Biomedical subjects

G P Liney

Publications and source records attributed to G P Liney.

13 recordsLinked to original sources

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↗

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↗

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

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↗

PubMed1999

In vivo magnetic resonance spectroscopy and dynamic contrast enhanced imaging of the prostate gland.

The quantitation of in vivo 1H MR spectroscopy and dynamic contrast enhanced MR imaging is described for patients with histologically confirmed prostate adenocarcinoma and benign prostatic hypertrophy (BPH). Results are presented which suggest that combined use of these techniques may be helpful in improving the characterization of prostate pathologies and ultimately increase the staging accuracy of magnetic resonance.

Aged↗

PubMed1999

Differentiation of prostatic carcinoma and benign prostatic hyperplasia: correlation between dynamic Gd-DTPA-enhanced MR imaging and histopathology.

One of the major factors limiting the staging accuracy of conventional magnetic resonance imaging (MRI) for prostatic carcinoma, is the similarity in signal intensity between tumor and coexisting benign prostatic hyperplasia (BPH). As neovascularity is an independent indicator of pathological state, dynamic contrast-enhanced MRI may yield additional information. This study correlates the histopathological findings from 12 radical prostatectomy patients on a region-by-region basis, with pharmacokinetic modeling of dynamic contrast-enhanced (0.2 mmol dimeglumine gadopentetate/kg), fast multiplanar spoilt gradient-recalled echo images, using a two-compartment simplex minimization technique. Quantitative analysis demonstrated differences in the amplitude of the initial contrast upslope and contrast exchange rate between tumor and fibromuscular BPH (P<0.03 and P<0.03, respectively) and for the contrast exchange rate between tumor and fibroglandular BPH (P<0.04), providing improved delineation of intraprostatic tumor extent compared with conventional imaging techniques.

Aged↗

PubMed1999

Dynamic contrast-enhanced MRI in the differentiation of breast tumors: user-defined versus semi-automated region-of-interest analysis.

Dynamic contrast-enhanced MR mammography is an increasingly used method of evaluating breast pathology. The purpose of this study was to compare two semi-automated methods of region of interest (ROI) analysis with a user-defined method, in the discrimination of breast tumors using dynamic contrast-enhanced MRI. Results are presented from the retrospective analysis of 81 malignant and 36 benign breast lesions. The study demonstrates the importance of a consistent ROI strategy and also shows that semi-automated approaches offer a standardized method, which may improve the discrimination of primary breast tumors. J. Magn. Reson. Imaging 1999; 10:945-949.

Adenocarcinoma↗

PubMed1999

A simple and realistic tissue-equivalent breast phantom for MRI.

A simple and inexpensive breast phantom is described for use in magnetic resonance imaging. The work demonstrates the similarity of the phantom materials to in vivo breast tissue in terms of T(1) relaxation times. The phantom is also qualitatively compared with images acquired from a patient with a primary breast lesion.J. Magn. Reson. Imaging 10:968-971, 1999.

Adipose Tissue↗

PubMed1997

In vivo quantification of citrate concentration and water T2 relaxation time of the pathologic prostate gland using 1H MRS and MRI.

We have previously reported a striking correlation between water T2 relaxation time and citrate concentration in the normal prostate (Liney G.P.; Lowry M.; Turnbull L.W.; Manton D.J.; Knowles A.J.; Blackband S.J.; Horsman A. Proton MR T2 maps correlate with the citrate concentration in the prostate. NMR Biomed. 9:59-64; 1996). In this study we present data from similar studies of the pathologic gland. The findings support the hypothesis that measurement of both citrate concentration and water T2 relaxation time in vivo may aid the differentiation of prostatic carcinoma from benign disease and normal tissue.

Adenocarcinoma↗

PubMed1996

Proton MR T2 maps correlate with the citrate concentration in the prostate.

A significant correlation between water T2 relaxation time and citrate concentration in the normal prostate is demonstrated using spatially localized spectroscopy and water T2 maps. These data imply that MR images may be used to infer the concentration of citrate at high spatial resolution. Preliminary results in patients demonstrate that this relationship is maintained in benign prostatic hyperplasia (BPH) and prostatic carcinoma. The determination of citrate concentration and water T2 may aid the differentiation of prostate carcinoma from BPH and normal tissue.

Adult↗

PubMed1996

Quantification of citrate concentration in the prostate by proton magnetic resonance spectroscopy: zonal and age-related differences.

A commercial phased-array multicoil was used to acquire water-suppressed localized proton spectra of the two major anatomical regions of the prostate. The signal-to-noise ratio and spectral resolution allowed identification of peaks from choline and creatine, as well as a major peak from citrate. Quantification of the citrate peak using experimentally determined relaxation parameters with tissue water as an internal concentration reference revealed a marked variability between different volunteers. Nevertheless, in each case, the citrate concentration was up to fourfold greater in the peripheral zone than in the central gland. Furthermore, the difference in citrate concentration between these two regions was positively correlated with the subjects age. The results indicate a consistent difference in cellular function between the major anatomical regions within the prostate and may have important consequences for the application of magnetic resonance spectroscopy to the diagnosis of prostatic pathology.

Adult↗

PubMedDate not supplied

Comparison of conventional single echo and multi-echo sequences with a fast spin-echo sequence for quantitative T2 mapping: application to the prostate.

The accuracy of water T2 maps generated from a fast spin-echo (FSE) sequence was compared with data obtained by conventional single and multi-echo spin-echo pulse sequences using a commercial gel phantom. Spatially localized stimulated echo acquisition mode (STEAM) proton spectroscopy was also used to confirm the reported water T2 values of the gels contained in the phantom. The FSE sequence was shown to be superior in accuracy to both the single and multi-echo spin echo sequences and comparable to STEAM, producing results that were within 10% of known values. The effectiveness of the FSE sequence was further demonstrated by generating T2 maps of the normal and diseased prostate in clinically acceptable imaging times, resulting in comparable T2 values to those obtained using STEAM. Accurate quantitative T2 maps can be produced with the FSE sequence.

Carcinoma↗

PubMedDate not supplied

A simple method for the correction of endorectal surface coil inhomogeneity in prostate imaging.

A simple method is described that corrects for the intensity inhomogeneity experienced when using endorectal surface coils in prostate imaging. The method uses a series of proton-density-weighted images, which are acquired to demonstrate the sensitivity profile of the coil and used to correct T2-weighted images acquired in the same plane. The results demonstrate improved image uniformity and visualization of prostatic anatomy.

Aged↗