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At least 685 records · Page 38Linked to original sources
PubMed1989

Computer-assisted two-dimensional echocardiography in preoperative evaluation of left ventricular function in patients with aortic valve disease.

Seventy-six healthy adults and 228 patients with aortic valve disease were studied by means of two-dimensional echocardiography (2D-EchoCG). Functional properties of the left ventricle in patients with aortic valve disease were studied by means of computer analysis of echocardiograms and patients requiring cardiac surgery were identified. It was found that an increased left ventricular (LV) end-systolic volume (110 ml and more), assessed by 2D-EchoCG, is an unfavourable prognostic sign, and elevated risk factor of cardiac surgery. It invariably proved to be related to LV dysfunction after the surgery. A decreased diastolic LV mass/volume ratio (1.255 and less), found in 16% of patients with pressure overload, means nonadequate development of hypertrophy and an elevated risk of cardiac surgery.

Adolescent↗
PubMedDate not supplied

Automated data collection and presentation in the operating room.

An 'Operating Room Data Integration System', is described which is used to collect, present and archive all important physiological parameters during open heart surgery. The system requires very little attention, and provides an easy to understand and coherent interface to the user. The system is adaptable to a large extend and thus data can be presented to the user in a manner, with which he or she is already familiar. Simple drivers can be written to enable connection of the system to almost any other piece of medical equipment, if the latter provides an analog or digital, output signal. Automatic logging of the acquired signals is then possible.

Computer Systems↗
PubMedDate not supplied

The causal diagnosis of obstructive jaundice. A Bayesian approach.

To compare the contribution of clinical, laboratory and imaging data for the diagnostic accuracy in establishing the cause of obstructive jaundice, the records of 333 patients operated on for a presumed obstruction of the biliary ducts were analysed. The final diagnoses, after surgery, were divided into six groups: stones of the gallbladder and biliary tract, pancreatic cancer, biliary tract neoplasms, ampullary carcinoma, postoperative stenosis of the bile ducts, intrahepatic cholestasis (biliary cirrhosis, chronic cholangitis) and other causes of jaundice (liver tumours, cysts, extended cancer of the upper abdomen). Twenty-three parameters (9 clinical symptoms and signs, 10 biochemical alterations and 4 imaging methods) were examined. Not every case had all the investigations performed but the number of each group of data was large enough to allow a statistically significant conclusion. The contribution of each of the 23 parameters in increasing the probability of correct diagnosis was determined using a computer program based on Bayes' theorem. This analysis showed that for patients which presented suggestive clinical signs and symptoms for stones of the gallbladder and biliary tract and for pancreatic cancer, the diagnosis can be predicted with a probability of 90% only on the basis of clinical findings. The probability of a correct preoperative diagnosis was increased to 99% by imaging methods. On the contrary, for patients with a less clear diagnostic probability (with ampullary carcinoma, intrahepatic cholestasis and other causes) only ultrasonography and computed tomography could increase the probability of correct diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Bayes Theorem↗
PubMed1988

The use of multiple logistic function to predict surgical risk.

A method for preoperative assessment of surgical risk, in function of several risk factors, was developed using the multiple logistic function, as a model of multivariate statistical analysis. This model has the advantage to express the two considered outcomes (perioperative complications and death) in numerical terms of probability. The data were obtained from 8630 consecutive patients admitted to 62 hospitals located in various regions of Italy. The patients were divided at random into two groups: group A (6040) was used to develop the method, and group B (2590) was used as control. The method is based on the role played by seven risk factors, that were shown to be significantly related to the two outcomes. These factors are age, systolic blood pressure, pathological changes of renal function, presence of concomitant diseases, estimated duration of surgical procedure, type (major or minor) and timing of surgery, (elective, delayed or emergency). The relative and independent role of each of these factors (beta) and the value of constant alpha were estimated by maximum likelihood method. The surgical risk is assessed by solving the multiple logistic equation, and multiplying the beta values by the corresponding individual coded values of the risk factors represented by the various x's. When the method was tested by applying the computed values of alpha and beta's to assess the outcomes in the control group, the predictions resulted highly accurate (r = 0.99). To simplify the calculation of surgical risk, in appendix a computer program in Basic, already predisposed to receive in code the individual values of x's, is reported.

Adolescent↗
PubMed1988

Computer graphics in medicine: a survey.

Increased interest is presently given to three-dimensional (3-D) medical applications due to simultaneous emergence of high-resolution imaging systems and computer graphics techniques. This paper intends to present a survey of this field together with discussion and prospective views. The general framework is composed of six parts: data acquisition and preprocessing, polygonal object representation, voxel description, system architecture, medical applications, and prospects. Data base acquisition includes characterization of imaging modalities and medical specificity. Preprocessing schemes are directed to improvements (filtering), windowing, and spatial anisotropy (linear or spline interpolation). The two following sections are devoted to descriptions of the main object representations. Particular emphasis is given to optimal contour approximation, surface triangulation, mathematical surfaces on one hand, and cuberille and voxel representations on the other. Display capabilities--hidden surface removal, surface normal shading, structure enhancement--and data base structuration--hierarchical and nonhierarchical (graph and tree encoding)--are, respectively, described. An overview of 3-D systems is further given (Section V), and features of medical applications are reviewed and gathered in basic functionalities, surgery, and radiotherapy specifications (Section VI). The last section provides some prospective views on reconstruction from a few projections, model-guided labeling, multimodality image overlay, and local image network. Some of these issues are illustrated by examples of 3-D images.

Computer Graphics↗
PubMed1988

[The PACS model plan at the Freiburg University Clinic. A first step toward a radiologic picture archiving and communication system].

In a study performed at several clinical departments of the University of Freiburg, West Germany, it was found that approximately 180,000 patient examinations based on computed tomography, magnetic resonance, nuclear medicine, ultrasound as well as digital and conventional radiography, produce over 1,000,000 pictures. It was assumed that modern technologies can greatly facilitate the handling of such a quantity of images. This applies to diagnosis and therapy planning as well as to communication and archiving of this large amount of data. The study also assumes that the technologies to be considered, e.g. fiber optical networks, optical archives and medical work stations, which represent the main components of PACS, should be introduced in a stepwise manner following a clear overall conception. As the first step the implementation of a local area network (LAN) in the departments of radiology and general surgery is planned. Important criteria for the selection of these particular departments are improvements in health care for a maximum number of patients and in the working profiles for the greatest possible number of physicians and assistant personnel. A cost reduction as compared to the present system through more efficient communication and archiving of the digital images is expected. New perspectives for medical research as well as for medico-technical developments are also expected. Examples are the 3-D representations of human anatomy and the manufacturing of custom-designed prothetic devices. Scheduling and budgetary plans for equipment and manpower are further study results for the Freiburg PACS-Project.

Germany, West↗
PubMed1985

In vitro computerized evaluation of biological cardiac prosthesis calcification.

The late valvular bioprostheses failure is mainly related to leaflet calcification. This study reports a new approach to testing the biological prostheses calcification applying a computerized technique to x-ray picture. A bovine glutaraldehyde-fixed bioprostheses (BB) was implanted in two sheep in mitral position. The experimental procedure was performed on valves explanted six months after surgery. The BB x-ray pictures were tested by means of a video display computer (VDC) that can process radiographic, photographic or microscopic images and also evaluate the optical density of image quantifiable. The calcification zone assumes different values according to the calcification degree. The VDC can colour the BB x-ray images and display them on monitors (one black and white, one colour) with the colours strictly related to the grey levels of the image.

Animals↗
PubMed1985

Computerized imaging for soft tissue and osseous reconstruction in the head and neck.

Recent developments in computer-aided medical imaging coupled with the related emergence of computer-aided design and manufacturing technology have had a significant effect on our management of patients with congenital and acquired head and neck deformities. In our institution, plain film skull radiography, cephalometry, and pluridirectional tomography have been largely replaced by high-resolution CT scanning augmented by planar reformations and three-dimensional surface reconstructions. A sophisticated computer-assisted radiologic imaging unit has been established to assist the surgeon and researcher. This marriage of advanced radiographic techniques, industrial computer-aided design technology, and clinical surgery have allowed us to better define aberrant anatomy, design new operative solutions for familiar as well as unusual problems, and quantitate changes of surgery and growth over time.

Adolescent↗
PubMed1981

Left ventriculometry: the Minnesota experience with a bioengineering approach.

Left ventriculography is used by cardiologists, surgeons, and pharmacologists. Cardiologists use it to assess ventricular function and to scan the results of longitudinal studies to follow the course of the patient. Surgeons employ the results to appreciate changes following surgery, as improvement postbypass, and to compare the effectiveness of alternative procedures or maneuvers. Pharmacologists examine the results to assess the consequences of drug administration. In patients with ischemic heart disease, left ventriculography is an indispensable adjunct to selective coronary arteriography, and it provides anatomic and functional information important for diagnosis and for predicting the outcome of the patient. Using the results from cine left ventriculography, it is possible to calculate the EDV, ESV, SV, and EF and thus to evaluate the pump function of the left ventricle objectively, quantitatively, and reproducibly. However, these measures indicate total left ventricular function. A more detailed analysis of the cine left ventriculogram can provide specific information about the impaired segments. Methods for measuring and calculating the volume changes of the entire left ventricle were described and illustrated with their clinical implementation. Five methods of determining regional myocardial wall motion were applied to a population of subjects with normal wall motion and to patients with abnormal wall motion. The method was chosen which agreed best with the visual assessment of the cine by experienced cardiovascular radiologists. Clinical applications of regional wall motion assessment were described. A computer-compatible data base was created for roentgen images of a normally and of an abnormally contracting left ventricle, and this data base was contributed to a national repository for computer-compatible data bases. An automatic pattern recognition method was used to determine whether regional wall motion was normal or abnormal, and it was able to distinguish between these two groups satisfactorily. Current trends in ventriculography were described. A bioengineering approach has been used to solve the problem of measuring and describing the wall motion of the left ventricle of the human heart. The approach has been applied to the analysis of the contraction of the whole ventricle, regional wall motion, and the temporal pattern of wall motion. The mathematical equations underlying the analysis have been given, explained, and illustrated with examples. The implementation of the analyses using computers was discussed. The assumptions and sources of error have received particular attention.

Angiocardiography↗
PubMed1995

[The value of 3D video endoscopy for surgical procedures].

We discuss the problems of spatial perception that arise by the transmission of endoscopic surgery by traditional video systems and analyse the improvements that can be achieved by two- und three-dimensional systems. Starting with a description of the physics of vision and the principles of two- and three-dimensional imaging, we demonstrate the importance of optimal adaptation of technology to the natural perception processes of the observer. In this context we review critically the technology that is presently available. Only stereoscopic video technology with 'shutter glasses' provides the observer with the spatial information that is of such decisive importance for minimally invasive surgery. Finally we discuss new technical developments that further improve three-dimensional vision in endoscopy, such as a 3D video module that is small enough to be used intracorporally.

Computer Peripherals↗
PubMed1995

[3-dimensional imaging of temporal bone structures using spiral CT. Initial results in normal temporal bone anatomy].

3D reconstruction of the temporal bone using spiral CT techniques was performed in 51 patients with various otological diseases during routine clinical work evaluation. The 3D display was optimized by a reduced study time and improved detail accuracy by special algorithms. We were able to demonstrate comprehensively in a 3D mode the normal anatomy of the inner ear and adjacent middle ear structures, such as the modiolus of the cochlea, the semicircular canals, the cochlear and vestibular aqueduct and the ossicles. We suggest routine 3D delineation of the substructures of the temporal bone prior to otologic surgery to provide the surgeon with a 3D view of individual anatomy and specific otosurgical sites.

Cochlea↗
PubMed1995

[Usefulness of 3-dimensional image analysis of skull base lesions].

We have evaluated three-dimensional (3D) images of the skull base lesions for planning cranial base surgery. Fifty 3D images were reconstructed from computed tomographies (CT), and/or magnetic resonance (MR) images or MR angiographic images of 30 patients with skull base lesions. These images have provided useful information for pre-operative evaluation. The 3D image reconstructed from CT provides clear information concerning the bone. Conversely, the 3D image from MR images demonstrates soft tissue very clearly, and that from MR angiography provides a detailed description of the vasculature. For skull base lesions, it is essential to evaluate 3D images from the different modalities, especially CT scan and MR image.

Adolescent↗
PubMed1995

Manometric vector volume analysis to assess lower esophageal sphincter function.

The resistance provided by the manometric high pressure zone at the gastroesophageal junction, is the major barrier against gastroesophageal reflux in man. Recent studies have shown that this high pressure zone has its correlate in the architecture of the gastric 'sling' fibres at the gastric notch and the semicircular 'clasps' at the lesser curvature side of the gastroesophageal junction. Pull-back manometry with radially oriented pressure transducers allows to assess these distinct components of the human lower esophageal sphincter. With the recent introduction of personal computers into the manometry laboratory, three-dimensional manometric images of the lower esophageal sphincter can be easily constructed, based on radially oriented pressures. The application of this new technology has shown that calculation of the sphincter pressure vector volume, i.e. the volume circumscribed by the three-dimensional manometric sphincter image, is superior to standard manometric techniques in the assessment of lower esophageal sphincter function. The sphincter pressure vector volume is a particularly helpful parameter to identify patients with gastroesophageal reflux disease who will not benefit from medical therapy and should consequently undergo early antireflux surgery. Vector volume analysis is also helpful in assessing the cause of recurrent symptoms in patients with previous antireflux surgery. In patients with achalasia three-dimensional sphincter imaging and vector volume analysis can illustrate a severely asymmetric and hypertensive sphincter and show the effect of myotomy with or without a concomitant antireflux procedure on the sphincter pressure profile.

Computer Graphics↗