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Biomedical subjects

H Friedburg

Publications and source records attributed to H Friedburg.

At least 37 records · Page 2Linked to original sources
PubMed1987

Sensitivity and specificity of brain stem potentials as a means of differentiating cochlear and retrocochlear disorders (acoustic neuromas).

Between 1980 and 1985 we examined a fairly large group of patients for retrocochlear disorders. Every patient was examined by at least two procedures, registration of brain stem potentials and CT; we had also magnetic resonance images taken of some of these patients. We diagnosed a total of 37 acoustic neuromas in 34 of the patients examined. From our study a conclusion can be drawn about the sensitivity and specificity of brain stem potentials as evidence of an acoustic neuroma. The rate of false negative diagnoses is about 6%. The false positive rate is considerably higher, and it is discussed in detail. The clinical utility of brain stem potentials is illustrated with two case histories. Because of the method's low false negative rate, cochlear disorders diagnosed by registering brain stem potentials need not as a rule be confirmed by modern imaging procedures.

Adult↗
PubMed1987

[Nuclear magnetic resonance tomography of the sacroiliac joint. A new examination technic in the differential diagnosis of rheumatic diseases of the lumbosacral transition].

25 patients with the clinical diagnoses of possible sacroiliitis were investigated by Magnetic Resonance Tomography (MR). Using axial or coronal tomography in a T1-weighted sequence (7 slices, 1 echo, NEX: 2, slice thickness 8 mm, TR: 600 ms, TE: 33 ms) and in a T2-weighted sequence (7 slices, 4 echos, NEX: 2, slice thickness 8 mm, TR: 1800 ms, TE: 33, 66, 99, 132 ms) we found normal sacroiliac joints in 10 patients, in 12 patients we diagnosed a sacroiliitis, in 3 patients a sacroiliac sclerosis. Descriptive evaluation and T2-calculation we showed, that MR is specific in differentiation of inflammation from sclerosis. The mean T2-relaxation time is 126 ms in healthy subjects, 320 ms in sacroiliitis and 87 ms in sclerotic areas. The results are significant in the Student-T-test (5% level). In addition the method allows the distinction of sclerosis from inflammation with a resolution of 2 mm. In evaluating sacroiliac rheumatic diseases MR may be helpful as a new imaging technique to complete the information of conventional radiography, computer assisted tomography and scintigraphy.

Adult↗
PubMed1987

[Medication and monitoring in young pediatric patients in NMR (nuclear magnetic resonance) studies].

Nuclear magnetic resonance (NMR) is a recently developed, noninvasive technique of increasing importance in pediatric diagnosis. In newborns and very young infants problems may arise with regard to adequate sedation and sufficient patient monitoring during NMR imaging. In 44 of 46 young pediatric patients sedation with oral promazine or rectal diazepam/intravenous ketamine provided good immobilization during NMR scanning. In two patients an additional drug was necessary in order to successfully complete the NMR procedure. Satisfactory monitoring of patients' respiratory motions was obtained by means of a simple optical system. Good cardiovascular monitoring was made possible by lengthening the rubber tubing of a blood pressure cuff. No complications were observed during the NMR-procedures.

Anesthesia↗
PubMed1986

RARE imaging: a fast imaging method for clinical MR.

Based on the principles of echo imaging, we present a method to acquire sufficient data for a 256 X 256 image in from 2 to 40 s. The image contrast is dominated by the transverse relaxation time T2. Sampling all projections for 2D FT image reconstruction in one (or a few) echo trains leads to image artifacts due to the different T2 weighting of the echo. These artifacts cannot be described by a simple smearing out of the image in the phase direction. Proper distribution of the phase-encoding steps on the echoes can be used to minimize artifacts and even lead to resolution enhancement. In spite of the short data acquisition times, the signal amplitudes of structures with long T2 are nearly the same as those in a conventional 2D FT experiment. Our method, therefore, is an ideal screening technique for lesions with long T2.

Humans↗
PubMed1986

Fat and water separation at 0.23 T using simultaneous shift selective imaging.

Based on the principle of selective inversion of the fat or water signal, we have developed a method which allows the simultaneous acquisition of separated fat and water images. In combination with multiecho techniques, this allows the determination of shift selective relaxation times. A detailed analysis of the relaxation behavior of a human leg at 0.23 T shows, that T2 of fat and water can differ by a factor of two or more. We think, that the potential of MRI for differential diagnosis can be greatly enhanced using our method.

Adipose Tissue↗
PubMed1986

Myocardial DNA content, ploidy level and cell number in geriatric hearts: post-mortem examinations of human myocardium in old age.

A reduced adaptation rate of the myocardium must, in many cases, be made responsible for heart insufficiency of old patients. The present investigations are aimed towards the question whether heart in old age is accompanied by a loss of myocardial cells and whether a polyploidisation of heart muscle cells takes place thus indicating an adaptive process. A total of 40 human hearts obtained from autopsy material were studied, among them 30 geriatric hearts. Following preparation of the hearts, the myocardium was weighed and the total amount of DNA was determined biochemically. By means of Feulgen cytophotometry the ploidy levels of the heart muscle nuclei were detected. We have used a special method for estimating the total number of heart muscle cells and connective tissue cells in the individual hearts. It could be shown that the total amount of DNA in the myocardium is correlated with the myocardial weight and not with the age of the individual. Instead, DNA synthesis occurs in the heart muscle cells of all age groups depending on the functional activity of the heart. The degree of polyploidisation is closely correlated with myocardial hypertrophy without any influence of age. In hypertrophic hearts the number of connective tissue cells increases from normally 4 to 5 X 10(9) to 12 X 10(9) (in hearts weighing more than 700 g); in hearts with interstitial fibrosis these values are even higher. In normal hearts 1.8 to 2.1 X 10(9) heart muscle cells can be estimated; in hearts weighing more than 500 g numerical hyperplasia of the heart muscle cells is produced, reaching a maximum number of 4.8 X 10(9) muscle cells in excessively hypertrophied hearts weighing more than 800 g. No correlation between age and myocardial cell number (i.e. heart muscle cells or connective tissue cells) could be observed. This means that no agespecific changes occur in the myocardium with regard to the DNA content and cell number. The structural changes found in the hearts of old individuals are produced by extracardial influences (i.e. arteriosclerosis, hypertension, etc.) leading to myocardial hypertrophy. Polyploidisation and augmentation of heart muscle cells in cardiac hypertrophy or decrease in the number of heart muscle cells in heart atrophy may occur at any time of life and are not age-specific.

Adult↗
PubMed1986

[Pathology of the craniocervical junction as shown by magnetic resonance tomography. 68 cases].

In cases of a suspected lesion at the level of the cranio-cervical junction, MR should be considered as the imaging technique of choice. Tumours, inflammation and degenerative processes can be reliably demonstrated and diagnosed. Administration of contrast media, for example, gadolinium-DTPA, is necessary in selected cases only. Comparing "examination time" of x-ray myelography and high resolution x-ray CT with MR, one can well tolerate the long "acquisition" of MR images.

Arnold-Chiari Malformation↗
PubMed1986

Magnetic resonance imaging of the cranio-cervical junction.

One hundred and thirty-three patients with a clinically suggested lesion of the cranio-cervical junction were investigated by magnetic resonance imaging (MRI). Based on pathologic findings in 68 cases, MRI is considered the diagnostic method of choice if a lesion of the cranio-cervical junction is expected. With this method it is possible to determine space-occupying lesions, and inflammatory, demyelinizing and degenerative changes. Only rarely contrast media are necessary in order to differentiate between tumor and tumor-edema.

Cervical Vertebrae↗
PubMed1986

Intracerebral cavernous angiomas in magnetic resonance imaging.

The findings obtained by magnetic resonance imaging (MRI) in 8 cases of surgically and histologically confirmed intracerebral cavernomas are reported. Six of the malformations were located temporally, one was located on the floor of the fourth ventricle, and one in the parietal lobe. All of the 8 cavernomas could be clearly demarcated, both in the T2 weighted image and in the spin density image. They are demonstrated as inhomogeneous zones with high or no signals. The tumors had irregular contours, which were clearly set off from the surrounding parenchyma. In 2 cases, the hemorrhage later detected surgically could already be assumed from the MR image. In 3 cases, zones with weak signals were found in the tumor, which were considered to be calcifications. One case of a vein with laminar flow could be established.

Adult↗
PubMed1986

[Diagnostic imaging potentialities of nuclear resonance tomography. Changes in vertebrae, ligaments and intervertebral disks in comparison with computed tomography].

This is a study of 49 patients with lesions of the spine excluding primary tumors of the spinal cord. All patients were examined by computed tomography and magnetic resonance imaging. Comparing both methods we observed slight diagnostic advantages for magnetic resonance imaging in inflammatory and neoplastic disease. Especially for evaluation of the spinal cord and subarachnoid space MR-imaging is far superior to computed tomography.

Adult↗
PubMed1985

Calculated T1 and T2 MR images and 31P MR spectra in rabbit thigh V2 carcinoma to monitor the effect of steroid administration.

T1 and T2 proton relaxation times in six rabbit thigh V2 carcinomas were obtained from regions of interest on calculated MR images at 2.35 tesla before and after steroid administration. Mean T1 and T2 values of viable tumor tissue decreased after steroid administration, consistent with decreased tissue water content. After steroid withdrawal, T1 and T2 values returned toward baseline. Relaxation times of peritumoral muscle tissue and normal contralateral thigh muscle essentially remained unchanged. In a separate experiment, six rabbit thigh V2 carcinomas were monitored before and after steroids by 31P spectroscopy using a surface coil. No substantial steroid-related changes were recognizable. A fall of the ratio of phosphocreatine to inorganic phosphate and a signal increase from phosphomonoester and phosphodiester compounds were observed during various stages of tumor growth. Analysis of 31P spectra changes and sequential measurements of relaxation times may prove valuable for assessment of tumor growth and therapeutic response in diagnostic oncology.

Animals↗
PubMed1985

[Low-field magnetic resonance tomography with an iron-shielded resistive magnet].

As an alternative to costly MRI systems with superconductive magnets, first experiences with an iron-shielded resistive system (Tomikon BMT 1100, Bruker Medizintechnik--Rheinstetten) are reported. The magnetic field strength is 0.235 T, corresponding to a proton resonance frequency of 10 MHz. Our system is used mainly for research, the image quality being comparable with that of superconducting systems. Especially favourable is the low magnetic stray field of the self-shielding system. It allows unproblematic handling of patients in a clinical environment. Economic aspects are not discussed.

Brain Diseases↗
PubMed1984

[Thin-layer NMR-imaging with a new T2-weighted 3-D-procedure].

Presentation of first experience with a new 3-dimensional data acquisition method. The new method yields sets of 120 continuous images of the head and brain in all 3 dimensions (slice thickness and spatial resolution both being 1.7 mm.) with a data acquisition time of 15 minutes. Depending on pulse sequences T1- or T2-images are available. Advantages and disadvantages are discussed.

Brain↗