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L W Turnbull

Publications and source records attributed to L W Turnbull.

At least 19 recordsLinked to original sources
PubMed2006

A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3T.

The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3T field strength and thereby improve the diagnostic quality of the images obtained.

Artifacts↗
PubMed2006

Recurrence rates after DCE-MRI image guided planning for breast-conserving surgery following neoadjuvant chemotherapy for locally advanced breast cancer patients.

BACKGROUND: Neoadjuvant therapy results in a significant increase in breast-conserving surgery. However, traditional imaging methods are unable to accurately predict the extent of viable residual disease leading to uncertainty in surgical planning and some previous studies have shown a disproportionately high incidence of locoregional recurrence. Dynamic contrast enhanced-MRI (DCE-MRI) has been shown to provide a potentially more accurate prediction of residual disease. RESULTS: Patients undergoing neoadjuvant chemotherapy for breast cancer in our unit are staged with the DCE-MRI of the breast performed at 1.5 T before, during and after treatment and the final result was used to plan surgery. Two hundred and four patients with breast cancer were treated with neoadjuvant chemotherapy between 1996 and April 2005. Eighteen of these patients had distant metastases at the time of initial diagnosis and so were excluded from the present study. Following neoadjuvant chemotherapy, 186 patients underwent surgical treatment. Of these, 68 patients had breast-conserving surgery. At a median follow up of 30 months (range: 5.6-72 months) 21 patients in this group developed subsequent recurrence (21/68 - 30%) of whom 9 (9/68 - 13%) had locoregional recurrence, 7 had local recurrence (7/68 - 10%), and 17 (17/68 - 25%) had distant recurrence. Logistic regression analysis revealed only vascular invasion (p=0.006) of the tumour to be significantly associated with overall recurrence. None of the pathological factors (ER, PR status, vascular invasion, lymph node metastases, pathological complete response to neoadjuvant chemotherapy) showed a significant association with locoregional recurrence. CONCLUSION: Breast-conserving surgery with DCE-MRI planning after neoadjuvant chemotherapy provides an acceptable level of local recurrence without the need for mastectomy.

Adult↗
PubMed2006

Cost-effectiveness of screening with contrast enhanced magnetic resonance imaging vs X-ray mammography of women at a high familial risk of breast cancer.

Contrast enhanced magnetic resonance imaging (CE MRI) is the most sensitive tool for screening women who are at high familial risk of breast cancer. Our aim in this study was to assess the cost-effectiveness of X-ray mammography (XRM), CE MRI or both strategies combined. In total, 649 women were enrolled in the MARIBS study and screened with both CE MRI and mammography resulting in 1881 screens and 1-7 individual annual screening events. Women aged 35-49 years at high risk of breast cancer, either because they have a strong family history of breast cancer or are tested carriers of a BRCA1, BRCA2 or TP53 mutation or are at a 50% risk of having inherited such a mutation, were recruited from 22 centres and offered annual MRI and XRM for between 2 and 7 years. Information on the number and type of further investigations was collected and specifically calculated unit costs were used to calculate the incremental cost per cancer detected. The numbers of cancer detected was 13 for mammography, 27 for CE MRI and 33 for mammography and CE MRI combined. In the subgroup of BRCA1 (BRCA2) mutation carriers or of women having a first degree relative with a mutation in BRCA1 (BRCA2) corresponding numbers were 3 (6), 12 (7) and 12 (11), respectively. For all women, the incremental cost per cancer detected with CE MRI and mammography combined was pound28 284 compared to mammography. When only BRCA1 or the BRCA2 groups were considered, this cost would be reduced to pound11 731 (CE MRI vs mammography) and pound15 302 (CE MRI and mammography vs mammography). Results were most sensitive to the unit cost estimate for a CE MRI screening test. Contrast-enhanced MRI might be a cost-effective screening modality for women at high risk, particularly for the BRCA1 and BRCA2 subgroups. Further work is needed to assess the impact of screening on mortality and health-related quality of life.

Adult↗
PubMed2006

Neoadjuvant chemotherapy in breast cancer: early response prediction with quantitative MR imaging and spectroscopy.

A prospective study was undertaken in women undergoing neoadjuvant chemotherapy for locally advanced breast cancer in order to determine the ability of quantitative magnetic resonance imaging (MRI) and proton spectroscopy (MRS) to predict ultimate tumour response (percentage decrease in volume) or to detect early response. Magnetic resonance imaging and MRS were carried out before treatment and after the second of six treatment cycles. Pharmacokinetic parameters were derived from T1-weighted dynamic contrast-enhanced MRI, water apparent diffusion coefficient (ADC) was measured, and tissue water:fat peak area ratios and water T2 were measured using unsuppressed one-dimensional proton spectroscopic imaging (30 and 135 ms echo times). Pharmacokinetic parameters and ADC did not detect early response; however, early changes in water:fat ratios and water T2 (after cycle two) demonstrated substantial prognostic efficacy. Larger decreases in water T2 accurately predicted final volume response in 69% of cases (11/16) while maintaining 100% specificity and positive predictive value. Small/absent decreases in water:fat ratios accurately predicted final volume non-response in 50% of cases (3/6) while maintaining 100% sensitivity and negative predictive value. This level of accuracy might permit clinical application where early, accurate prediction of non-response would permit an early change to second-line treatment, thus sparing patients unnecessary toxicity, psychological morbidity and delay of initiation of effective treatment.

Adult↗
PubMed2005

Differentiation of benign from malignant breast disease associated with screening detected microcalcifications using dynamic contrast enhanced magnetic resonance imaging.

Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) is an effective diagnostic modality for symptomatic breast disease. However, its role in evaluating clinically occult disease associated with mammographically detected microcalcification remains unclear. Women recalled following screening mammography with microcalcification had DCE-MRI examination of the breast. The data were evaluated subjectively and objectively using both empirical and 2-compartment pharmacokinetic modelling techniques to evaluate signal intensity parameters. Eighty-eight patients aged 50-75 years (median 58) were recruited. Comparing malignant and benign lesions, the mean values in arbitrary units for the enhancement index at 1 min in the most enhancing 9-pixel square +/-1 standard deviation were 0.61+/-0.40 vs. 0.22+/-0.26 p=<0.001 with sensitivity, specificity, PPV, NPV and accuracy of 80.0%, 82.4%, 57.1%, 93.3% and 81.8%, respectively. The corresponding values attained by the radiologist were 75.0%, 89.7%, 68.2%, 92.4% and 86.4%. DCE-MRI is able to differentiate malignant from benign clinically occult lesions associated with microcalcification and may therefore offer an alternative to open surgical biopsy for women with equivocal findings following initial triple assessment for microcalcification in the breast.

Aged↗
PubMed2005

MRI and conservative treatment of locally advanced breast cancer.

AIMS: The objectives of this study were to compare the efficacy of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in assessing the response of primary breast carcinoma to neoadjuvant chemotherapy compared to conventional imaging modalities, and to see how surgical outcome was influenced as a result of these findings. METHODS: Thirty-four patients with locally advanced primary breast cancer underwent conventional imaging and DCE-MRI following six cycles of neoadjuvant chemotherapy prior to surgery. Changes in surgical management based on the post-chemotherapy DCE-MRI findings were recorded. RESULTS: Prior to neoadjuvant chemotherapy, 22 of the 34 patients were assessed as requiring mastectomy and the remaining 12 were considered inoperable. Following chemotherapy two patients were still considered inoperable. In 11 of the 34 patients, the final decision to proceed to either mastectomy or non-surgical management was based primarily on pre-treatment disease status or patient choice. DCE-MRI findings, therefore, contributed to the operative decision in 21 of 34 patients. Two of these 21 patients were spared surgery as DCE-MRI demonstrated complete response to chemotherapy and one declined surgery. The remaining 18 were able to undergo wide local excision, with only two patients subsequently requiring mastectomy for involved margins. CONCLUSIONS: DCE-MRI is able to accurately predict those patients suitable for breast conserving surgery following neoadjuvant chemotherapy and should be the imaging modality of choice in assessing the response of patients with primary breast carcinoma to neoadjuvant chemotherapy.

Adult↗
PubMed2004

Differentiation of benign and malignant sub-1 cm breast lesions using dynamic contrast enhanced MRI.

The purpose of this work is to assess the additional benefit of MRI-based morphology and quantification of contrast enhancement in the differential diagnosis of sub-1cm breast lesions. Forty-three women with suspected breast cancer were examined using X-ray mammography, ultrasound mammography, and MRI. Dynamic contrast imaging was performed and relative enhancement at various time-points was calculated. The dynamic data was also processed using a two-compartment pharmacokinetic model. Radiological interpretation of high-resolution post-contrast images revealed a similar accuracy (69%) compared to X-ray mammography (69%) and ultrasound mammography (67%). The best individual parameter calculated from the dynamic images was found to be the exchange rate constant which revealed a diagnostic accuracy of 0.74 +/- 0.08. When information from the post-contrast images and dynamic data was combined in a logistic regression model a diagnostic accuracy of 0.92 +/- 0.03 was achieved. In conclusion, MR imaging of small breast lesions is feasible and the incorporation of quantitative MR derived parameters is beneficial.

Adult↗
PubMed2003

Current applications and future direction of MR mammography.

Compared with triple assessment for symptomatic and occult breast disease, magnetic resonance mammography (MRM) offers higher sensitivity for the detection of multifocal cancer, which is important in selecting patients appropriately for breast-conserving surgery. It is an ideal tool for the screening of patients with a high risk of breast cancer or where there is axillary disease or nipple discharge and conventional imaging has not revealed the primary focus. Techniques are now available to biopsy lesions only apparent on MRM. MRM can differentiate scar tissue from tumour; therefore, it is useful in patients in which there is possible recurrent disease. Clinical and X-ray mammographic assessment of response to neoadjuvant chemotherapy may be unreliable because of replacement of the tumour with scar tissue. MRM can identify responders and nonresponders with more accuracy. It is the modality of choice for the assessment of breast implants for rupture with accuracy higher than X-ray mammography and ultrasound. Advances in both spatial and temporal resolutions, the imaging sequences employed, pharmacokinetic modelling of contrast uptake, the use of dedicated and now phased-array breast coils, and gadolinium-based contrast agents have all played their part in the advancement of this imaging technique. Despite the limitations of patient compliance, scan-time and cost, this review describes how MRM has become a valuable tool in breast disease, especially in cases of diagnostic uncertainty. However, MRM must make the transition from research institutions into routine clinical practice.

Breast Diseases↗
PubMed2003

Dynamic contrast enhanced magnetic resonance imaging aids the surgical management of invasive lobular breast cancer.

AIMS: Infiltrating Lobular Carcinoma (ILC) accounts for 5-10% of all breast cancers and is associated with subtle clinical and mammographic changes. It is also frequently multifocal and traditional diagnostic methods are unable to reliably detect this preoperatively. The aim of the study was to evaluate the efficacy of current imaging modalities compared with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the evaluation of ILC. METHODS: Data from women with ILC treated between 1996 and 2000 who had undergone preoperative triple assessment and DCE-MRI was analysed. The diagnostic accuracy and the detection of multifocal disease for each modality was assessed and any changes in clinical management following DCE-MRI were recorded. RESULTS: Twenty-one women (mean age 57, range 43-72 years) were recruited. The sensitivity of X-ray mammography, ultrasound, clinical assessment, fine needle aspiration cytology or core biopsy and DCE-MRI was 90.5, 87.5, 76.2, 85.7 and 95.2% respectively. DCE-MRI identified all the patients with subsequently histologically proven multifocal disease (n=11) with PPV and NPV of 100 and 95.2% respectively. X-ray mammography and ultrasound combined identified only 27% (n=3/11) with PPV and NPV of 100 and 55.6% respectively. Management was changed in 24% (5/21) of the cases following DCE-MRI. CONCLUSION: DCE-MRI has a higher sensitivity than other imaging modalities and is able to accurately delineate multifocal disease not evident on conventional imaging. DCE-MRI should therefore be used for accurate staging prior to surgery for invasive lobular breast cancer.

Adult↗
PubMed2002

Localisation of somatostatin and somatostatin receptors in benign and malignant ovarian tumours.

Somatostatin has been identified as having anti-proliferative, anti-angiogenic and pro-apoptotic actions in many tumour systems, and these effects are mediated through a family of five transmembrane G-protein coupled SRIF receptors. Ovarian cancer is the commonest gynaecological malignancy in the UK and maintenance therapy is urgently required. Native somatostatin expression and its receptors sst(1,2,3 and 5) were studied with immunohistochemistry in 63 malignant and 35 benign ovarian tumours of various histological types. Fifty-seven out of 63 (90%) of malignant and 26/35 (74%) benign tumours expressed somatostatin. Receptors sst(1,2,3 and 5) were expressed variably in epithelial, vascular and stromal compartments for both benign and malignant tumours. Somatostatin was found to correlate significantly with stromal sst(1) (P=0.008), epithelial sst(1) (P<0.001), stromal sst(2) (P=0.019), vascular sst(2) (P=0.026), epithelial sst(3) (P=0.026), stromal sst(5) (P=0.013) and vascular sst(5) (P=0.038). Increased expression of native somatostatin correlating with somatostatin receptors in malignant ovarian tumours raises the possibility that either synthetic somatostatin antagonists or receptor agonists may have therapeutic potential.

Adenocarcinoma↗
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

Comparison of quantitative T2 mapping and diffusion-weighted imaging in the normal and pathologic prostate.

In this study, diffusion-weighted images of the human prostate were successfully obtained, enabling quantification of apparent diffusion coefficients (ADCs) in normal and pathologic regions. A dual acquisition fast spin-echo sequence was used for accurate T2 calculation. T2 values were significantly higher in the peripheral zone than the central gland (P = 0.015). No significant correlations were found in either normal or pathologic tissue between ADC values and relaxation rates for all three gradient directions and the orientationally averaged water diffusion coefficient. Evidence suggesting that diffusional anisotropy is present in normal prostatic tissue is also detailed, with significant differences noted between the z-component and both the x- and y-components of the ADC for peripheral zone (P < 0.040) and central gland (P < 0.001).

Adult↗
PubMed2001

Evaluation of response to neoadjuvant chemoradiotherapy for locally advanced breast cancer with dynamic contrast-enhanced MRI of the breast.

AIMS: This study aimed to examine the feasibility of utilizing dynamic contrast-enhanced MRI (DCE-MRI) of the breast for the planning of surgical intervention following neoadjuvant therapy for locally advanced breast cancer (LABC). METHODS: Following their neoadjuvant therapy, women with LABC were followed-up by DCE-MRI in addition to clinical examination and mammography. If any modality suggested residual disease, surgery was carried out--initially salvage mastectomy and then breast-conserving surgery where appropriate. RESULTS: Seventeen women were recruited: stage III (n=16), stage IV (n=1) mean age 55 (range 34-74). Following neoadjuvant therapy, 10 mastectomies and two local excisions were performed for 10 histologically confirmed residual cancers. Median follow-up for those women not undergoing surgery is 3.24 (IQR 2.8-3.5) years. DCE-MRI proved 100% accurate for the delineation of residual disease and facilitated the planning of the local excisions. Clinical examination and mammography proved inaccurate (PPV 83% and 75% and NPV 55% and 80%, respectively). CONCLUSIONS: DCE-MRI is a potentially accurate method of delineating residual tumour following neoadjuvant therapy for LABC and may be used to plan appropriate operative intervention where required.

Adult↗
PubMed2000

Bilateral open breast coil and compatible intervention device.

Dynamic contrast-enhanced breast MRI is an extremely sensitive method for breast lesion detection. For MR-only detected lesions it is essential that needle biopsy or localization prior to surgery is carried out under MR guidance. This work describes a bilateral open breast coil and prototype intervention device, which may be used in these situations. Results demonstrate that the open coil provides images superior to those obtained with a conventional closed breast coil. Initial phantom tests with the intervention device indicate a potential for this system to be used in the MR-guided localization of breast lesions. J. Magn. Reson. Imaging 2000;12:984-990.

Biopsy, Needle↗
PubMed2000

Combined proton MR spectroscopy and dynamic contrast enhanced MR imaging of human intracranial tumours in vivo.

A study was undertaken to determine if the vascular characteristics measured by dynamic contrast-enhanced magnetic resonance imaging (primarily permeability surface area product and extracellular-extravascular tissue volume fraction) would be beneficial in explaining the inter-lesion metabolic heterogeneity displayed by human intracranial tumours. Magnetic resonance spectroscopy was carried out using a single-voxel STEAM sequence and dynamic imaging was carried out using a combination of pre-contrast proton density-weighted FSPGR images (to remove the influence of native tissue T1), bolus injection of Gd-DTPA and subsequent T1-weighted FSPGR dynamic imaging. A two-compartment pharmacokinetic model was employed to determine vascular characteristics. Results obtained from 12 meningiomas suggest a possible correlation between the level of lipids/macromolecules and permeability surface area product, although the confounding issue of extra-voxel contamination arising from lipids in the scalp and skull marrow cannot be ruled out in the more superficial lesions. Results obtained from 11 gliomas (four low and seven high grade) demonstrate that permeability surface area product is not specific for the range of vascular characteristics and metabolite profiles observed in gliomas and is therefore unable to explain metabolic heterogeneity in these lesions.

Brain Neoplasms↗
PubMed2000

Magnetic resonance imaging screening in women at genetic risk of breast cancer: imaging and analysis protocol for the UK multicentre study. UK MRI Breast Screening Study Advisory Group.

The imaging and analysis protocol of the UK multicentre study of magnetic resonance imaging (MRI) as a method of screening for breast cancer in women at genetic risk is described. The study will compare the sensitivity and specificity of contrast-enhanced MRI with two-view x-ray mammography. Approximately 500 women below the age of 50 at high genetic risk of breast cancer will be recruited per year for three years, with annual MRI and x-ray mammography continuing for up to 5 years. A symptomatic cohort will be measured in the first year to ensure consistent reporting between centres. The MRI examination comprises a high-sensitivity three-dimensional contrast-enhanced assessment, followed by a high-specificity contrast-enhanced study in equivocal cases. Multiparametric analysis will encompass morphological assessment, the kinetics of contrast agent uptake and determination of quantitative pharmacokinetic parameters. Retrospective analysis will identify the most specific indicators of malignancy. Sensitivity and specificity, together with diagnostic performance, diagnostic impact and therapeutic impact will be assessed with reference to pathology, follow-up and changes in diagnostic certainty and therapeutic decisions. Mammography, lesion localisation, pathology and cytology will be performed in accordance with the UK NHS Breast Screening Programme quality assurance standards. Similar standards of quality assurance will be applied for MR measurements and evaluation.

Adult↗