PubMed Health⌕ Search

Biomedical subjects

G M Bydder

Publications and source records attributed to G M Bydder.

At least 91 records · Page 5Linked to original sources
PubMed1988

Localized cerebral infarction in the premature infant: an ultrasound diagnosis correlated with computed tomography and magnetic resonance imaging.

Findings on cranial ultrasonography strongly suggested the diagnosis of a localized infarct in four premature infants. CT was performed to differentiate between hemorrhagic and nonhemorrhagic lesions, and magnetic resonance imaging was used to obtain information about the late effect of the lesions. The clinical findings, imaging findings, and later outcome in these premature infants were compared with the existing knowledge of this type of lesion in the full-term infant. A localized infarct appears to carry a good prognosis in the premature infant and should be differentiated from other types of lesions, such as periventricular leukomalacia or parenchymal hemorrhage, which are more common in the premature infant and carry a worse prognosis.

Brain↗
PubMed1987

The design of a multiple inversion recovery sequence for T1 measurement.

Inversion recovery has the potential to be a powerful method of determining the values of T1 in in vivo studies. However, because of its relative slowness it is not practical to undertake several experiments with different values of the interval between the magnetization inverting 180 degree pulse and the interrogating 90 degree one. The multiple inversion recovery method described here uses a series of sampling pulses, most much less than 90 degrees, to produce a series of images. It is shown that slice shape is relatively reproducible from one sample to another and that, largely as a result, the accuracy of the sequence in measuring T1 is encouraging.

Brain↗
PubMed1987

Spectral resolution in clinical magnetic resonance spectroscopy.

We observe linewidths of 0.1-0.4 ppm in 31P spectra of human muscle, liver, and brain. T2 measurements of muscle phosphocreatine, together with previous brain studies, indicate that further improvements in linewidth to 0.02-0.05 ppm might often be achieved, but in some lesions magnetic susceptibility variations may limit spectral resolution.

Brain↗
PubMed1987

MRI-directed stereotactic biopsy of cerebral lesions.

Using a modified CT-directed stereotactic system we have performed MRI-directed biopsies in five patients whose intracerebral lesions were not clearly shown by CT. Tissue sampling from targets defined on the MR image enabled a histological diagnosis to be made in four of the five cases.

Adult↗
PubMed1986

Flow measurement by the development of phase differences during slice formation in MR imaging.

A method for measuring flow based on the shifting of the rephasing pulse following slice selection in partial saturation is described. The technique is based on a partial saturation sequence and retains much of the high signal which is a feature of the use of this sequence. Images obtained while encoding for the flow signal compated with those when not encoding appear very similar.

Humans↗
PubMed1986

Nuclear magnetic resonance of the brain.

Recent developments in MRI of the brain are reviewed. Over the past year there has been a general improvement in image quality, a paramagnetic contrast agent has been used in clinical practice, and surface coils have been used more generally in imaging. A wider range of disease has been studied, and there has been considerable agreement about the advantages and disadvantages of MRI at a basic level. As the technique moves into routine clinical use, questions about the economics of the technique are becoming more pressing.

Adult↗
PubMed1986

Magnetic resonance imaging of the brain in children.

Differences between MRI of the brain in children and adults are discussed. These include the need for sedation, greater difficulties in obtaining normal controls and substantial differences in pulse sequences due to changes in T1 and T2 with age. The common features in the major pathological entities are presented and the need to relate them to physiological changes is emphasized.

Brain↗
PubMed1986

High-resolution magnetic resonance imaging of the brain in children.

Magnetic resonance image quality in infants and children has been improved by the use of spherical receiver coils and age-adjusted sequences allowing use of a high-resolution (256 X 256) image reconstruction matrix, provided adequate immobilisation is maintained. This increased resolution provides more satisfactory demonstration of the cortical mantle and details of sulci, as well as pathological processes such as periventricular oedema, infarction and tumours.

Brain↗
PubMed1986

A magnetic resonance study of early schizophrenia.

Patients with untreated first schizophrenic episodes and others who had made varying degrees of recovery from such episodes were blindly compared with normal volunteers in terms of the periventricular appearances on spin echo magnetic resonance scans. Significant differences were not found.

Adult↗
PubMed1985

Nuclear magnetic resonance imaging (NMR), (MRI), of brain stem tumours.

The NMR scans of twenty-six patients who were referred with the clinically suspected or histologically verified diagnoses of brain stem tumour were reviewed. Twenty-one patients (eleven children and ten adults) had scans that were positive for tumour. Nine of these had histological confirmation. Eleven were irradiated without histology on the basis of the clinical diagnosis. The remaining patient was treated expectantly. The other five patients (two children and three adults) had CT and NMR scans that were negative for tumours. Clinical follow-up of these five cases for 9 to 29 months disclosed no further evidence of tumour. All but one tumour had evidence of an increased T1 and T2. Mass effects were seen in all but one case (not the same as the first exception). Multiplanar imaging was useful in determining intra- or extra-axial location as well as tumour extent. Intravenous Gadolinium-DTPA (a paramagnetic contrast agent) showed tumour enhancement in the two patients in whom it was used. NMR showed more extensive abnormality than CT in nineteen patients and similar abnormality to CT in two patients. CT demonstrated calcification better than NMR in the three cases in which it was observed.

Adolescent↗
PubMed1985

The short TI inversion recovery sequence--an approach to MR imaging of the abdomen.

Initial clinical experience with magnetic resonance imaging (MRI) of the abdomen using short TI inversion-recovery (STIR) pulse sequences is described and compared with X-ray CT in a variety of abdominal disease. The extent of abnormality shown with MRI was greater than that with CT in 21 of 30 cases and equal in 9 cases. Lesion contrast was greater with MRI in 15 cases, equal in 14 and less in 1. The level of artefact was equal in 27 cases and greater with MRI in 3 cases. The STIR pulse sequence has significant advantages in producing high soft-tissue contrast, controlling respiratory artefact, avoiding confusion with intra-abdominal fat and identifying bowel loops.

Abdomen↗
PubMed1985

Developmental sequence of periventricular leukomalacia. Correlation of ultrasound, clinical, and nuclear magnetic resonance functions.

The evolution of severe periventricular leukomalacia was followed by ultrasonography in three newborn infants, and the subsequent myelination of the brain was assessed by nuclear magnetic resonance imaging. Four stages of periventricular leukomalacia could be identified by ultrasonography; (1) initial congestion, followed by (2) relative normalisation, (3) development of cysts, and (4) resolution of cysts but development of ventricular enlargement. All infants exhibited abnormal neurological signs from 36 weeks conceptual age and had unequivocal signs of cerebral palsy by 6 to 9 months of age. One infant became cortically blind but the other two seemed to have normal vision. Nuclear magnetic resonance imaging showed some abnormality of the ventricular system and delayed myelination in all three infants. The delay was most noticeable in the opticothalamic region, which was also the site of the most extensive lesions observed on ultrasonography. Progress in myelination was observed in the infants where a repeat scan was performed.

Brain Diseases↗