Sophie Berg

Combined saturation/inversion recovery sequences for improved evaluation of scar and diffuse fibrosis in patients with arrhythmia or heart rate variability.

To develop arrhythmia‐insensitive inversion recovery sequences for improved visualization of myocardial scar and quantification of diffuse fibrosis.

Improved quantitative myocardial T2 mapping: Impact of the fitting model

To develop an improved T2 prepared (T2prep) balanced steady‐state free‐precession (bSSFP) sequence and signal relaxation curve fitting method for myocardial T2 mapping.

Free-breathing post-contrast three-dimensional T1 mapping: Volumetric assessment of myocardial T1 values

To develop a three‐dimensional (3D) free‐breathing myocardial T1 mapping sequence for assessment of left ventricle diffuse fibrosis after contrast administration.

Free-breathing combined three-dimensional phase sensitive late gadolinium enhancement and T1 mapping for myocardial tissue characterization

To develop a novel MR sequence for combined three‐dimensional (3D) phase‐sensitive (PS) late gadolinium enhancement (LGE) and T1 mapping to allow for simultaneous assessment of focal and diffuse myocardial fibrosis.

Accelerated three‐dimensional cine phase contrast imaging using randomly undersampled echo planar imaging with compressed sensing reconstruction

The aim of this study was to implement and evaluate an accelerated three‐dimensional (3D) cine phase contrast MRI sequence by combining a randomly sampled 3D k‐space acquisition sequence with an echo planar imaging (EPI) readout. An accelerated 3D cine phase contrast MRI sequence was implemented by combining EPI readout with randomly undersampled 3D k‐space data suitable for compressed sensing (CS) reconstruction. The undersampled data were then reconstructed using low‐dimensional structural self‐learning and thresholding (LOST). 3D phase contrast MRI was acquired in 11 healthy adults using an overall acceleration of 7 (EPI factor of 3 and CS rate of 3). For comparison, a single two‐dimensional (2D) cine phase contrast scan was also performed with sensitivity encoding (SENSE) rate 2 and approximately at the level of the pulmonary artery bifurcation. The stroke volume and mean velocity in both the ascending and descending aorta were measured and compared between two sequences using Bland–Altman plots. An average scan time of 3 min and 30 s, corresponding to an acceleration rate of 7, was achieved for 3D cine phase contrast scan with one direction flow encoding, voxel size of 2 × 2 × 3 mm3, foot–head coverage of 6 cm and temporal resolution of 30 ms. The mean velocity and stroke volume in both the ascending and descending aorta were statistically equivalent between the proposed 3D sequence and the standard 2D cine phase contrast sequence. The combination of EPI with a randomly undersampled 3D k‐space sampling sequence using LOST reconstruction allows a seven‐fold reduction in scan time of 3D cine phase contrast MRI without compromising blood flow quantification. Copyright

Heart-rate independent myocardial T1-mapping using combined saturation and inversion preparation pulses

Background Myocardial T1 mapping remains a challenging task due to restrictions imposed by cardiac and respiratory motion. Modified Look-Locker Inversion Recovery (MOLLI) [1] is widely used for 2D cardiac T1-mapping. In MOLLI, the spin-lattice relaxation curve is sampled several times after a single magnetization preparation. The ECG triggered imaging induces a disturbance in the relaxation curve, which varies based on the heart rate. Hence, MOLLI T1 measurements show strong correlations to the heart rate especially in pre-contrast. We developed a novel T1 mapping sequence that enables heart-rate invariant myocardial T1 mapping.

3D late gadolinium enhancement in a single prolonged breath-hold using supplemental oxygenation and hyperventilation

To evaluate the feasibility of three‐dimensional (3D) single breath‐hold late gadolinium enhancement (LGE) of the left ventricle (LV) using supplemental oxygen and hyperventilation and compressed‐sensing acceleration.

Accelerated cardiac MR stress perfusion with radial sampling after physical exercise with an MR-compatible supine bicycle ergometer

To evaluate the feasibility of accelerated cardiac MR (CMR) perfusion with radial sampling using nonlinear image reconstruction after exercise on an MR‐compatible supine bike ergometer.

Accelerated free breathing ECG triggered contrast enhanced pulmonary vein magnetic resonance angiography using compressed sensing

BackgroundTo investigate the feasibility of accelerated electrocardiogram (ECG)-triggered contrast enhanced pulmonary vein magnetic resonance angiography (CE-PV MRA) with isotropic spatial resolution using compressed sensing (CS).MethodsNineteen patients (59 ± 13 y, 11 M) referred for MR were scanned using the proposed accelerated free breathing ECG-triggered 3D CE-PV MRA sequence (FOV = 340 × 340 × 110 Mm3, spatial resolution = 1.5 × 1.5 × 1.5 Mm3, acquisition window = 140 Ms at mid diastole and CS acceleration factor = 5) and a conventional first-pass breath-hold non ECG-triggered 3D CE-PV MRA sequence. CS data were reconstructed offline using low-dimensional-structure self-learning and thresholding reconstruction (LOST) CS reconstruction. Quantitative analysis of PV sharpness and subjective qualitative analysis of overall image quality were performed using a 4-point scale (1: poor; 4: excellent).ResultsQuantitative PV sharpness was increased using the proposed approach (0.73 ± 0.09 vs. 0.51 ± 0.07 for the conventional CE-PV MRA protocol, p < 0.001). There were no significant differences in the subjective image quality scores between the techniques (3.32 ± 0.94 vs. 3.53 ± 0.77 using the proposed technique).ConclusionsCS-accelerated free-breathing ECG-triggered CE-PV MRA allows evaluation of PV anatomy with improved sharpness compared to conventional non-ECG gated first-pass CE-PV MRA. This technique may be a valuable alternative for patients in which the first pass CE-PV MRA fails due to inaccurate first pass timing or inability of the patient to perform a 20-25 seconds breath-hold.

Free-breathing cardiac MR stress perfusion with real-time slice tracking

To develop a free‐breathing cardiac MR perfusion sequence with slice tracking for use after physical exercise.