PubMed Health⌕ Search

Biomedical subjects

G Bielke

Publications and source records attributed to G Bielke.

13 recordsLinked to original sources
PubMed1989

[Intracranial hemorrhage in MRT].

About 10% of all intracranial findings in cranial MRI were hemorrhages, or findings associated with bleeding. There was great variation in the hemorrhages as a result of their location and their age, and this could disguise the underlying lesions. Therefore a knowledge of the typical appearance of spontaneous bleeding and tumor bleeding is necessary for interpretation of the MRI findings. During its course, cerebral bleeding shows all of the known interactions between biochemical and histological factors and MRI signal. Thus, an understanding of the variations during the clinical course of bleeding is helpful for a better understanding of contrast mechanisms in MRI.

Cerebral Hemorrhage↗
PubMed1988

[Gadolinium dimeglumine gadopentetate compared to CPMG sequencing and image synthesis].

The skulls of 46 patients were examined by means of ordinary scans and after contrast. 24 of these patients with cerebral abnormalities had scans, using identical planes, with and without contrast and with CPMG sequences. Contrast in intracranial, but extracerebral (extra-axial), tumours (meningiomas, neurinomas) was much better after using contrast, but intracerebral (intra-axial) tumours were mostly shown as well on T2-rated CPMG sequences. Image synthesis has shown that contrast uptake occurred only in solid tumour regions.

Brain Diseases↗
PubMed1987

[Definitions of pulse sequences and parameter weightings in the NMR tomogram].

Due to the different possibilities of image creation in MR tomography there is no clear terminology of pulse sequences and MR images. This paper tries to define the designation of pulse sequence parameters in a practical way and to specify the term "parameter weighting of MR images". Starting with general definitions, special definitions for CNS and liver are elaborated.

Central Nervous System↗
PubMed1987

[Initial clinical results of tissue characterization by T1, T2 and proton density in nuclear magnetic resonance tomography].

The NMR parameters (proton density, relaxation times T1 and T2) have been assessed by Carr-Purcell-Meiboom-Gill (CPMG) spin echo sequences. A computer assisted analysis of the data of 21 patients with cerebral tumours allowed a classification of tumour tissue in different tumours. The use of quantitative procedures for tissue characterisation allows the differentiation of benign and malignant brain tissue by characteristic colour coding demonstrating morphological details like tumour, edema and necrosis as well as indicating the histological types of the tumours of the central nervous system.

Brain↗
PubMed1987

[Reference substance for initialling the marker space in NMR tomography].

Dimethylsiloxane polymers are tested to serve as a reference medium in quantitative MR imaging. Simultaneously measured during the patient's examination, the reference data are used to normalize the intrinsic MR tissue parameters. This method helps to achieve interindividual comparability of tissue vectors which are defined by proton density, spin-spin and spin-lattice relaxation times, thus leading to a remarkable improvement in tissue classification.

Brain↗
PubMed1986

[Tissue characterization with T1, T2 and proton density: dream and reality].

A survey of the measurement values T1 and T2 based on radiological studies of the last two years shows a high degree of variation in these measurement values with regard to normal and pathological tissues of different organs and regions of the body. T1, which is dependent on field strength, is not suitable for interinstitutional comparison. At present the methods used for T2 measurements are so different from one another that the potential comparability of T2 cannot be realised. The combinations of T1 and T2--as presented in various radiological studies -show signs of tissue characterisation. The expected high degree of selectivity caused by using different measurement methods has not yet been confirmed. The measurement of T1 and T2 in lesions under drug and radiotherapeutic treatment seems to be informative in respect of prognosis.

Bone Neoplasms↗
PubMed1986

[Possibilities in using a specific pulse sequence (interlocking sequence) to improve the specificity in NMR tomography].

Methods and possibilities of application of a doubled and interlaced pulse sequence ("interlaced sequence") are discussed. This makes it possible to perform contrast variations and pulse sequence variations subsequently, as well as to determine the parameters proton density, T1 and T2. The selectivity of the combination of all three parameters for tissue classification is demonstrated by means of an individual case and seems to promise a higher specificity of MR tomography.

Brain Neoplasms↗
PubMed1985

[T2-analysis of normal and pathological structures of the head].

Analyses of T2 values (spin-spin relaxation time constant) in magnetic resonance tomography were carried out in 29 patients with brain tumours. 21 of these had tumours of the glioma group (17 astrocytomas WHO I-III and oligoastrocytomas, 4 glioblastomas). Measurements were effected both pixel by pixel and according to relevant ROI (regions of interest). Although the measurements yielded a T2 value which was typical of the disease, it was individually difficult to effect proper grading on account of the scatter occurring from case to case. Markedly more relevant information was obtained by the introduction of profile measurements in T2 images. The relation between T2 profile and histology of the gliomas permits rough grading between more or less differentiated gliomas.

Adolescent↗
PubMedDate not supplied

Information processing in nuclear magnetic resonance imaging.

An extended image analysis and classification system is presented to discuss the principal composition of the components as well as the methods of its realization in the field of reference based NMR diagnostics and tissue characterization.

Brain↗
PubMedDate not supplied

A method for optimization of pulse sequences in NMR-imaging.

The diagnostic quality of NMR-images is very much dependent on the pulse sequences and the associated parameters. Therefore, one could use pulse sequences as 'electronic contrast media', if one knew the interrelation between the appearance of pathological alterations in NMR-images and the pulse sequences used. A method is demonstrated which allows a simulation of NMR experiments in the computer, based upon two measurements of one single plane with different recovery times. During this procedure, proton density-, T1- and T2-pictures are calculated and a systematic parameter variation can be done with any programmed pulse sequence equation, by calculating new pictures with different contrast. Even virtual images which cannot be achieved by real NMR experiments can be created. In some cases these virtual images have advantages over real NMR-pictures which are demonstrated. The method may be helpful by answering the questions about optimal parameters and may be one step towards a standardization in NMR-imaging.

Brain Neoplasms↗