Publications
431 results found
Keenan NG, Grasso A, Locca D, et al., 2009, Comparison of 2D and multislab 3D magnetic resonance techniques for measuring carotid wall volumes (vol 28, pg 1476, 2008), JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 29, Pages: 1493-1493, ISSN: 1053-1807
He T, Smith GC, Gatehouse PD, et al., 2009, On Using <i>T</i><sub>2</sub> to Assess Extrinsic Magnetic Field Inhomogeneity Effects Myocardial Siderosis on <i>T</i><sub>2</sub>* Measurements in in Thalassemia, MAGNETIC RESONANCE IN MEDICINE, Vol: 61, Pages: 501-506, ISSN: 0740-3194
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- Citations: 19
Scott AD, Keegan J, Firmin DN, 2009, Motion in Cardiovascular MR Imaging, RADIOLOGY, Vol: 250, Pages: 331-351, ISSN: 0033-8419
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- Citations: 120
Bradlow WM, Gatehouse PD, Hughes RL, et al., 2009, Transit-Time Method to Demonstrate Whether or Not an Impedance Matching Occurs at the Pulmonary Junction Response, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 29, Pages: 499-499, ISSN: 1053-1807
Torii R, Keegan J, Wood NB, et al., 2009, The effect of dynamic vessel motion on haemodynamic parameters in the right coronary artery: a combined MR and CFD study, BRITISH JOURNAL OF RADIOLOGY, Vol: 82, Pages: S24-S32, ISSN: 0007-1285
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- Citations: 25
Chan CF, Gatehouse PD, Hughes R, et al., 2009, Novel Technique Used to Detect Swallowing in Volume-Selective Turbo Spin-Echo (TSE) for Carotid Artery Wall Imaging, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 29, Pages: 211-216, ISSN: 1053-1807
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- Citations: 9
Ferreira P, Gatehouse P, Kellman P, et al., 2009, Variability of myocardial perfusion dark rim Gibbs artifacts due to sub-pixel shifts, Journal of Cardiovascular Magnetic Resonance, Vol: 11, Pages: 17-17
Keenan NG, Grasso A, Locca D, et al., 2008, Comparison of 2D and Multislab 3D Magnetic Resonance Techniques for Measuring Carotid Wall Volumes, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 28, Pages: 1476-1482, ISSN: 1053-1807
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- Citations: 7
Chan KM, Wage R, Symmonds K, et al., 2008, Towards comprehensive assessment of mitral regurgitation using cardiovascular magnetic resonance. Chan KM, Wage, J Cardiovasc Magn Reson., Vol: 22
He T, Gatehouse PD, Smith GC, et al., 2008, Myocardial T2* measurements in iron-overloaded thalassemia: An in vivo study to investigate optimal methods of quantification., Magn Reson Med, Vol: 60, Pages: 1082-1089, ISSN: 1522-2594
Reproducible and accurate myocardial T(2) (*) measurements are required for the quantification of iron in heart tissue in transfused thalassemia. The aim of this study was to determine the best method to measure the myocardial T(2) (*) from multi-gradient-echo data acquired both with and without black-blood preparation. Sixteen thalassemia patients from six centers were scanned twice locally, within 1 week, using an optimized bright-blood T(2) (*) sequence and then subsequently scanned at the standardization center in London within 4 weeks, using a T(2) (*) sequence both with and without black-blood preparation. Different curve-fitting models (monoexponential, truncation, and offset) were applied to the data and the results were compared by means of reproducibility. T(2) (*) measurements obtained using the bright- and black-blood techniques. The black-blood data were well fitted by the monoexponential model, which suggests that a more accurate measure of T(2) (*) can be obtained by removing the main source of errors in the bright-blood data. For bright-blood data, the offset model appeared to underestimate T(2) (*) values substantially and was less reproducible. The truncation model gave rise to more reproducible T(2) (*) measurements, which were also closer to the values obtained from the black-blood data. Magn Reson Med 60:1082-1089, 2008. (c) 2008 Wiley-Liss, Inc.
Chen S, Keegan J, Wage R, et al., 2008, Tagging in the basal RV free wall for the assessment of RV myocardial functiion in congenital heart disease, EUROPEAN HEART JOURNAL, Vol: 29, Pages: 117-118, ISSN: 0195-668X
He T, Gatehouse PD, Kirk P, et al., 2008, Myocardial T2* measurement in iron-overloaded thalassemia: An ex vivo study to investigate optimal methods of quantification., Magn Reson Med, Vol: 60, Pages: 350-356, ISSN: 1522-2594
Myocardial T(*) (2) measurement has been increasingly used for iron quantification to assess the risk of cardiac complications in thalassemia patients. In this study the noise effects were evaluated along with different curve-fitting models on an iron overloaded ex vivo heart in order to determine the optimal method of T(*) (2) measurement and to help understand issues affecting reproducibility and accuracy. Gradient multiecho short axis images were acquired with differing numbers of excitations to generate varying signal-to-noise ratio (SNR) images. A noise correction method was implemented; linear and nonlinear curve-fitting algorithms were compared and different curve-fitting models (monoexponential, truncation, baseline subtraction, and offset) were evaluated. This study suggests that the T(*) (2) decay curve in an ex vivo heart can be fitted by a monoexponential model and accurate T(*) (2) measurements can be obtained with proper noise correction. With MRI noise, T(*) (2) is generally overestimated by including late low SNR data points, but underestimated by the offset or baseline subtraction models, which are in fact equivalent. In this situation the truncation model proves to be reproducible and more accurate than the other models. The study also shows that the nonlinear algorithm is preferred in T(*) (2) curve fitting.
Keenan NG, Mason JC, Maceira A, et al., 2008, Integrated cardiac and vascular assessment in Takayasu's arteritis and systemic lupus erythematosus by cardiovascular magnetic resonance, Annual Scientific Conference of the British-Cardiovascular-Society/British-Society-for-Cardiovascular-Research, Publisher: B M J PUBLISHING GROUP, Pages: A78-A79, ISSN: 1355-6037
Keenan NG, Grasso A, Locca D, et al., 2008, Comparison of two-dimensional and multi-slab three-dimensional magnetic resonance techniques for measuring carotid wall volumes, Annual Scientific Conference of the British-Cardiovascular-Society/British-Society-for-Cardiovascular-Research, Publisher: B M J PUBLISHING GROUP, Pages: A78-A78, ISSN: 1355-6037
Long Q, Merrifield R, Xu XY, et al., 2008, Subject-specific computational simulation of left ventricular flow based on magnetic resonance imaging, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE, Vol: 222, Pages: 475-485, ISSN: 0954-4119
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- Citations: 43
Downie SP, Raynor SM, Firmin DN, et al., 2008, Effects of elastic compression stockings on wall shear stress in deep and superficial veins of the calf, AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, Vol: 294, Pages: H2112-H2120, ISSN: 0363-6135
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- Citations: 36
Mason JC, Keenan N, Maceira A, et al., 2008, Integrated cardiac and vascular assessment in Takayasu's arteritis and systemic lupus erythematosus using cardiovascular magnetic resonance, Annual Meeting of the British-Society-Rheumatology/Spring Meeting of British Health Professional in Rheumatology, Publisher: OXFORD UNIV PRESS, Pages: II101-II101, ISSN: 1462-0324
He T, Kirk P, Firmin DN, et al., 2008, Multi-center transferability of a breath-hold T2 technique for myocardial iron assessment, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 10, ISSN: 1097-6647
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- Citations: 80
Huntbatch A, Lee S-L, Firmin D, et al., 2008, Bayesian Motion Recovery Framework for Myocardial Phase-Contrast Velocity MRI, 11th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI2008), Publisher: SPRINGER-VERLAG BERLIN, Pages: 79-86, ISSN: 0302-9743
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- Citations: 4
Ferreira P, Gatehouse P, Bucciarelli-Ducci C, et al., 2008, Measurement of myocardial frequency offsets during first pass of a gadolinium-based contrast agent in perfusion studies, Magnetic resonance in medicine, Vol: 60, Pages: 860-870
Huntbatch A, Lee S-L, Firmin D, et al., 2008, Bayesian motion recovery framework for myocardial phase-contrast velocity MRI., Pages: 79-86
Detailed assessment of myocardial motion provides a key indicator of ventricular function, enabling the early detection and assessment of a range of cardiac abnormalities. Existing techniques for myocardial contractility analysis are complicated by a combination of factors including resolution, acquisition time, and consistency of quantification results. Phase-contrast velocity MRI is a technique that provides instantaneous, in vivo measurement of tissue velocity on a per-voxel basis. It allows for the direct derivation of contractile indices with minimal post-processing. For this method to be clinically useful, SNR and image artifacts need to be addressed. The purpose of this paper is to present a Maximum a posteriori (MAP) restoration technique for high quality myocardial motion recovery. It employs an accurate noise modeling scheme and a generalized Gaussian Markov random field prior tailored for the myocardial morphology. The quality of the proposed method is evaluated with both simulated myocardial velocity data with known ground truth and in vivo phase-contrast MR velocity acquisitions from a group of normal subjects.
Lyne JC, Gatehouse PD, Assomull RG, et al., 2007, Direct comparison of myocardial perfusion cardiovascular magnetic resonance sequences with parallel acquisition, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 26, Pages: 1444-1451, ISSN: 1053-1807
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- Citations: 15
Dowsey AW, Keegan J, Lerotic M, et al., 2007, Motion-compensated MR valve imaging with COMB tag tracking and super-resolution enhancement., Medical Image Analysis, Vol: 11, Pages: 478-491, ISSN: 1361-8415
Understanding the morphology and function of heart valves is important to the study of underlying causes of heart failure. Existing techniques such as those based on echocardiography are limited by the relatively low signal-to-noise ratio (SNR), attenuation artefacts, and restricted access. The alternative of cardiovascular MR imaging offers versatility and accuracy in 3D localisation, but is hampered by large movements of the valves throughout the cardiac cycle. This paper presents a motion-compensated adaptive imaging approach for MR valve imaging. To illustrate its clinical potential, 3D motion of the aortic valve plane is first captured through a single breath-hold COMB tag pre-scan and then tracked in real-time with an automatic method based on multi-resolution image registration. Motion-compensated coverage of the aortic valve is then acquired prospectively, thus allowing its clear 3D reconstruction and visualisation. To provide isotropic voxel coverage of the imaging volume, retrospective projection onto convex sets (POCS) super-resolution enhancement is applied to the slice-select direction. In vivo results demonstrate the effectiveness of the proposed motion-compensation and super-resolution schemes for depicting the structure of the valve leaflets throughout the cardiac cycle. The proposed method fundamentally changes the way MR imaging is performed by transforming it from a spatially to materially localised imaging method. This also has important implications for quantifying blood flow and myocardial perfusion, as well as tracking anatomy and function of the heart.
Keegan J, Gatehouse PD, Yang G-Z, et al., 2007, Non-model-based correction of respiratory motion using beat-to-beat 3D spiral fat-selective imaging, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 26, Pages: 624-629, ISSN: 1053-1807
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- Citations: 42
Downie SP, Firmin DN, Wood NB, et al., 2007, Role of MRI in investigating the effects of elastic compression stockings on the deformation of the superficial and deep veins in the lower leg, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 26, Pages: 80-85, ISSN: 1053-1807
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- Citations: 20
He T, Gatehouse PD, Kirk P, et al., 2007, Black-blood T2*technique for myocardial iron measurement in thalassemia, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 25, Pages: 1205-1209, ISSN: 1053-1807
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- Citations: 74
Bradlow WM, Gatehouse PD, Hughes RL, et al., 2007, Assessing normal pulse wave velocity in the proximal pulmonary arteries using transit time: A feasibility, repeatability, and observer reproducibility study by cardiovascular magnetic resonance, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 25, Pages: 974-981, ISSN: 1053-1807
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- Citations: 30
Firmin DN, Mohiaddin RH, 2007, Blood Flow: Quantitative Measurement by MRI, eMagRes, Vol: 2007
Kilner PJ, Gatehouse PD, Firmin DN, 2007, Flow measurement by magnetic resonance: A unique asset worth optimising, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 9, Pages: 723-728, ISSN: 1097-6647
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- Citations: 140
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