Biomedical subjects

F J Gilbert

Publications and source records attributed to F J Gilbert.

At least 19 recordsLinked to original sources

PubMed2003

Research misconduct.

Good research practice is important to the scientific community. An awareness of what constitutes poor practice is important. Various types of research misconduct are defined in this article. The extent of research misconduct in the field of radiology has been assessed by contacting five English language radiology journals. Redundant or duplicate publication has been reported infrequently, Radiology (1), American Journal of Roentgenology (3), Clinical Radiology (3), British Journal of Radiology (2) and European Radiology (1). The issue of how the radiology community might tackle research misconduct is discussed with reference to guidance from the Medical Research Council, the Wellcome Trust and the Committee of Publication Ethics.

Authorship↗

PubMed2002

Axillary lymph node metastases: a statistical analysis of various parameters in MRI with USPIO.

PURPOSE: To assess the value of plain vs. iron oxide-enhanced MRI vs. the combined study (plain + postcontrast) based on qualitative and quantitative parameters of three pulse sequences. MATERIALS AND METHODS: Data from two sites were acquired using the same technique; therefore, this data could be pooled. T1W-SE, T2W-FSE, and 3D-PSIF were used before and 24-36 hours after MRI with ultra small particles of iron oxide (USPIO) was performed. A total of 52 lymph nodes (LNs) in nine patients (25 benign, 27 malignant) were evaluated by two readers who were visually and quantitatively blinded to the histology. Combinations of the following diagnostic parameters were compared using logistic regression analysis: the short-axis diameter of the LN, the signal distribution of the LN on postcontrast agent MRI (homogeneous or heterogeneous), and qualitatively and quantitatively determined signal changes of the LN following administration of contrast agent in the three evaluated sequences. RESULTS: Using pre- and postcontrast data, the optimized accuracy based on the statistically most significant parameters (LN diameter > 6 mm, visual assessment of signal change on T2W-SE) was 87% (81% sensitivity, 92% specificity). Precontrast data alone yielded 75% accuracy (63% sensitivity, 86% specificity). Postcontrast data alone yielded 75% accuracy (56% sensitivity, 96% specificity). CONCLUSION: Based on our results, USPIO-MRI improved the diagnosis of metastatic axillary LNs compared with precontrast MRI alone. Both pre- and postcontrast studies are needed. T1W-SE and T2W-PSIF did not yield significant additional information. This study may help to further improve the technique of USPIO imaging.

Axilla↗

PubMed2002

Effects of mailed dissemination of the Royal College of Radiologists' guidelines on general practitioner referrals for radiography: a time series analysis.

AIM: To evaluate the effect of postal dissemination of the third edition of the Royal College of Radiologists' (RCR) guidelines on general practitioner referrals for radiography. MATERIALS AND METHODS: An interrupted time series using monthly data for 34 months before and 14 months after dissemination of the guidelines was employed. Data were abstracted for the period April 1994 to March 1998 from the computerized administrative systems of open access radiological services provided by two teaching hospitals in one region of Scotland. The time series results are contrasted with those obtained by using a simple before and after design. RESULTS: A total of 117 747 imaging requests from general practice were received in the two departments. There were no significant effects of disseminating the guidelines on the total number of requests, or on requests for individual examinations. If a simple before and after study had been used, then we would have erroneously concluded that significant changes had occurred in referral practice for 11 of the 18 procedures concerned. CONCLUSION: Mailing of copies of the RCR guidelines had a small effect on general practitioners' use of X-ray investigations of uncertain clinical significance. Additional dissemination and implementation strategies appear necessary to promote the use of guidelines.

Family Practice↗

PubMed2002

Dynamic contrast enhanced MRI of the axilla in women with breast cancer: comparison with pathology of excised nodes.

Axillary lymph node status is the most important prognostic factor in breast cancer patients and is currently determined by surgical dissection. This study was performed to assess whether dynamic gadopentetate dimeglumine (Gd) enhanced MRI is an accurate method for non-invasive staging of the axilla. 47 women with a new primary breast cancer underwent pre-operative dynamic Gd enhanced MRI of the ipsilateral axilla. Lymph node enhancement was quantitatively analysed using a region of interest method. Enhancement indices and nodal area were compared with histopathology of excised nodes using a receiver operating characteristic (ROC) curve approach. 10 patients had axillary metastases pathologically and all had > or =1 lymph node with an enhancement index of >21% and a nodal area of >0.4 cm(2). 37 patients had negative axillary nodes pathologically. 20 of these had enhancement indices <21% and nodal areas <0.4 cm(2). Using this method, a sensitivity of 100%, a specificity of 56%, a positive predictive value of 38% and a negative predictive value of 100% could be achieved. Using this method of quantitative assessment, dynamic Gd enhanced MRI may be a reliable method of predicting absence of axillary nodal metastases in women with breast cancer, thereby avoiding axillary surgery in women with a negative MRI study.

Aged↗

PubMed2002

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS).

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS) is in progress. The study design, accrual to date, and related research projects are described. Revised accrual rates and expected recruitment are given. 15 cancers have been detected to date, from a total of 1236 screening measurements. This event rate and the tumour grades reported are compared with recent reports from other studies in women at high risk of breast cancer.

Adult↗

PubMed2001

What is achieved by mammographic surveillance after breast conservation treatment for breast cancer?

BACKGROUND: After breast conservation surgery for breast cancer, patients are followed up by regular clinical examination and mammography, at intervals which vary according to local practice. However, the optimum interval remains unclear with current guidelines suggesting mammography should be carried out every 1 to 2 years. This study has investigated this aspect and, in particular, whether mammography or clinical examination or both allowed an early detection of recurrence of the disease in the conserved breast. METHODS: A total of 695 patients who had undergone breast conservation surgery were identified from a database of prospectively recorded data during the period 1990 to 1995. Clinical examination and annual mammography were performed in accordance with local protocol. The results of clinical examination, mammography, and local recurrence rates were evaluated. RESULTS: A total of 2,181 mammograms were undertaken in the 695 patients studied. Local recurrence of disease in the conserved breast occurred in 21 patients (3%), at a mean follow-up of 3.5 years. The first identification of tumor recurrence was by clinical examination in 11 patients with local recurrence, and by the surveillance mammography in the other 10 patients with local recurrence. Overall, mammography detected the local recurrence in 13 of 20 (65%) patients who underwent this examination. In the other patients, the recurrence was detected on clinical examination only. In addition, in 52 patients, mammography was falsely positive, giving a false positive rate of 2.3%. Contralateral cancers in the opposite breast were detected in 2 patients. CONCLUSIONS: The detection of local disease after breast conservation surgery requires both clinical examination and mammography. In the context of our follow-up policy, in 52% of patients with local recurrence, this was first identified by clinical examination. Disease recurrence was identified in the other 48% of patients by mammographic surveillance. Overall, mammography will identify or confirm local recurrence in two thirds of women. However, in a small number of cases (2.3% in our series) mammography will give false positive results. New imaging modalities to assist in the diagnosis of local recurrence of disease after breast conservation surgery are required.

Adult↗

PubMed2001

The measurement of fetal liver T(*)(2) in utero before and after maternal oxygen breathing: progress towards a non-invasive measurement of fetal oxygenation and placental function.

Utero-placental insufficiency is thought to be a major cause of growth retardation in utero and an important risk factor in the perinatal period. The purpose of this study was to investigate whether MRI could detect changes of fetal oxygenation, based on the blood oxygenation level dependence (BOLD) of the MRI tissue signal. Nine third trimester women (34-38 weeks) with normal pregnancies underwent abdominal MRI examinations. Following localization of the fetal liver using T(2)-weighted single-shot HASTE scans, up to 7 breath-held transaxial single-slice gradient-echo image sets were obtained through the fetal liver. The mother then commenced oxygen breathing with the imaging procedure repeated after 20 minutes of O(2) breathing. For each image set, T(*)(2) values are calculated using linear regression of log (signal) versus TE for a region of interest within the fetal liver selected by the attending radiologist. Fetal liver T(*)(2) values were calculated before and after O(2) breathing for each multi-echo image acquisition set. A signed rank test was used to test for a significant change in fetal liver T(*)(2) between the pre-O(2) and post-O(2) image sets. A significant increase in T*(2) (alpha < 0.05) was seen in 5 of the 9 fetal livers, a smaller increase (of borderline statistical significance, alpha = 0.057) in 2 livers, and no significant change (alpha > 0.05) in 2 livers. Our study indicates that T(*)(2) measurement of the fetal liver may detect alteration in fetal oxygen level following maternal oxygenation using the BOLD effect. This technique may potentially be applied to the identification and understanding of placental dysfunction in intra-uterine growth retardation.

Adolescent↗

PubMed2001

Influence of imaging on clinical decision making in the treatment of lower back pain.

PURPOSE: To assess the impact of cross-sectional imaging with magnetic resonance (MR) imaging or computed tomography (CT) on clinical decision making for patients with lower back pain (LBP). MATERIALS AND METHODS: A randomized controlled before-and-after study was performed in 145 patients who had symptomatic lumbar spinal disorders and had been referred to orthopedists or neurosurgeons. Participants were a subgroup within a multicenter pragmatic randomized comparison of two imaging policies on LBP treatment: "imaging" versus "no imaging," unless a clear indication developed. Paired assessments were made of diagnosis, diagnostic confidence, proposed treatment, treatment confidence at trial entry and follow-up, and expectations of imaging. Data were analyzed according to the groups as randomized. RESULTS: At follow-up, there were no statistically significant differences between the groups with respect to diagnosis or treatment plans. Significant increases in diagnostic and therapeutic confidence between trial entry and follow-up were observed for both groups, with a significantly greater increase in diagnostic confidence (P =.01) in the imaging group. CONCLUSION: Imaging may increase diagnostic confidence but has minimal influence on diagnostic or therapeutic decisions for patients with LBP. The results highlight the need for evidence-based guidelines for imaging in LBP treatment.

Adult↗

PubMed2000

A comparison of digital and screen-film mammography using quality control phantoms.

AIM: To compare the performance of a direct digital mammography system with normal-view and magnified-view conventional screen-film methods using quality control phantoms. MATERIALS AND METHODS: Using a Siemens Mammomat((R))3000 and an Opdima((R))digital spot imaging and biopsy attachment, film and direct digital images of two phantoms [DuPont and TOR (MAM)] were obtained under normal operating conditions. These were assessed by three groups of observers with differing expertise - radiologists, radiographers and medical physicists. Each observer was asked to compare the direct digital image with films taken in standard view and magnified view, providing scores for object visibility and confidence. For the digital images, observers were allowed to vary the image presentation parameters. RESULTS: Both phantoms showed that overall the direct digital view and the magnified view film performed significantly better (P < 0.05) than standard view film. For certain small or low contrast objects the differences became very highly significant (P < 0.001). CONCLUSION: Only the TOR (MAM) phantom showed any significant difference between digital and magnified modalities, with magnified views performing better for fine, faint filaments and digital acquisition better for low contrast objects. Almost no difference existed between the three observer groups. Undrill, P. E. (2000). Clinical Radiology53, 782-790.

Breast Neoplasms↗

PubMed2000

Positron emission tomography using [(18)F]-fluorodeoxy-D-glucose to predict the pathologic response of breast cancer to primary chemotherapy.

PURPOSE: To determine whether [(18)F]-fluorodeoxy-D-glucose ([(18)F]-FDG) positron emission tomography (PET) can predict the pathologic response of primary and metastatic breast cancer to chemotherapy. PATIENTS AND METHODS: Thirty patients with noninflammatory, large (> 3 cm), or locally advanced breast cancers received eight doses of primary chemotherapy. Dynamic PET imaging was performed immediately before the first, second, and fifth doses and after the last dose of treatment. Primary tumors and involved axillary lymph nodes were identified, and the [(18)F]-FDG uptake values were calculated (expressed as semiquantitative dose uptake ratio [DUR] and influx constant [K]). Pathologic response was determined after chemotherapy by evaluation of surgical resection specimens. RESULTS: Thirty-one primary breast lesions were identified. The mean pretreatment DUR values of the eight lesions that achieved a complete microscopic pathologic response were significantly (P =.037) higher than those from less responsive lesions. The mean reduction in DUR after the first pulse of chemotherapy was significantly greater in lesions that achieved a partial (P =.013), complete macroscopic (P =.003), or complete microscopic (P =.001) pathologic response. PET after a single pulse of chemotherapy was able to predict complete pathologic response with a sensitivity of 90% and a specificity of 74%. Eleven patients had pathologic evidence of lymph node metastases. Mean pretreatment DUR values in the metastatic lesions that responded did not differ significantly from those that failed to respond (P =.076). However, mean pretreatment K values were significantly higher in ultimately responsive cancers (P =.037). The mean change in DUR and K after the first pulse of chemotherapy was significantly greater in responding lesions (DUR, P =.038; K, P =.012). CONCLUSION: [(18)F]-FDG PET imaging of primary and metastatic breast cancer after a single pulse of chemotherapy may be of value in the prediction of pathologic treatment response.

Adult↗

PubMed2000

The diagnostic acceptability of low-bandwidth transmission for tele-ultrasound.

Ultrasound recordings were made of 100 consecutive patients attending for obstetric examination in Peterhead and 100 patients attending for non-obstetric examination in Aberdeen. Two identical video-conferencing machines were used to transmit and receive the original ultrasound images at data rates of 384 kbit/s and 128 kbit/s, thus producing a total of three tapes for each case. Four experienced observers, who were blinded to the transmission bandwidth, each viewed 300 examinations and decided whether the images were acceptable or not for diagnosis. Almost 100% of the obstetric ultrasound images on the original recordings were considered diagnostically acceptable, compared with 93% of the 384 kbit/s transmissions and 44% of the 128 kbit/s transmissions. Similarly, 99% of the non-obstetric ultrasound images were considered acceptable, compared with 87% of the 384 kbit/s transmissions and 21% of the 128 kbit/s transmissions. For the obstetric ultrasound images the intra-observer diagnostic agreement was 93% (kappa = 0.89) between the original and the 384 kbit/s transmissions, and 78% (kappa = 0.63) between the original and the 128 kbit/s transmissions. For the non-obstetric ultrasound images the respective intra-observer diagnostic agreements were 77% (kappa = 0.62) and 78% (kappa = 0.63). The quality of dynamic ultrasound images transmitted at 384 kbit/s was diagnostically acceptable, but was unsatisfactory at 128 kbit/s.

Female↗

PubMed2000

Methods of measurement of image quality in teleultrasound.

In recent years, teleultrasound has emerged as a potentially effective method of provision of ultrasound services to remote areas of the community. Transmission of teleultrasound, however, requires a high degree of compression when utilizing the relatively low bandwidth ISDN connections available within the UK. The actual amount of compression occurring varies both with the connection and the image content, often on a frame to frame basis. For this reason, traditional measurements of image quality using test tools are ineffective. Most studies to date have assessed equipment performance by testing diagnostic performance. Although this is the most important method of assessing the results of image degradation, few studies have attempted to perform physical measurements of degradation. The aims of this study were to measure the amount of degradation within a teleultrasound system and, using a number of methods, to ascertain the most useful indicators of loss of image quality. Groups of successive abdominal ultrasound images were captured and digitized both before and after degradation via an ISDN6 teleultrasound system. Normalized mean squared error (NMSE), pixel histograms, line and surface plots, Fourier spectra and contrast measurements were carried out on regions of interest in both sets of images. The NMSE was most sensitive to degradation, with alterations in the NMSE value depending on image content and degree of degradation. Fourier analysis was also indicative, showing consistent changes in high frequency content again varying with image content.

Fourier Analysis↗

PubMed2000

Recruitment to multicentre trials: the impact of external influences.

A multicentre randomised controlled trial needs to recruit sufficiently large numbers of centres, clinicians and patients Delays in reaching recruitment targets are common and often necessitate extended recruitment periods with associated increased costs. The Scottish Back Trial and the MRC Laparoscopic Hernia Trial are used to illustrate how national clinical, economic and political factors can impact on the conduct of a multicentre trial. Changes in clinical practice, restructuring of the NHS and research and development funding, and changes in the procedures for obtaining local research ethics committee approval had adverse effects on recruitment. In addition, the extent to which changes in patient knowledge and attitudes to clinical trials could influence recruitment should not be ignored. In response to these obstacles both trials extended the recruitment period, identified additional recruitment centres and reduced the overall sample size. External factors which could compromise the successful completion of a d trial need to be recognised and addressed at an early stage.

Herniorrhaphy↗

PubMed1999

Accuracy of T1 measurement in dynamic contrast-enhanced breast MRI using two- and three-dimensional variable flip angle fast low-angle shot.

In vivo T1 measurements, used to monitor the uptake of contrast agent by tissues, are typically performed as a first step in implementing compartmental analysis of contrast-enhanced breast magnetic resonance imaging (MRI) data. We have extended previously described methodology for in vivo T1 measurement (using a variable flip-angle gradient-recalled echo technique) to two-dimensional (2D), fast low-angle shot (FLASH). This approach requires computational modeling of slice-selective radiofrequency (RF) excitation to correct for nonrectangular slice profiles. The accuracy with which breast tissue T1 values can be measured by this approach is examined: T1 measurements from phantom and in vivo image data acquired with 2D and 3D FLASH imaging sequences are presented. Significant sources of error due to imaging pulse sequence quality and RF transmit field nonuniformity in the breast coil device that will have detrimental consequences for compartmental analysis are identified. Rigorous quality assurance programs with calibrated phantoms are thus recommended, to verify the accuracy with which T1 measurements are obtained.

Breast↗

PubMed1999

Protrusio acetabuli in Marfan's syndrome.

Marfan's syndrome is an autosomal dominant disorder of connective tissue, commonly involving the cardiovascular, ocular, and skeletal systems. Revised criteria for the clinical diagnosis of Marfan's syndrome regard skeletal involvement as a major criterion if at least four of eight typical skeletal manifestations are present, one of which is protrusio acetabuli. Using Kulman's method to determine the presence of protrusio, we analysed the pelvic X-rays of 15 patients with Marfan's syndrome and 15 controls. Protrusio was present in 47% (7/15) of Marfan patients, compared with 7% (1/15) of controls (P = 0.035). Using the revised criteria, the presence of protrusio would have affected the final diagnosis of Marfan's syndrome in only one patient out of 15. Therefore, we recommend that a pelvic X-ray is reserved for those cases in which the presence of protrusio will alter the final diagnosis. With regard to the radiological assessment of protrusio, in our opinion this can be performed simply and reliably using the position of the acetabular line alone.

Acetabulum↗

PubMed1999

The diagnostic performance of a PC-based teleradiology link.

AIM: Evaluation of the diagnostic performance of a personal computer based teleradiology link. MATERIALS AND METHODS: Two experienced radiologists assessed 100 cases, all based on chest and skeletal films using teleradiology for 50. These assessments were compared with the consensus of a panel of three independent radiologists. RESULTS: Diagnostic performance of teleradiology and conventional film was similar (sensitivity 88 vs. 90%; specificity 96 vs. 90%; accuracy 91 vs. 90%; not significant). However, the quality of teleradiology images was rated poorer, and the confidence in diagnosis was lower with teleradiology. ROC curve analysis, taking into account diagnostic confidence, showed significantly poorer performance for teleradiology at all thresholds when chest X-rays only were considered. There was no significant difference for skeletal images, although the two smooth curves crossed, suggesting teleradiology might be better when the specificity is high. CONCLUSION: These findings suggest that when this type of teleradiology system is used, the value of rapid reporting must be balanced against poorer image quality, particularly for chest X-rays.

Bone and Bones↗

PubMed1999

Metformin and contrast media--a dangerous combination?

Metformin is a biguanide used to treat type II diabetes mellitus. Since the recent introduction of this drug into the United States there has been considerable interest in metformin associated lactic acidosis (MALA) following intravenous contrast media. The Royal College of Radiologists published advice in November, 1996 (Advice to Members and Fellows with regard to metformin-induced lactic acidosis and X-ray contrast medium agents, RCR Publication) supporting the manufacturers' advice that metformin should not be used in the 48 h before or after intravenous (i.v.) contrast medium. We performed a systematic review of the literature and this has shown that almost all reported cases of MALA following i.v. contrast medium occurred where there was either pre-existing poor renal function or another contraindication to metformin usage. There has been only one reported case of lactic acidosis following the use of intravenous contrast medium in a patient with normal renal function. We suggest that the Royal College of Radiologists' advice should be modified and that it is safe to give i.v. contrast medium to patients on metformin with normal renal function.

Acidosis, Lactic↗

PubMed1999

The Scottish breast screening programme's experience of monitoring interval cancers.

OBJECTIVES: To present the Scottish interval cancer data from 1991 to 1995, compare the Scottish experience with results published by other programmes and trials, and document appropriate methodologies to achieve maximum ascertainment of interval cancers. SETTING: Scottish breast screening programme (part of the UK National Health Service breast screening programme). METHODS: Interval cancers were identified by linking breast screening data with registrations of invasive breast cancers from the National Scottish Cancer Register. The main outcome measures were the numbers, rates, and proportionate incidence of interval cancers, and rates of total and small (< 10 mm) screen detected invasive cancers diagnosed in this cohort of women. SUBJECTS: Women who attended the Scottish breast screening programme (Scottish NHSBSP) from 1 April 1991 to 31 March 1995. RESULTS: Interval cancer rates of 4.8, 12.1, and 12.1 per 10,000 women screened were calculated for the first, second, and third year after the last negative screen. Expressed as a proportion of the underlying incidence, the figures are 23%, 60%, and 59%. CONCLUSIONS: The Scottish data are comparable with those reported by other UK NHS breast screening programmes for the first and second years after the last negative screen. The interval cancer rate for the third year is appreciably lower. A longer follow up period would be of interest to provide greater evidence on which to base comparisons. Ascertainment of interval cancers depends vitally on the availability of complete, accurate, and timely national cancer registration data and highlights the value of national datasets.

Breast Neoplasms↗