Biomedical subjects

M Wiltgen

Publications and source records attributed to M Wiltgen.

8 recordsLinked to original sources

PubMed2004

Evaluation of the influence of image compression to the automatic discrimination of histological images of skin lesions.

OBJECTIVES: Telemedicine offers the possibility to get the opinion of an expert within a short time. To reduce data transfer via a network image compression is recommended. The disadvantage of error-free compression is a low compression rate. On the other hand an increased compression rate affects the information content of the image. In this study we evaluated the influence of the compression rate on the automatic discrimination of histological skin lesions in dermatopathology. METHODS: To be independent from subjective reviewing by a dermatopathologist we used tissue counter analysis (TCA) for automatic discrimination of skin tissue. TCA is based on the partition of the image into square elements where the features are calculated out of each square element. 40 cases of benign common nevi and 40 cases of malignant melanoma were used as the study set. First TCA was applied to the uncompressed images to check the discrimination power of the method. Then in the next steps the method was applied to the images with successively higher compression rates. For image compression the wavelet compression was used, where the compression rate was determined by neglecting wavelet coefficients with a magnitude below a given threshold. The number of remaining wavelet coefficients was used as criteria for the compression rate. RESULTS: This study shows that TCA allows automated discrimination even at higher compression rates where only 6-18% of the wavelet coefficients are used for image reconstruction. The recognition rate at higher compression is better for malignant melanoma than for benign common nevi. CONCLUSION: The power of automated discrimination is not essential affected by wavelet image compression.

Austria↗

PubMed2003

Tissue counter analysis of benign common nevi and malignant melanoma.

OBJECTIVE: The aim of this study was to evaluate the applicability of tissue counter analysis to the interpretation of skin images. METHOD: Digital images from microscopic views of benign common nevi and malignant melanoma were classified by the use of features extracted from histogram and co-occurrence matrix. Eighty cases were sampled and split into a training set and a test set. The images were dissected in square elements and the different features were calculated for each element. The classification was done by classification and regression trees (CART) analysis. In the CART procedure, the square elements were split into disjunctive nodes, which were characterized by a relevant subset of the features. The classification results were indicated in the original image in order to evaluate the performance of the procedure. RESULTS: For the learning set and the test set there is a significant difference between benign nevi and malignant melanoma without overlap. Discriminant analysis based on the percentage of 'malignant elements' facilitated a correct classification of all cases. DISCUSSION: Since no image segmentation was needed, problems related to this task were avoided. Though wrong classification of individual elements is unavoidable to some degree, tissue counter analysis shows a good discrimination between benign common nevi and malignant melanoma. CONCLUSION: In conclusion, tissue counter analysis may be a useful method for the interpretation of melanocytic skin tumors.

Diagnosis, Differential↗

PubMed1995

[A new concept in imaging pelvic recurrence of curatively operated rectal carcinoma--image fusion of nuclear magnetic resonance tomography and anti-CEA immunoscintigraphy (SPECT): technique and clinical example].

We present a new technique of image fusion (IF) of magnetic resonance imaging (MRT) and anti-CEA-immunoscintigraphy (Behring 431/26) and single photon emission computed tomography (SPECT). We performed SPECT and MRT within 8 hours on the same day. Glucagon intravenously was used to reduce artefacts due to intestinal motility. Before image fusion we analysed the SPECT and MRT images independently of each other. The MRT and SPECT were connected by a local area network (LAN) to a Gateway computer, which is also used as a picture archive. There a program automatically starts, translates the MRT data from the ACR/NEMA format to the Elscint one and these data are sent for image fusion to the nuclear medicine computer Elscint SP1. By means of a clinical example we present anatomic concordant superimposition and explain the findings and the clinical value of our technique. This system and technique are equally applicable to other digital imaging investigations. By IF, on the basis of the certain evidence of the tracer depot of a pathological lesion diagnosed by MRT and the reliability of the anatomical assignment of a focal lesion diagnosed by SPECT, early detection of local recurrence after surgical treatment of rectal cancer, the correct localisation of recurrent disease and its distinction from non-malignant tissue becomes possible. This enables planning of further therapeutical strategies.

Adenocarcinoma↗

PubMed1993

An integrated picture archiving and communications system-radiology information system in a radiological department.

In this report we present an integrated picture archiving and communication system (PACS)--radiology information system (RIS) which runs as part of the daily routine in the Department of Radiology at the University of Graz. Although the PACS and the RIS have been developed independently, the two systems are interfaced to ensure a unified and consistent long-term archive. The configuration connects four computer tomography scanners (one of them situated at a distance of 1 km), a magnetic resonance imaging scanner, a digital subtraction angiography unit, an evaluation console, a diagnostic console, an image display console, an archive with two optical disk drives, and several RIS terminals. The configuration allows the routine archiving of all examinations on optical disks independent of reporting. The management of the optical disks is performed by the RIS. Images can be selected for retrieval via the RIS by using patient identification or medical criteria. A special software process (PACS-MONITOR) enables the user to survey and manage image communication, archiving, and retrieval as well as to get information about the status of the system at any time and handle the different procedures in the PACS. The system is active 24 hours a day. To make the PACS operation as independent as possible from the permanent presence of a system manager (electronic data processing expert), a rule-based expert system (OPERAS; OPERating ASsistant) is in use to localize and eliminate malfunctions that occur during routine work. The PACS-RIS reduces labor and speeds access to images within radiology and clinical departments.

Austria↗

PubMed1992

[Computer-assisted mechanical ventilation of newborn infants].

Mechanical ventilation of mature or premature newborns is supposed to provide pulmonary gas exchange while causing minimal side effects to the respiratory system and circulation of the infants. A certain degree of alveolar ventilation, for example, can be achieved by different ventilator settings with different airway pressures (Fig. 1), and thus the corresponding effects on lung mechanics, barotrauma, and circulation differ. Parameters indicating optimal ventilator settings cannot be measured often enough in routine daily care and sometimes are difficult to interpret because of complex interactivity factors. The aim of the computer program "RespCalc" is to shorten the empirical steps of adapting respirator settings to the status of the ventilated patient by calculating the necessary data and drawing patient-specific nomograms. The computer program "RespCalc" makes use of the mathematical relationships characterizing the determinants of lung mechanics. The following data are necessary for use of the program: patient identification, weight, alveolar ventilation, recent paCO2, compliance, and resistance. By using the time-constant tau, the minimal inspiratory time as well as a maximal possible respirator rate are displayed without inducing inadvertent PEEP at a ratio of 1:1. Afterward, the planned figures of the different respirator rates and corresponding inspiration times must be typed in. The program simultaneously checks whether the previously calculated minimal figures for in- and exhalation time are maintained. If the above-mentioned figures and the typed-in ones differ, an optical and acoustical error message appears, and thus the user is forced to correct the problem.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed1991

[PACS: use in routine operations].

In the Department of Radiology at the University of Graz, parts of a picture archiving and communication system (PACS) are routinely used. The PACS includes 4 CT scanner, an evaluation console, an MR scanner, a diagnostic console with three monitors and an archive with two drives for optical disks. All the CT examinations are archived on optical disk. It is possible to store up to 26,000 images on one optical disk. The management of the archived images and the retrieval is done by a radiological information system (RIS). There are no problems with the transfer rates and network capacity. Failures that occur during the routine work may spread out and hamper the routine. Reporting on the diagnostic console is still not routinely accepted.

Austria↗

PubMedDate not supplied

Some software requirements for a PACS: lessons from experiences in clinical routine.

In the Department of Radiology of the University of Graz a PACS which includes CT-scanners as modalities was installed. Parts (communication and archiving) of this PACS are used in routine work. Summarizing our experiences from routine work we discuss a minimal set of software requirements that a PACS must meet to allow a fast and non-problematic operation concerning communication and archiving. Most of the functionality of the PACS is provided by software processes which are running automatically in the background. These processes convert images into the ACR-Nema format, submit data in the image database and so on. If a process does not work correctly or crashes, it may happen that examinations are only partially or even not archived. If the user recognises a malfunction too late the troubles spread over the whole system and great time delays or loss of data may occur. Examples of such malfunctions are software crashes, interruptions of the connection between 2 processes or a hardware crash. A PACS that is used in routine work should conform to a set of requirements like autonomous supervising of the single processes, automatical elimination of malfunctions, communication with the user and others. Then the PACS will operate without problems and safely. An intelligent process-structure which conforms to these requirements will be discussed.

Radiology Information Systems↗

PubMedDate not supplied

The PACS project in the radiology department of the LKH-Graz.

The PACS-project of Graz was started two years ago in cooperation with Siemens Erlangen. The system environment consists of three CT-devices (DR2, DR3, DRH) connected to an Ethernet-based LAN (CTnet), which is linked to a second Ethernet via a MicroVAX II. This computer works as a gateway, as an image-converter and as an archive. All CT-images of one device (DRH) are transmitted to the PACS system. The images are organized in patient-oriented folders. The physician is able to make reports about those examinations for which he is responsible. The availability of tools for secondary image processing during the reporting session (windowing, zooming, displaying statistic information, etc.) and further image-functions should make the PACS system more convenient for the physician than film-based images. After reporting, all scans which are relevant for the diagnosis (according to the physician's opinion) are selected, automatically reorganized in folders and transmitted to the archive. This needs about one to two minutes per examination. Some internal data-structures and further future aspects concerning the improvement of reliability and user acceptance are mentioned.

Database Management Systems↗