cases. These data demonstrate that certain types of behavior characterize the lesions under discussion and that this information may be helpful in diagnosis.
Bone Neoplasms↗