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Biomedical subjects

H P Higer

Publications and source records attributed to H P Higer.

At least 37 records · Page 2Linked to original sources
PubMed1988

Magnetic resonance imaging of dysraphic myelodysplasia. Findings in 56 children and adolescents with postrepair meningomyelocele.

The spinal cord in 56 children and adolescents was examined by magnetic resonance imaging (MRI) many years after neonatal surgery on a meningomyelocele (average age 12 years). In a high percentage of cases, the diagnosis "tethered cord" was made. Associated anomalies were found with a frequency of 21%. Typical findings are presented and the impact of these results on therapy planning is discussed.

Child↗
PubMed1988

Errors in T1-determination using multislice technique and Gaussian slice profiles.

Multislice SE- or IR-sequences with different TR- and T1-times, respectively, are often used, to determine T1- and T2-values for tissue characterisation. To investigate the perturbating influence of the sequential excitation in multislice technique, we measured the signal intensities and calculated the T1-values of phantoms as a function of gap widths between neighboured slices. Phantoms contained fluids of different T1. We found a strong dependence of signal intensities and therefore of calculated T1-values on the gap width, when a T1/TR-ratio of more than 0.3-0.4 was reached. T1-values are considerably overestimated in this case, whereas T2-values are not influenced by the sequential excitation. We conclude that reliable T1-measurements necessitate a large spacing of more than 1 slice thickness between adjacent slices.

Humans↗
PubMed1988

[MR tomography in tumors of the posterior cranial fossa in childhood].

MR tomography was performed on 23 children with tumors in the posterior fossa. In 14 cases, the MR tissue parameters were determined. Astrocytomas can be easily differentiated from medulloblastomas and ependymomas on the basis of their localization and signal intensities. Grading of astrocytomas and distinction between medulloblastomas and ependymomas was not possible. Because of high tissue contrast, multiplanar imaging and minimal artifacts, MR proved to be the method of choice for planning surgery and for the follow-up of tumours in the posterior fossa.

Adolescent↗
PubMed1988

[MR tomography of thoracic and abdominal tumors in childhood and adolescence].

MRI was performed on 25 infants, children and adolescents with thoracic and abdominal tumours. The specific contribution of MRI to diagnosis, treatment planning and therapy monitoring is demonstrated. In some cases the T1 and T2 relaxation times were determined; this may clarify the different signal intensities of tumour and neighbouring organs and contribute to differentiation between Wilm's tumour and neuroblastoma.

Abdominal Neoplasms↗
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↗
PubMed1988

[Results of nuclear magnetic resonance tomography studies in endocrine orbitopathy].

Magnetic resonance imaging (T1- and T2-weighted) was performed in 65 patients with Graves' disease. In addition, T2 relaxation times of each ocular muscle were measured. Of the muscles thus studied, 54.8% showed a thickening in coronary tomograms. An interaction between the optic nerve and the thickened ocular muscles at the apex of the orbit was suspected in 30.1%. It could not be confirmed that the thickening of the muscles and the T2 value were related. However, there was a high correlation between the rise in intraocular pressure and the T2 relaxation time. These results imply that the T2 relaxation time is extremely useful in interpreting the activity of Graves' disease and provide a diagnostic tool of prognostic value in monitoring and treating this disease.

Adolescent↗
PubMed1987

[Proton spin tomography in childhood. Experience with 407 studies in 275 children and adolescents].

Over a period of three years magnetic resonance imaging (MRI), mostly neuroradiological, was performed 407 times in 275 children. It was found that MRI largely replaced previously applied imaging methods for solving oncological and neurological problems. The sensitivity of the method is poor for demonstrating small calcifications (computed tomography is better), for diffuse meningeal lesions (lumbar puncture is better), and diffuse spinal-canal metastases (myelography is better). The great advantage of the method lies in its low x-ray exposure because of the low field strength, and it can therefore be safely used repeatedly.

Adolescent↗
PubMed1987

MRI of Listeria rhombencephalitis.

A case of Listeria rhombencephalitis in a patient, who was evaluated by MRI, is reported. MRI showed areas of high signal intensity on T2-weighted images in the rhombencephalon and confirmed the clinical diagnosis of a brainstem affection by Listeria monocytogenes.

Adult↗
PubMed1987

Long-term follow-up of children with magnetic resonance imaging and ultrasound after treatment of brain tumors.

This paper compares the results of MRI and US follow-up examinations of 46 children who had undergone surgery for brain tumors. The cases included 42 posterior fossa tumors, 3 supratentorial tumors and 1 upper cervical spinal cord tumor. US examination proved to be less specific and sensitive than MRI. However, when a "bone window" is available, US is, because of the ease of its application, better suited for frequent routine examinations. Long-term follow-up should, therefore, consist of frequent regular US examinations combined with yearly MRI examinations.

Adolescent↗
PubMed1987

Magnetic resonance imaging of postrepair-myelomeningocele--findings in 31 children and adolescents.

Magnetic resonance imaging has clearly demonstrated its efficacy in the diagnosis of pathological processes in the C.N.S. We examined 31 children who had undergone plastic closure of myelomeningocele a few days post partum. We could show that a high percentage of the patients (89%) presented the pathological anatomy of a tethered spinal cord; clinical symptoms of the tethered spinal cord syndrome, i.e. progressive neurological symptoms, however, are rarely observed. Possible revision of neurosurgical treatment of MMC is discussed.

Adolescent↗
PubMed1987

Magnetic resonance imaging in infections of the brain: findings in tuberculosis, listeriosis, toxoplasmosis, subacute sclerosing panencephalitis, and multiple sclerosis.

A total of 6 patients with various inflammatory brain diseases were investigated by MRI. Typical diagnostic criteria like signal intensity, location, and morphology of the lesions are presented. MRI proves to be a highly sensitive method to detect encephalitic foci, which, however, suffers from a low specificity. Therefore additional informations like case history, clinical findings, and serological data have to be considered to find the correct diagnosis.

Brain↗
PubMed1987

[31-phosphorus spectroscopy of osteogenic sarcoma. Possibilities in therapy control in comparison with imaging methods].

31-phosphorus spectroscopy was used to control the results of chemotherapy in a patient with an osteogenic sarcoma. The findings were compared with conventional imaging methods (DSA, MRT and conventional radiography). The imaging methods do not provide reliable information regarding growth of tumour tissue during treatment, whereas the determination of phosphate concentration in the tumour provides direct information concerning tumour metabolism.

Adolescent↗
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

[MR tomography in intracranial meningiomas].

The typical findings of intracranial meningiomas seen in 24 patients are described. The signal intensities at different acquisition parameters are analysed and optimal pulse sequences derived from these data. In 90% of the patients MR-tissue parameters were measured and correlated with the histological findings. Marked prolongation of T2-times was found in tumours showing regressive changes.

Female↗
PubMed1987

[MRT in neurofibromatosis and tuberous sclerosis].

The relatively rare neurocutaneous syndromes may produce neurological symptoms during childhood. After closure of the fontanelle, the radiological methods of choice are CT and MRT. The value of these two methods is demonstrated by twelve examples (eight neurofibromatoses, four tuberous scleroses). CT is superior to MRT in being able to show calcification; it is therefore the method of choice for tuberous sclerosis. On the other hand, MRT may show foci of neurofibromatosis; these can hardly be seen on CT. In order to show cerebral lesions in these two conditions, T2-weighted sequences are necessary.

Adolescent↗