Publications
245 results found
Soresen MB, Ong PJ, Hayward CS, et al., 1999, Gradient echo magnetic resonance imaging of the brachial artery: A novel method far assessing vascular reactivity, CIRCULATION, Vol: 100, Pages: 49-49, ISSN: 0009-7322
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- Citations: 1
Panting JR, Gatehouse PD, Yang GZ, et al., 1999, Parametric map analysis of adenosine stress echo-planar spin echo myocardial perfusion imaging at 0.5T: Comparison with SPECT and coronary angiography, CIRCULATION, Vol: 100, Pages: 226-226, ISSN: 0009-7322
Panting J, Taylor A, Gatehouse P, et al., 1999, First pass myocardial perfusion imaging and equilibrium signal changes using the new intravascular contrast agent, NC100150 injection, Journal of Magnetic Resonance Imaging, Vol: 10, Pages: 404-410
Panting JR, Taylor AM, Gatehouse PD, et al., 1999, First-pass myocardial perfusion imaging and equilibrium signal changes using the intravascular contrast agent NC100150 injection, JMRI-JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 10, Pages: 404-410, ISSN: 1053-1807
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- Citations: 27
Taylor AM, Keegan J, Jhooti P, et al., 1999, Differences between normal subjects and patients with coronary artery disease for three different MR coronary angiography respiratory suppression techniques, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 9, Pages: 786-793, ISSN: 1053-1807
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- Citations: 50
Gatehouse PD, Firmin DN, 1999, Flow distortion and signal loss in spiral imaging, MAGNETIC RESONANCE IN MEDICINE, Vol: 41, Pages: 1023-1031, ISSN: 0740-3194
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- Citations: 18
Jhooti P, Keegan J, Gatehouse PD, et al., 1999, 3D coronary artery imaging with phase reordering for improved scan efficiency, MAGNETIC RESONANCE IN MEDICINE, Vol: 41, Pages: 555-562, ISSN: 0740-3194
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- Citations: 30
Keegan J, Gatehouse PD, Taylor AM, et al., 1999, Coronary artery imaging in a 0.5-Tesla scanner: Implementation of real-time, navigator echo-controlled segmented k-space FLASH and interleaved-spiral sequences, MAGNETIC RESONANCE IN MEDICINE, Vol: 41, Pages: 392-399, ISSN: 0740-3194
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- Citations: 21
Yang GZ, Burger P, Gatehouse PD, et al., 1999, Locally focused 3D coronary imaging using volume-selective RF excitation, MAGNETIC RESONANCE IN MEDICINE, Vol: 41, Pages: 171-178, ISSN: 0740-3194
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- Citations: 21
Yang GZ, Gatehouse PD, Firmin DN, 1999, Reduced FOV imaging with motion adaptation, 7th IEE Conference on Image Processing and its Applications (IPA99), Publisher: INST ELECTRICAL ENGINEERS INSPEC INC, Pages: 502-506, ISSN: 0537-9989
Taylor AM, Panting JR, Keegan J, et al., 1999, Use of the intravascular contrast agent NC100150 Injection in spin-echo and gradient-echo imaging of the heart, J.Cardiovascular MR, Vol: 1, Pages: 23-32
Taylor AM, Panting JR, Keegan J, et al., 1999, Use of the intravascular contrast agent NC100150 injection in spin-echo and gradient-echo imaging of the heart, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 1, Pages: 23-32, ISSN: 1097-6647
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- Citations: 37
Keegan J, Gatehouse PD, Taylor AM, et al., 1999, Coronary artery imaging at 0.5T esla scanner: implementation of real-time, navigator echo-controlled segmented k-space FLASH and interleaved-spiral sequences, Magn Reson Med, Vol: 41, Pages: 392-399
Taylor AM, Panting JR, Keegan J, et al., 1999, Safety and preliminary findings with the new intravascular contrast agent, NC100150 injection, for MR coronary angiography, J Magn.Reson.Imag, Vol: 9, Pages: 220-227
Yang GZ, Burger P, Panting J, et al., 1998, Motion and deformation tracking for short-axis echo-planar myocardial perfusion imaging., Med Image Anal, Vol: 2, Pages: 285-302, ISSN: 1361-8415
The assessment of regional myocardial perfusion during the first-pass of a contrast agent bolus requires tracking of the signal time course for each myocardial segment so that a detailed perfusion map can be derived. To obtain such a map in practice, however, is not trivial because deformation of the shape of the myocardium and respiratory-induced motion render a major difficulty in this process. This study describes an automated approach for motion and deformation tracking of functional myocardial perfusion images. The effectiveness of the described method has been evaluated using a numerical phantom and results are compared with those from existing techniques which use deformable models. Preliminary results from applying our approach to 20 patients are discussed and compared with those from SPECT studies.
Jhooti P, Wiesmann F, Taylor A, et al., 1998, Hybrid ordered phase encoding (HOPE): an improved approach for respiratory artifact reduction, Journal of Magnetic Resonance Imaging, Vol: 8, Pages: 968-980
Panting JR, Gatehouse PD, Yang GZ, et al., 1998, Myocardial perfusion imaging by MR: Optimisation of multislice single shot echo-planar imaging at 0.5T, Heart, Vol: 79, ISSN: 1355-6037
Perfusion imaging is important in the assessment of the physiological significance of ischaemic heart disease. First pass MR techniques have advantages over SPECT (lack of radiation and higher resolution). We have previously demonstrated good correlation of MR and SPECT with a spin echo, echo-planar MR technique, but these studies imaged only a single slice, which is not clinically viable. In order to improve coverage, we have now assessed methods of multislice MRI. We studied 8 normal subjects, 4 using a Single Inversion Pulse (SIP), to null myocardial signal, before imaging all the slices in rapid succession, and 4 where Multiple Inversion Pulses (MIP) were used, one before each slice. In all cases the image acquisition time was 100 ms. With SIP, there was an inversion delay of 200 ms before the first acquisition, with minimal delay between images, however with MIP, there was a delay of 100 ms before each image acquisition, increasing the apparent acquisition time of each slice to 200ms. With SIP the baseline signal intensity varied with length of time after inversion pulse to slice acquisition. Despite this, the net signal change with contrast for each slice was similar and all slices were evaluable. With MIP, the signal intensity was similar in all slices, but the increase in apparent acquisition time typically limited the maximum number of slices to 3. When compared to the 5 slices obtained with SIP, complete coverage of the ventricle was limited with MIP. Following these results we pursued a study of 20 patients with coronary artery disease using SIP during rest and stress with adenosine. Correlation with SPECT was good in all cases, good coverage of the LV possible, and defects were not missed by MR because of the non-contiguity of slices. Thus with further development, this MR technique is a candidate rival for SPECT in clinical practice, but large comparative studies are required.
Schmidt M, Yang G, Gatehouse P, et al., 1998, FID-Based MRI at 0.5T: Theoretical Considerations and Practical Implications, Journal of Magnetic Resonance Imaging, Vol: 39, Pages: 666-672
Yang G, Gatehouse P, Keegan J, et al., 1998, Three-dimensional coronary MR angiography using zonal echo-planar imaging, Journal of Magnetic Resonance Imaging, Vol: 39
Schmidt MA, Yang GZ, Keegan J, et al., 1997, Non-breath-hold lung magnetic resonance imaging with real-time navigation, MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE, Vol: 5, Pages: 123-128, ISSN: 1352-8661
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- Citations: 14
Wiesmann F, Gatehouse PD, Jhooti P, et al., 1997, Accuracy of ultrafast magnetic resonance imaging for assessment of right and left ventricular volume and mass, Heart, Vol: 77, ISSN: 1355-6037
In this study we investigated the accuracy and feasibility of 3 ultrafast imaging breath-hold cine sequences in the assessment of right (RV) and left ventricular (LV) volumes and LV mass in comparison with conventional cine gradient echo imaging at the lower field strength of 0.5T. We investigated 15 healthy volunteers (8male, 7female) with mean age 33 yrs (range 21 to 59 yrs). Imaging was performed at 0.5T using echo planar imaging (EPI), fast spiral imaging (SPI), fast gradient echo imaging (FLASH), all with k-space segmentation, and conventional gradient echo imaging (GRE). For all imaging methods, cine images were obtained in contiguous ventricular short axis slices to cover the entire RV and LV. Acquisition of EPI, SPI and FLASH cines took 16 cardiac cycles per slice and was performed during breath-holds. Scan time of the conventional gradient echo sequence (single average) was 128 cardiac cycles per slice. Comparison of LV stroke volume of GRE versus FLASH, EPI and SPI showed good agreement of methods and revealed a mean difference (±sd) of 1.7±13.8, 0.7±13.2 and 0.3±13.8 [ml]. RV stroke volume comparison showed a mean difference (±sd) of 0.1±13.9, 3.3±13.1 and 3.0±13.9 respectively. There was also good agreement of LV enddiastolic (LVEDV) and endsystolic volume (LVESV). RVEDV showed slightly higher variation of values than LVEDV, which represents the fact that clear identification of RV anterior wall is often more difficult than LV wall delineation. The level of agreement in assessing ejection fraction (EF) was high in all three ultrarast imaging sequences for both LV and RV. LV mass was in general underestimated by all three ultrafast breath-hold sequences and showed to comparison with GRE mean differences (±sd) of 11.6±23.7, 14.5±21.8 and 15.5±26.6 [g]for FLASH, EPI and SPI. The degree of agreement with GRE results showed no significant differences between the three ultrafas
Panting JR, Gatehouse PD, Yang GZ, et al., 1997, Adenosine stress myocardial perfusion imaging using echo-planar MRI with a 0.5T scanner, Heart, Vol: 77, ISSN: 1355-6037
Myocardial perfusion imaging assesses the physiological significance of coronary stenosis. Current techniques involve the use of ionising radiation and have relatively poor resolution. We compared magnetic resonance imaging (MRI) perfusion studies with radionuclide SPECT scans. In 22 patients with abnormal SPECT (18 males, 4 females, mean age 65, range 46-77) single shot echo-planar imaging with an acquisition time of between 50-100 ms, was performed on a mobile 0.5T scanner. End systolic gating was used with a pixel size of 3.9 x 3.9 mm giving several pixels across the myocardium. Fat suppression reduced the signal from surrounding tissues, and a preparatory inversion pulse was used to null the myocardial signal. For the perfusion study, a bolus of 0.05mmol/kg Gadolinium DTPA was given through a right atrial catheter placed using intravascular electrocardiography via the right antecubital fossa. Two scans were performed, the first at rest and another during the infusion of adenosine at a dose of 140 μg/kg/min to induce maximal coronary hyperaemia. Images were interpreted by visual analysis of the contrast wash-in, and by drawing signal intensity curves obtained from 16 regions of interest around the myocardium. Of the 22 patients, 20 (91%) had interpretable results, the other 2 being hindered by gating problems during acquisition. Of 320 segments, 112 were abnormal by SPECT, of which 94 were reversible and 18 fixed. By MRI, 96 segments were abnormal with 80% concordance with SPECT studies. MRI is fast in comparison to nuclear imaging (1 hour vs typically 4-6 hours) and the use of multislice imaging, which has now been implemented, will enable complete coverage of the myocardium.
Mohiaddin RH, Gatehouse PD, Henien M, et al., 1997, Cinemagnetic resonance Fourier velocimetry of blood flow through cardiac valves: Comparison with Doppler echocardiography, Heart, Vol: 77, ISSN: 1355-6037
Non-invasive measurement of blood flow velocity through the cardiac valves has important clinical applications. A wide variety of magnetic resonance (MR) methods are available for flow measurement. The aim of this study was to investigate the ability of cine MR Fourier velocimetry to measure flow through healthy cardiac valves and to compare MR and Doppler peak velocity measurements. Ten healthy volunteers (age mean ± SD, 24 ± 4 years) without history of valvular disease were studied. Four of the subjects were females. In each subject, aortic, pulmonary, mitral and tricuspid valves were evaluated with MR and Doppler. The heart rate during magnetic resonance and Doppler studies was not significantly different. The mean difference between the two studies was 2 beats / minute, with a 95% confidence interval of (- 22 beats /minute, + 25 beats / minute). Peak systolic flow velocity in the aortic and pulmonary valves, and peak diastolic flow velocity in the mitral and tricuspid valves measured with MRI and Doppler echocardiography correlated well. The mean difference between the two measurements (MR - Doppler) was 63 mm/sec, with a 95% confidence interval of (-180 mm/sec, + 310 mm /sec). The agreement between two observers interpreting the same magnetic resonance velocity maps was close. The mean difference between their two measurements was 23 mm/sec, with a 95% confidence interval of (- 20 mm/sec, + 60 mm /sec). There was no significant difference between MR and Doppler, or between the two MR observers. Magnetic resonance Fourier velocimetry has the necessary ease, reliability and speed to measure blood flow through the cardiac valves. Measurement of peak blood velocity through the cardiac valves by this method showed satisfactory agreement with Doppler but its clinical application for assessing diseased cardiac valves needs to be established.
Yang GZ, Gatehouse PD, Panting J, et al., 1997, Motion analysis for Magnetic Resonance myocardial perfusion imaging, IEE Conference Publication, Pages: 838-842, ISSN: 0537-9989
The assessment of regional myocardial perfusion using Magnetic Resonance (MR) imaging during the first-pass of a contrast agent bolus requires tracking of the signal time course for each myocardial segment so that a detailed perfusion map can be derived. To obtain such a map in practice, however, is not trivial because deformation of the shape of the myocardium and respiratory induced motion render a major difficulty in this process. This study describes a practical implementation of a real-time interactive MR Echo-Planar (EPI) myocardial perfusion imaging system and demonstrates an automated approach for motion and deformation tracking of functional myocardial perfusion images.
Mohiaddin RH, Bogren HG, Lazim F, et al., 1996, Magnetic resonance coronary angiography in heart transplant recipients, CORONARY ARTERY DISEASE, Vol: 7, Pages: 591-597, ISSN: 0954-6928
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- Citations: 24
Pennell DJ, Gatehouse PD, Burman ED, et al., 1996, Myocardial perfusion imaging performed using echo-planar single shot magnetic resonance imaging with a mobile 0.5 tesla scanner, HEART, Vol: 75, Pages: 225-225, ISSN: 1355-6037
KEEGAN J, FIRMIN D, GATEHOUSE P, et al., 1994, Velocity mapping of coronary artery blood flow, 1st Nottingham Symposium on Magnetic Resonance Imaging, Publisher: CHAPMAN HALL LTD, Pages: 311-314, ISSN: 1352-8661
Longmore D, Firmin D, Keegan J, et al., 1994, Functional evaluation in congenital and acquired heart disease., MAGMA Magnetic resonance materials in physics, biology and medicine, Vol: 2, Pages: 211-218
GATEHOUSE PD, FIRMIN DN, COLLINS S, et al., 1994, REAL-TIME FLOOD FLOW IMAGING BY SPIRAL SCAN PHASE-VELOCITY MAPPING, MAGNETIC RESONANCE IN MEDICINE, Vol: 31, Pages: 504-512, ISSN: 0740-3194
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- Citations: 78
KEEGAN J, FIRMIN D, GATEHOUSE P, et al., 1994, THE APPLICATION OF BREATH-HOLD PHASE-VELOCITY MAPPING TECHNIQUES TO THE MEASUREMENT OF CORONARY-ARTERY FLOOD FLOW VELOCITY - PHANTOM DATA AND INITIAL IN-VIVO RESULTS, MAGNETIC RESONANCE IN MEDICINE, Vol: 31, Pages: 526-536, ISSN: 0740-3194
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- Citations: 77
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