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T Wetter

Publications and source records attributed to T Wetter.

15 recordsLinked to original sources
PubMed2002

Semiautomated registration using new markers for assessing the accuracy of a navigation system.

OBJECTIVES: New markers are described that can be used for an improved registration procedure and for the exact comparison of navigation systems. The advantages of the markers are demonstrated, together with an automated segmentation algorithm for locating the centroid of the markers in image space. Compared to manual registration, this method shows an improved registration accuracy. MATERIALS AND METHODS: The new markers are detected completely automatically within all scan images. This allows a semiautomatic registration, as a preregistration is performed via the algorithm. Furthermore, the exact coordinates within one scan slice are now determined with the calculation procedure. The calculated data from the preregistration were matched up with a manual preregistration and some reference data, so as to confirm the quality of this new algorithm. The accuracies of several manual and semiautomatic registrations were also compared. RESULTS: The average deviation between the coordinates of the algorithm and the reference data (coordinate measuring machine) was 0.3 mm. The standard deviation amounted to 0.131 mm. Comparing several manual registrations with the reference data showed that the middle fiducial registration error (FRE) was between 0.7 and 2 mm. In comparison, the FRE remained constant at around 0.7 mm for the semiautomatic registration procedure. CONCLUSIONS: The measured results show a significant improvement in the preregistration data using the new markers together with the algorithm. This improvement leads to a reproducible and more accurate registration. The combination of the new marker type with the automated segmentation algorithm minimizes the human error factor, and provides the opportunity to directly compare image-guided and robotic systems.

Algorithms↗
PubMed2002

AIDA--experiences in compensating the mutual weaknesses of knowledge-based and object-oriented development in a complex dental planning domain.

OBJECTIVES: Dentistry is a discipline with two properties that pose a serious challenge to knowledge based decision support: (1) It has to integrate six subdisciplines ranging from conservative measures to invasive disciplines, such as implantology; (2) A plan may have to cover a complex treatment often lasting one year or more. It is the aim of the AIDA-project to set up a planning strategy that is suited to incorporate all dental peculiarities in one methodology. METHODS: Generic tasks, that can be assigned to individual persons involved in dental treatment, have been designed with the help of KADS. They have been integrated into a planning super-structure for the planning of all dental solution alternatives, that can principally be applied on the basis of the given patient status. RESULTS: Besides an evaluation of the implemented planning system itself, it has been evaluated how well the development is supported by (1) knowledge-engineering methods and (2) object-oriented methods. CONCLUSION: Common knowledge-based tools are not powerful enough for the planning of complex dental constructions. Therefore, a solution combining object-oriented and knowledge-based methods is proposed.

Artificial Intelligence↗
PubMed2000

Requirements for speech recognition to support medical documentation.

Recent advances in the development of automated speech recognition (ASR) have made routine applications for medical documentation possible. To achieve this, ASR has to be optimally integrated into the specific documentation scenario. The classification presented in this paper allows the definition of specification requirements. For two different documentation scenarios the appropriate product selection has been done according to this classification. Two evaluation studies are presented, addressing the usefulness of applying automated speech recognition.

Data Collection↗
PubMed2000

[Results of a survey on the use of guidelines in neonatology].

To assess the use of guidelines in neonatology we conducted a survey on hyperbilirubinemia in 185 German pediatric hospitals from June to September 1999. Of these 136 hospitals (73%) treating infants with hyperbilirubinemia responded. Specific standards or guidelines were used by 99% of participating hospitals. 49% of those used a hospital-based guideline, 54% the recommendations of the Gesellschaft für Neonatologie und pädiatrische Intensivmedizin, 24% another not further specified guideline. In 98% of the hospitals paper copies were used. In 21% of the hospitals the implemented guidelines were also electronically available. A coordinator for their guidelines was available in 51% of the hospitals, whereas 49% did not coordinate locally the use of their guidelines. In conclusion, guidelines should be well maintained and regularly updated in order that they do not lose their impact and significance. In addition, the potential of these concise summaries of medical expertise do not seem to be fully exploited.

Germany↗
PubMed2000

Physicians' attitudes towards health telematics--an empirical survey.

Telemedical networks and services have received high attention in professional and scientific media in the recent past. In Germany some institutions and few physicians volunteer in experimenting with diverse telemedical service offerings. However, much is speculated but little is known about attitudes and expectations of the majority of physicians in local offices towards this new medium. Therefore we conducted an empirical survey using a random regional sample to poll the respective opinions. Encouraged by a high response rate to our paper questionnaire, we offer as conclusion: that physicians are surprisingly realistic about costs and benefits and can therefore be expected to subscribe as soon as benefits become obvious; that this trend increases with offices being taken over or newly established by younger physicians; and that the establishment of networks of comprehensive care offered by health care professionals from different disciplines is regarded as essential future advantage of telemedical networks.

Adult↗
PubMed2000

IPHIE: an International Partnership in Health Informatics Education.

Medical informatics contributes significantly to high quality and efficient health care and medical research. The need for well educated professionals in the field of medical informatics therefore is now worldwide recognized. Students of medicine, computer science/informatics are educated in the field of medical informatics and dedicated curricula on medical informatics have emerged. To advance and further develop the beneficial role of medical informatics in the medical field, an international orientation of health and medical informatics students seems an indispensable part of their training. An international orientation and education of medical informatics students may help to accelerate the dissemination of acquired knowledge and skills in the field and the promotion of medical informatics research results on a more global level. Some years ago, the departments of medical informatics of the university of Heidelberg/university of applied sciences Heilbronn and the university of Amsterdam decided to co-operate in the field of medical informatics. Now, this co-operation has grown out to an International Partnership of Health Informatics Education (IPHIE) of 5 universities, i.e. the university of Heidelberg, the university of Heilbronn, the university of Minnesota, the university of Utah and the university of Amsterdam. This paper presents the rationale behind this international partnership, the state of the art of the co-operation and our future plans for expanding this international co-operation.

Curriculum↗
PubMed1995

L-dopa therapy of uremic and idiopathic restless legs syndrome: a double-blind, crossover trial.

We report the effects of a single bedtime dose of L-dopa 100-200 mg on sleep quality, frequency of periodic leg movements (PLM) and daily living in patients with idiopathic and uremic restless legs syndrome (RLS). Seventeen patients with idiopathic and 11 with uremic (on continuous hemodialysis) RLS were evaluated comparatively by polysomnography, actigraphy and subjective ratings in a randomized, controlled and double-blind crossover trial with L-dopa and placebo for 4 weeks each. Neurophysiologic assessments showed significant reduction of the number of periodic leg movements (p = 0.003) and the PLM-index (p = 0.005) most pronounced during the first 4 hours of bedtime after L-dopa (p = 0.001). Subjective evaluation confirmed improvement of sleep quality (p = 0.002) and showed significantly higher quality of life during daytime (p = 0.030) while the patients received L-dopa therapy. We conclude that L-dopa 100-200 mg proved to be effective in idiopathic RLS and for the first time under controlled conditions in uremic RLS without any severe side effects.

Adult↗
PubMed1994

Insomnia in generalized anxiety disorder: polysomnographic, psychometric and clinical investigations before, during and after therapy with a long- versus a short-half-life benzodiazepine (quazepam versus triazolam).

Within a double-blind, comparative study on the effects of the long-half-life benzodiazepine (BDZ), quazepam, and the short-half-life BDZ, triazolam, on clinical symptomatology, sleep and anxiety of 45 patients with insomnia based on a mild to moderate generalized anxiety disorder (GAD) (ICD-9 code: 307.42-1, 300,0; ASDC-APSS-Code: A.2.a), we compared, in a first step at baseline, drug-free polysomnographic and psychometric data of 22 patients recorded in the laboratory (L-group) and 21 patients recorded by the Oxford Medilog 9000 system at home (H-group) with those of normal controls. Sleep efficiency, total sleep time, wake within total sleep period (middle insomnia) and wake before buzzer (late insomnia) were significantly deteriorated in both patient groups as compared with controls, while sleep induction time only differed significantly in home recordings. Regarding sleep architecture, stage (S)2 was reduced, S3 and S4 increased in the H-group only, while no intergroup differences were seen in S1, SREM and REM latency. Subjective sleep quality was reduced in both patient groups, but not awakening quality. Psychometric tests in the morning demonstrated for the noopsyche, only a significantly deteriorated psychomotor activity in both patient groups. In the thymopsyche, evening well-being and mood in the morning were reduced in both the L- and H-group, affectivity and morning well-being only in the H-group. The psychopharmacological part of the study was completed by 40 patients (there were 4 drop-outs in the triazolam, 1 in the quazepam group). They were treated after 1 week placebo with either 15-30 mg (median 15 mg) quazepam or 0.25-0.5 mg (median 0.25 mg) triazolam for 4 weeks, and thereafter for 2 weeks with placebo. Anxiety (rated by HAMA and SAS) improved significantly with both drugs and remained improved throughout 2 weeks post-drug placebo, with quazepam being slightly superior to triazolam. Polysomnography demonstrated a shortened sleep onset only after quazepam. Sleep efficiency improved after acute administration of both drugs, but the improvement was maintained by quazepam only (tolerance development with triazolam). Rebound insomnia was observed only in the 1st post-triazolam placebo night (significant intergroup difference based on confirmatory testing). S2 increased, S3 + S4 decreased under and after quazepam, which represents a normalization in home-recorded GAD patients. S1 decreased with both drugs, SREM only under quazepam. Subjective sleep quality behaved very similarly to objective sleep efficiency. Awakening quality improved after acute therapy with both drugs, somatic complaints only with quazepam.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1984

Flow distribution in closed networks: minimal sets of measuring sites.

In microvascular research it is of great importance to know how the flow of blood is distributed to all the vessels in a capillary network. However, it is generally impossible to obtain simultaneous measurements of the flow values in all branches of a network. A method of selecting minimal subsets of branches is presented, by which the flow measurements in these branches can be used to compute the flow values in all other branches. It is sufficient to measure between half and one-third of the branch flows. The experimenter can also specify a subset of the branches as inaccessible to measurement; nevertheless the method allows him to decide whether determination of all flows is possible from the remaining branches, and in which branches the measuring devices should then be optimally placed.

Blood Flow Velocity↗
PubMed1983

Analysis of network flow distribution: computational aid to minimize experimental expenditure.

Several problems in microvascular research, e.g., total blood flow and red cell flux distribution, can only be solved by evaluating the flow distribution to all branches of microvessel networks. We present a method to obtain values of volumetric blood flow and red cell flux in individual networks by taking measurements in an adequately chosen number of the vessels (50-33%) in the network. Actual measurements are not mandatory in all vessels because in a major part of them computational quantification of flows and fluxes is possible. The proposed method consists of a procedure to document in matrix form the connections of a network found in a preparation. By appropriate mathematical manipulations of the matrix, a preselection of measuring sites within the network can be achieved. From the flow values in these sites the remaining vessel flows can be calculated by utilizing the law of mass conservation in all branching points and confluxes. The worst case error of the procedure can be calculated from the errors of the single measurements. The method can also be applied, whenever, for experimental reasons (e.g., poor microscopic focus, flow too rapid or too slow), certain branches do not lend themselves for measurement. A BASIC program can be made available upon request, which carries out all calculations necessary for an appropriate selection in such a short time (about 1 min) so that it can easily be performed before the start of data acquisition.

Animals↗
PubMedDate not supplied

AIDA: Web agents to support dental treatment planning.

Dental treatment planning is highly dependent on the educational background and personal experience of the dentist and on the thoroughness with which findings are taken. The objective of research in the AIDA (Artificially Intelligent Dental Agents) project is therefore the analysis of dental decision making and the design of a decision-supportive software module to test the decision-making process and make it transparent for both dentists and patients. In the AIDA project (aida.uni-hd.de), an expert system has been set up to identify treatment alternatives with integrated decision rationale for experts, practicing dentists, and eventually also patients. It is based on a top-down structure for dental decision-making, which was developed to standardize argumentation. For prosthetic dentistry, how one uses individual patient findings to arrive at possible treatment alternatives was clarified in greater detail. The planning rules for fixed prostheses have already been integrated into a software agent. Other modules should soon specify and verify these suggestions in terms of further fields of dentistry (e.g., restorative dentistry). In the near future, AIDA will be able to deliver dentally-founded justifications for every individual decision.

Decision Making, Computer-Assisted↗