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Biomedical subjects

G M Bydder

Publications and source records attributed to G M Bydder.

At least 127 records · Page 7Linked to original sources
PubMed1983

Peripheral and axial measurements of trabecular bone density in patients suspected of idiopathic vertebral osteoporosis.

In 18 patients with idiopathic crush fracture syndrome, iliac trabecular bone volume measured in 8 mm trephine biopsies correlated well with trabecular bone density as estimated in low thoracic or high lumbar vertebrae by computed tomography (CT). The CT of trabecular bone in the radius correlated poorly with the other two measurements, but it discriminated fairly well between patients and age-matched controls. These results suggest that abnormally low trabecular bone density values in the radius may be useful in predicting some patients at risk for crush fractures, but ranking patients in order of severity of axial bone loss after they have acquired a fracture requires measurements on the spine or iliac crest.

Aged↗
PubMed1983

Nuclear magnetic resonance imaging of the posterior fossa: 50 cases.

Fifty patients with clinical diagnoses of disease within the posterior fossa were examined with a nuclear magnetic resonance (NMR) scanner and the results were compared with X-ray computed tomography (CT). A variety of NMR pulse sequences reflecting proton density, T1, T2 and blood flow were used and imaging was performed in transverse coronal and sagittal planes. In many cases NMR provided diagnostic information unavailable from CT scans. This included recognition of lesions not seen with CT in infarction and multiple sclerosis, as well as more precise definition of mass effects, oedema and anatomical relationships in other diseases. Extrinsic and intrinsic tumours were readily distinguished, as were brain-stem and cerebellar tumours. Arnold-Chiari malformations were demonstrated with sagittal scans and cerebellar atrophy was identified. A patient treated with radiotherapy displayed more extensive changes in the surrounding brain with NMR than with CT. Evidence of occlusion or reduced flow was found in two cases with vertebro-basilar disease. Occlusion of the internal carotid artery was also demonstrated. Computed tomography was superior to NMR in demonstrating calcification and bone erosion. In four of 14 tumours studied, contrast-enhanced CT demonstrated the margin between tumour and surrounding oedema or brain better than NMR. Nuclear magnetic resonance imaging is a versatile, non-invasive technique capable of demonstrating a wide spectrum of disease within the posterior fossa.

Adolescent↗
PubMed1983

Nuclear magnetic resonance (NMR) imaging in white matter disease of the brain using spin-echo sequences.

Attention is drawn to the use of nuclear magnetic resonance (NMR) spin-echo sequences in the recognition of white matter disease of the brain. In 5 patients with multiple sclerosis, 8 lesions were seen with postcontrast x-ray computed tomography (CT) (37.5 g of iodine), 33 with inversion-recovery (IR) scans, and 47 with spin-echo (SE) scans. Partial volume effects were less of a diagnostic difficulty with SE scans than with IR scans. Extensive areas of abnormal white matter were seen with CT, IR, and SE scans in a patient with leucodystrophy associated with congenital muscular dystrophy. In a patient with adrenoleucodystrophy focal lesions were seen with CT, IR, and SE scans. In addition, loss of gray-white matter contrast was seen in both occipital lobes with IR scans. Extensive areas of white matter involvement were also seen in a case of Binswangers disease.

Adrenoleukodystrophy↗
PubMed1983

Nuclear magnetic resonance (NMR) imaging of the brain in systemic lupus erythematosus.

Nuclear magnetic resonance (NMR) and X-ray computed tomographic (CT) imaging of the brain were performed on nine patients with clinical evidence of cerebral involvement by systemic lupus erythematosus (SLE). Focal lesions were demonstrated in eight patients by NMR and in six by CT. The examinations with both techniques were negative in one patient and showed essentially identical pathological conditions in three patients. In three patients NMR demonstrated more numerous lesions than CT. All lesions seen on CT were also seen on NMR, mostly with greater clarity and extent. In view of the limited number of patients, this study is preliminary, but it appears that NMR demonstrates more accurately the degree of brain involvement in SLE than CT.

Adult↗
PubMed1983

Nuclear magnetic resonance imaging of the heart. Current status and future prospects.

The basic principles and current status of proton nuclear magnetic resonance imaging are outlined. Nuclear magnetic resonance images of the heart have improved in quality with advances in technique and better gating but clinical experience remains very limited. Myocardial infarction has been shown in animals and man, and plaques of atheroma have been seen with nuclear magnetic resonance flow studies. Further improvements in image quality, faster examination times, 23Na imaging, and the use of paramagnetic contrast agents are advances that are anticipated in the near future.

Animals↗
PubMed1983

Nuclear magnetic resonance imaging of posterior fossa tumors.

The results of nuclear magnetic resonance (NMR) examinations in 26 patients with histologic (15 cases) or clinical (11 cases) diagnoses of tumors within the posterior fossa were reviewed and compared with x-ray computed tomography (CT). Most tumors displayed an increase in T1 and T2 relative to brain. All seven benign tumors were seen with both CT and NMR, although one of these cases initially was misdiagnosed on the basis of the CT findings. The extent of these tumors was equally well shown with CT and NMR in three cases but was demonstrated better by NMR in four. Calcification was seen with CT but not with NMR in two of these patients. All 19 malignant tumors were demonstrated with NMR. Two of these were not seen with CT. In 12 patients minimal changes consisting of a poorly defined low-attenuation are or minor displacement of the fourth ventricle were noted with CT, although much more extensive changes were seen with NMR. In three patients the changes were equally well shown with both techniques. In the remaining two cases, the extent of the tumor was defined more accurately with contrast-enhanced CT, where the margin between tumor and surrounding edema was better seen than with NMR. Mass effects were better demonstrated with NMR in 13 patients and equally well shown in six. Bony erosion was better demonstrated with CT in two cases. Hydrocephalus with periventricular edema was seen in five patients; in each it was more clearly demonstrated with NMR. The NMR diagnosis of tumors is discussed and relevant new developments are summarized.

Brain Neoplasms↗
PubMed1983

Clinical NMR imaging of the brain in children: normal and neurologic disease.

The results of initial clinical nuclear magnetic resonance imaging of the brain in eight normal and 52 children with a wide variety of neurologic diseases were reviewed. The high level of gray-white matter contrast available with inversion-recovery sequences provided a basis for visualizing normal myelination as well as delays or deficits in this process. The appearances seen in cases of parenchymal hemorrhage, cerebral infarction, and porencephalic cysts are described. Ventricular enlargement was readily identified and marginal edema was demonstrated with spin-echo sequences. Abnormalities were seen in cerebral palsy, congenital malformations, Hallervorden-Spatz disease, aminoaciduria, and meningitis. Space-occupying lesions were identified by virtue of their increased relaxation times and mass effects. Nuclear magnetic resonance imaging has considerable potential in pediatric neuroradiologic practice, in some conditions supplying information not available by computed tomography or sonography.

Brain↗
PubMed1982

Nuclear magnetic resonance imaging of the brain in children.

A preliminary study of nuclear magnetic resonance imaging of the brains of four normal children (36 weeks' postmenstrual age to 5 years) showed long T(1) areas in the periventricular region of the neonate as well as evidence of progressive myelinisation with increasing age. Study of 18 patients of 40 weeks' postmenstrual age to 4 years showed an apparent deficit in myelinisation in an infant with probable rubella embryopathy and another with ventricular dilatation of unknown cause. Abnormal scans were obtained in an infant with congenital muscular dystrophy, and abnormalities were visualised at the lateral ventricular margins in a case of acute hydrocephalus after shunt blockage. Periventricular regions of increased T(2) were seen in a term infant aged 4 days after severe birth asphyxia and convulsions.Nuclear magnetic resonance imaging appears to provide a unique demonstration of myelinisation in vivo and shows changes in pathological processes of importance in paediatric practice.

Brain↗
PubMed1982

NMR imaging of the brain.

The basic features of an NMR imaging system are outlined and three pulse sequences which produce images with varying dependence on proton density T1 and T2 are described. The first of these sequences, Repeated Free Induction Decay produces images which demonstrate changes in proton density as well as flow effects. The second sequence, Inversion-recovery, produces images which are dependent on T1 and show a high level of grey, white matter contrast giving considerable anatomical detail. In addition pathological processes such as infarction, haemorrhages, demyelination and malignancy, produce changes in T1 enabling lesions to be localised. The third sequence, Spin-echo, produces images which are dependent on T2. These show very little grey, white matter contrast but demonstrate acute and space occupying lesions as well as cerebral oedema. The high level of grey, white matter contrast, lack of bone artefact, variety of sequences, capacity for multiplanar imaging, sensitivity to pathological change and lack of known hazard make NMR an important addition to existing techniques of neurological diagnosis.

Brain↗
PubMed1982

Regional bone density measurements compared to total body calcium in osteoporosis.

In 21 women with crush fracture osteoporosis quantities related to trabecular bone density in lumbar vertebrae and in the distal radius were significantly correlated (r = 0.50, P less than 0.05). When the group was enlarged to include data from other patients without osteoporosis, a higher coefficient of correlation was obtained (r = 0.69, P less than 0.001). Total body calcium, measured by in vivo neutron activation analysis, was significantly correlated to quantities related to cortical bone mass in the radius and femur. Thus, these quantities could be used to make estimates of total body calcium in osteoporotic patients. There was no significant correlation between total body calcium and quantities related to trabecular bone density, measured by computed tomography, in vertebrae or in the distal radius.

Bone and Bones↗
PubMed1982

NMR imaging of the brain using spin-echo sequences.

Eight normal volunteers and 32 patients with a variety of neurological disease were studied with a nuclear magnetic resonance (NMR) scanner using repeated free induction decay (RFID), inversion-recovery (IR) and spin-echo (SE) sequences. The results were compared with X-ray computed tomography (CT). RFID sequences which produce images that reflect changes in proton density displayed very little grey-white matter contrast and relatively small changes in disease. IR sequences which produce images that are dependent on T1 showed a high level of grey-white matter contrast and demonstrated changes in a variety of pathological processes. Although SE scans, which have a strong T2 dependence, had shown no abnormality in previous studies of patients with neurological disease, sequences of this type with longer values of tau displayed abnormalities in cerebral infarction, haemorrhage, herpes encephalitis, multiple sclerosis, cerebral oedema, hydrocephalus, tumours and Wilson's disease. All of these conditions were associated with an increase in T2. Abnormalities were demonstrated in cases of multiple sclerosis and brainstem infarction with NMR scans where no abnormality was seen with CT. More extensive changes were seen with NMR in cases of hemisphere infarction, systemic lupus erythematosis, herpes encephalitis, hydrocephalus (periventricular oedema) and Sturge-Weber disease. The margin between malignant tumour and surrounding oedema was better defined with contrast enhanced CT in four of eight malignant tumours, equally well defined in one, and better defined with NMR in three cases. NMR spin-echo sequences provide a sensitive technique for detecting abnormalities in a variety of neurological disease.

Adult↗