Imperial College London

DrPeterGatehouse

Faculty of MedicineNational Heart & Lung Institute

Honorary Clinical Senior Lecturer
 
 
 
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+44 (0)20 7351 8807p.gatehouse

 
 
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MRISydney StreetRoyal Brompton Campus

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Summary

 

Publications

Publication Type
Year
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245 results found

Roehl M, Conway M, Ghonim S, Ferreira P, Nielles-Vallespin S, Babu-Narayan S, Pennell D, Gatehouse P, Scott Aet al., 2024, STEAM-SASHA: A novel approach for blood and fat suppressed native T1 measurement in the right ventricular myocardium, Magnetic Resonance Materials in Physics, Biology and Medicine, ISSN: 0968-5243

Objective:The excellent blood and fat suppression of stimulated echo acquisition mode (STEAM) can be combined with saturation recovery single-shot acquisition (SASHA) in a novel STEAM-SASHA sequence for right ventricular (RV) native T1 mapping.Materials and methods:STEAM-SASHA splits magnetization preparation over two cardiac cycles, nulling blood signal and allowing fat signal to decay. Breath-hold T1 mapping was performed in a T1 phantom and twice in 10 volunteers using STEAM-SASHA and a modified Look-Locker sequence at peak systole at 3T. T1 was measured in 3 RV regions, the septum and left ventricle (LV).Results:In phantoms, MOLLI under-estimated while STEAM-SASHA over-estimated T1, on average by 3.0% and 7.0% respectively, although at typical 3T myocardial T1 (T1 > 1200 ms) STEAM-SASHA was more accurate. In volunteers, T1 was higher using STEAM-SASHA than MOLLI in the LV and septum (p = 0.03, p = 0.006, respectively), but lower in RV regions (p > 0.05). Inter-study, inter-observer and intra-observer coefficients of variation in all regions were < 15%. Blood suppression was excellent with STEAM-SASHA and noise floor effects were minimal.Discussion:STEAM-SASHA provides accurate and reproducible T1 in the RV with excellent blood and fat suppression. STEAM-SASHA has potential to provide new insights into pathological changes in the RV in future studies.

Journal article

Gatehouse PD, Captur G, Nielles-Vallespin S, Pennell DJet al., 2023, Field camera input to virtual phantom (ViP) scanner acquisitions for quality assurance of derived MRI quantities: first implementation and proof-of-principle., MAGMA

INTRODUCTION: Quality assurance (QA) of measurements derived from MRI can require complicated test phantoms. This work introduces a new QA concept using gradient and transmit RF recordings by a limited field camera (FC) to govern the previous Virtual Phantom (ViP) method. The purpose is to describe the first technical implementation of combined FC+ViP, and illustrate its performance in examples, including quantitative first-pass myocardial perfusion. MATERIALS AND METHODS: The new QA concept starts with a synthetic test object (STO) representing some arbitrary test input. Using recordings of the unmodified standard sequence by a gradient and RF waveform camera (FC), ViP calculates by Bloch simulation the continuous RF signal emitted by the STO during this sequence (hence FC+ViP). During nominally identical repetition of the sequence acquisition, ViP transmits the RF signal for scanner reception, reconstruction and any further parametric derivations by the unmodified standard scanner image reconstruction and analysis software. RESULTS: The scanner outputs were compared against the input STOs. CONCLUSION: First proof-of-principle was discussed and supported by correlation between scanner outputs and the input STO. The work makes no claim that its examples are valid QA methods. It concludes by proposing a new industrial standard for QA without the FC.

Journal article

Pan Y, Varghese J, Tong MS, Yildiz VO, Azzu A, Gatehouse P, Wage R, Nielles-Vallespin S, Pennell DJ, Jin N, Bacher M, Hayes C, Speier P, Simonetti OPet al., 2023, Two-center validation of Pilot Tone based cardiac triggering of a comprehensive cardiovascular magnetic resonance examination., Int J Cardiovasc Imaging

The electrocardiogram (ECG) signal is prone to distortions from gradient and radiofrequency interference and the magnetohydrodynamic effect during cardiovascular magnetic resonance imaging (CMR). Although Pilot Tone Cardiac (PTC) triggering has the potential to overcome these limitations, effectiveness across various CMR techniques has yet to be established. To evaluate the performance of PTC triggering in a comprehensive CMR exam. Fifteen volunteers and 20 patients were recruited at two centers. ECG triggered images were collected for comparison in a subset of sequences. The PTC trigger accuracy was evaluated against ECG in cine acquisitions. Two experienced readers scored image quality in PTC-triggered cine, late gadolinium enhancement (LGE), and T1- and T2-weighted dark-blood turbo spin echo (DB-TSE) images. Quantitative cardiac function, flow, and parametric mapping values obtained using PTC and ECG triggered sequences were compared. Breath-held segmented cine used for trigger timing analysis was collected in 15 volunteers and 14 patients. PTC calibration failed in three volunteers and one patient; ECG trigger recording failed in one patient. Out of 1987 total heartbeats, three mismatched trigger PTC-ECG pairs were found. Image quality scores showed no significant difference between PTC and ECG triggering. There was no significant difference found in quantitative measurements in volunteers. In patients, the only significant difference was found in post-contrast T1 (p = 0.04). ICC showed moderate to excellent agreement in all measurements. PTC performance was equivalent to ECG in terms of triggering consistency, image quality, and quantitative image measurements across multiple CMR applications.

Journal article

Xing X, Del Ser J, Wu Y, Li Y, Xia J, Xu L, Firmin D, Gatehouse P, Yang Get al., 2023, HDL: hybrid deep learning for the synthesis of myocardial velocity maps in digital twins for cardiac analysis, IEEE Journal of Biomedical and Health Informatics, Vol: 27, Pages: 5134-5142, ISSN: 2168-2194

Synthetic digital twins based on medical data accelerate the acquisition, labelling and decision making procedure indigital healthcare. A core part of digital healthcare twins is model based data synthesis, which permits the generation of realisticmedical signals without requiring to cope with the modelling complexity of anatomical and biochemical phenomena producing themin reality. Unfortunately, algorithms for cardiac data synthesis havebeen so far scarcely studied in the literature. An important imagingmodality in the cardiac examination is three-directional CINE multi-slice myocardial velocity mapping (3Dir MVM), which provides aquantitative assessment of cardiac motion in three orthogonal directions of the left ventricle. The long acquisition time and complexacquisition produce make it more urgent to produce syntheticdigital twins of this imaging modality. In this study, we proposea hybrid deep learning (HDL) network, especially for synthetic 3DirMVM data. Our algorithm is featured by a hybrid UNet and a Generative Adversarial Network with a foreground-background generation scheme. The experimental results show that from temporallydown-sampled magnitude CINE images (six times), our proposedalgorithm can still successfully synthesise high temporal resolution 3Dir MVM CMR data (PSNR=42.32) with precise left ventriclesegmentation (DICE=0.92). These performance scores indicate thatour proposed HDL algorithm can be implemented in real-worlddigital twins for myocardial velocity mapping data simulation. Tothe best of our knowledge, this work is the first one in the literatureinvestigating digital twins of the 3Dir MVM CMR, which has showngreat potential for improving the efficiency of clinical studies viasynthesised cardiac data.

Journal article

Allen JJ, Keegan J, Mathew G, Conway M, Jenkins S, Pennell DJ, Nielles-Vallespin S, Gatehouse P, Babu-Narayan SVet al., 2023, Fully-modelled blood-focused variable inversion times for 3D late gadolinium-enhanced imaging, Magnetic Resonance Imaging, Vol: 98, Pages: 44-54, ISSN: 0730-725X

PurposeVariable heart rate during single-cycle inversion-recovery Late Gadolinium-Enhanced (LGE) scanning degrades image quality, which can be mitigated using Variable Inversion Times (VTIs) in real-time response to R-R interval changes. We investigate in vivo and in simulations an extension of a single-cycle VTI method previously applied in 3D LGE imaging, that now fully models the longitudinal magnetisation (fmVTI).MethodsThe VTI and fmVTI methods were used to perform 3D LGE scans for 28 3D LGE patients, with qualitative image quality scores assigned for left atrial wall clarity and total ghosting. Accompanying simulations of numerical phantom images were assessed in terms of ghosting of normal myocardium, blood, and myocardial scar.ResultsThe numerical simulations for fmVTI showed a significant decrease in blood ghosting (VTI: 410 ± 710, fmVTI: 68 ± 40, p < 0.0005) and scar ghosting (VTI: 830 ± 1300, fmVTI: 510 ± 730, p < 0.02). Despite this, there was no significant change in qualitative image quality scores, either for left atrial wall clarity (VTI: 2.0 ± 1.0, fmVTI: 1.8 ± 1.0, p > 0.1) or for total ghosting (VTI: 1.9 ± 1.0, fmVTI: 2.0 ± 1.0, p > 0.7).ConclusionsSimulations indicated reduced ghosting with the fmVTI method, due to reduced Mz variability in the blood signal. However, other sources of phase-encode ghosting and blurring appeared to dominate and obscure this finding in the patient studies available.

Journal article

Hatipoglu S, Mohiaddin RH, Gatehouse P, Alpendurada F, Baksi AJ, Izgi C, Prasad SK, Pennell DJ, Krupickova Set al., 2022, Performance of artificial intelligence for biventricular cardiovascular magnetic resonance volumetric analysis in the clinical setting, INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING, Vol: 38, Pages: 2413-2424, ISSN: 1569-5794

Journal article

Moscatelli S, Gatehouse P, Krupickova S, Mohiaddin R, Voges I, Giese D, Nielles-Vallespin S, Pennell DJet al., 2022, Impact of compressed sensing (CS) acceleration of two-dimensional (2D) flow sequences in clinical paediatric cardiovascular magnetic resonance (CMR), Publisher: SPRINGER, Pages: 220-220, ISSN: 1352-8661

Conference paper

Puricelli F, Voges I, Gatehouse P, Rigby M, Izgi C, Pennell DJ, Krupickova Set al., 2022, Performance of Cardiac MRI in Pediatric and Adult Patients with Fontan Circulation, RADIOLOGY-CARDIOTHORACIC IMAGING, Vol: 4, ISSN: 2638-6135

Journal article

Hatipoglu S, Gatehouse P, Krupickova S, Banya W, Daubeney P, Almogheer B, Izgi C, Weale P, Hayes C, Firmin D, Pennell DJet al., 2022, Reliability of pediatric ventricular function analysis by short-axis "single-cycle-stack-advance" single-shot compressed-sensing cines in minimal breath-hold time, EUROPEAN RADIOLOGY, Vol: 32, Pages: 2581-2593, ISSN: 0938-7994

Journal article

Xing X, Wu Y, Firmin D, Gatehouse P, Yang Get al., 2022, Synthetic velocity mapping cardiac MRI coupled with automated left ventricle segmentation, Publisher: ArXiv

Temporal patterns of cardiac motion provide important information for cardiacdisease diagnosis. This pattern could be obtained by three-directional CINEmulti-slice left ventricular myocardial velocity mapping (3Dir MVM), which is acardiac MR technique providing magnitude and phase information of themyocardial motion simultaneously. However, long acquisition time limits theusage of this technique by causing breathing artifacts, while shortening thetime causes low temporal resolution and may provide an inaccurate assessment ofcardiac motion. In this study, we proposed a frame synthesis algorithm toincrease the temporal resolution of 3Dir MVM data. Our algorithm is featured by1) three attention-based encoders which accept magnitude images, phase images,and myocardium segmentation masks respectively as inputs; 2) three decodersthat output the interpolated frames and corresponding myocardium segmentationresults; and 3) loss functions highlighting myocardium pixels. Our algorithmcan not only increase the temporal resolution 3Dir MVMs, but can also generatesthe myocardium segmentation results at the same time.

Working paper

Fair MJ, Gatehouse PD, Firmin DN, 2021, Minimisation of slab-selective radiofrequency excitation pulse durations constrained by an acceptable aliasing coefficient, MAGNETIC RESONANCE IMAGING, Vol: 81, Pages: 94-100, ISSN: 0730-725X

Journal article

Bermejo IA, Bautista-Rodriguez C, Fraisse A, Voges I, Gatehouse P, Kang H, Piccinelli E, Rowlinson G, Lane M, Semple T, Moscatelli S, Dwornik M, Lota A, Di Salvo G, Wage R, Prasad SK, Mohiaddin R, Pennell DJ, Thavendiranathan P, Krupickova Set al., 2021, Short-Term sequelae of Multisystem Inflammatory Syndrome in Children Assessed by CMR, JACC-CARDIOVASCULAR IMAGING, Vol: 14, Pages: 1666-1667, ISSN: 1936-878X

Journal article

Kuang M, Wu Y, Alonso-Álvarez D, Firmin D, Keegan J, Gatehouse P, Yang Get al., 2021, Three-dimensional embedded attentive RNN (3D-EAR) segmentor for leftventricle delineation from myocardial velocity mapping, Publisher: arXiv

Myocardial Velocity Mapping Cardiac MR (MVM-CMR) can be used to measureglobal and regional myocardial velocities with proved reproducibility. Accurateleft ventricle delineation is a prerequisite for robust and reproduciblemyocardial velocity estimation. Conventional manual segmentation on thisdataset can be time-consuming and subjective, and an effective fully automateddelineation method is highly in demand. By leveraging recently proposed deeplearning-based semantic segmentation approaches, in this study, we propose anovel fully automated framework incorporating a 3D-UNet backbone architecturewith Embedded multichannel Attention mechanism and LSTM based Recurrent neuralnetworks (RNN) for the MVM-CMR datasets (dubbed 3D-EAR segmentor). The proposedmethod also utilises the amalgamation of magnitude and phase images as input torealise an information fusion of this multichannel dataset and exploring thecorrelations of temporal frames via the embedded RNN. By comparing the baselinemodel of 3D-UNet and ablation studies with and without embedded attentive LSTMmodules and various loss functions, we can demonstrate that the proposed modelhas outperformed the state-of-the-art baseline models with significantimprovement.

Conference paper

Raphael C, Mitchell F, Kanaganayagam G, liew A, Di Pietro E, Vieira M, Kanapeckaite L, Newsome S, Gregson J, Owen R, Hsu L-Y, Vassiliou V, Cooper R, Ali A, Ismail T, Wong B, Sun K, Gatehouse P, Firmin D, Cook S, Frenneaux M, Arai A, O'Hanlon R, Pennell D, Prasad Set al., 2021, Cardiovascular magnetic resonance predictors of heart failure in hypertrophic cardiomyopathy: the role of myocardial replacement fibrosis and the microcirculation, Journal of Cardiovascular Magnetic Resonance, Vol: 26, ISSN: 1097-6647

IntroductionHeart failure (HF) in hypertrophic cardiomyopathy (HCM) is associated with high morbidity and mortality. Predictors of HF, in particular the role of myocardial fibrosis and microvascular ischemia remain unclear. We assessed the predictive value of cardiovascular magnetic resonance (CMR) for development of HF in HCM in an observational cohort study.MethodsSerial patients with HCM underwent CMR, including adenosine first-pass perfusion, left atrial (LA) and left ventricular (LV) volumes indexed to body surface area (i) and late gadolinium enhancement (%LGE- as a % of total myocardial mass). We used a composite endpoint of HF death, cardiac transplantation, and progression to NYHA class III/IV.ResultsA total of 543 patients with HCM underwent CMR, of whom 94 met the composite endpoint at baseline. The remaining 449 patients were followed for a median of 5.6 years. Thirty nine patients (8.7%) reached the composite endpoint of HF death (n = 7), cardiac transplantation (n = 2) and progression to NYHA class III/IV (n = 20). The annual incidence of HF was 2.0 per 100 person-years, 95% CI (1.6–2.6). Age, previous non-sustained ventricular tachycardia, LV end-systolic volume indexed to body surface area (LVESVI), LA volume index ; LV ejection fraction, %LGE and presence of mitral regurgitation were significant univariable predictors of HF, with LVESVI (Hazard ratio (HR) 1.44, 95% confidence interval (95% CI) 1.16–1.78, p = 0.001), %LGE per 10% (HR 1.44, 95%CI 1.14–1.82, p = 0.002) age (HR 1.37, 95% CI 1.06–1.77, p = 0.02) and mitral regurgitation (HR 2.6, p = 0.02) remaining independently predictive on multivariable analysis. The presence or extent of inducible perfusion defect assessed using a visual score did not predict outcome (p = 0.16, p = 0.27 respectively).DiscussionThe annual incidence of HF in a contemporary ambulatory HCM population undergoing CMR

Journal article

Wu Y, Hatipoglu S, Alonso-Álvarez D, Gatehouse P, Li B, Gao Y, Firmin D, Keegan J, Yang Get al., 2021, Fast and automated segmentation for the three-directional multi-slice cine myocardial velocity mapping, Diagnostics, Vol: 11, ISSN: 2075-4418

Three-directional cine multi-slice left ventricular myocardial velocity mapping (3Dir MVM) is a cardiac magnetic resonance (CMR) technique that allows the assessment of cardiac motion in three orthogonal directions. Accurate and reproducible delineation of the myocardium is crucial for accurate analysis of peak systolic and diastolic myocardial velocities. In addition to the conventionally available magnitude CMR data, 3Dir MVM also provides three orthogonal phase velocity mapping datasets, which are used to generate velocity maps. These velocity maps may also be used to facilitate and improve the myocardial delineation. Based on the success of deep learning in medical image processing, we propose a novel fast and automated framework that improves the standard U-Net-based methods on these CMR multi-channel data (magnitude and phase velocity mapping) by cross-channel fusion with an attention module and the shape information-based post-processing to achieve accurate delineation of both epicardial and endocardial contours. To evaluate the results, we employ the widely used Dice Scores and the quantification of myocardial longitudinal peak velocities. Our proposed network trained with multi-channel data shows superior performance compared to standard U-Net-based networks trained on single-channel data. The obtained results are promising and provide compelling evidence for the design and application of our multi-channel image analysis of the 3Dir MVM CMR data.

Journal article

Wu Y, Hatipoglu S, Alonso-Álvarez D, Gatehouse P, Firmin D, Keegan J, Yang Get al., 2021, Automated multi-channel segmentation for the 4D myocardial velocity mapping cardiac MR, Medical Imaging 2021: Computer-Aided Diagnosis, Publisher: SPIE, Pages: 1-7

Four-dimensional (4D) left ventricular myocardial velocity mapping (MVM) is a cardiac magnetic resonance (CMR) technique that allows assessment of cardiac motion in three orthogonal directions. Accurate and reproducible delineation of the myocardium is crucial for accurate analysis of peak systolic and diastolic myocardial velocities. In addition to the conventionally available magnitude CMR data, 4D MVM also acquires three velocity-encoded phase datasets which are used to generate velocity maps. These can be used to facilitate and improve myocardial delineation. Based on the success of deep learning in medical image processing, we propose a novel automated framework that improves the standard U-Net based methods on these CMR multi-channel data (magnitude and phase) by cross-channel fusion with attention module and shape information based post-processing to achieve accurate delineation of both epicardium and endocardium contours. To evaluate the results, we employ the widely used Dice scores and the quantification of myocardial longitudinal peak velocities. Our proposed network trained with multi-channel data shows enhanced performance compared to standard UNet based networks trained with single-channel data. Based on the results, our method provides compelling evidence for the design and application for the multi-channel image analysis of the 4D MVM CMR data.

Conference paper

Fair MJ, Gatehouse PD, Reyes E, Adluru G, Mendes J, Khan T, de Silva R, Wage R, DiBella EVR, Firmin DNet al., 2020, Initial investigation of free-breathing 3D whole-heart stress myocardial perfusion MRI., Glob Cardiol Sci Pract, Vol: 2020, ISSN: 2305-7823

Objective: Myocardial first-pass perfusion imaging with MRI is well-established clinically. However, it is potentially weakened by limited myocardial coverage compared to nuclear medicine. Clinical evaluations of whole-heart MRI perfusion by 3D methods, while promising, have to date had the limit of breathhold requirements at stress. This work aims to develop a new free-breathing 3D myocardial perfusion method, and to test its performance in a small patient population. Methods: This work required tolerance to respiratory motion for stress investigations, and therefore employed a "stack-of-stars" hybrid Cartesian-radial MRI acquisition method. The MRI sequence was highly optimised for rapid acquisition and combined with a compressed sensing reconstruction. Stress and rest datasets were acquired in four healthy volunteers, and in six patients with coronary artery disease (CAD), which were compared against clinical reference information. Results: This free-breathing method produced datasets that appeared consistent with clinical reference data in detecting moderate-to-strong induced perfusion abnormalities. However, the majority of the mild defects identified clinically were not detected by the method, potentially due to the presence of transient myocardial artefacts present in the images. Discussion: The feasibility of detecting CAD using this 3D first-pass perfusion sequence during free-breathing is demonstrated. Good agreement on typical moderate-to-strong CAD cases is promising, however, questions still remain on the sensitivity of the technique to milder cases.

Journal article

Raphael CE, Liew AC, Mitchell F, Kanaganayagam GS, Di Pietro E, Newsome S, Owen R, Gregson J, Cooper R, Amin FR, Gatehouse P, Vassiliou V, Ernst S, O'Hanlon R, Frenneaux M, Pennell DJ, Prasad SKet al., 2020, Predictors and Mechanisms of Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy, AMERICAN JOURNAL OF CARDIOLOGY, Vol: 136, Pages: 140-148, ISSN: 0002-9149

Journal article

Mendes JK, Adluru G, Likhite D, Fair MJ, Gatehouse PD, Tian Y, Pedgaonkar A, Wilson B, DiBella EVRet al., 2020, Quantitative 3D myocardial perfusion with an efficient arterial input function, MAGNETIC RESONANCE IN MEDICINE, Vol: 83, Pages: 1949-1963, ISSN: 0740-3194

Journal article

Mahon C, Gatehouse P, Baksi J, Mohiaddin RHet al., 2020, The mysterious needle in the heart: a case report, EUROPEAN HEART JOURNAL-CASE REPORTS, Vol: 4

Journal article

Captur G, Bhandari A, Bruehl R, Ittermann B, Keenan KE, Yang Y, Eames RJ, Benedetti G, Torlasco C, Ricketts L, Boubertakh R, Fatih N, Greenwood JP, Paulis LEM, Lawton CB, Bucciarelli-Ducci C, Lamb HJ, Steeds R, Leung SW, Berry C, Valentin S, Flett A, de Lange C, DeCobelli F, Viallon M, Croisille P, Higgins DM, Greiser A, Pang W, Hamilton-Craig C, Strugnell WE, Dresselaers T, Barison A, Dawson D, Taylor AJ, Mongeon F-P, Plein S, Messroghli D, Al-Mallah M, Grieve SM, Lombardi M, Jang J, Salerno M, Chaturvedi N, Kellman P, Bluemke DA, Nezafat R, Gatehouse P, Moon JCet al., 2020, <i>T</i><sub>1</sub> mapping performance and measurement repeatability: results from the multi-national <i>T</i><sub>1</sub> mapping standardization phantom program (T1MES), JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 22, ISSN: 1097-6647

Journal article

Gulati A, Ismail TF, Ali A, Hsu L-Y, Goncalves C, Ismail NA, Krishnathasan K, Davendralingam N, Ferreira P, Halliday BP, Jones DA, Wage R, Newsome S, Gatehouse P, Firmin D, Jabbour A, Assomull RG, Mathur A, Pennell DJ, Arai AE, Prasad SKet al., 2019, Microvascular Dysfunction in Dilated Cardiomyopathy A Quantitative Stress Perfusion Cardiovascular Magnetic Resonance Study, JACC-CARDIOVASCULAR IMAGING, Vol: 12, Pages: 1699-1708, ISSN: 1936-878X

Journal article

Ghonim S, Gatehouse PD, Giblin G, Keegan J, Smith GC, Mathews GC, Jenkins S, Alpendurada F, Dimopoulos K, Pennell DJ, Li W, Moon JC, Gatzoulis M, Babu-Narayan Set al., 2019, Can RV optimised native T1 mapping and ECV add clinical value in repaired tetralogy of Fallot?, Publisher: OXFORD UNIV PRESS, Pages: 204-205, ISSN: 2047-2404

Conference paper

Hofman MBM, Rodenburg MJA, Bloch KM, Werner B, Westenberg JJM, Buechel ERV, Nijveldt R, Spruijt OA, Kilner PJ, van Rossum AC, Gatehouse PDet al., 2019, In-vivo validation of interpolation-based phase offset correction in cardiovascular magnetic resonance flow quantification: a multi-vendor, multi-center study, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, Vol: 21, ISSN: 1097-6647

Journal article

Gorodezky M, Ferreira P, Nielles-Vallespin S, Gatehouse P, Pennell D, Scott A, Firmin Det al., 2019, High resolution in-vivo DT-CMR using an interleaved variable density spiral STEAM sequence, Magnetic Resonance in Medicine, Vol: 81, Pages: 1580-1594, ISSN: 0740-3194

Purpose: Diffusion tensor cardiovascular magnetic resonance (DT-CMR) has a limited spatial resolution. Thepurpose of this study was to demonstrate high-resolution DT-CMR using a segmented variable density spiralsequence with correction for motion, off-resonance and T2* related blurring.Methods: A single-shot STEAM EPI DT-CMR sequence at 2.8x2.8x8mm3 and 1.8x1.8x8mm3 was compared to asingle shot spiral at 2.8x2.8x8mm3 and an interleaved spiral sequence at 1.8x1.8x8mm3resolution in 10 healthyvolunteers at peak-systole and diastasis. Motion-induced phase was corrected using the densely sampledcentral k-space data of the spirals. STEAM field maps and T2* measures were obtained using a pair ofstimulated echoes each with a double spiral readout, the first used to correct the motion-induced phase of thesecond.Results: The high resolution spiral sequence produced similar DT-CMR results and quality measures to thestandard resolution sequence in both cardiac phases. Residual differences in fractional anisotropy and helixangle gradient between the resolutions could be due to spatial resolution and/or signal to noise ratio. The dataquality increased after both motion-induced phase correction and off-resonance correction and sharpnessincreased after T2* correction. The high resolution EPI sequence failed to provide sufficient data quality forDT-CMR reconstruction.Conclusion: In this study an in-vivo DT-CMR acquisition at 1.8x1.8mm2in-plane resolution was demonstratedusing a segmented spiral STEAM sequence. The motion-induced phase and off-resonance corrections areessential for high resolution spiral DT-CMR. Segmented variable density spiral STEAM was found to be theoptimal method for acquiring high resolution DT-CMR data.

Journal article

Ghonim S, Gatehouse PD, Gatzoulis MA, Babu-Narayan SVet al., 2018, Is cardiovascular magnetic resonance measurement of diffuse fibrosis ready for clinical use in the systemic RV?, International Journal of Cardiology, Vol: 271, Pages: 66-67, ISSN: 0167-5273

Journal article

Vassiliou VS, Cameron D, Prasad SK, Gatehouse PDet al., 2018, Magnetic resonance imaging: Physics basics for the cardiologist, JRSM CARDIOVASCULAR DISEASE, Vol: 7, ISSN: 2048-0040

Magnetic resonance imaging physics can be a complex and challenging topic for the practising cardiologist. Its evolving nature and the increasing number of novel sequences used in clinical scanning have been topics of excellent reviews; however, the basic understanding of physics underlying the creation of images remains difficult for many cardiologists. In this review, we go back to the basic physics theories underpinning magnetic resonance and explain their application and use in achieving good quality cardiac imaging, whilst describing established and novel magnetic resonance sequences. By understanding these basic principles, it is anticipated that cardiologists and other health professionals will then appreciate more advanced physics manuscripts on cardiac scanning and novel sequences.

Journal article

Scott AD, Nielles-Vallespin S, Ferreira P, Khalique Z, Gatehouse P, Kilner P, Pennell D, Firmin Det al., 2018, An in-vivo comparison of stimulated-echo and motion compensated spin-echo sequences for 3T diffusion tensor cardiovascular magnetic resonance at multiple cardiac phases, Journal of Cardiovascular Magnetic Resonance, Vol: 20, ISSN: 1097-6647

BackgroundStimulated-echo (STEAM) and, more recently, motion-compensated spin-echo (M2-SE) techniques have been used for in-vivo diffusion tensor cardiovascular magnetic resonance (DT-CMR) assessment of cardiac microstructure. The two techniques differ in the length scales of diffusion interrogated, their signal-to-noise ratio efficiency and sensitivity to both motion and strain. Previous comparisons of the techniques have used high performance gradients at 1.5 T in a single cardiac phase. However, recent work using STEAM has demonstrated novel findings of microscopic dysfunction in cardiomyopathy patients, when DT-CMR was performed at multiple cardiac phases. We compare STEAM and M2-SE using a clinical 3 T scanner in three potentially clinically interesting cardiac phases.MethodsBreath hold mid-ventricular short-axis DT-CMR was performed in 15 subjects using M2-SE and STEAM at end-systole, systolic sweet-spot and diastasis. Success was defined by ≥50% of the myocardium demonstrating normal helix angles. From successful acquisitions DT-CMR results relating to tensor orientation, size and shape were compared between sequences and cardiac phases using non-parametric statistics. Strain information was obtained using cine spiral displacement encoding with stimulated echoes for comparison with DT-CMR results.ResultsAcquisitions were successful in 98% of STEAM and 76% of M2-SE cases and visual helix angle (HA) map scores were higher for STEAM at the sweet-spot and diastasis. There were significant differences between sequences (p < 0.05) in mean diffusivity (MD), fractional anisotropy (FA), tensor mode, transmural HA gradient and absolute second eigenvector angle (E2A). Differences in E2A between systole and diastole correlated with peak radial strain for both sequences (p ≤ 0.01).ConclusionM2-SE and STEAM can be performed equally well at peak systole at 3 T using standard gradients, but at the sweet-spot and diastole STEAM is more rel

Journal article

Nyktari E, Vassiliou VS, Arzanauskaite M, Gatehouse P, Greiser A, Wechalekar A, Gilbertson J, Pierce I, Sharma R, Mohiaddin Ret al., 2017, Challenging Occam's Razor: An Unusual Combination of Sarcoidosis and Amyloidosis. The Value of Cardiac Magnetic Resonance Imaging in Infiltrative Cardiomyopathies, CANADIAN JOURNAL OF CARDIOLOGY, Vol: 33, ISSN: 0828-282X

Journal article

Cameron D, Vassiliou VS, Higgins DM, Gatehouse PDet al., 2017, Towards accurate and precise T 1 and extracellular volume mapping in the myocardium: a guide to current pitfalls and their solutions, Magnetic Resonance Materials in Physics, Biology and Medicine, Vol: 31, Pages: 143-163, ISSN: 0968-5243

Mapping of the longitudinal relaxation time (T 1) and extracellular volume (ECV) offers a means of identifying pathological changes in myocardial tissue, including diffuse changes that may be invisible to existing T 1-weighted methods. This technique has recently shown strong clinical utility for pathologies such as Anderson-Fabry disease and amyloidosis and has generated clinical interest as a possible means of detecting small changes in diffuse fibrosis; however, scatter in T 1 and ECV estimates offers challenges for detecting these changes, and bias limits comparisons between sites and vendors. There are several technical and physiological pitfalls that influence the accuracy (bias) and precision (repeatability) of T 1 and ECV mapping methods. The goal of this review is to describe the most significant of these, and detail current solutions, in order to aid scientists and clinicians to maximise the utility of T 1 mapping in their clinical or research setting. A detailed summary of technical and physiological factors, issues relating to contrast agents, and specific disease-related issues is provided, along with some considerations on the future directions of the field.

Journal article

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