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Biomedical subjects

F Träber

Publications and source records attributed to F Träber.

64 records · Page 4Linked to original sources
PubMed1988

[Artifact reduction via motion-compensating gradient shifting in MR tomography].

In 62 patients spinecho or gradientecho sequences compensated for motion were compared with corresponding non-compensated sequences. Compensation during MRT reduces those artifacts which are caused by regular motion. This is particularly effective during examination of the brain stem, spinal canal and the heart. The improved demonstration of the morphology of normal and diseases organs simplifies the analysis of the types of movement.

Brain↗
PubMed1988

[MR tomography of hepatic hemangioma].

MR tomography of the liver using 1.5 T has been carried out in 63 patients with focal lesions in order to demonstrate haemangiomas and to differentiate these from primary and secondary malignant liver tumours. This differentiation was possible in all patients, using conventional spin echo and inversion recovery sequences in combination with sonography. Accuracy was much less good when using gradient echo sequences. With sufficiently large tumours, measurement of relaxation time made possible diagnosis of all the 22 haemangiomas.

Adult↗
PubMed1987

[Rapid MR tomography of the liver. Technic and initial results].

The fast-field-echo (FFE) sequence provides a new rapid imaging method for MR tomography. By using gradient echoes with shorter high frequency pulse repetitions than conventional sequences with 180 degrees echo pulses, it is possible to produce single cuts in 10 to 20 s with good signal-to-noise ratio. In this way the liver can be examined while respiratory movement artifacts are reduced. The possibility of obtaining T1- and T 2-weighted FFE images with good contrast resolution and the ability to determine relaxation times suggests a wide application of this rapid imaging procedure in the diagnosis of liver disease.

Carcinoma, Hepatocellular↗
PubMed1987

[Modified T2-weighted gradient echo sequence for MR tomography of the CNS].

We introduced a modification of T2-weighted rapid sequence imaging which combines the advantages of conventional spin echo sequences with those of gradient echo sequences. It provides a method which is suitable for clinical routine use. Using a 1.5 Tesla field, one obtains good image quality with contrast comparable to spin echo sequences, while reducing the time taken to examine the brain to one-half and that of the spine to one-third. Our experience in 54 patients is described.

Brain↗
PubMed1986

[Diagnosis of lymphomas on the MR tomogram].

MR tomography provides images equal to, or superior to, CT of lymph node involvement in the thorax or abdomen. It may be possible to achieve tissue characterisation by means of T1 and T2 images. Chronic inflammatory diseases causing lymph node enlargement, such as sarcoidosis, show characteristic T1 intervals (about 650 msecs), whereas lymphomas show intervals of 900 msecs. Enlarged lymph nodes of low malignancy show lower T2 values (78 to 94 msecs), highly malignant show higher T2 values (83 to 145 msecs). Already we believe MR to be the method of choice in evaluating lymphoma and sarcoidosis.

Abdomen↗
PubMed1986

[MR tomography of hemophilic arthropathy of the knee joint].

The value of MR tomography in the diagnosis and follow-up of haemophilic arthropathy of the knee was studied in 40 examinations, using special surface coils. Good spatial resolution and reconstruction in various planes provide an accurate demonstration of the lesion, particularly of the intra-articular structures. Abnormalities of the synovia and of hyaline cartilage can be demonstrated. MR tomography is an important imaging method which is superior to sonography or CT in demonstrating complications resulting from the bleeding, such as effusions and haemarthroses.

Adolescent↗
PubMedDate not supplied

Determination of 1H relaxation times of water in human bone marrow by fat-suppressed turbo spin echo in comparison to MR spectroscopic methods.

Relaxation times of water were measured in human vertebral bodies by a fat-suppressed dual-echo turbo spin echo/turbo inversion recovery MRI sequence. Comparison was made with T1 and T2 values obtained by localized 1H-MR spectroscopy. The accuracy of the results and the diagnostic potential of the fast quantitative MRI technique were evaluated in 20 volunteers, 11 patients with osteoporosis, 6 patients with lymphoma, and 6 patients with bone marrow metastasis. No significant alterations of T1 and T2 relaxation times of water and fat were found in osteoporosis. With both methods, an increase in the T1 values of the water resonance by 16% was observed in lymphomas, which was highly significant (P < .001) in the MRS measurements, and an elevation by the same amount was obtained by the MRI sequence for the metastases (P = .040). A strong reduction of fat fraction was quantified by MRS in the tumorous cases. T2 of the water resonance increased by more than 30% (P < .003) in metastases. Water T2 values obtained by the MRI sequence showed systematic deviations from the MRS results, especially at short echo spacings.

Adipose Tissue↗
PubMedDate not supplied

Magnetic resonance spectroscopic and relaxometric determination of bone marrow changes in anorexia nervosa.

OBJECTIVE: The objective of this study was to assess and quantify bone marrow changes in patients with anorexia nervosa using 1H magnetic resonance spectroscopy and relaxometry. METHODS: The bone marrow fat fraction and the longitudinal and transverse relaxation times (T1 and T2, respectively) of water were measured in the lumbar and femoral marrow of 20 patients with anorexia nervosa and 19 healthy control subjects. RESULTS: Patients with anorexia nervosa showed significant hyperhydration and reduction of the fat fraction in their bone marrow, predominantly in the proximal femur. These changes were associated with hematological abnormalities. In a retest of seven patients after psychotherapy and gain of weight, the pathological changes in marrow proved to be largely reversible in correlation with the increase in body mass index. CONCLUSIONS: Fat depletion and excess of tissue water in the bone marrow in anorexia nervosa can be quantified by 1H magnetic resonance spectroscopy and relaxometry. The distribution of the pathological changes in the lumbar and femoral marrow follows the pattern of normal bone marrow conversion from hematopoietic to cellular during childhood.

Adolescent↗
PubMedDate not supplied

[Magnetization transfer contrast (MTC): optimizing off-resonance and on-resonance frequency MTC methods at 0.5 and 1.5 T].

AIM: To compare technical parameters and clinically relevant aspects of on- and off-resonance MTC sequences in mid- and high-field MR systems. MATERIAL AND METHODS: Both on- and off-resonance techniques were combined with an FFE sequence using 0.5 and 1.5 Tesla superconducting systems. Parameters were systematically measured by scanning a cadaveric knee joint. Signal-to-noise ratios and MT ratios for fat, cartilage and reference solution (copper sulphate) were determined. Minimal TR and the energy absorption rate were also compared. RESULTS: The MT effect at 1.5 T was more pronounced. However, using optimized parameters, clinically adequate MT contrast was achieved with both techniques and both MT units. The most important parameters for the off-resonance method are pulse angle and off-centre frequency; for the on-resonance method, pulse angle and number of composite pulse elements. Energy absorption was below 2 W/kg. Minimal TR was prolonged by up to 400%. CONCLUSION: In order to produce MTC images, optimized parameters should be applied. Using optimized pulse parameters, adequate MTC imaging is achievable with mid- and high-field systems using on- and off-resonance techniques. To ensure comparability of MTC studies, the pulse parameters need to be given, and, ideally, standardized.

Arterial Occlusive Diseases↗