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Biomedical subjects

F J Gilbert

Publications and source records attributed to F J Gilbert.

At least 37 records · Page 2Linked to original sources
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

Role of positron emission tomography in the management of breast cancer.

Positron emission tomography (PET) is an imaging modality that utilises tracers based on biologically important compounds and can be used to study in vivo tissue function. This article reviews the current status of PET imaging in breast disease. The positron emitting glucose analogue 18F-FDG is used to image tissue glycolysis and has been extensively evaluated. Studies have shown that 18F-FDG PET has a high sensitivity and specificity for the detection of primary breast cancers, however its use is not superior that of conventional imaging modalities. Considerable interest is now focussing on the application of PET to non-invasively determine the lymph node status of patients with breast cancer and to predict and evaluate tumour response to chemotherapy. Relatively low cost gamma camera systems are now available that are capable of PET imaging, and thus it may therefore be possible to perform PET imaging in the majority of hospitals.

Journal Article↗
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↗
PubMed1999

Low-bandwidth tele-ultrasound.

We examined the acceptability and diagnostic accuracy of dynamic ultrasound images transmitted at 128 kbit/s and 384 kbit/s. The gold standard was the direct recording of 200 ultrasound examinations on video-tape. The taped images were later transmitted at both 128 kbit/s and 384 kbit/s and recorded, resulting in three tapes for each case. Four observers viewed each tape individually. Ninety per cent of images transmitted at 384 kbit/s were rated as diagnostically acceptable compared with 32% of images transmitted at 128 kbit/s. Diagnostic agreement between tapes transmitted at 384 kbit/s and the gold standard was 85%, compared with 78% for 128 kbit/s transmissions. Observers were not satisfied with low-bandwidth transmission of ultrasound images despite adequate diagnostic accuracy. Dynamic ultrasound images transmitted at 384 kbit/s were viewed as both diagnostically acceptable and accurate.

Electronics↗
PubMed1999

Evaluation of 18F-FDG positron emission tomography in gastric and oesophageal carcinoma.

The aim of this study was to evaluate 18F-fluoro-deoxyglucose (FDG) positron emission tomography (PET) in gastric and oesophageal carcinoma. 16 patients with biopsy proven oesophageal or gastric carcinoma had PET scans. Four patients had advanced disease and received palliative treatment. The remaining 12 patients were randomized to immediate surgery or neoadjuvant chemotherapy. Three patients had repeat PET scans following chemotherapy. PET detected the primary tumour in all cases including stage T1 lesions. Involved locoregional nodes (N1, N2) were not identified separately from the primary tumour. Semiquantitative analysis was performed in the form of tumour to liver activity ratios (TLR). In general, the TLR values were higher in the higher T stages, although there was only one case each of T1 and T2 lesions. PET scanning using 18F-FDG is a sensitive method for detecting primary oesophageal and gastric cancers but is limited in locoregional staging.

Adult↗
PubMed1999

Magnetic resonance imaging in oncology: an overview.

This review discusses a growing area of imaging in oncology. Traditionally, the primary role of magnetic resonance imaging (MRI) has been in the investigation of neurological diseases and in the diagnosis of musculoskeletal abnormalities. With the increasing availability of MRI systems and with the advances in technology, the role of this modality out with these areas is rapidly expanding. This review outlines the areas where MRI has a specific role in the imaging of patients with cancer. In particular, emphasis is placed on areas outside of the central nervous and musculoskeletal systems. This review describes the areas where MRI may be advantageous over other imaging modalities such as computerised tomography (CT). Specific emphasis is placed on the staging of abdominal and pelvic malignancies, the detection of recurrence and the impact of MRI in hepatic imaging. In addition this article reviews the value of dynamic contrast enhanced MRI sequences, as well as the importance of newer organ specific MR contrast agents in hepatic and lymph node imaging.

Abdominal Neoplasms↗
PubMed1999

The accuracy of "one-stop" diagnosis for 1,110 patients presenting to a symptomatic breast clinic.

UNLABELLED: To minimise delay in diagnosis and reduce patient anxiety, triple assessment with immediate reporting has been used in our symptomatic breast clinic since 1991. This article examines the accuracy of the diagnostic modalities used and the efficacy of the "one-stop" diagnostic policy. The data on 1,110 new patients presenting to the symptomatic breast clinic between January and July 1993, were analysed and subsequent three year follow-up and outcome established. Fine needle aspiration cytology (FNAC) gave the highest predictive value (97.3%) with a sensitivity of 93.5% and a specificity of 98.1%. Ultrasonography provided a 97.0% prediction with a sensitivity of 88.9% and a specificity of 97.4%, whereas mammography had a prediction of 96.4% with sensitivity of 93.2% and a specificity of 96.7%. When the mammogram or ultrasound scan were reported as unequivocally benign (M1), there were no missed cancers. The false positive and false negative rates for FNAC were 0% and 1.4%, respectively. Following assessment, a diagnosis was made in 96% of patients. Sixty-two percent of the patients were discharged at the first clinic visit. Four breast malignancies were subsequently diagnosed in the discharged group; two with new microcalcifications due to ductal carcinoma in situ, one with invasive disease in a different quadrant of the breast from that originally investigated, and in one patient the cancer was missed. CONCLUSION: A "one-stop" symptomatic breast clinic provides an accurate and effective means of establishing a correct diagnosis.

Adolescent↗
PubMed1998

Incident round cancers: what lessons can we learn?

At the time of implementation of the National Health Service Breast Screening Programme a range of targets were set, and have since been updated. This study looks at a subset of cancers detected by screening - the incident round cancers - which are not currently identified and addressed by the targets. In our first incident round we screened 24838 women and detected 112 breast cancers in 111 women. On the basis of a two-stage retrospective evaluation of the prevalent round mammograms in these 111 women, we classified the prevalent mammograms as false negative 21 (19%), minimal signs 32 (28%) and new tumours 59 (53%). Analysis of the radiographic features revealed a disproportionate number with parenchymal deformity (21%) and asymmetry (17%) among the missed tumours when compared to all tumours detected by our screening programme (12% and < 1%, respectively). Identification and quantification of these incidence detected missed cancers could be incorporated into the Quality Assurance Data Set, and used as another performance indicator. Reviewing the mammograms proved a valuable teaching exercise and has allowed us to develop a test set of challenging mammograms.

Breast Neoplasms↗