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Biomedical subjects

N R Moore

Publications and source records attributed to N R Moore.

At least 37 records · Page 2Linked to original sources
PubMed1996

Fate of the native aorta after repair of acute type A dissection: a magnetic resonance imaging study.

OBJECTIVE: To determine late patency of the aortic false lumen and propensity for aneurysm formation after repair of type A dissection. DESIGN: Retrospective follow up study. SETTING: Regional cardiac surgical unit. PATIENTS: 28 patients after repair of type A dissection. METHODS: Magnetic resonance imaging (MRI) was performed between 6 weeks and 12 months after operation. RESULTS: A patent distal false lumen with demonstrable blood flow was found in 22 patients (78%). Only six patients had complete obliteration of the false lumen by thrombus. The conduct of operation did not influence this. Nine patients (32%) showed aneurysmal dilatation of the false lumen and three had a repeat operation. CONCLUSIONS: So-called "successful repair" of aortic dissection does not obliterate the distal false lumen. MRI is a safe and effective radiological procedure for determining patency and dilatation in the false lumen. Patients with type A dissection with blood flow in the false lumen should be studied every 6 months to look for aneurysmal dilatation.

Acute Disease↗
PubMed1995

Pelvic and perineal complications of Crohn's disease: assessment using magnetic resonance imaging.

This study evaluated the role of magnetic resonance imaging (MRI) in the demonstration of the pelvic and perianal complications of Crohn's disease. Twenty five patients with active Crohn's disease were studied (12 male; mean age 41.1 years). MRI examinations were performed using a 1.5 Tesla system, within 14 days after clinical assessment. T1 and T2 weighted fast spin echo sequences in two or three orthogonal planes were performed, with fat suppression in some cases. The MRI results were correlated with surgical and clinical findings. In 16 patients, cutaneous, deep perineal or enterovesical fistulas or abscesses were diagnosed at MRI which showed close correlation with findings at examination under anaesthetic. In eight patients no fistulas or abscesses were seen at MRI nor was there any evidence of complications on clinical examination and flexible sigmoidoscopy. There was one false negative examination in a patient who had a colovesical fistula. In conclusion, MRI can accurately show the pelvic and perineal complications of Crohn's disease and may render examination under anaesthetic unnecessary.

Abdominal Abscess↗
PubMed1995

Magnetic resonance imaging in myelodysplastic syndromes.

In this study we used magnetic resonance imaging (MRI) to examine the axial bone marrow of 11 patients with myelodysplastic syndromes (MDS). T1 weighted images showed a reduction in signal intensity in all patients. The degree of reduction in signal intensity correlated with bone marrow cellularity rather than percentage blasts or French-American-British Co-operative group (FAB) classification. T2 weighted images showed an increase in signal intensity in 10 out of 11 patients; however, reliable grading was not possible using this sequence. Both T1 and T2 weighted images indicated a homogeneous pattern of disease within the axial skeleton in MDS. We have also shown that iron deposition in multiply transfused patients is a significant factor influencing signal reduction. The results of this study suggest that MRI may have a diagnostic role in MDS but is unlikely to be of value in staging.

Adult↗
PubMed1995

Magnetic resonance imaging of endocrine tumours of the pancreas.

Seven patients who had functioning or non-functioning endocrine pancreatic tumours were investigated by magnetic resonance imaging. Combinations of fat suppressed T1 weighted spin echo and gradient recalled echo (n = 7), T2 weighted spin echo (n = 3) and gadolinium diethylamine triamine pentaacetic acid (Gd-DTPA) enhanced fat suppressed T1 images were acquired. Magnetic resonance imaging detected five of seven tumours prospectively (three of which were smaller than 10 mm) and a further 10 mm tumour retrospectively. Tumours were low signal on T1 weighted images and showed enhancement after Gd-DTPA. On T2 weighted images one tumour was hyperintense, and two were isointense with normal pancreas. Computed tomography, transabdominal ultrasound and angiography were performed in six patients but detected only one tumour each. Intraoperative palpation and ultrasound detected all tumours. If pre-operative imaging is required magnetic resonance imaging is the technique of choice to detect small endocrine pancreatic tumours.

Adult↗
PubMed1995

Magnetic resonance imaging of metastatic bone disease.

Traditional imaging methods used in the detection and evaluation of metastatic bone disease lack either sensitivity (plain radiography) or specificity (bone scintigraphy). Magnetic resonance imaging now has been shown to be the most sensitive imaging technique available for the detection of bone metastases. On T1-weighted images bone metastases tend to stand out as focal or diffuse hypointense (dark) lesions against a background of higher-signal-intensity marrow. Use of fat suppression techniques may further increase the conspicuity of metastatic lesions. Magnetic resonance imaging is unlikely to replace bone scintigraphy as an initial screening technique for bone metastases because scintigraphy can image the whole skeleton quickly and at relatively low cost. Magnetic resonance is particularly useful for imaging the spine because vertebral bodies, paraspinal, and intraspinal soft tissues can be evaluated, providing a noninvasive method of detection of spinal cord compression. Magnetic resonance imaging also is useful in discriminating between benign and malignant vertebral collapse.

Bone Neoplasms↗
PubMed1994

Tissue plasminogen activator, plasminogen activator inhibitors, and activator-inhibitor complex in liver disease.

AIMS: To identify the relative contribution of plasminogen activators, particularly tissue plasminogen activator (t-PA) and specific plasminogen activator inhibitors (PAI-1, PAI-2), to the fibrinolytic changes associated with various types of liver disease or severe chemical and physical damage to the liver. METHODS: Platelet rich (PRP) and platelet poor plasma (PFP) from patients with alcoholic cirrhosis, primary biliary cirrhosis, hepatic malignancy, or paracetamol overdose, or who were undergoing partial hepatectomy or liver transplantation, were assayed for t-PA, PAI-1, t-PA-PAI-1 complex and PAI-2 antigen values using specific enzyme linked immunosorbent assays (ELISAs) developed in this laboratory. RESULTS: Appreciable increases in the plasma concentration of t-PA, PAI-1, and t-PA-PAI-1 were seen in patients with alcoholic cirrhosis, primary biliary cirrhosis, and hepatic malignancy. Liver damage due to paracetamol overdose and partial hepatectomy both resulted in a striking increase in plasma PAI-1 concentration, although concentrations of t-PA and t-PA-PAI-1 complex were less affected. Concentrations of t-PA, PAI-1, and t-PA-PAI-1 complex returned to near normal values after successful liver transplantation in a patient with chronic active hepatitis. PAI-2 was also detected in several patients with chronic liver disorders. CONCLUSIONS: Haemorrhage due to fibrinolytic bleeding is commonly associated with liver disease. The patients studied here all had appreciable increases in circulating t-PA antigen concentrations. This was associated with increased concentrations of PAI-1 antigen and t-PA-PAI-1 complex and the balance between activator and inhibitor did not result in systemic plasmin generation. Reduced PAI-1 activity in cirrhosis or a critical difference in the ratio of t-PA to PAI-1 concentrations may explain the enhanced plasminogen activator activity previously noted in cirrhosis but not metastatic disease. Reduced hepatic clearance of t-PA and t-PA-PAI-1 complex due to impaired liver function may account for increased concentrations of free and complexed t-PA.

Enzyme-Linked Immunosorbent Assay↗
PubMed1994

The indeterminate breast mass: assessment using contrast enhanced magnetic resonance imaging.

Magnetic resonance imaging of the breast was performed on 25 lesions in 24 patients. These lesions were indeterminate on clinical and mammographic examination. The imaging findings were compared with pathological results in all cases. Conventional T1 and T2 spin echo images provided a certain diagnosis in only one case. The pattern of signal enhancement following gadolinium diethylamine triamine pentaacetic acid injection as demonstrated by a T1-weighted gradient recalled echo sequence permitted accurate diagnosis of four recurrent carcinomas and 19 cases of non-malignant disease (17 postoperative scars and two cases of benign breast disease). One false positive diagnosis of cancer was made in a case of fibroadenoma. Dynamic contrast enhanced magnetic resonance imaging may have a role in the assessment of the indeterminate breast mass.

Adult↗
PubMed1994

MR imaging of the breast after surgery for breast cancer.

Unenhanced scans, with any sequence, often give limited and unreliable information when trying to distinguish tumor recurrence from scarring. Dynamic scanning very soon after the intravenous injection of Gd-DTPA is the best available method of distinguishing between benign tissue and neoplastic recurrence after conservation treatment for breast cancer. 3-D T1-weighted gradient echo images appear to be the technique of choice, preferably with image subtraction. Rapid and pronounced tissue enhancement is strongly suggestive of tumor recurrence; however, scanning within 6 months of surgery and 9 months of radiation therapy may lead to false-positive results. Benign proliferative disease and recent fat necrosis may also mimic cancer on dynamic contrast enhanced MR images. The indications for MR imaging after tylectomy and radiotherapy are findings that are equivocal or suspicious of neoplastic recurrence on clinical examination, mammography, or ultrasound, often on a combination of these modalities. Typical clinical findings are a mass or induration at the site of surgery, a mass lesion with spiculated and irregular outline on mammography, or variable echogenicity on ultrasound. The development of these appearances on sequential examination is particularly suggestive of recurrence. When microcalcification is the only finding of a carcinoma on mammography after treatment for breast cancer, contrast enhancement is consistently present.

Breast↗
PubMed1993

Plasminogen activator inhibitors (PAI-1 and PAI-2) in normal pregnancies, pre-eclampsia and hydatidiform mole.

OBJECTIVE: To examine the behaviour of the major inhibitors of fibrinolysis (PAI-1 and PAI-2) in normal pregnancy and pregnancy complicated by either pre-eclampsia or hydatidiform mole. DESIGN: Prospective study. SETTING: Antenatal Clinic and Maternity Hospital. SUBJECTS: Eleven women with established pre-eclampsia and eleven women, matched by age, parity, and duration of pregnancy who were undergoing uncomplicated pregnancy. Two women having surgery for hydatidiform mole. MAIN OUTCOME MEASURE: Plasma levels of PAI-1 and PAI-2 antigens determined by sensitive specific ELISA. Functional identification of PAI-2 by nondenaturing gel electrophoresis with overlay zymography. RESULTS: In pre-eclampsia PAI-2 antigen was significantly lower than in normal pregnancy (105.3 +/- 34.9 versus 187.1 +/- 67.9 ng/ml; P < 0.001). In contrast PAI-1 antigen was significantly higher in pre-eclampsia than in normal pregnancy (170.7 +/- 71.2 versus 113.8 +/- 35.6 ng/ml; P < 0.05). In consequence the ratio of PAI-1/PAI-2 increased markedly in pre-eclampsia (2.5 versus 0.6). No PAI-2 was detected in plasma of women with hydatidiform moles. CONCLUSIONS: PAI-2 levels fell significantly in pre-eclampsia probably as a result of decreased placental mass or function. The raised PAI-1 level in pre-eclampsia may reflect a response to hypertension or renal damage that is not specific to pregnancy or may reflect altered placental function. The use of the ratio of PAI-1/PAI-2 assists in separating normal from abnormal pregnancies.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Increasing patient throughput in magnetic resonance imaging: a practical approach. Oxford MRI Group.

A major factor governing the throughput of patients in a magnetic resonance imaging (MRI) service is the number and length of sequences employed. This study investigated the feasibility of prospectively selecting patients for whom a pre-planned examination of the brain, spine or knee could be applied with a high chance of success. The implications on throughput of using these pre-planned examinations were determined. 173 patients were studied. A successful outcome was defined as an examination in which a diagnosis could be made with 100% confidence and without the need for further sequences. Examinations of the brain (n = 113), knee (n = 23) and lumbar spine (for disc degeneration, n = 14) were performed with success rates of 96%, 87% and 64%, respectively. Examinations of the lumbar spine (for radicular symptoms, n = 20) and cervical spine (n = 3) were performed with success rates of 85% and 66%, respectively. The examinations of the brain, knee and lumbar spine (for disc degeneration) were completed within the target time of 20 min in 92%, 95% and 69% of cases, respectively. Examinations of the lumbar spine (for radicular symptoms) and cervical spine were completed within 30 min in 75% and 33% of cases, respectively. Analysis of our results suggests that success rates could be improved by minor changes in sequence design. Carefully selected patients can be successfully examined in short examination times. Instituting these practices would increase the efficiency of MR machine time and improve patient throughput by 80-125%. This would have a marked effect on the length of waiting lists, and would increase the general availability of MRI.

Brain Diseases↗
PubMed1991

Magnetic resonance imaging: when is one sequence sufficient?

We have studied 100 patients undergoing magnetic resonance imaging (MRI) in eight well-defined clinical problems. The relative values of the clinical details and the initial imaging sequence in reaching the final MR diagnoses were assessed. For each patient, two radiologists independently predicted the likely radiological findings from the clinical details. They then assessed the radiological appearances shown by the initial imaging sequence (which was chosen according to the clinical problem). Lastly, they made a final interpretation using all the available information. Prediction of likely radiological abnormalities from the clinical details proved unreliable. However, the radiological assessment of the initial imaging sequence was reliable for clinical problems related to the pituitary fossa, posterior fossa, internal auditory meatus and for suspected multiple sclerosis. In these patient groups additional sequences might be reserved for those with equivocal findings. Conversely, assessment of the initial imaging sequence proved unreliable compared with the full radiological assessment for clinical problems in the lumbar spine, the axilla and the knee. This study has led us to reduce the number of sequences performed for some clinical problems, with a commensurate increase in the throughput of patients.

Clinical Competence↗
PubMed1991

Distribution of plasminogen activator inhibitor (PAI-1) in tissues.

Extracts of human tissue were analysed for plasminogen activator inhibitor (PAI-1) antigen and activity. PAI-1 was localised in tissues by an immunochemical method, using monoclonal antibodies. PAI-1 occurred throughout the body; its concentration and activity differed considerably from organ to organ. Extracts of liver and spleen had the greatest abundance of PAI-1, but the activity of the inhibitor was much higher in liver than in spleen: the liver may be a source of plasma PAI-1. Immunochemical staining for PAI-1 was observed in endothelium, platelets and their precursor cells, the megakaryocytes, and locations central to the process of haemostasis. PAI-1 also occurred in neutrophil polymorphs and macrophages, cells important in inflammatory and immune processes, but not in lymphocytes. Other cell types, in particular, vascular smooth muscle cells and mesangial cells, also stained positively for PAI-1 and such cells seem to represent an important reservoir of PAI-1.

Autopsy↗
PubMed1990

Axillary fibrosis or recurrent tumour. An MRI study in breast cancer.

Magnetic resonance imaging was performed in 35 patients with breast carcinoma in an attempt to elucidate the cause for arm oedema or neurological symptoms. In each patient the clinician was asked to predict at the outset whether tumour recurrence or radiation fibrosis was more likely on clinical grounds. MRI demonstrated features compatible with fibrosis in 21 and tumour recurrence in 10; the MRI findings were equivocal in four patients. The range of these appearances is described and demonstrated. The MRI findings were at gross variance with the clinical opinion in 10 patients, upgrading eight patients to tumour recurrence and downgrading two to radiation fibrosis. Although histological confirmation is only available in three patients, corroborative evidence (that is repeat MRI, clinical follow up) is presented which suggests that the MRI interpretation was correct in the remaining patients. MRI can provide a working diagnosis in these patients; this allows a more rational approach to treatment than a diagnosis based on clinical examination alone.

Adult↗
PubMed1990

The platelet and plasma pools of plasminogen activator inhibitor (PAI-1) vary independently in disease.

The relative importance and behaviour of plasma and platelet plasminogen activator inhibitor (PAI-1) in disease has not hitherto been examined. In this study the concentration of PAI-1 in the plasma and platelets of patients with a variety of disorders was examined using a specific ELISA and a functional assay. Mean plasma PAI-1 was elevated in groups of patients with diabetes mellitus, hypertension, alcoholic cirrhosis, angina and myocardial infarction. Plasma PAI-1 was raised in the post-operative phase and the PAI-1 released after surgery was not derived from platelets. In all groups PAI-1 in the platelet pool reflected the platelet count, except in type II diabetes mellitus and chronic renal failure, where a reduced quantity of PAI-1 antigen per platelet was found. In severe chronic renal failure, abnormal platelets and diminished platelet PAI-1 may contribute to the haemorrhagic tendency sometimes seen in this disorder. Plasma PAI-1 represents a larger proportion of total circulating PAI-1 in disease than it does in healthy individuals; PAI-1 per platelet is abnormal only in a minority of disorders. Plasma and platelet pools of PAI-1 vary independently in disease and both merit consideration in evaluating the importance, if any, of PAI-1 in thrombosis or haemorrhage.

Blood Platelets↗