Cardiovascular MR Unit

London, United Kingdom

Cardiovascular MR Unit

London, United Kingdom

Time filter

Source Type

Nielles-Vallespin S.,Cardiovascular MR Unit | Nielles-Vallespin S.,Imperial College London | Mekkaoui C.,Harvard University | Gatehouse P.,Cardiovascular MR Unit | And 17 more authors.
Magnetic Resonance in Medicine | Year: 2013

The aim of this study was to implement a quantitative in vivo cardiac diffusion tensor imaging (DTI) technique that was robust, reproducible, and feasible to perform in patients with cardiovascular disease. A stimulated-echo single-shot echo-planar imaging (EPI) sequence with zonal excitation and parallel imaging was implemented, together with a novel modification of the prospective navigator (NAV) technique combined with a biofeedback mechanism. Ten volunteers were scanned on two different days, each time with both multiple breath-hold (MBH) and NAV multislice protocols. Fractional anisotropy (FA), mean diffusivity (MD), and helix angle (HA) fiber maps were created. Comparison of initial and repeat scans showed good reproducibility for both MBH and NAV techniques for FA (P > 0.22), MD (P > 0.15), and HA (P > 0.28). Comparison of MBH and NAV FA (FAMBHday1 = 0.60 ± 0.04, FA NAVday1 = 0.60 ± 0.03, P = 0.57) and MD (MDMBHday1 = 0.8 ± 0.2 × 10-3 mm2/s, MD NAVday1 = 0.9 ± 0.2 × 10-3 mm2/s, P = 0.07) values showed no significant differences, while HA values (HA MBHday1Endo = 22 ± 10°, HAMBHday1Mid-Endo = 20 ± 6°, HAMBHday1Mid-Epi = -1 ± 6°, HA MBHday1Epi = -17 ± 6°, HANAVday1Endo = 7 ± 7°, HANAVday1Mid-Endo = 13 ± 8°, HA NAVday1Mid-Epi = -2 ± 7°, HANAVday1Epi = -14 ± 6°) were significantly different. The scan duration was 20% longer with the NAV approach. Currently, the MBH approach is the more robust in normal volunteers. While the NAV technique still requires resolution of some bulk motion sensitivity issues, these preliminary experiments show its potential for in vivo clinical cardiac diffusion tensor imaging and for delivering high-resolution in vivo 3D DTI tractography of the heart. © 2012 Wiley Periodicals, Inc.


Canali E.,University of Rome La Sapienza | Masci P.,Cardiovascular MR Unit | Masci P.,Cardiovascular Medicine Unit | Bogaert J.,University Hospitals Leuven | And 9 more authors.
European Heart Journal Cardiovascular Imaging | Year: 2012

Aims: There is conflicting evidence on the impact of gender on reperfusion after primary coronary angioplasty (PPCI), and on left ventricular (LV) remodelling (LVR). In a cohort of patients with reperfused ST elevation myocardial infarction (STEMI), gender-related differences on myocardial reperfusion, and sex-related differences on LVR were assessed by using a comprehensive cardiac magnetic resonance (CMR) approach. Methods and results: In four tertiary referral centres, 283 (238 males and 45 females) consecutive STEMI patients, treated with PPCI within 12 h from symptoms onset underwent CMR 3 ± 2 days after STEMI and at 4-month follow-up. By CMR, the area at risk, infarct size (IS), microvascular obstruction (MVO), and myocardial salvage index (MSI) were assessed. Women were older than men (P 0.014), more hypertensive (P < 0.001) and more frequently presented with pre-infarct angina (P 0.018). An MSI extent was significantly higher (P 0.013), IS was significantly smaller at both time points (acute P < 0.001, follow-up P < 0.001), and the MVO extent was significantly smaller (P < 0.001) in women. At multivariate analysis, Killip class and female sex were independently associated with a higher MSI (P 0.02, P 0.05, respectively). A similar incidence of LVR in both sexes was observed at follow-up (P 0.808). Conclusions: The better reperfusion pattern observed in women by CMR in our population of reperfused STEMI suggests sex-based differences exist. No gender differences were observed with respect to incidence of LV remodelling at the follow-up mainly occurring in the subset of patients with a larger IS. © The Author 2012.


Piccini D.,Friedrich - Alexander - University, Erlangen - Nuremberg | Littmann A.,Siemens AG | Nielles-Vallespin S.,Cardiovascular MR Unit | Zenge M.O.,Siemens AG
Magnetic Resonance in Medicine | Year: 2012

Free-breathing three-dimensional whole-heart coronary MRI is a noninvasive alternative to X-ray coronary angiography. However, the existing navigator-gated approaches do not meet the requirements of clinical practice, as they perform with suboptimal accuracy and require prolonged acquisition times. Self-navigated techniques, applied to bright-blood imaging sequences, promise to detect the position of the blood pool directly in the readouts acquired for imaging. Hence, the respiratory displacement of the heart can be calculated and used for motion correction with high accuracy and 100% scan efficiency. However, additional bright signal from the chest wall, spine, arms, and liver can render the isolation of the blood pool impossible. In this work, an innovative method based on a targeted combination of the output signals of an anterior phased-array surface coil is implemented to efficiently suppress such additional bright signal. Furthermore, an algorithm for the automatic segmentation of the blood pool is proposed. Robust self-navigation is achieved by cross-correlation. These improvements were integrated into a three-dimensional radial whole-heart coronary MRI sequence and were compared with navigator-gated imaging in vivo. Self-navigation was successful in all cases and the acquisition time was reduced up to 63%. Equivalent or slightly superior image quality, vessel length, and sharpness were achieved. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc. Copyright © 2011 Wiley Periodicals, Inc.


PubMed | Cardiovascular MR Unit
Type: Comparative Study | Journal: Magnetic resonance in medicine | Year: 2013

The aim of this study was to implement a quantitative in vivo cardiac diffusion tensor imaging (DTI) technique that was robust, reproducible, and feasible to perform in patients with cardiovascular disease. A stimulated-echo single-shot echo-planar imaging (EPI) sequence with zonal excitation and parallel imaging was implemented, together with a novel modification of the prospective navigator (NAV) technique combined with a biofeedback mechanism. Ten volunteers were scanned on two different days, each time with both multiple breath-hold (MBH) and NAV multislice protocols. Fractional anisotropy (FA), mean diffusivity (MD), and helix angle (HA) fiber maps were created. Comparison of initial and repeat scans showed good reproducibility for both MBH and NAV techniques for FA (P > 0.22), MD (P > 0.15), and HA (P > 0.28). Comparison of MBH and NAV FA (FAMBHday1 = 0.60 0.04, FANAVday1 = 0.60 0.03, P = 0.57) and MD (MDMBHday1 = 0.8 0.2 10(-3) mm(2) /s, MDNAVday1 = 0.9 0.2 10(-3) mm(2) /s, P = 0.07) values showed no significant differences, while HA values (HAMBHday1Endo = 22 10, HAMBHday1Mid-Endo = 20 6, HAMBHday1Mid-Epi = -1 6, HAMBHday1Epi = -17 6, HANAVday1Endo = 7 7, HANAVday1Mid-Endo = 13 8, HANAVday1Mid-Epi = -2 7, HANAVday1Epi = -14 6) were significantly different. The scan duration was 20% longer with the NAV approach. Currently, the MBH approach is the more robust in normal volunteers. While the NAV technique still requires resolution of some bulk motion sensitivity issues, these preliminary experiments show its potential for in vivo clinical cardiac diffusion tensor imaging and for delivering high-resolution in vivo 3D DTI tractography of the heart.

Loading Cardiovascular MR Unit collaborators
Loading Cardiovascular MR Unit collaborators