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Biomedical subjects

W Buchberger

Publications and source records attributed to W Buchberger.

At least 37 records · Page 2Linked to original sources
PubMed1999

Analysis of low-molecular-mass inorganic and organic anions by ion chromatography-atmospheric pressure ionization mass spectrometry.

Different nonvolatile mobile phases have been tested for the combination of ion-exchange chromatography combined with mass spectrometric detection of anions and organic acids. Buffer systems based on carbonate, sulfate, oxalate and citrate as the eluting species have been used. Among these, citrate proved to be the most versatile eluent allowing the separation of anions with absolute detection limits between 0.4 and 0.7 ng and of organic acids with detection limits between 0.4 and 4 ng in the non-suppressed mode. In the suppressed eluent mode iodate, bromate and chlorate could be separated using sodium carbonate as the mobile phase resulting in detection limits of 50 pg. The method was applied to the analysis of water samples containing oxyhalides originating from ozonization. Additionally, organic acids were separated by chromatographic separation techniques like reversed-phase, ion-pair or ion-exclusion chromatography and the compatibility with mass spectrometry was investigated with special respect to sensitivity of this detection mode.

Anions↗
PubMed1999

Optimization of conductivity detection of low-molecular-mass anions in capillary zone electrophoresis.

The optimization of background electrolyte compositions for capillary zone electrophoresis in combination with conductivity detection focusing on maximal detector response is discussed. A theoretical approach pointing out the influence of the electrolyte co- and counter-ion mobilities on the detector signal has been developed. Using this model, running buffer compositions providing optimum S/N ratios for the selected analytes could be calculated. The results derived from these examinations have been verified by experimental investigations, namely the determination of inorganic and organic anionic solutes.

Anions↗
PubMed1999

Combination of suppressed and non-suppressed ion chromatography with atmospheric pressure ionization mass spectrometry for the determination of anions.

Non-suppressed and suppressed ion chromatography in combination with atmospheric pressure ionization mass spectrometry are compared with special respect to sensitivity for the analysis of low-molecular-mass anions. Iodate, bromate, bromide, sulfate, thiosulfate and bromide could be separated by non-suppressed ion chromatography using a low-capacity anion-exchange column and ammonium citrate as mobile phase. Absolute detection limits between 0.4 and 0.7 ng could be achieved; employing a column requiring a flow-rate of 1 ml/min for optimum performance, splitting was necessary so that only 120 microliters/min entered the interface of the mass spectrometer resulting in detection limits between 0.03 and 0.06 mg/l. The same stationary phase (packed into a narrow-bore column which allowed operation without splitting) was suitable for the separation of oxyhalides in the suppressed mode with detection limits of 0.5 microgram/l (50 pg) with sodium carbonate as eluent. The method was applied to the analysis of drinking water for oxyhalides. The sample pretreatment for the removal of matrix anions (sulfate, chloride and hydrogencarbonate) is described.

Anions↗
PubMed1999

Incidental findings on sonography of the breast: clinical significance and diagnostic workup.

OBJECTIVE: The purpose of this study was to determine how often physician-performed high-resolution sonography can detect nonpalpable breast lesions not revealed by mammography. A sonographic classification scheme was tested for its accuracy in predicting malignancy of incidentally detected breast lesions. SUBJECTS AND METHODS: Six thousand one hundred thirteen asymptomatic women with breast density grades 2-4 and 687 patients with palpable or mammographically detected breast masses underwent sonography as an adjunct to mammography. All sonographically detected, clinically and mammographically occult breast lesions that were not simple cysts were prospectively classified into benign, indeterminate, or malignant categories. Diagnoses were confirmed by sonographically guided fine-needle aspiration or core needle biopsy. RESULTS: In 6113 asymptomatic women, 23 malignancies in 21 patients were detected with sonography only (prevalence, 0.31%). Five additional malignant lesions were found in patients with a malignant (n = 3) or a benign (n = 2) palpable or mammographically detected index lesion. The mean size of invasive malignancies detected only by sonography was 9.1 mm, which was not significantly different from the mean size of invasive cancers detected by mammography (p = .07). The sensitivity of the prospective sonographic classification for malignancy was 100%, and the specificity was 33.5%. CONCLUSION: The use of high-resolution sonography as an adjunct to mammography in women with dense breasts may lead to detection of a significant number of otherwise occult malignancies that are no different in size from nonpalpable mammographically detected lesions. Prospective classification of these lesions based on sonographic characteristics results in a significant reduction in number of unnecessary biopsies performed.

Aged↗
PubMed1998

Separation of inorganic and organic anions by capillary zone electrophoresis with simultaneous indirect UV and conductivity detection.

The analysis of low-molecular-mass anionic compounds using capillary zone electrophoresis (CZE) with simultaneous direct conductivity and indirect UV detection is described. A number of carrier electrolyte compositions has been investigated with respect to the crucial parameters for their compatibility with both detection principles discussed in this paper (UV absorptivity and electrophoretic mobility of the buffer coion). Additionally, parameters including pH and buffer concentration affecting both peak symmetry and signal-to-noise ratio obtained for the analytes of interest had to be optimized. Best results could be achieved with a carrier electrolyte consisting of 4-aminobenzoic acid, bis(2-hydroxyethyl)imino-tris(hydroxymethyl)aminomethane (BIS-Tris) and a pH of 7.0 adjusted with LiOH. This running buffer was used for the analysis of low-molecular-mass anionic compounds in a sample of white wine.

4-Aminobenzoic Acid↗
PubMed1998

[ACOnet (Austrian Academic Computer Network) as data carrier for teleradiologic consultations].

PURPOSE: To assess the feasibility of image transfer for teleradiologic consultations using the Austrian Academic Computer Network (ACOnet). The ACOnet corresponds between the main universities to a MAN (Metropolitan Area Network) with a transfer rate of 4 Mbps. Its use is free of charge for university institutions. MATERIALS AND METHODS: 1740 test image data sets and 620 image data sets for teleradiological consultations were exchanged without annotations between the Departments of Diagnostic Radiology of the universities of Innsbruck and Graz, using the ACOnet. RESULTS: Data transmission was reliable and fast with an average transfer capacity of 170.2 kBytes/s (94-341 kBytes/s). There were no major problems with image transfer during the test phase. CONCLUSION: Due to its high transfer capacity, the ACOnet is considered a reasonable alternative to the ISDN service.

Austria↗
PubMed1998

The Austrian Academic Computer Network and its usefulness for teleradiology.

To study the value of the Austrian Academic Computer Network (ACOnet) for teleradiology, 1740 test image data-sets and 620 image data-sets were exchanged between the departments of diagnostic radiology of the Universities of Innsbruck and Graz using the ACOnet service. Data transmission was reliable and fast with an average transfer capacity of 170 kByte/s (range 94-341). During the test phase, no major problems with image transfer occurred. Assuming that problems like security of patient data-sets, data compression and data verification can be solved, the ACOnet service would be a useful additional tool for telemedicine applications throughout Austria and eastern Europe.

Austria↗
PubMed1997

[Value of MR tomography in inconclusive mammography findings].

PURPOSE: To evaluate the usefulness of magnetic resonance (MR) imaging in the assessment of inconclusive findings at mammography, such as indeterminate focal or diffuse breast abnormalities, post-treatment breasts with extensive scarring, dense breasts, and findings suggesting multifocal or multicentric breast cancer. MATERIAL AND METHODS: 254 patients underwent mammography, sonography, and MRI of the breast. Dynamic MR imaging was done using a thin-section three-dimensional gradient-echo sequence (FLASH, TR = 11.8 ms; TE = 5 ms; flip angle = 25 degrees) which was applied in a dynamic fashion before and every 90 seconds after injection of gadopentetate dimeglumine. Diagnoses were confirmed at biopsy (n = 165) or by follow-up (n = 89). RESULTS: Among various breast anomalies, the highest proportion of breast cancers was associated with dense breast tissue (27.8%), architectural distortion (26.9%), and irregular scars (15.8%). Sensitivity of dynamic MR imaging was 93.7%, and specificity was 83.3%. As compared to mammography and sonography, MR detected 6 occult carcinomas, and showed additional malignant lesions in 19/63 women (30.2%) with biopsy-proven breast cancer. CONCLUSION: MR imaging of the breast may provide valuable additional information in indeterminate breast anomalies. However, because of its inherent limitations, it should not replace core needle biopsy in all lesions which are amenable to biopsy. Because of its high sensitivity in the detection of invasive carcinomas in any type of breast tissue, MR imaging is considered the modality of choice in the evaluation of dense breasts in high-risk patients or in patients with clinical suspicion of occult breast cancer, and for preoperative tumor staging.

Breast↗
PubMed1997

Radiologic imaging of the carpal tunnel.

Compression neuropathy of the median nerve (carpal tunnel syndrome) is the most common nerve compression syndrome of the extremities. Although the disease is usually diagnosed on the basis of clinical examination and nerve conduction studies, radiologic imaging plays an important role in equivocal cases and especially in the assessment of recurrent or unrelieved symptoms after surgical carpal tunnel release. While plain radiographs and computed tomography are of limited diagnostic value except for the evaluation of osseous carpal stenosis and soft tissue calcifications, high-resolution sonography and magnetic resonance imaging allow for direct visualization of the compressed median nerve and the other soft tissue structures of the carpal tunnel. Due to its excellent contrast resolution, magnetic resonance imaging is superior in detecting mild degrees of median nerve compression and in identifying potential causes of carpal tunnel syndrome, such as tenovaginitis of the flexor tendons or space-occupying lesions. However, the low cost and time requirement favor the use of sonography as the initial imaging study in evaluating the carpal tunnel.

Carpal Tunnel Syndrome↗
PubMed1997

Virtual computed tomography gastroscopy: a new technique.

BACKGROUND AND STUDY AIMS: The aim of the present study was to establish a suitable method for virtual computed tomography (CT) gastroscopy. PATIENTS AND METHODS: Three-millimeter helical CT scans of a pig stomach were obtained after air insufflation and instillation of diluted diatrizoic acid (Gastrografin), and with double contrast. In addition, three patients with gastric tumors were studied after ingestion of an effervescent agent (Duplotrast, 6 g) and intravenous injection of hyoscine butylbromide (Buscopan, 1 ml). Virtual endoscopy images were computed on a Sun Sparc 20 workstation (128 megabytes of random access memory, four gigabytes of hard disk space), using dedicated software (Navigator, General Electric Medical System Company). The endoscopy sequences were compared with real endoscopic examinations and with anatomical specimens. RESULTS: In the cadaver studies, the best results were obtained with plain air insufflation, whereas virtual CT gastroscopy with diluted contrast and with double contrast showed artifacts simulating polyps, erosions, and flat ulcers. Patient studies showed good correlation with the fiberoptic endoscopy findings, although large amounts of retained gastric fluid substantially reduced the quality of the surface reconstruction. CONCLUSION: These preliminary results show that virtual CT gastroscopy is able to provide insights into the upper gastrointestinal tract similar to those of fiberoptic endoscopy. However, due to the limited spatial resolution of the CT protocol used, as well as inherent image artifacts associated with the Navigator program's reconstruction algorithm, the form of virtual CT gastroscopy studied was not capable of competing with the imaging quality provided by fiberoptic gastroscopy.

Animals↗
PubMed1997

MR and CT anatomy of the axilla.

PURPOSE: To depict the complex anatomy of the axilla with CT and MR imaging. MATERIAL AND METHODS: The axillary regions of 2 cadavers (with arms hyperabducted) were examined by means of CT and MR. In this position the cadavers were frozen and cryosectioned. The anatomical sections documented by the MR and CT images were compared and anatomical structures were designated. To show the reproducibility of the anatomical structures and to find variations, 20 volunteers were also examined by MR, and 20 consecutive patients without axillary symptoms were examined by CT. RESULTS: The complexity of the axilla was excellently shown by both CT and MR, but MR was able to demonstrate more detail in the small vessels and in the brachial plexus. The comparability of the examinations of the different individuals was best in the axial plane. Some differences appeared in the coronal and sagittal planes caused by different positions of the arm. CONCLUSION: Axillary anatomy was demonstrated in detail and was reproducible with CT and MR imaging.

Adult↗
PubMed1997

A cost analysis of an emergency computerized tomography teleradiology system.

We carried out a cost analysis of a teleradiology system for emergency computerized tomography (CT) examinations. Teleradiology was implemented by connecting two spiral CT scanners in the University Hospital in Innsbruck and the Regional Hospital in Zwettl. It enabled the remote hospital in Zwettl to get fast and competent reports of emergency CT examinations when there was no specialist radiologist available. In 13 months' use for routine night and weekend service, the system proved fast and reliable. During the study period 121 emergency examinations of 116 patients were transmitted from Zwettl to Innsbruck. The fixed costs of teleradiology were for the ISDN connection and amounted to DM230 plus DM696/year rental. The average cost of one emergency CT examination by teleradiology was DM372 (range 308-453). One possible alternative, transporting the films by taxi for reporting elsewhere, was cheaper (estimated cost DM156), but would have been much slower. Another alternative, transporting the patient to the nearest central hospital for scanning, was much more expensive: DM524 by road or DM4667 by helicopter ambulance.

Austria↗
PubMed1997

[Virtual CT colonoscopy. Examination technique, limitations and perspectives].

Virtual CT-colonoscopy is a post-processing method which allows for reconstruction of inner bowel surface structures from helical CT datasets. The reconstructed images simulate the views which are known from fiberoptic endoscopy. Since colorectal cancer is the second main cause of death in USA and Europe today and since recent screening recommendations are often ignored by the public, a non-invasive or minimal-invasive procedure for colonic evaluation would offer some benefits. Virtual CT-colonoscopy generally involves three essential steps: patient preparation with cleansing of the bowel and administration of an air enema, helical CT-examination by using appropriate scan parameters, and interactive 3D rendering of the volume data-set. Although recent studies have demonstrated that polypoid lesions of about 5 mm size are well detectable and although virtual colonoscopy offers many advantages over fiberoptic endoscopy, some technical and clinical limitations must still be noted. Thus, the current inability of virtual colonoscopy to provide texture and color leads to problems in identifying flat lesions; the presence of retained or adherent fecal matter may result to false positive diagnosis and collapsed segments of bowel may cause problems as they cannot subsequently be evaluated during image reconstruction. Virtual endoscopy is still in its infancy and further technical and clinical developments are necessary. Virtual CT-colonoscopy may then prove to be equal or superior to colonoscopy in sensitivity and specificity for polyp detection and be able to reduce the number of unnecessary colonoscopic procedures.

Colonoscopes↗
PubMed1996

Rotation cryotomy: medical and scientific value of a new serial sectioning procedure.

Preparation of thin serial sections for comparative macromorphologic investigations has always represented a grave technical problem, especially in the case of regions in which bone as well as soft tissue are to be documented within their natural relations to each other in any desired sectional plane. Non-decalcified specimens up to the size of a whole cadaver are embedded in physiologic medium, precisely positioned, and deep-frozen to a specimen-ice block. A newly developed device, working on the basis of blades rotating at high speed, allows quick, successive removal of sections from the surface of the specimen block, with a thickness of each section infinitely variable between 0.1 and 5 mm. Following each cut, the new surface of the block can be documented photographically or on videotape for macromorphologic evaluation. So far more than 1,000 human, animal, and botanical specimens have been sectioned and evaluated with this method. In none of the cases were specimens damaged. Furthermore, any desired sectional plane could be adjusted: consequently a definite correlation between these sections and previous sonography, magnetic resonance (MR), or computed tomography (CT) images could be established. As serial cryosectioning becomes available to a far wider circle of medical and natural scientists, high-quality results should be obtained at lower costs.

Adult↗
PubMed1996

Speciation studies by capillary electrophoresis- Simultaneous determination of chromium(III) and chromium(VI).

A method for the simultaneous determination of chromium(III) and chromium(VI) by capillary electrophoresis (CE) has been developed. The chromium(III) has been chelated with 1,2-cyclohexanediaminetetraacetic acid (CDTA) in order to impart a negative charge and similar mobility to both the chromium(III) and the chromium(VI) species. The effects of the amount of the reagent, pH and heating time required to complete the complexation have been studied. Factors affecting the CE behaviour such as the polarity of electrodes and the pH of electrophoretic buffer have been investigated. The separated species have been monitored by direct UV measurements at 214 nm. The detection limits achieved are 10 microg/l for Cr(VI) and 5 microg/l for Cr(III) and linear detector response is observed up to 100 mg/l. The procedure has been applied to the determination of both chromium species in industrial electroplating samples and its accuracy was checked by comparing the results (as total chromium) with those of atomic absorption spectrometry. No interference occurred from transition metal impurities under optimized separation conditions. The method is also shown to be feasible for determining Cr(III) as well as other metal ions capable to form complexes with CDTA (like iron(III), copper(II), zinc(II) and manganese(II)) in pharmaceutical preparations of essential trace elements.

Journal Article↗
PubMed1996

Electrochemical detectors - tailormade techniques for liquid chromatography and capillary electrophoresis?

Electrochemical detectors for liquid chromatography and capillary electrophoresis are reviewed with special emphasis on electrode materials that allow the amperometric detection of otherwise non-electroactive compounds such as aliphatic alcohols, carbohydrates or amino acids. Noble metal electrodes can catalyze the oxidation of aliphatic compounds in alkaline media if multistep potential-time waveforms are employed. Various metal and metal oxide electrodes such as Ni, Cu or Co allow the detection of carbohydrates and similar compounds under constant potential conditions. Metallic copper electrodes operating in an amperometric mode or in a potentiometric mode can also serve as selective detectors for complexing species. A range of applications in combination with chromatography and electrophoresis is summarized. The current state of electrochemical detectors indicates that both amperometric and potentiometric detectors are on the verge of becoming tailormade detectors for micro-separation techniques.

Journal Article↗