Publications
82 results found
Pennell DJ, Khalique Z, Ferreira PF, et al., 2018, Deranged myocyte microstructure in situs inversus totalis demonstrated by diffusion tensor cardiovascular magnetic resonance, JACC: Cardiovascular Imaging, Vol: 11, Pages: 1360-1362, ISSN: 1936-878X
Gorodezky M, Scott AD, Ferreira PF, et al., 2018, Diffusion tensor cardiovascular magnetic resonance with a spiral trajectory: An in vivo comparison of echo planar and spiral stimulated echo sequences, Magnetic Resonance in Medicine, Vol: 80, Pages: 648-654, ISSN: 0740-3194
PURPOSE: Diffusion tensor cardiovascular MR (DT-CMR) using stimulated echo acquisition mode (STEAM) with echo-planar-imaging (EPI) readouts is a low signal-to-noise-ratio (SNR) technique and therefore typically has a low spatial resolution. Spiral trajectories are more efficient than EPI, and could increase the SNR. The purpose of this study was to compare the performance of a novel STEAM spiral DT-CMR sequence with an equivalent established EPI technique. METHODS: A STEAM DT-CMR sequence was implemented with a spiral readout and a reduced field of view. An in vivo comparison of DT-CMR parameters and data quality between EPI and spiral was performed in 11 healthy volunteers imaged in peak systole and diastasis at 3 T. The SNR was compared in a phantom and in vivo. RESULTS: There was a greater than 49% increase in the SNR in vivo and in the phantom measurements (in vivo septum, systole: SNREPI = 8.0 ± 2.2, SNRspiral = 12.0 ± 2.7; diastasis: SNREPI = 8.1 ± 1.6, SNRspiral = 12.0 ± 3.7). There were no significant differences in helix angle gradient (HAG) (systole: HAGEPI = -0.79 ± 0.07 °/%; HAGspiral = -0.74 ± 0.16 °/%; P = 0.11; diastasis: HAGEPI = -0.63 ± 0.05 °/%; HAGspiral = -0.56 ± 0.14 °/%; P = 0.20), mean diffusivity (MD) in systole (MDEPI = 0.99 ± 0.06 × 10-3 mm2 /s, MDspiral = 1.00 ± 0.09 × 10-3 mm2 /s, P = 0.23) and secondary eigenvector angulation (E2A) (systole: E2AEPI = 61 ± 10 °; E2Aspiral = 63 ± 10 °; P&thi
Khalique Z, Ferreira PF, Scott AD, et al., 2018, ASSESSMENT OF THE MICROSTRUCTURE IN RECOVERED DILATED CARDIOMYOPATHY WITH DIFFUSION TENSOR CARDIOVASCULAR MAGNETIC RESONANCE, Joint Meeting of the British-Society-of-Cardiovascular-Imaging/British-Society-of-Cardiovascular-CT, British-Society-of-Cardiovascular-Magnetic-Resonance and British-Nuclear-Cardiac-Society on British Cardiovascular Imaging, Publisher: BMJ PUBLISHING GROUP, Pages: A6-A7, ISSN: 1355-6037
Scott AD, Nielles-Vallespin S, Ferreira P, et 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
Ferreira PF, Nielles-Vallespin S, Scott AD, et al., 2017, Evaluation of the impact of strain correction on the orientation of cardiac diffusion tensors with in vivo and ex vivo porcine hearts, Magnetic Resonance in Medicine, Vol: 79, Pages: 2205-2215, ISSN: 0740-3194
PurposeTo evaluate the importance of strain-correcting stimulated echo acquisition mode echo-planar imaging cardiac diffusion tensor imaging.MethodsHealthy pigs (n = 11) were successfully scanned with a 3D cine displacement-encoded imaging with stimulated echoes and a monopolar-stimulated echo-planar imaging diffusion tensor imaging sequence at 3 T during diastasis, peak systole, and strain sweet spots in a midventricular short-axis slice. The same diffusion tensor imaging sequence was repeated ex vivo after arresting the hearts in either a relaxed (KCl-induced) or contracted (BaCl2-induced) state. The displacement-encoded imaging with stimulated echoes data were used to strain-correct the in vivo cardiac diffusion tensor imaging in diastole and systole. The orientation of the primary (helix angles) and secondary (E2A) diffusion eigenvectors was compared with and without strain correction and to the strain-free ex vivo data.ResultsStrain correction reduces systolic E2A significantly when compared without strain correction and ex vivo (median absolute E2A = 34.3° versus E2A = 57.1° (P = 0.01), E2A = 60.5° (P = 0.006), respectively). The systolic distribution of E2A without strain correction is closer to the contracted ex vivo distribution than with strain correction, root mean square deviation of 0.027 versus 0.038.ConclusionsThe current strain-correction model amplifies the contribution of microscopic strain to diffusion resulting in an overcorrection of E2A. Results show that a new model that considers cellular rearrangement is required.
Nielles-Vallespin S, Khalique Z, Ferreira PF, et al., 2017, Assessment of myocardial microstructural dynamics by in vivo diffusion tensor cardiac magnetic resonance, Journal of the American College of Cardiology, Vol: 69, Pages: 661-676, ISSN: 0735-1097
BackgroundCardiomyocytes are organized in microstructures termed sheetlets that reorientate during left ventricular thickening. Diffusion tensor cardiac magnetic resonance (DT-CMR) may enable noninvasive interrogation of in vivo cardiac microstructural dynamics. Dilated cardiomyopathy (DCM) is a condition of abnormal myocardium with unknown sheetlet function.ObjectivesThis study sought to validate in vivo DT-CMR measures of cardiac microstructure against histology, characterize microstructural dynamics during left ventricular wall thickening, and apply the technique in hypertrophic cardiomyopathy (HCM) and DCM.MethodsIn vivo DT-CMR was acquired throughout the cardiac cycle in healthy swine, followed by in situ and ex vivo DT-CMR, then validated against histology. In vivo DT-CMR was performed in 19 control subjects, 19 DCM, and 13 HCM patients.ResultsIn swine, a DT-CMR index of sheetlet reorientation (E2A) changed substantially (E2A mobility ∼46°). E2A changes correlated with wall thickness changes (in vivo r2 = 0.75; in situ r2 = 0.89), were consistently observed under all experimental conditions, and accorded closely with histological analyses in both relaxed and contracted states. The potential contribution of cyclical strain effects to in vivo E2A was ∼17%. In healthy human control subjects, E2A increased from diastole (18°) to systole (65°; p < 0.001; E2A mobility = 45°). HCM patients showed significantly greater E2A in diastole than control subjects did (48°; p < 0.001) with impaired E2A mobility (23°; p < 0.001). In DCM, E2A was similar to control subjects in diastole, but systolic values were markedly lower (40°; p < 0.001) with impaired E2A mobility (20°; p < 0.001).ConclusionsMyocardial microstructure dynamics can be characterized by in vivo DT-CMR. Sheetlet function was abnormal in DCM with altered systolic conformation and reduced mobility, contrasting with HCM, which showed reduced mobility with alte
Serbanovic-Canic J, de Luca A, Warboys C, et al., 2016, Zebrafish model for functional screening of flow-responsive genes, Arteriosclerosis Thrombosis and Vascular Biology, Vol: 36, ISSN: 1524-4636
OBJECTIVE: Atherosclerosis is initiated at branches and bends of arteries exposed to disturbed blood flow that generates low shear stress. This mechanical environment promotes lesions by inducing endothelial cell (EC) apoptosis and dysfunction via mechanisms that are incompletely understood. Although transcriptome-based studies have identified multiple shear-responsive genes, most of them have an unknown function. To address this, we investigated whether zebrafish embryos can be used for functional screening of mechanosensitive genes that regulate EC apoptosis in mammalian arteries. APPROACH AND RESULTS: First, we demonstrated that flow regulates EC apoptosis in developing zebrafish vasculature. Specifically, suppression of blood flow in zebrafish embryos (by targeting cardiac troponin) enhanced that rate of EC apoptosis (≈10%) compared with controls exposed to flow (≈1%). A panel of candidate regulators of apoptosis were identified by transcriptome profiling of ECs from high and low shear stress regions of the porcine aorta. Genes that displayed the greatest differential expression and possessed 1 to 2 zebrafish orthologues were screened for the regulation of apoptosis in zebrafish vasculature exposed to flow or no-flow conditions using a knockdown approach. A phenotypic change was observed in 4 genes; p53-related protein (PERP) and programmed cell death 2-like protein functioned as positive regulators of apoptosis, whereas angiopoietin-like 4 and cadherin 13 were negative regulators. The regulation of perp, cdh13, angptl4, and pdcd2l by shear stress and the effects of perp and cdh13 on EC apoptosis were confirmed by studies of cultured EC exposed to flow. CONCLUSIONS: We conclude that a zebrafish model of flow manipulation coupled to gene knockdown can be used for functional screening of mechanosensitive genes in vascular ECs, thus providing potential therapeutic targets to prevent or treat endothelial injury at atheroprone sites.
McGill L-A, Ferreira P, Scott A, et al., 2016, Non-invasive Interrogation of Myocardial Disarray in Hypertrophic Cardiomyopathy, Annual Conference of the British Cardiovascular Society (BCS) on Prediction and Prevention, Publisher: BMJ Publishing Group, Pages: A96-A96, ISSN: 1355-6037
Scott AD, Ferreira P, Nielles-Vallespin S, et al., 2016, Can we predict the diffusion “sweet-spot” based on a standard cine?, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-3, ISSN: 1097-6647
- Cite
- Citations: 1
Scott AD, Nielles-Vallespin S, Ferreira P, et al., 2016, In-vivo cardiac DTI: An initial comparison of M012 compensated spin-echo and STEAM, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-3, ISSN: 1097-6647
- Cite
- Citations: 2
Scott AD, Tayal U, Nielles-Vallespin S, et al., 2016, Accelerating cine DENSE using a zonal excitation, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 1-3, ISSN: 1097-6647
- Cite
- Citations: 7
Scott AD, Nielles-Vallespin S, Ferreira PF, et al., 2016, The effects of noise in cardiac diffusion tensor imaging and the benefits of averaging complex data, NMR in Biomedicine, Vol: 29, Pages: 588-599
McGill LA, Ferreira PF, Scott AD, et al., 2016, Relationship between cardiac diffusion tensor imaging parameters and anthropometrics in healthy volunteers, Journal of Cardiovascular Magnetic Resonance, Vol: 18, Pages: 2-2
Scott AD, Ferreira P, Nielles-Vallespin S, et al., 2015, Directions vs. averages: An in-vivo comparison for cardiac DTI, Journal of Cardiovascular Magnetic Resonance, Pages: 1-2, ISSN: 1097-6647
- Cite
- Citations: 1
Scott AD, Nielles-Vallespin S, Ferreira P, et al., 2015, Improving the accuracy of cardiac DTI by averaging the complex data, Journal of Cardiovascular Magnetic Resonance, Pages: 1-3, ISSN: 1097-6647
McGill LA, Scott AD, Ferreira P, et al., 2015, Heterogeneity of diffusion tensor imaging measurements of fractional anisotropy and mean diffusivity in normal human hearts in vivo, Journal of Cardiovascular Magnetic Resonance, Vol: 17, ISSN: 1097-6647
Kilner PJ, McCarthy K, Murillo M, et al., 2015, Histology of human myocardial laminar microstructure and consideration of its cyclic deformations with respect to interpretation of in vivo cardiac diffusion tensor imaging, Journal of Cardiovascular Magnetic Resonance, Pages: 1-3, ISSN: 1097-6647
Giannakidis A, Ferreira P, Gullberg GT, et al., 2015, Transmural gradients of preferential diffusion motility in the normal rat myocardium characterized by diffusion tensor imaging, Journal of Cardiovascular Magnetic Resonance, Vol: 17, Pages: 1-3, ISSN: 1097-6647
Ferreira PF, Firmin DN, 2015, Imaging artifacts, Basic Principles of Cardiovascular MRI: Physics and Imaging Technique, Pages: 97-133, ISBN: 9783319221403
Cardiovascular MR offers a large range of applications. Many of these are still currently under active development by the research community, for improved accuracy and reliability. The complex nature of the cardiovascular system offers many challenges to clinicians. Its unique mixture of respiratory and cardiac motion; fast fl owing blood; and the tissue-air interface between the heart and the lungs, are just some of the diffi culties faced. Many of these challenges can result in imaging artifacts and measurement errors, which may limit the diagnostic potential of the scan or even contribute to misinterpretation. A good understanding of the physical principles behind the formation of such artifacts is imperative to identifying and minimising them. This chapter summarises, in a language accessible for a clinical readership, the most problematic artifacts specifi c to cardiovascular MR, with particular regard to their physical basis, and implications for the different sequences and applications. It includes motion (respiratory, cardiac and blood fl ow); Gibbs ringing; aliasing; chemical-shift; and B 0 -inhomogeneities.
McGill L-A, Scott AD, Ferreira PF, et al., 2015, Heterogeneity of fractional anisotropy and mean diffusivity measurements by in vivo diffusion tensor imaging in normal human hearts, PloS one, Vol: 10, Pages: e0132360-e0132360
Scott AD, Ferreira PFADC, Nielles-Vallespin S, et al., 2015, Optimal diffusion weighting for in vivo cardiac diffusion tensor imaging, Magnetic resonance in medicine, Vol: 74, Pages: 420-430
Ferreira PF, Kilner PJ, McGill L-A, et al., 2014, In vivo cardiovascular magnetic resonance diffusion tensor imaging shows evidence of abnormal myocardial laminar orientations and mobility in hypertrophic cardiomyopathy, Journal of Cardiovascular Magnetic Resonance, Vol: 16, Pages: 1-16, ISSN: 1097-6647
BackgroundCardiac diffusion tensor imaging (cDTI) measures the magnitudes and directions of intramyocardial water diffusion. Assuming the cross-myocyte components to be constrained by the laminar microstructures of myocardium, we hypothesized that cDTI at two cardiac phases might identify any abnormalities of laminar orientation and mobility in hypertrophic cardiomyopathy (HCM).MethodsWe performed cDTI in vivo at 3 Tesla at end-systole and late diastole in 11 healthy controls and 11 patients with HCM, as well as late gadolinium enhancement (LGE) for detection of regional fibrosis.ResultsVoxel-wise analysis of diffusion tensors relative to left ventricular coordinates showed expected transmural changes of myocardial helix-angle, with no significant differences between phases or between HCM and control groups. In controls, the angle of the second eigenvector of diffusion (E2A) relative to the local wall tangent plane was larger in systole than diastole, in accord with previously reported changes of laminar orientation. HCM hearts showed higher than normal global E2A in systole (63.9° vs 56.4° controls, p =0.026) and markedly raised E2A in diastole (46.8° vs 24.0° controls, p < 0.001). In hypertrophic regions, E2A retained a high, systole-like angulation even in diastole, independent of LGE, while regions of normal wall thickness did not (LGE present 57.8°, p =0.0028, LGE absent 54.8°, p =0.0022 vs normal thickness 38.1°).ConclusionsIn healthy controls, the angles of cross-myocyte components of diffusion were consistent with previously reported transmural orientations of laminar microstructures and their changes with contraction. In HCM, especially in hypertrophic regions, they were consistent with hypercontraction in systole and failure of relaxation in diastole. Further investigation of this finding is required as previously postulated effects of strain might be a confounding factor.
Nielles-Vallespin S, Mekkaoui C, Gatehouse P, et al., 2014, In Vivo Diffusion Tensor MRI of the Human Heart: Reproducibility of Breath-Hold and Navigator Based Approaches (vol 70, pg 454, 2013), MAGNETIC RESONANCE IN MEDICINE, Vol: 72, Pages: 599-599, ISSN: 0740-3194
- Author Web Link
- Cite
- Citations: 5
Scott AD, Ferreira P, Nielles-Vallespin S, et al., 2014, Improved in-vivo cardiac DTI using optimal b-values, Journal of Cardiovascular Magnetic Resonance, Vol: 16, ISSN: 1097-6647
- Cite
- Citations: 3
Tunnicliffe EM, Scott AD, Ferreira P, et al., 2014, Inter-centre reproducibility of cardiac diffusion tensor measures, Journal of Cardiovascular Magnetic Resonance, Vol: 16, ISSN: 1097-6647
Ali A, Hsu LY, Gulati A, et al., 2014, The association between ECV and microcirculation perfusion abnormalities in non-ischemic dilated cardiomyopathy, Journal of Cardiovascular Magnetic Resonance, Vol: 16, ISSN: 1097-6647
Giannakidis A, Ferreira P, Scott AD, et al., 2014, Scanner-efficient diffusion tensor imaging of human cardiac microstructure using the fast composite splitting reconstruction algorithm, Journal of Cardiovascular Magnetic Resonance, Vol: 16, ISSN: 1097-6647
- Cite
- Citations: 1
Ferreira P, Kilner PJ, McGill L-A, et al., 2014, Aberrant myocardial sheetlet mobility in hypertrophic cardiomyopathy detected using in vivo cardiovascular magnetic resonance diffusion tensor imaging, Journal of Cardiovascular Magnetic Resonance, Vol: 16, Pages: P338-P338
McGill L-A, Ferreira P, Scott AD, et al., 2014, Comparison of cardiac DTI parameters between systole and diastole, Journal of Cardiovascular Magnetic Resonance, Vol: 16, Pages: P39-P39
Tunnicliffe EM, Scott AD, Ferreira P, et al., 2014, Intercentre reproducibility of cardiac apparent diffusion coefficient and fractional anisotropy in healthy volunteers, Journal of Cardiovascular Magnetic Resonance, Vol: 16, Pages: 31-31
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.