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Biomedical subjects

H Baddeley

Publications and source records attributed to H Baddeley.

At least 19 recordsLinked to original sources
PubMed1994

Pattern of disease in spinal cord compression on MRI scan and implications for treatment.

Recent trends in the management of bone metastases include the use of prophylactic bisphosphonates and low dose single fraction radiotherapy in favour of high dose fractionated radiotherapy. A recent animal model [1] suggests that cord compression is often associated with predominant soft tissue epidural disease, with bone collapse as a late event. In the present study, potential implications were investigated by retrospective evaluation of the pattern of disease on MRI scans of patients with spinal cord compression. The dominant component of spinal cord compression was determined in 62 patients. Two main patterns were identified, 45 (73%) had predominant soft tissue epidural disease and 15 (24%) had bone collapse. There were two with intrathecal deposits. The patterns were correlated with response to radiotherapy. Positive response was observed in 64% of those with soft tissue epidural disease and 27% of those with bone collapse. These data support the animal model, suggesting soft tissue epidural disease rather than collapse as the predominant cause of cord compression. This implies that prophylactic bisphosphonates alone would be unlikely to reduce the incidence of spinal cord compression. It also introduces concern about the long term safety of low dose single fraction radiotherapy for bone metastases in patients with a medium term life expectancy (e.g. > 2 years). These patients may benefit from more than a single fraction of radiotherapy to produce longer growth delay for sub-clinical epidural disease.

Adolescent↗
PubMed1991

Primary bone tumors. MR morphologic appearance correlated with pathologic examinations.

Eighty-three MR studies for primary bone tumors, performed with both spin echo and short time inversion recovery (STIR) sequences, were reviewed. Twenty-six patients underwent surgery within 10 days after MR imaging. Specimens were cut and directly compared with MR images. In the remainder, pathologic slides were compared in order to obtain a better understanding of MR pattern. All MR images were examined with a traditional morphologic approach and, upon comparison with surgical macroslides and with pathology samples, some MR distinctive patterns were identified: the bulky appearance of osteosarcoma surrounded by muscle edema, the multilobular high signal intensity (SI) chondroid lesions, the subtle infiltration of Ewing's sarcoma, rarely accompanied by muscle edema and prone to MR underestimation, the well defined "multiple shells" pattern of giant cell tumor, and the ill defined "storiform" appearance of malignant fibrous histocytoma are all typical MR features strictly corresponding to pathologic findings. The chondroid origin tumors may be identified based on the lobular high SI pattern whereas a benign fibrous lesion was the only one in this series to be distinguished relying on the SI. Peritumoral soft tissue edema was found by the STIR sequence only in malignant tumors (69%) of this series, and particularly in osteosarcoma (96%), chondrosarcoma (83%), and giant cell tumor (100%): this associate finding may further contribute to the diagnosis.

Adolescent↗
PubMed1990

The role of the STIR sequence in magnetic resonance imaging examination of bone tumours.

Sixty patients with primary bone tumours were evaluated with magnetic resonance imaging (MRI) at 0.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. The results have been reviewed in order to evaluate the accuracy of STIR and conventional SE sequences in the detection of tumours, the definition of intramedullary extent and soft-tissue involvement. The intraosseous neoplastic extent has been compared with macroslides of surgical specimens in 24 cases. The role of the STIR sequence in detection of recurrences in the post-surgical follow-up was also evaluated. The STIR sequence, designed to suppress signal from fat, also enhances the signal from tissue with long T1 and T2 relaxation times, such as neoplastic and inflammatory tissue. The STIR sequence with T1 of 120-130 ms in all cases suppressed the high signal from fatty bone marrow, giving a clear depiction of tumour extent, in both its intramedullary and soft-tissue components, and is superior to conventional SE images. The high sensitivity (100% of our cases) of this technique is counterbalanced by its lack of specificity: on STIR sequences both tumour and peritumorous oedema give an increase of signal intensity, limiting assessment of tumour extent. Peritumoral oedema, only present in our series in malignant neoplasms, may however be differentiated on the basis of the configuration of the abnormal areas, and by comparing STIR images with short repetition time/echo time sequence results.

Adolescent↗
PubMed1987

Use of high resolution in vivo volume selected 1H-magnetic resonance spectroscopy to investigate leukemia in humans.

In vivo high resolution volume-selected 1H magnetic resonance spectroscopy of human tibia has been undertaken using spatial coordinates obtained from magnetic resonance images. Adult tibial marrow has a 1H spectrum rich in fatty acid resonances and is readily distinguished from the 1H spectra of surrounding leg muscle. In all four leukemic patients examined, infiltration of fat cells of tibial marrow by proliferating cells rich in mobile H2O protons was evident by magnetic resonance imaging. Selective examination of volumes of tibial marrow (1 cm3) by 1H magnetic resonance spectroscopy confirmed marked differences in the 1H spectra of marrow from these patients. Increases in the H2O peak of the 1H spectra were correlated with infiltration of blast cells and lack of control of the neoplastic disease. These studies are the first to report the use of volume selected magnetic resonance spectroscopy to selectively monitor leukemia in humans.

Adolescent↗
PubMed1987

A comparison of some gradient-encoded volume-selection techniques for in vivo NMR spectroscopy.

Four of the techniques proposed for in vivo volume-selected NMR spectroscopy have been compared using a simple phantom with a large background water signal which was outside the region of interest. The methods VSE, SPACE, SPARS, and DIGGER all use pulsed field gradients for spatial encoding and were tested with a symmetric and an asymmetric phantom. SPACE was used to obtain volume-selected 1H NMR spectra of a human leg, demonstrating excellent discrimination between bone marrow and muscle.

Humans↗
PubMed1987

Painful bone end sclerosis. Variant of renal osteodystrophy simulating osteonecrosis.

Painless sclerotic change in bone ends occurring as a manifestation of renal osteodystrophy has been reported in two previous cases. The sclerotic change can, however, be accompanied by nonspecific periarticular pain. Radiologic changes in "bone ends" may mimic osteonecrosis. Nuclear bone scanning may show increased radionuclide uptake early in both conditions but late uptake may be less in "bone end sclerosis." The "rugger jersey" spine occurring in the usual osteosclerosis of renal osteodystrophy has been consistently absent in this variant. Osteonecrosis should be excluded in making the diagnosis of "bone end sclerosis."

Adult↗
PubMed1986

The introduction of clinical magnetic resonance imaging in Australia.

Magnetic resonance imaging is a new, but expensive, modality that is being introduced into clinical use in Australia. While it promises increased safety and accuracy in many situations, its precise role when compared with computed tomography and other modalities is not fully established. Therefore, a Government financed evaluation of costs and efficacy of magnetic resonance imaging units in five teaching hospitals is to be conducted over two years (1986-1988). Experience with the introduction of computed tomography to Australia and other nations has revealed difficulties in the evaluation by conventional methods of a diagnostic technology that is improving rapidly; it is to be hoped that a systematic evaluation of the clinical applications of magnetic resonance imaging will be more achievable and useful. Open cooperation between the Commonwealth and State Governments and the medical profession in this evaluation should lead to a rational policy for the clinical availability of magnetic resonance imaging within Australia in the future.

Australia↗
PubMed1986

Magnetic resonance imaging--first human images in Australia.

The use of magnetic resonance imaging, in the demonstration of internal human anatomy and in the diagnosis of disease, has the major advantages that the technique is noninvasive, does not require the use of ionizing radiation and that it can demonstrate neurological and cardiovascular lesions that cannot be diagnosed easily by other imaging methods. Magnetic resonance imaging is derived from the principle that certain atomic nuclei in a strong magnetic field will absorb pulses of radiofrequency energy; when the pulse is finished the nuclei will emit radiowaves at the same frequency. These radiowaves are received by specially designed aerials or coils and the information is collected by a computer which reconstructs an image of internal anatomy in a similar way to that of x-ray computed tomography (CT). By changing the strength of the magnetic fields and the frequency of the radiowave pulses, it is possible to examine different sections within the body. The first magnetic resonance images of humans were obtained in Australia in October 1985 on the research instrument of the Queensland Medical Magnetic Resonance Research Centre, which is based at the Mater Hospital in Brisbane, and is part of the University of Queensland's Department of Radiology.

Abdomen↗
PubMed1986

The utilization of two frequency-shifted sinc pulses for performing volume-selected in vivo NMR spectroscopy.

A new approach to volume-selected in vivo NMR spectroscopy uses two frequency-shifted sinc pulses, in conjunction with pulsed field gradients, to destroy the coherence of the unwanted signals. A hard pi/2 pulse can then be used to read the z magnetization in the region of interest. This method is independent of T2, provides complete volume selection in a single acquisition, and can be readily implemented on most high-field commercial imaging/spectroscopy systems.

Magnetic Resonance Spectroscopy↗
PubMed1986

Chronic lead nephropathy in Queensland: alternative methods of diagnosis.

Indices of past lead absorption were measured and compared in patients with chronic renal failure from many causes, including some with chronic lead nephropathy. X-ray fluorescence (XRF) yielded finger bone lead concentrations by a new in vivo method. These correlated significantly with excess urinary lead following calcium di-sodium EDTA (ethylenediamine tetra-acetate) and erythrocyte lead concentration. Discriminant function analysis demonstrated that the patients in the study could be separated into two groups without any reference to the EDTA lead excretion test using the following variables, all of which contributed significantly to the discrimination. In order of importance, these were: a childhood history of acute lead poisoning, a history of gout, a family history of gout and detectable XRF finger bone lead. Although the XRF finger bone lead measurement is convenient and non-invasive, its lack of sensitivity (48%) limits its usefulness as a screening test for chronic lead nephropathy.

Aged↗