Hypertrophic obstructive cardiomyopathy-left ventricular outflow tract shapes and their hemodynamic influences applying CMR.

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic cardiac disorders and is characterized by different phenotypes of left ventricular hypertrophy with and without obstruction. The effects of left ventricular outflow tract (LVOT) obstruction based on different anatomies may be hemodynamically relevant and influence therapeutic decision making. Cardiovascular magnetic resonance (CMR) provides anatomical information.

Autocalibrated cardiac tissue phase mapping with multiband imaging and k-t acceleration.

Purpose: To develop an autocalibrated multiband (MB) CAIPIRINHA acquisition scheme with in-plane k-t acceleration enabling multislice three-directional tissue phase mapping in one breath-hold.

Methods: A k-t undersampling scheme was integrated into a time-resolved electrocardiographic-triggered autocalibrated MB gradient-echo sequence. The sequence was used to acquire data on 4 healthy volunteers with MB factors of two (MB2) and three (MB3), which were reconstructed using a joint reconstruction algorithm that tackles both k-t and MB acceleration.

4D flow imaging with UNFOLD in a reduced FOV.

Purpose: Two-dimensional selective excitation (2DRF) allows shortening 4D flow scan times by reducing the FOV, but the longer 2DRF pulse duration decreases the temporal resolution, yielding underestimated peak flow values. Multiple k-space lines per cardiac phase, n ≥ 2, are commonly applied in 4D flow MRI to shorten the inherent long scan times. We demonstrate that 2DRF 4D flow with n ≥ 2 can be easily combined with UNFOLD (UNaliasing by Fourier-encoding the Overlaps using the temporaL Dimension), a technique that allows regaining nominally the temporal resolution of the respective acquisition with n = 1, to assure peak flow quantification.

4D flow imaging with 2D-selective excitation.

Purpose: 4D flow MRI permits to quantify non-invasively time-dependent velocity vector fields, but it demands long acquisition times. 2D-selective excitation allows to accelerate the acquisition by reducing the FOV in both phase encoding directions. In this study, we investigate 2D-selective excitation with reduced FOV imaging for fast 4D flow imaging while obtaining correct velocity quantification.

Autocalibrated multiband CAIPIRINHA with through-time encoding: Proof of principle and application to cardiac tissue phase mapping.

Purpose: In conventional multiband (MB) CAIPIRINHA, additional reference scans are acquired to allow the separation of the excited slices. In this study, an acquisition-reconstruction technique that makes use of the MB data to calculate these reference data is presented. The method was integrated into a 2D time-resolved phase-contrast MR sequence used to assess velocities of the myocardium.