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At least 829 records · Page 46Linked to original sources
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↗
PubMed1995

Computer-aided preoperative planning in knee osteotomy.

It has been demonstrated that osteoarthritis (OA) is activity related and may worsen when joint contact stress becomes excessive due to overloading. Hence, joint alignment and loading are considered to be the key biomechanical determinants for OA. The initiation of pathologic changes in the knee has been described by the mechanism termed, "vicious cycle" in which joint axial malalignment creates excessive stresses to the localized joint cartilage/subchondral bone regions and the surrounding soft tissue which in turn produces more laxity and joint deformity and thus repeats the cyclic degradation mechanism. If this degenerative cycle can be broken with joint alignment surgery such as osteotomy, a procedure to realign the knee joint and thus redistribute joint forces applied to each compartment, performed properly and at the appropriate time, the osteoarthritic disease process can be decelerated and even reversed. The main goals of this paper are to emphasize the importance of accurate preoperative planning for osteotomy in order to properly correct joint alignment, and to justify the application of an existing computer program, OASIS (Osteotomy Analysis and Simulation Software) using plain radiographs to perform appropriate surgical planning. Normal subjects and knee osteotomy patients were studied to establish a database for the purpose of establishing the utility and efficacy of the presently proposed concept. We wish to rationalize knee osteotomy as a preferred and cost-effective treatment for patients with early symptoms of OA in the knee. This paper presents a new concept of preoperative planning for knee osteotomy based on the underlying etiology of the disease and biomechanical viewpoint with strong emphasis on surgical treatment rationales. The established principles in this paper can be applied to other joints of the body and will help implement preventive measures and other non-surgical means to manage patients with axial malalignment or early degenerative changes.

Algorithms↗
PubMed1994

[Computer prognostication in surgery of choledocholithiasis].

The automatized value of treatment results and postoperative period course was done according to special programs in 218 patients with choledocholithiasis using the united computer system. Integral risk factors and four regressional patterns of postoperative period course were obtained using the factor analysis. Prognosis was quite right in 87,5-97,5% of patients.

Adult↗
PubMed1976

An analysis of potential physiological predictors of respiratory adequacy following cardiac surgery.

More than 50 potential physiological and clinical predictors of postoperative respiratory adequacy were examined in an attempt to identify those few variables which, singly or in combination, best predicted the outcome of the first trial of spontaneous respiration following cardiac surgery. This trial was initiated when patients seemed hemodynamically stable and relatively alert following surgery. Analysis of data from 124 patients identified the following useful predictors: forced vital capacity, total lung capacity, and maximal mid-expiratory flow rate from preoperative pulmonary function tests; resting cardiac index from preoperative cardiac catheterization; postoperative compliance and resistance measured by a computer-based monitoring system; postoperative vital capacity per kilogram, and maximum inspiratory force, measured at the bedside prior to the weaning trial. Stepwise linear discriminant analysis indicated that vital capacity per kilogram and maximum inspiratory force were the most useful predictors, the dividing line between successes and failures being represented by a vital capacity per kilogram of 15 ml. and a maximum inspiratory force of 28 cm. H2O. Mean values of successes were 18.3 +/- 7 ml. per kilogram and 30.7 +/- 9 cm. H2O and, for failures, 11.9 +/- 4 ml. per kilogram and 24.3 +/- 8.4 cm H2O. These physiological variables assess patient effort acting upon an abnormal pulmonary system. Measurements of passive pulmonary mechanics, cardiac function, and the measurement of arterial blood gases were suprisingly poor predictors.

Airway Resistance↗
PubMed1995

[Anatomical analysis of small bronchial arteries in front of the trachea by 3D-CT and digital subtraction angiography: implications for esophageal cancer surgery].

To preserve blood supply to the trachea and bronchus in the surgical procedure for esophageal cancer, anatomical characteristics of small bronchial arteries which course in front of the trachea were analysed by three-dimensional computed tomography (3D-CT) and digital subtraction angiography (DSA). In the 3D-CT study using five mediastina, three dimensional images of the bronchial arteries were reconstructed after the injection of contrast medium into the intercostobronchial arteries. Thus the detailed vascular network of the course of the small bronchial arteries in front of the trachea could be delineated. In the DSA study using seven mediastina, through this network of bronchial arteries, the branches originating from the aorta and the arteries supplying the cranial portion of the trachea could be viewed. These results indicate that the bronchial arteries are connected by a vascular network in front of the trachea. Based on these detailed findings, it is considered critical to avoid damage to the intercostobronchial artery and also the network of bronchial arteries in order to preserve blood supply to the trachea and bronchus.

Angiography, Digital Subtraction↗
PubMed1995

[3-dimensional computerized tomography in diagnosis and surgical planning of intracranial aneurysms].

Established alternative methods of visualisation of intracranial vessels--MR-angiography and angio-CT--give only two dimensional views similar to angiography. It is a subjective matter of the neurosurgeon's imagination to produce three dimensional views on the basis of these methods. Three dimensional processing of dynamic sequence or helical axial computed tomograms give any number you like of stereo-scopic views of the Willisi circulus. Comparing the usefulness of DSA and 3D-CT in 34 aneurysms, the latter often gives supplementary information concerning the direction, neck and adjacent arteries, helpful in planning surgery treatment. It is difficult or sometimes impossible to separate basal aneurysms (a.c.i.) from sinus cavernosus and skull base by this method, but especially in aneurysms located in the area of a.com.a. and c.m.a. the 3D-CT is sufficient for diagnosis and planning surgical treatment without DSA.

Angiography, Digital Subtraction↗
PubMedDate not supplied

[Late results of pathogenetically-oriented surgical treatment in congenital glaucoma and problems of medical rehabilitation].

Results of pathogenetical surgical treatment of congenital glaucoma were analyzed in late periods after surgery, from 1 to 17 years, in 105 patients (171 eyes). Ophthalmic tone normalization was attained in 87.5% of cases. High vision acuity was retained in 57.7% of cases. The principal causes of reduced central vision in process stabilization were astigmatism in 61.7%, amblyopia in 71.5%, strabismus in 59%, anisometropia in 22.8%. To improve vision acuity computer-aided pleoptic treatment was carried out in the postoperative period in 42 children (76 eyes). The efficacy of the method was 84.2%.

Age Factors↗
PubMed1994

[Evaluation of the aorta and supra-aortic vessels with spiral CT and 3-dimensional vascular reconstruction after operation of aortic isthmus stenosis].

Aneurysm formation, restenosis, and hypertension are well known complications after surgery for coarctation of the aorta (CoA). In order to assess long-term results, 46 patients were studied by spiral computed tomography and three-dimensional reconstruction after an interval ranging from 1 to 21 years (median 10 years) after surgery for coarctation. Spiral computed tomography showed pathological changes of the aorta in the majority of patients. Typical findings were ectasy or aneurysm formation of the ascending aorta, hypoplastic aortic arch, ectasy or aneurysm formation of the supraaortic vessels, circumscript aneurysm of the descending aorta at the side of surgery, restenosis of the descending aorta and malformations and anomalies of arterial vessels. In order to initiate adequate treatment of such specific complications as restenosis, aneurysm and/or arterial hypertension, regular controls are necessary in patients after surgery for aortic coarctation. In addition to clinical examination and besides magnetic resonance imaging and angiography, spiral computed tomography is an effective non-invasive imaging method for follow-up.

Adolescent↗
PubMed1994

Image analysis of the distribution of intraperitoneally administered fluids in patients with ovarian cancer.

Patients are selected for intraperitoneal chemotherapy based on the condition of the peritoneal cavity and the volume of residual disease, as determined by second-look surgery. Several techniques have been described to assess the distribution of intraperitoneal fluids. They rely on point, as opposed to area, measurements. We performed serial radionuclide scans of 15 patients undergoing intraperitoneal chemo for ovarian cancer. Scans were performed following intraperitoneal administration of 500-1000 ml of 99Tc-labeled human serum albumin in normal saline. Each patient underwent three scans at least 4 weeks apart. Radionuclide scans were digitized for computerized analysis. Area in picture elements (pixels) and optical density (mass) of the 99Tc-labeled regions were determined and analyzed for similarities in the pattern of distribution. Area analysis was used to divide the patients into two groups. Group 2 patients (n = 7) had more patients with < 0.5 cm of residual disease (P = .051) and no evidence of disease (P = 0.1) compared with group 1 patients (n = 8). No differences in overall survival were found (P = 0.21). No objective measurement of distribution of intraperitoneally administered fluids exists. Computer image analysis may be an improvement over static scoring techniques to assess non-invasive imaging studies.

Antineoplastic Combined Chemotherapy Protocols↗