PubMed Health⌕ Search

Biomedical subjects

M Buxton-Thomas

Publications and source records attributed to M Buxton-Thomas.

17 recordsLinked to original sources
PubMed2000

Quantitative perfusion imaging in carotid artery stenosis using dynamic susceptibility contrast-enhanced magnetic resonance imaging.

Quantitative, multislice dynamic susceptibility contrast-enhanced MRI perfusion measurements were used to determine the patterns of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and normalized first moment of the tissue deltaR2-time curve (N) in 11 subjects with carotid artery occlusion or stenosis. MTT correlated with degree of carotid stenosis, whereas a range of alterations in CBF and CBV were found presumably reflecting variables degrees of collateral flow. There was no significant correlation between MRI and SPET flow perfusion measurements, with increasing disparity between the two techniques at higher inter-hemispheric flow ratios. The effect of obtaining the arterial input function (AIF) from the middle cerebral artery (MCA) ipsilateral or contralateral to the stenosis was determined. Despite the use of an AIF from the MCA, which is distal to the circle of Willis, and hence the major sources of collateral supply, there was still some extra dispersion of the contrast agent bolus due to differences in arrival time.

Aged↗
PubMed2000

Cushing's syndrome associated with a chemodectoma and a carcinoid tumour.

We present a case of Cushing's syndrome where 111In-octreotide scanning provided evidence for the presence of two neuroendocrine tumours. Uptake in the right neck corresponded to a chemodectoma, but there was no change in the clinical condition or fall in ACTH levels following surgical resection. Uptake in the left chest was assumed to relate to a bronchial carcinoid, but a tumour could not initially be localized on magnetic resonance imaging (MRI), spiral CT scanning or on selective venous sampling. A 1 cm bronchial carcinoid tumour was identified post-mortem which immunostained for ACTH. This case demonstrates that 111ln-octreotide scanning is a useful technique for identifying the source of ectopic ACTH production in difficult cases of Cushing's syndrome. Reliance should not be placed solely on standard imaging techniques to localize the tumour prior to surgery. Although rare, the possibility of a non-ACTH secreting neuroendocrine tumour should also be considered in patients with ectopic ACTH syndrome, who have positive 111In-octreotide scans.

Adult↗
PubMed1997

Effect of calcium intake and physical activity level on bone mass and turnover in healthy, white, postmenopausal women.

Calcium intake and physical activity level (PAL) were assessed by questionnaire in 124 healthy women aged 52-62 y to determine the effect of calcium intake and PAL on bone mass and turnover. Four groups were identified according to their different reported calcium intakes and PALs. Bone mineral density (BMD) at the spine, hip, and left os calcis was measured together with total bone mineral content (TBMC) with dual-energy X-ray absorptiometry. Bone formation and resorption biochemical markers were measured in fasting samples of blood and urine. Women with the highest calcium intakes and PALs had the highest BMD at all sites compared with those with the lowest calcium intakes and PALs (P < 0.001). Calcium intake and PAL were positively correlated with BMD at all sites. Bone turnover markers did not explain the variation in bone mass between groups. In stepwise-multiple-regression analysis only calcium intake, physical activity, age, or weight remained as independent predictors of BMD and TBMC. When subjects were divided by past PALs, calcium intake and PAL were second to age and weight in their influence on spinal and hip BMD, but remained influential on the os calcis and whole body. We conclude that current high calcium intakes and PALs influence BMD at the os calcis and TBMC and protect bone mass in women 5-12 y postmenopausal at all measured sites, including the spine and hip. This finding does not exclude the possibility of past influences of calcium and activity on bone mass.

Biomarkers↗
PubMed1997

The development of regional nuclear medicine audit in south Thames.

A programme of audit, including clinical audit, organizational audit and patient/clinician satisfaction surveys, has been implemented in nuclear medicine departments throughout the South Thames Regional Health Authority (RHA). The clinical topics which have been audited include. ventilation-perfusion lung imaging, bone imaging, liver imaging, thyroid imaging and renal static DMSA imaging. Guidelines have been set for nuclear medicine practice in each of these areas against which further audit can be performed. Organizational audits have been performed in 10 nuclear medicine departments in the South Thames RHA and a confidential report supplied to the head of each department, consisting of findings and recommendations. A programme of re-audit has also commenced. The main findings have been a lack of facilities and space. Patient satisfaction surveys have been implemented in nine departments and a high level of patient satisfaction has been demonstrated. A clinical satisfaction survey has been implemented in 13 departments. It is hoped to continue this successful programme of audit to improve nuclear medicine practice by closing audit loops.

England↗
PubMed1997

Use of extracorporeal liver assist device and auxiliary liver transplantation in fulminant hepatic failure.

The case history of a 14-year-old boy with fulminant hepatic failure secondary to non-A, non-B hepatitis who fulfilled selection criteria for orthotopic liver transplantation is described. Two forms of liver support were used (extracorporeal liver assist device and an auxiliary partial orthotopic liver transplantation) to provide additional time to allow spontaneous recovery to occur. During the 66 h of extracorporeal haemoperfusion through the device, haemodynamic stability was maintained along with improvements in serum bilirubin (555 to 381 mumol/l), and international normalized ratio (INR) (3.7 to 2.9). Deterioration in these parameters was observed following cessation of treatment and 10 h later, after a donor liver had become available, an auxiliary transplant was performed. Clinical recovery, though initially slow, was eventually complete, with histopathological and scintigraphic evidence of full liver regeneration at 3 months. Withdrawal of his immunosuppressive drugs began at 6 months and was complete by 14 months after auxiliary transplantation. He has since remained well with normal liver function tests. Temporary liver support may provide additional time for spontaneous recovery of the native liver to occur in selected cases of fulminant hepatic failure, even when criteria are fulfilled for orthotopic liver grafting.

Adolescent↗
PubMed1997

Reduced bone density in patients with inflammatory bowel disease.

BACKGROUND: Reduced bone mineral density in patients with inflammatory bowel disease is thought to be due to disturbances in calcium homeostasis or the effects of corticosteroid treatment. AIMS: To assess the prevalence and mechanism of reduced bone mineral density in 79 patients with inflammatory bowel disease (44 with Crohn's disease, 35 with ulcerative colitis) who did not have significant risk factors for low bone densities. METHODS: Dual x ray absorptiometry was used to measure bone mineral density and serum and urinary markers of osteoblast (alkaline phosphatase, procollagen 1 carboxy terminal peptide and osteocalcin) and osteoclast (pyridinoline, deoxypyridinoline, and type 1 collagen carboxy terminal peptide) activities to assess bone turnover. RESULTS: There was a high prevalence of low bone mineral density (prevalence of T scores < -1.0 from 51%-77%; T scores < -2.5 (osteoporosis) from 17%-28%) with hips being more often affected than vertebrae (p < 0.001). Reduced bone mineral density did not relate to concurrent or past corticosteroid intake, or type, site, or severity of disease. Whereas calcium homeostasis was normal, bone markers showed increased bone resorption without a compensatory increase in bone formation. CONCLUSIONS: The greater prevalence of reduced hip bone mineral density, as opposed to vertebral, mineral density and the pattern of a selective increase in bone resorption contrasts with that found in other known causes of metabolic bone disease.

Absorptiometry, Photon↗
PubMed1996

Imaging secondary neuroendocrine tumours of the liver: comparison of I123 metaiodobenzylguanidine (MIBG) and In111-labelled octreotide (Octreoscan).

Functional imaging of neuroendocrine tumours with Octreoscan and I123-metaiodobenzylguanidine (MIBG) is important for assessment prior to various therapies and assessing response. The two imaging methods have not been directly compared in hepatic neuroendocrine tumours. Patients (n = 18) were studied with both imaging techniques. The sensitivity of Octreoscan was 94%, and that of MIBG 39%. No previously occult primary sites were detected. Concurrent octreotide therapy did not reduce the sensitivity of Octreoscan. Widespread bone metastases were seen in two post-liver-transplant patients using Octreoscan. Octreoscan is a sensitive means of detecting hepatic neuroendocrine tumours, and the more specific technique. MIBG has poor sensitivity, reducing its clinical utility. Therapy with I131-MIBG is likely to be applicable to relatively few patients.

3-Iodobenzylguanidine↗
PubMed1995

Gamma camera purchasing.

The purchase of a new gamma camera is a major undertaking and represents a long-term commitment for most nuclear medicine departments. The purpose of tendering for gamma cameras is to assess the best match between the requirements of the clinical department and the equipment available and not necessarily to buy the 'best camera' [1-3]. After many years of drawing up tender specifications, this paper tries to outline some of the traps and pitfalls of this potentially perilous, although largely rewarding, exercise.

Gamma Cameras↗
PubMed1991

201Tl scintigraphy in the assessment of patients with multi-vessel coronary disease undergoing angioplasty who have previously had a coronary bypass graft operation.

Percutaneous transluminal coronary angioplasty (PTCA) has an important therapeutic role in the treatment of coronary artery disease. The purpose of this study was to investigate the role of 201Tl scintigraphy in symptomatic patients with multi-vessel coronary artery disease undergoing angioplasty who had previously undergone coronary graft operations. 201Tl imaging was carried out in 12 patients prior to PTCA, 6 weeks and 6 months to 1 year post-PTCA. Prior to PTCA, 201Tl imaging correctly identified the site of the dominant lesion in all patients in correlation with the catheter results. Six weeks post-PTCA, seven cases who had angiographically successful angioplasty showed persistent defects on 201Tl imaging. In five of these cases, follow-up catheter showed that re-stenosis had occurred. Six months to 1 year post-PTCA, 201Tl imaging was found to have good correlation (11 out of 12 patients) with the catheter results. The results suggest that 201Tl imaging is useful in the management of patients with multi-vessel disease undergoing angioplasty.

Aged↗
PubMed1990

The current cost of nuclear medicine.

In the light of the control of expenditure and changes in radiopharmaceutical costs, changes in study protocols, new investigation procedures and inappropriate placing in Korner categories, the BNMS Council set up a working party to derive an agreed set of costings for Nuclear Medicine techniques. Using data from three hospitals with additional information from another nine, we have agreed the 1988 cost of individual nuclear medicine procedures in the UK. These figures include staffing (radiopharmacy, nursing, physics, medical including consultant), radiopharmaceuticals and other consumables, indirect costs (secretarial, administrative, portering), variable overheads (service contracts, stationery) and fixed overheads (rates, lighting, heating, building and engineering). Capital costs, equipment and buildings were not included. Because figures include salary and overhead costs they are difficult to compare with the majority of other previous nuclear medicine costings, apart from Bretland et al., or with data for other imaging modalities. Comparison of these costings with Korner schedules shows marked overlap between the Korner groups. Such groups therefore form a poor method of costing nuclear medicine procedures. We propose alternative groupings.

Costs and Cost Analysis↗
PubMed1985

Abdominal scintigraphy with 99Tcm-labelled red cells in the detection of rebleeding from peptic ulcers.

The technique of 99Tcm-labelled red cell scintigraphy as a means of detecting rebleeding was investigated in 33 patients with bleeding peptic ulcers. Scintigrams were performed twice during the 24 h period succeeding diagnostic endoscopy. There was scintigraphic evidence of rebleeding in 23 patients but this was clinically manifest in 14 patients only. Thirteen of the 14 patients with clinical rebleeding had positive scintigrams while only in one patient with clinical rebleeding was the scintigram negative (P less than 0.05). These results show that rebleeding is common and often clinically inapparent during the first 24 h following gastroscopy but that in the absence of scintigraphic rebleeding serious clinical rebleeding is unlikely to occur.

Adult↗
PubMed1985

Intrahepatic bile duct dilatation shown by computed tomography--predilection for the left lobe?

Dilated biliary duct radicles were most obvious within the left lobe of the liver in 30 out of 42 patients with obstructive jaundice in whom intrahepatic duct dilatation was satisfactorily demonstrated by computed tomography. In 19 of these 30 patients the level of obstruction was at the lower end of the common bile duct. Recognition of this finding may prevent the erroneous diagnosis of intrahepatic or multiple obstructing lesions.

Cholestasis, Intrahepatic↗
PubMed1984

Cryptogenic fibrosing alveolitis: pattern of disease in the lung.

The distribution of disease has been studied in 10 patients with histologically confirmed cryptogenic fibrosing alveolitis by means of computed tomography of the lungs, gallium 67 uptake scintigraphy, and ventilation and perfusion scintigraphy. The findings of computed tomography and scintigraphy showed no correlation with the UICC/Cincinnati grades of the plain chest radiographs, even when these were supplemented with information from lateral and oblique chest films. Computed tomography showed subpleural shadowing in every patient except one who had responded well to corticosteroid treatment. Subpleural shadowing was commoner in the inferior and posterior parts of the lung lobes and was commonest in the posterior lower subpleural areas. The central lung showed three types of change--firstly, a dense shadowing, which was sometimes associated with much increased gallium uptake; secondly, dilated smaller airways with small bullae, suggesting airway disease; and, thirdly, gross bullous change.

Humans↗
PubMed1983

Adult idiopathic pulmonary haemosiderosis: a comparison of lung function changes and the distribution of pulmonary disease in patients with and without coeliac disease.

Seven patients with idiopathic pulmonary haemosiderosis were investigated with chest radiographs, pulmonary function tests, computed axial tomograms, and isotope ventilation and perfusion scans. Three of the patients had coeliac disease (CD) and a fourth an abnormal small bowel mucosa under the dissecting microscope which was normal histologically. Five patients showed airflow limitation with a low transfer coefficient. Three of these had air trapping, two of whom had hyperinflation of the lungs, and the third a total lung capacity at the upper limit of normal. Two patients showed a central distribution of radiographic opacities, and the other five had changes throughout the lung fields. The presence or absence of CD showed no relationship to these findings.

Adult↗
PubMedDate not supplied

Pathophysiological assessment of nitric oxide (given as sodium nitroprusside) in acute ischaemic stroke.

Acute ischaemic stroke is characterised by reductions in local cerebral blood flow (CBF) and activation of circulating platelets and leucocytes. Nitric oxide is a vasodilator and can inhibit these circulating cells. The aim of this study was to assess the effect of nitric oxide on platelet function and regional CBF in patients with acute ischaemic stroke. Sodium nitroprusside (SNP), a spontaneous nitric oxide donor, was administered at a dose which caused a 10 mm Hg fall in mean arterial blood pressure (MABP) in a pathophysiological study to 22 patients with acute ischaemic stroke and 12 matched control subjects. Platelet function (whole blood aggregation and flow cytometry) was assessed before and during SNP administration. Changes in regional CBF were measured using single photon emission computerised tomography (SPECT) scanning. SNP significantly reduced platelet aggregation in both the patient and control subject groups. Equally, the expression of platelet adhesion molecules P-selectin (CD62) and glycoprotein (GP) GP IIIa (CD61) were significantly reduced in both groups. GP Ia (CDw49b) expression was significantly attenuated in the patient but not in the control group. Four patients underwent SPECT scanning and improvements in local CBF corresponding to the penumbral area of the clinical stroke site were seen in 3 of these patients. A total of 24 regions of asymmetrical perfusion were examined, pre-SNP (median (SQR)), 0.68 (0.14) vs. peri-SNP 0.78 (0.17), 2p = 0.065. SNP, given at a dose which reduced MABP by 10 mm Hg, significantly inhibited platelet aggregation and adhesion molecule expression. Improved regional CBF was seen in some patients. SNP is a candidate therapeutic agent for patients with acute ischaemic stroke and warrants further study.

Blood Coagulation↗
PubMedDate not supplied

Clearance of inhaled 99mTc DTPA from regions of the lung recently affected by pulmonary embolus.

Pulmonary emboli lead to regional limitation of pulmonary artery perfusion, often without affecting distribution of ventilation. We have studied the effect of this regional reduction of pulmonary artery perfusion on the integrity of epithelium of alveoli (and possibly bronchioli). Integrity of alveolar epithelium was assessed by measuring regional rates of clearance from lung to blood of an inhaled aerosol of a small molecular weight solute, 99mTc DTPA (technetium-99m diethylene-triamine-pentaacetate). Ten patients with pulmonary emboli were studied, where the diagnosis was made from 'mismatching' seen on ventilation (V) and perfusion (Q) lung scintigraphy. Rates of clearance of DTPA in regions with normal V/Q ratios were compared with embolized regions with high V/Q ratios. Clearance rates were increased in embolized regions (V/Q ratio greater than 1): 2.59 +/- (SD) 0.89% X min-1, compared with normal regions (V/Q ratio less than 1): mean 1.39 +/- 0.60% X min-1 (p less than 0.01). In repeat studies in nine patients (one died), after intervals between 2 and 12 weeks, the V/Q ratio of previously embolized regions decreased towards unity in all nine patients, suggesting resolution. The differences in clearance rates for DTPA between normal and embolized regions decreased in association with this return towards normal of V/Q ratios. We surmise that reduction in pulmonary artery perfusion which occurs in pulmonary embolic disease alters the integrity of the alveolar (and possibly bronchiolar) epithelium. This effect is largely reversible, recovering with return of pulmonary artery perfusion.

Aerosols↗