Contrast-enhanced specific absorption rate-efficient 3D cardiac cine with respiratory-triggered radiofrequency gating.

Purpose: To investigate the use of radiofrequency (RF) gating in conjunction with a paramagnetic contrast agent to reduce the specific absorption rate (SAR) and increase the blood-myocardium contrast in balanced steady-state free precession (bSSFP) 3D cardiac cine.

Materials And Methods: RF gating was implemented by synchronizing the RF-excitation with an external respiratory sensor (bellows), which could additionally be used for respiratory gating. For reference, respiratory-gated 3D cine images were acquired without RF gating.

Accelerated contrast-enhanced whole-heart coronary MRI using low-dimensional-structure self-learning and thresholding.

We sought to evaluate the efficacy of prospective random undersampling and low-dimensional-structure self-learning and thresholding reconstruction for highly accelerated contrast-enhanced whole-heart coronary MRI. A prospective random undersampling scheme was implemented using phase ordering to minimize artifacts due to gradient switching and was compared to a randomly undersampled acquisition with no profile ordering. This profile-ordering technique was then used to acquire contrast-enhanced whole-heart coronary MRI in 10 healthy subjects with 4-fold acceleration.

Free-breathing cardiac MR with a fixed navigator efficiency using adaptive gating window size.

A respiratory navigator with a fixed acceptance gating window is commonly used to reduce respiratory motion artifacts in cardiac MR. This approach prolongs the scan time and occasionally yields an incomplete dataset due to respiratory drifts. To address this issue, we propose an adaptive gating window approach in which the size and position of the gating window are changed adaptively during the acquisition based on the individual's breathing pattern.

Low-dimensional-structure self-learning and thresholding: regularization beyond compressed sensing for MRI reconstruction.

An improved image reconstruction method from undersampled k-space data, low-dimensional-structure self-learning and thresholding (LOST), which utilizes the structure from the underlying image is presented. A low-resolution image from the fully sampled k-space center is reconstructed to learn image patches of similar anatomical characteristics. These patches are arranged into "similarity clusters," which are subsequently processed for dealiasing and artifact removal, using underlying low-dimensional properties.

Noncontrast SSFP pulmonary vein magnetic resonance angiography: impact of off-resonance and flow.

Purpose: To investigate pulmonary vein (PV) off-resonance and blood flow as causes of signal void artifacts in noncontrast steady-state-free-precession (SSFP) PV magnetic resonance angiography (MRA).

Materials And Methods: PV blood off-resonance was measured on 11 healthy adult subjects and 10 atrial fibrillation (AF) patients. Noncontrast PV MRA was performed using a 3D slab-selective SSFP sequence at 1.

Non-contrast-enhanced pulmonary vein MRI with a spatially selective slab inversion preparation sequence.

We propose a non-contrast-enhanced, three-dimensional, free-breathing, electrocardiogram-gated, gradient recalled echo sequence with a slab-selective inversion for pulmonary vein (PV) MRI. A sagittal inversion slab was applied prior to data acquisition to suppress structures adjacent to the left atrium (LA) and PVs, thereby improving the conspicuity of the PV and LA. Compared with other MR angiography methods using an inversion pulse, the proposed method does not require signal subtraction and the inversion slab is not parallel to the imaging slab.

Coronary MR imaging: effect of timing and dose of isosorbide dinitrate administration.

Purpose: To quantify the effect of sublingual isosorbide dinitrate (ISDN) administration on coronary magnetic resonance (MR) imaging.

Materials And Methods: Written informed consent was obtained from all participants, and the HIPAA-compliant protocol was approved by the Institutional Review Board. Coronary MR imaging was performed at 1.