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Biomedical subjects

S Field

Publications and source records attributed to S Field.

At least 19 recordsLinked to original sources
PubMed2001

A pilot evaluation of the R2 image checker system and users' response in the detection of interval breast cancers on previous screening films.

AIM: Breast screening radiologists are under considerable pressure to maximize cancer detection and minimize the number of interval cancers. This study used screening films, previously reported as normal, taken before the development of an interval cancer. The aim was to determine the sensitivity and specificity of the R2 Image Checker System and the responses of users in detecting abnormalities in these previous films. MATERIALS AND METHODS: The first R2 Image Checker System in the U.K. was installed in the Canterbury Assessment Centre for evaluation purposes. System performance was compared with the standard protocol for assessing interval cancers used in the NHS Breast Screening Programme (NHSBSP) Three readers examined the previous films blind before switching on R2 and compared the prompts generated with the location of the subsequent interval cancer. RESULTS: The previous screening films for 104 cases generated 134 R2 prompts on the subsequent cancer side and 109 on the non-cancer side. Readers classified 29 cancers as false-negative or minimal signs and R2 correctly prompted in 15 of these cases (52%). At least one reader rejected the correct prompt in five cases. CONCLUSION: From this preliminary study it appears that R2 overprompts normal areas and underprompts some cancers in these difficult cases. A full multi-centre evaluation is needed to assess the possible contribution of R2 to the NHSBSP.

Aged↗
PubMed2001

The cost-effectiveness of magnetic resonance imaging for investigation of the knee joint.

OBJECTIVES: This study considered the role of magnetic resonance imaging (MRI) in the diagnosis of knee injuries in a district general hospital (DGH) setting. The principal objective was to identify whether the use of MRI had a major impact on the clinical management of patients presenting with chronic knee problems, in whom surgery was being considered, whether it reduced overall costs and whether it improved patient outcome. In addition, the research: (1) explored the 'diagnostic accuracy' of initial clinical investigation of the knee by an orthopaedic trainee, consultant knee specialist and consultant radiologist; (2) considered the variability and diagnostic accuracy of interpretations of knee MRI investigations between radiologists; (3) measured the strength of preference for the potential diagnostic/therapeutic impact of knee MRI (i.e. the avoidance of surgery). METHODS - RANDOMISED CONTROLLED TRIAL: The research was based on a single-centre randomised controlled trial conducted at Kent and Canterbury Hospital. Patients attending with knee problems in whom surgery was being considered were recruited from routine orthopaedic clinics. Most patients had been referred by their general practitioner. Patients were randomised to either investigation using an MRI scan (MRI trial arm) or investigation using arthroscopy (no-MRI trial arm). The study investigated the benefits of knee MRI at two levels: diagnostic/therapeutic impact (i.e. avoidance of surgery) and patient outcome (using the Short Form with 36 items and EQ-5D quality-of-life measurement instruments). Quality of life was assessed at baseline and at 6 and 12 months. Costs were assessed from the perspectives of the NHS and patients. All analyses were by intention to treat. METHODS - SUBSTUDIES (INVESTIGATION OF DIAGNOSTIC ACCURACY): For the investigation of diagnostic accuracy of initial clinical investigation, the sample comprised 114 patients recruited in a separate study conducted at St Thomas' Hospital. The sample was drawn from patients presenting at the Accident and Emergency Department with an acute knee injury. All study patients received an MRI scan, but initial diagnosis was made without access to the scan or the radiologist's report. After 12 months, all clinical notes and MRI scans of study patients were reviewed and a final 'reference standard' diagnosis for each patient was reached. Comparison was made between the diagnosis recorded by each clinician (i.e. orthopaedic trainee, knee specialist and consultant radiologist) and the reference diagnosis. METHODS - SUBSTUDIES (INVESTIGATION OF THE GENERALISABILITY OF RESULTS): For this substudy, the MRI images from 80 patients (recruited at St Thomas' Hospital) were interpreted independently by seven consultant radiologists at DGHs and the St Thomas' Hospital MRI radiologist. For each area of the knee, the level of agreement (measured using weighted kappa) between the responses of the eight radiologists and the reference standard diagnosis was assessed. METHODS - SUBSTUDIES (INVESTIGATION OF PREFERENCES): The investigation of potential patient preferences for the diagnostic/therapeutic impact of MRI was explored using a discrete choice conjoint measurement research design. Choices involved selecting between two alternative scenarios described using four attributes, and data were collected from 585 undergraduate sports science students and analysed using a random-effects probit model. RESULTS - RANDOMISED CONTROLLED TRIAL: The trial recruited 118 patients (59 randomly allocated to each arm). The two groups were similar in important respects at baseline. The central finding was of no statistically significant differences between groups in all measures of health outcome, although a trend in favour of the no-MRI group was observed. However, the use of MRI was found to be associated with a positive diagnostic/therapeutic impact: a significantly smaller proportion of patients in the MRI group underwent surgery (MRI = 0.41, no-MRI = 0.71; p = 0.001). There was a similar mean overall NHS cost for both groups. RESULTS - SUBSTUDIES (INVESTIGATION OF DIAGNOSTIC ACCURACY): The exploration of diagnostic accuracy found that, when compared to orthopaedic trainees (44% correct diagnoses) or to radiologists reporting an MRI scan (68% correct diagnoses), the accuracy rate was higher for knee specialists (72% correct diagnoses). RESULTS - SUBSTUDIES (INVESTIGATION OF THE GENERALISABILITY OF RESULTS): This generalisability study indicated that, in general terms, radiologists in DGHs provide accurate interpretations of knee MRI images that are similar to a radiologist at a specialist centre. The one area of the knee for which this did not hold was the lateral collateral ligament. RESULTS - SUBSTUDIES (INVESTIGATION OF PREFERENCES): The central finding for this substudy was that, on average and within the range specified, choices in this group of potential patients were not significantly influenced by variation in the chance of avoiding surgery. CONCLUSIONS - IMPLICATIONS FOR HEALTHCARE: The evidence presented in this report supports the conclusions that the use of MRI in patients presenting at DGHs with chronic knee problems in whom arthroscopy was being considered did not increase NHS costs overall, was not associated with significantly worse outcomes and avoided surgery in a significant proportion of patients. CONCLUSIONS - RECOMMENDATIONS FOR FURTHER RESEARCH (IN PRIORITY ORDER): (1) The trial data demonstrated that the use of MRI in patients with chronic knee problems reduced the need for surgery. However, the link between diagnostic processes and changes in health outcome is indirect and the finding of no-MRI-related effect on health outcome may, therefore, be a consequence of the limited power of the trial. Further research to confirm (or contradict) these findings would be valuable. (2) The investigation of diagnostic accuracy involved comparison with a reference diagnosis established by a panel of two clinical members of the research team. It would be interesting to explore the extent to which the results would differ using an external panel. (3) The result from the preference study, indicating that the potential diagnostic/therapeutic impact of knee MRI was not highly valued, is a surprising finding that would be important to explore in general public or patient populations. (4) The focus for the trial-based aspects of this research was the DGH and patients presenting with chronic knee problems who were being considered for surgery. Care should be taken in generalising from these results to other patient groups (e.g. acute knee injuries) or to other settings (e.g. specialist centres). Further clinical trials would be required in order to answer such questions.

Adolescent↗
PubMed2000

Job stress and satisfaction among clinical radiologists.

AIMS: Consultant radiologists appear to be at greater risk of burnout than consultants working in other specialties. The aim of this study was to examine sources of stress and satisfaction at work for radiologists and hospital consultants in other specialties in order to try to understand this difference. MATERIALS AND METHODS: A postal questionnaire survey of psychiatric morbidity (12-item General Health Questionnaire), burnout (Maslach Burnout Inventory) and sources of job stress and satisfaction (study-specific questionnaires) was carried out among a random sample of 882 hospital consultants working in radiology and three other specialties (surgery, gastroenterology and oncology). RESULTS: The most stressful aspect of work for radiologists was work overload. Inadequacies in current staffing and facilities and concerns about funding were also major sources of stress, as were impositions made on radiologists by other clinicians. The most important sources of satisfaction for radiologists were their relationships with patients and being perceived to do their job well by colleagues. Importantly, radiologists reported less satisfaction than the other specialists from many of the aspects of work measured. A greater proportion of radiologists than other specialists felt insufficiently trained in communication skills [80% (n = 168) vs 47% (n = 310);P < 0.001] and management skills [84% (n = 179) vs 76% (n = 506);P < 0.05]. CONCLUSION: These data highlight aspects of radiologists' work which need to be tackled in order to reduce their stress and increase their satisfaction, and thereby their risk of burnout.

Burnout, Professional↗
PubMed2000

An investigation into why two-view mammography is better than one-view in breast cancer screening.

AIM: To determine why two-view mammography in screening for breast cancer is more effective than using a single medio-lateral oblique view. MATERIALS AND METHODS: In the United Kingdom Coordinating Committee on Cancer Research randomized trial of one- vs two-view mammography in breast cancer screening the oblique view was assessed by one radiologist and two views (oblique and cranio-caudal) assessed by another. For the present study the mammographic films were retrieved from the screening centres and assessed by three consultant radiologists. Mammographic films were available from 110 women; 87 had their breast cancer detected by both one and two views and in 23 it was missed by one view but detected using two views. Outcome measures were breast size, location and size of the cancer, mammographic features, presence of microcalcification and overall radiological assessment. RESULTS: Although 23 cancers were missed in the original trial when one view was used, only two were not visible on the oblique view. Cancers missed using a single oblique view (and only detected if the cranio-caudal view was available with the oblique) tended to be smaller by about 4 mm (P = 0.05), centrally located in the breast (P = 0.16), not spiculated or round, (P </= 0. 001) and lacked microcalcification (P = 0.15). Breast size and breast radiographic density were not significantly associated with breast cancer detection. CONCLUSIONS: The results provide the basis for the observation that two-view mammographic screening is more effective than one-view mammographic screening.Hackshaw, A. (2000). Clinical Radiology55, 454-458.

Breast Neoplasms↗
PubMed2000

The effect of the general practice registrar year on perceived skills in palliative care in the West Midlands.

OBJECTIVES: To ascertain the effect of 12 months spent as a GP registrar on perceived skills in palliative care. DESIGN: A previously validated questionnaire for use with medical undergraduates is modified and used to survey perceived skills in five aspects of providing palliative care in five different scenarios at two points during the 12-month period of general practice vocational training where no specific teaching intervention is conducted. SETTING: The West Midlands. PARTICIPANTS: 210 GP registrars. RESULTS: Perceived skill ratings were seen to significantly increase during the 12-month period, but anxiety in caring for the dying did not significantly decrease. Ratings of skills were lowest when caring for a child dying with leukaemia or a young adult dying with AIDS. In addition, other important variables which had a statistically significant influence were gender and age, but interestingly not the number of previous senior house officer (SHO) posts undertaken or whether the respondent had had formal teaching on the subject in the past. CONCLUSION: It might therefore be postulated that training as a GP registrar has an important impact on the development of perceived skills in palliative care.

Adult↗
PubMed1999

Attendance at cancer screening in the wake of widespread adverse publicity surrounding test results.

The largest error ever discovered in cervical smear test results was reported by an East Kent Hospitals' NHS Trust in 1996. To test whether the incident would have an impact on a separate NHS screening programme within the affected area, 1000 women who were due to be called for x ray mammography were asked how confident they would be about the accuracy of their mammogram result. Most women reported that they would be confident, but significantly fewer unconfident than confident women subsequently kept their appointment for breast screening. Attendance and non-attendance at breast screening in the area did not differ from previous screening rounds, suggesting that the error in the cervical cytology results had not adversely affected a separate screening programme.

Attitude to Health↗
PubMed1998

GB virus C prevalence in blood donors and high risk groups for parenterally transmitted agents from Gauteng, South Africa.

The prevalence of GBV-C infection in voluntary blood donors and in groups at high risk for parenteral exposure to infectious agents was studied. The high risk groups included chronic renal failure patients on haemodialysis, renal transplant patients and haemophiliacs from Gauteng. The presence of GBV-C RNA in these populations was determined using reverse transcription polymerase chain reaction (RT-PCR) in the 5' non-coding region (NCR) of the virus. Of the blood donors, 11.1% (95% CI 7.6, 15.8) were positive, whereas 23.8% (95% CI 12.6, 40.2) of haemodialysis patients and 23.5% (95% CI 15.9, 33.3) of the haemophiliacs were infected with GBV-C. The highest proportion of infection was in the renal transplant patients, where 41.2% (95% CI 35.1, 47.7) were found to have circulating GBV-C RNA. Serological markers for hepatitis B (HBV) and hepatitis C viruses (HCV) were also measured as indicators of other hepatitis viruses with important parenteral transmission routes. Of the GBV-C positive blood donors, 3.6% were also HBsAg positive and none were positive for HCV. The GBV-C positive patients on haemodialysis were not positive for either HBsAg or antibodies to HCV, but had evidence of past infection with HBV since 40% were anti-HBc positive. The greatest proportion of HCV positives was in the haemophiliac group, 91.3%, none of these were HBsAg positive but 39.1% had anti-HBc. In the GBV-C positive renal transplant patients, 4% had HBsAg, 13.3% had anti-HBc and 2.1% had antibodies to HCV. This is the first report describing the prevalence of GBV-C in South African populations.

Blood Donors↗
PubMed1998

Second round cancers: how many were visible on the first round of the UK National Breast Screening Programme, three years earlier?

The first round screening films of 100 women who had cancers detected in the second round of the NHS Breast Screening Programme, were reviewed blindly, and then retrospectively, with knowledge of the site of the subsequent cancer. On initial blind viewing of the first screening mammograms, a lesion, later histologically proven to be the cancer, was correctly identified in 25 false-negative lesions. However, 51 false positive lesions which did not develop into cancer were also identified. Review with knowledge of the site of the lesions at second round screening identified an additional 19 false negative lesions. The mammographic features of the 25 false negative lesions initially identified on blind review were ill-defined masses (52%), architectural distortion (20%), asymmetrical densities (16%), enlarged lymph nodes (8%) and a well defined lesion (4%). Sixteen of these lesions were classified as minimal change, suspicious change in four, clearly malignant in three and benign in two. Forty-eight percent of the false negative lesions occurred in the established review areas of the breast. On retrospective review, 25% of incident round screen detected breast cancers were potentially detectable on the previous screening mammograms and the majority of these lesions were ill-defined masses that were more likely to occur in the 'review areas' of the breast. However, only 7% demonstrated mammographic features that were clearly recognized as suspicious of malignancy. We therefore recommend that radiologists involved in screen reading should pay particular attention to abnormalities occurring in the so-called review areas.

Aged↗
PubMed1998

Direct access MRI for general practitioners--influence on patient management.

At the Kent and Canterbury Hospital between April 1994 and September 1995, 170 magnetic resonance imaging (MRI) examinations were requested by 58 different general practitioners by direct access. By use of a retrospective postal questionnaire, information regarding subsequent patient management was obtained and compared with the proposed management, had MRI not been available. Speed of diagnosis with a consultant opinion was shown to be a major advantage compared with conventional outpatient referral. Hospital outpatient referral was avoided in 55/135 (41%) patients. In 20/83 (24 %) patients who were subsequently referred, the speciality to which the patient was referred was changed as a result of the MRI, ensuring more appropriate initial referral. Twenty-three of 54 (43%) general practitioners have said that they have changed their request pattern for plain radiographs now that they have direct access to MRI. We have shown MRI to be valuable to the general practitioner for patient management decisions and so we recommend that MRI should be available to general practitioners by direct access.

Attitude of Health Personnel↗
PubMed1998

Video assessment.

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Clinical Competence↗
PubMed1997

Just how valuable is double reporting in screening mammography?

The double reporting of screening mammograms has become an aim of most United Kingdom screening units although it is not Department of Health policy. It is recognized that mammogram reporting sensitivity improves with experience. This study was designed to assess how valuable double reporting has been in our unit. The data from the first screening round, including the interval cancers which were detected during the subsequent 3 years, were analysed. The reporting sensitivities of the less experienced radiologist improved during the 3 years of the first screening round from 90.6% to 98.9%. For the more experienced radiologist sensitivities ranged from 97.1% to 98.9%. Overall the increased sensitivity from double reporting over single reporting was 1.5% over the best to 4.2% over the worst single reader. With such a relatively small difference between single and double reporting and high individual reporting standards, it is hard to justify the additional resources required for double reporting.

Breast Neoplasms↗
PubMed1997

The use of magnetic resonance imaging to assess tracheal stenosis following percutaneous dilatational tracheostomy.

The incidence of tracheal stenosis following conventional tracheostomy has been reported as lying between one and 30 per cent. Methods used to assess the degree of stenosis include CT scanning, fibreoptic visualization and plain X-ray tomographs. The aim of this study was to assess the degree of stenosis in patients following percutaneous dilatational tracheostomy (PDT) using MRI scanning. This method has not been reported in the literature previously. Nine patients without symptoms of tracheal stenosis were studied for at least six months following PDT performed in the intensive therapy unit. The tracheas were assessed for scarring and stenosis using a three dimensional volume scanning MRI technique. Although scarring could be detected in the wall of the trachea and subcutaneous tissues of all patients, tracheal stenosis was not demonstrated at the insertion site or at the site of the cuff (p > 0.05). MRI scanning provides an excellent non-invasive method of assessing the tracheal lumen. Our patients who had undergone PDT do not appear to have any degree of post-operative stenosis.

Adult↗
PubMed1997

Vessel growth and collapsible pressure-area relationship.

The role that the pattern of vessel wall growth plays in determining pressure-lumen area (P-A) and pressure-compliance curves was examined. A P-A vessel model was developed that encompasses the complete range of pressure, including negative values, and accounts for size given the fixed length, nonlinear elastic wall properties, constant wall area, and collapse. Data were obtained from excised canine carotid and femoral arteries, jugular veins, and elastic tubing. The mean error of estimate was 8 mmHg for all vessels studied and 2 mmHg for blood vessels. The P-A model was employed to examine two patterns of arterial wall thickening, outward growth and remodeling (constant wall area), under the assumption of constant wall properties. The model predicted that only outward wall growth resets compliance such that it increases at a given arterial pressure, explaining previously contradictory data. In addition, it was found that outward wall growth increases the lumen area between normal and high pressures. Remodeling resulted in lumen narrowing and a decrease in compliance for positive pressures.

Animals↗