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Purpose To develop a free-breathing whole-heart isotropic-resolution 3D late gadolinium enhancement (LGE) sequence with Dixon-encoding, which provides co-registered 3D grey-blood phase-sensitive inversion-recovery (PSIR) and complementary 3D fat volumes in a single scan of Methods A free-breathing 3D PSIR LGE sequence with dual-echo Dixon readout with a variable density Cartesian trajectory with acceleration factor of 3 is proposed. Image navigators are acquired to correct both inversion recovery (IR)-prepared and reference volumes for 2D translational respiratory motion, enabling motion compensated PSIR reconstruction with 100% respiratory scan efficiency. An intermediate PSIR reconstruction is performed between the in-phase echoes to estimate the signal polarity which is subsequently applied to the IR-prepared water volume to generate a water grey-blood PSIR image. The IR-prepared water volume is obtained using a water/fat separation algorithm from the corresponding dual-echo readout. The complementary fat-volume is obtained after water/fat separation of the reference volume. Ten patients (6 with myocardial scar) were scanned with the proposed water/fat grey-blood 3D PSIR LGE sequence at 1.5 T and compared to breath-held grey-blood 2D LGE sequence in terms of contrast ratio (CR), contrast-to-noise ratio (CNR), scar depiction, scar transmurality, scar mass and image quality. Results Comparable CRs (p = 0.98, 0.40 and 0.83) and CNRs (p = 0.29, 0.40 and 0.26) for blood-myocardium, scar-myocardium and scar-blood respectively were obtained with the proposed free-breathing 3D water/fat LGE and 2D clinical LGE scan. Excellent agreement for scar detection, scar transmurality, scar mass (bias = 0.29%) and image quality scores (from 1: non-diagnostic to 4: excellent) of 3.8 ± 0.42 and 3.6 ± 0.69 (p > 0.99) were obtained with the 2D and 3D PSIR LGE approaches with comparable total acquisition time (p = 0.29). Similar agreement in intra and inter-observer variability were obtained for the 2D and 3D acquisition respectively. Conclusion The proposed approach enabled the acquisition of free-breathing motion-compensated isotropic-resolution 3D grey-blood PSIR LGE and fat volumes. The proposed approach showed good agreement with conventional 2D LGE in terms of CR, scar depiction and scan time, while enabling free-breathing acquisition, whole-heart coverage, reformatting in arbitrary views and visualization of both water and fat information.

Background MR Fingerprinting (MRF) [1] offers a novel approach for quantifying extracellular volume (ECV) in a single scan without contrast agent. Whereas conventional parameter mapping assumes chemical exchange occurs much faster than the experiment time scale, usually on the order of T1, MRF measurements are acquired every TR (less than 12ms). This project investigates the feasibility of a new MRF acquisition termed MRF-X, which takes chemical exchange effects into account, to generate voxel-wise maps of ECV and T1.

Background Multi-contrast weighted imaging is a commonly used cardiovascular magnetic resonance (CMR) protocol for characterization of carotid plaque composition. However, this approach is limited in several aspects including low slice resolution, long scan time, image mis-registration, and complex image interpretation. In this work, a 3D CMR technique, named Multi-contrast Atherosclerosis Characterization (MATCH), was developed to mitigate the above limitations. Methods MATCH employs a 3D spoiled segmented fast low angle shot readout to acquire data with three different contrast weightings in an interleaved fashion. The inherently co-registered image sets, hyper T1-weighting, gray blood, and T2-weighting, are used to detect intra-plaque hemorrhage (IPH), calcification (CA), lipid-rich necrotic core (LRNC), and loose-matrix (LM). The MATCH sequence was optimized by computer simulations and testing on four healthy volunteers and then evaluated in a pilot study of six patients with carotid plaque, using the conventional multi-contrast protocol as a reference. Results On MATCH images, the major plaque components were easy to identify. Spatial co-registration between the three image sets with MATCH was particularly helpful for the reviewer to discern co-existent components in an image and appreciate their spatial relation. Based on Cohen’s kappa tests, moderate to excellent agreement in the image-based or artery-based component detection between the two protocols was obtained for LRNC, IPH, CA, and LM, respectively. Compared with the conventional multi-contrast protocol, the MATCH protocol yield significantly higher signal contrast ratio for IPH (3.1 ± 1.3 vs. 0.4 ± 0.3, p

Summary The aim of this study is to investigate the feasibility of extracting motion information from a single scan with one low VENC, followed by robust phase unwrapping, for characterizing both intra-ventricular flow and myocardial motion. Background Intra-ventricular blood flow and regional myocardial motion are two key components used in assessing cardiac function. Both can be quantified using phase contrast MRI, but typically require two imaging sequences to be acquired - one with a high velocity encoding value (VENC) and one with a low VENC, selected to optimize velocity sensitivity while avoiding aliasing. In an effort to obtain velocity information from both ventricular blood and myocardial motion in one acquisition, dual-VENC techniques (Buchenberg, ISMRM 2011) have been proposed and evaluated. Methods MR imaging was performed on a 3.0-T whole-body scanner (MR 750, GE Medical Systems). Phase-contrast images with through-plane velocity-encoding were acquired in the short-axis plane with a retrospectively triggered 2D fast cine phase contrast pulse sequence (segmented k-space gradient-echo; TR/TE, 7.3/4.4 ms; flip angle 15 degree, slice thickness 8 mm) with firstorder flow compensation in all dimensions to minimize artifacts from flow and motion. Three VENCs - 75, 20 and 10 cm/s - were used and the images acquired with VENC = 75 cm/s were used as a reference. The acquisition time (per VENC) was about 15 seconds, enabling

Background The conventional MRI protocol for the characterization of atherosclerotic plaques involves a series of scans that provide multiple contrast weightings for resolving highrisk plaque characteristics [1]. However, mis-registration between image sets due to the inter-scan motion often compromises evaluation accuracy and image interpretation is expertise dependent [2]. The aim of this work was to develop a 3D MRI technique that acquires multiple image sets in a single scan with distinct contrast weightings.

Background The dual bolus method is conventionally used for quantification of myocardial blood flow (MBF). The method necessitates an additional scan for each first-pass measurement, which increases total scan time and is sensitive to change in heart rates between the two scans. A single scan method to measure the arterial input function (AIF) using highly constrained back projection (HYPR) reconstruction for integrated T1 mapping was previously developed [1]. Mistriggering due to arrhythmias, changing heart rates, and poor electrocardiogram (ECG) signal may cause motion artifacts in HYPR reconstructed images because data is shared across multiple cardiac cycles. We propose using a non-ECG-triggered acquisition with cardiac motion self-triggering for integrated T1 mapping derived AIF for MBF quantification.