Biomedical subjects

W Bautz

Publications and source records attributed to W Bautz.

134 records · Page 8Linked to original sources

PubMed1976

[Anaerobic serum ultrafiltration--a new method for determination of protein-binding rates of drugs under physiological conditions (author's transl)].

Only the free and not the protein-bound fraction of a drug shows pharmacologic activity. Therefore the rates of drug-binding to serum proteins are of great importance for clinical and pharmacological purposes. A basis prerequisite for accurate measurements are experimental designs giving the possibility of keeping the most important factors influencing the protein-binding rate within physiological ranges. In vivo these factors are, among others, the concentration of albumin, the absorption of different exogenous and endogenous substances to albumin, the type and the amount of ions present, the total ionic strength, the pH-value and hence the pCO2 as well as the temperature. An experimental set-up was described giving the possibility of keeping all these factors absolutely constant under in vivo conditions by means of a newly developed and simply to handle ultrafiltration device. From withdrawing the blood sample from the vein to the complete separation of the protein-bound fraction the blood sample can be processed under strictly anaerobic conditions (to prevent loss of CO2!). Compared to common methods generally used for the determination of protein-binding rates, such as equilibrium dialysis, column chromatography and ultracentrifugation, this new procedure saves a considerable amount of time. Within 1 h up to 8 samples can be processed in a single device. Besides short filtration times there is no need for any additional sample preparation such as buffering or adding antibacterial substances, etc.

Blood Proteins↗

PubMedDate not supplied

Magnetic resonance angiography of the peripheral vessels in patients with peripheral arterial occlusive disease: when is an additional conventional angiography required?

The purpose of this work was to find out how often the clinician asks for a conventional angiography (CA) in patients with peripheral arterial occlusive disease (PAOD) after a magnetic resonance angiography (MRA) has been performed and how often the CA reveals additional information for therapy planning. Quality criteria for the MRA were defined and tested to see whether they can predict the need for an additional CA. In this prospective study, 81 patients suffering from PAOD (Fontaine classification IIa, n = 13; IIb, n = 33; III, n = 10; IV, n = 25) were examined with a 1.5-T MR-scanner with dedicated coils using a step-by-step technique. The vascular surgeon decided whether he could plan the therapy on the basis of the MRA or if he needed an additional CA. The MRA was assessed in terms of the image quality of the MRA and regarding therapeutic management of the patient in a two-grade scale: sufficient and insufficient. In 27/81 (33%) patients, the clinician asked for a CA, which revealed new information in only 11 patients. The relative number of MRAs with insufficient image quality was significantly higher (p < 0.01) in the group with additional information on CA (8/11) compared to the group without additional information (0/16). The assessment of an MRA based on image quality and regarding therapeutic management of the patient might reduce the number of CAs for therapy planning in patients with PAOD.

Aged↗

PubMedDate not supplied

MR diagnosis of vein of Galen aneurysmal malformations using virtual cisternoscopy.

Vein of Galen aneurysmal malformations (VGAMs) are rarely seen intracranial congenital vascular malformations with extremely complex vascular architectures. We present two newborns with an unclear intracranial mass being discovered in routine intrauterine ultrasonography. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) identified these lesions as VGAMs. Besides conventional MRA analysis, "virtual cisternoscopy"-a special kind of virtual endoscopy combining perspective volume rendering and motion-was applied to assess the intracranial vasculature. One newborn was treated by means of interventional neuroradiology with coiling of the median prosencephalic vein. The clinical outcome in this case was excellent. The other will undergo interventional therapy shortly.

Cerebral Veins↗

PubMedDate not supplied

Semiautomatic evaluation procedures for quantitative CT of the lung.

Accuracy, reproducibility, and objectivity are important in quantitative assessment of lung density and structure by CT, and the measurement has to be carried out under tightly controlled conditions. We therefore employ respiratory gating at defined levels of inspiration for CT scanning. In the evaluation process, we found operator-induced errors of 2-6 HU standard deviation for the relatively simple task of global lung density estimates; in regional evaluations, they frequently exceeded 10 HU. We therefore developed semi-automated evaluation algorithms that isolate lung parenchyma by fast contour tracking and define subregions by shrinking, radial segmenting, and anteroposterior subdividing of the left and the right lung. Global and regional mean density values and histogram parameters were extracted. Based on our clinical studies, we estimate that an overall precision of better than 5% can be achieved in quantitative CT of the lung with cooperative patients.

Algorithms↗

PubMedDate not supplied

[Body packing: the value of modern imaging procedures in the detection of intracorporeal transport media].

The necessity of rapid objective appraisal of the suspicion of intracorporeal drug smuggling (body-packing) by effective methods of investigation in the course of the first criminal investigation department measures raises the questions of suitable and admissible methods. The proportion of undetected crimes in intracorporeal narcotic smuggling must be rated as very high according to the data of the Federal Criminal Investigation Department. In the present paper, the suitability of various imaging techniques for drug detection are reported in terms of their risk, practicability and costs. For this purpose, the value of digital radiography, two-spectra radiography and X-ray computer tomography as compared to conventional X-ray investigations is examined in human experiments. A reality-oriented narcotics dummy (glucose pressed hard in preservative) was developed and administered to nine volunteers per os with a variable initial alimentary situation. Four radiograms were taken at fixed times up to 12 hours after administration with each imaging technique. The highest rate of detection was attained with computer tomography. In contrast to the other methods, more than 90% of the body packs could be identified here. Nevertheless, an application in criminal investigation practice cannot be recommended owing to various disadvantages. The recovery rate of the remaining methods is between 20% and 25%.

Adult↗

PubMedDate not supplied

Ultrasonic guided microbiopsy in mammary diagnosis: indications, technique and results.

Between 1992 and 1993, 307 ultrasonic guided highspeed core cut biopsies were performed. In 119 of the 307 women, we dispensed with further surgical and histological procedures when the tentative diagnosis from complementary mammary diagnostic procedures revealed no pathological findings and concurred with the histological results of the core cut biopsy. In 188 women, the biopsy was followed by surgical intervention and correlation of the histological findings. This group of patients showed a sensitivity of 98%, a specificity and positive predictive value of 100%, and a negative predictive value of 91%. If we combine the results of the complementary mammary diagnosis (including the core cut biopsy), then the sensitivity, specificity, and positive and negative predictive values for this surgically and histologically confirmed group of patients reach 100%. In trained hands, the ultrasonic-guided high-speed core cut biopsy is a reliable means for determining the histological nature of lesions detected in ultrasonic scans. This technique has been perfected in our facility. Along with preoperative carcinoma detection, it permits us to avoid unnecessary operations when, under defined conditions, there are no pathological findings.

Biopsy↗

PubMedDate not supplied

Magnetic resonance imaging in the diagnosis of local recurrences in breast cancer.

Breast conserving therapy (BCT) has turned out to be the standard procedure for the treatment of breast cancer. While the risk of local recurrences was reported as 1-2% or more per year after treatment, follow-up including clinical examination, mammography and even sonography is of priority. This study was performed to assess the efficacy of contrast-enhanced dynamic magnetic resonance tomography (NMR) for the diagnosis of local recurrences after breast conserving therapy, compared to palpation, mammography and ultrasound. In 33 patients local recurrences within the breast were diagnosed after breast conserving surgery. The sensitivity for the diagnosis of local recurrences after BCT was as follows: palpation (51%), mammography (67%), ultrasound (85%) and NMR (91%). All multicentric local recurrences were diagnosed by NMR. Mammography was not able to diagnose 11 local recurrences in radiodense breasts. Here ultrasound was able to diagnose 8 of 11 recurrences, while NMR was able to diagnose 10 of 11 recurrences. Therefore, ultrasound should be included into routine follow-up protocols after BCT to achieve an acceptable sensitivity for the detection of local recurrences. Under defined conditions and indications MRI is the best method to complement mammography and sonography with the highest sensitivity for the diagnosis of local recurrences in the radiodense breast.

Adult↗

PubMedDate not supplied

Magnetic resonance imaging and its role in the diagnosis of multicentric breast cancer.

Multicentric breast cancer is one of the most important contraindications for breast conserving therapy. While the sensitivity of mammography decreases in the dense breast, the present study was designed to assess the efficacy of contrast-enhanced magnetic resonance imaging (MRI) for the diagnosis of multicentric breast cancer compared to clinical examination, mammography and sonography. In 38 of 46 patients who underwent modified radical mastectomy, multicentric breast cancer was found histologically according to the definition of Holland et al The sensitivity for the diagnosis of multicentricity in breast cancer was as follows: palpation (47%), mammography (66%), sonography (79%) and MRI (89%). While MRI had the highest sensitivity, the specificity was the lowest showing 8 false positive enhancements (proliferative fibroadenomas, fibrocystic disease and papilloma). Compared to the other methods, MRI assessed the multicentric extent of breast cancer with the highest sensitivity which appears most important in radiodense breasts when breast conserving therapy is planned.

Breast Neoplasms↗