Dataset Information

A-f BLAST: Non-Iterative Radial k-t BLAST Reconstruction for Real-Time Imaging.

ABSTRACT: Non-Cartesian trajectories are advantageous in the collection and reconstruction of dynamic MR images. Like many other fast imaging methods, the reconstruction technique k-t broad-use linear acquisition speed-up technique (BLAST) has been extended to non-Cartesian k-t BLAST through a conjugate gradient-based approach. However, it is necessary to transform and grid the data to a Cartesian domain as part of the reconstruction, a process which can be time consuming and computationally intensive. In this paper, a new non-iterative reconstruction, a-f BLAST, is proposed to extend k-t BLAST to radial sampling. The a-f BLAST reconstruction is performed in a previously unexplored domain termed the angular frequency-temporal frequency (a-f) space and uses similar steps to Cartesian k-t BLAST. The performance of this method was demonstrated on retrospectively undersampled numerical phantoms and compared with k-t BLAST, non-Cartesian k-t BLAST, and the sliding window technique. In addition, the reconstruction was tested on retrospectively and prospectively undersampled in vivo cardiac data. The a-f BLAST is shown to have a similar reconstruction time as k-t BLAST as well as outperform k-t BLAST in terms of root-mean-square error.

SUBMITTER: Kretzler M

PROVIDER: S-EPMC6469684 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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a-f BLAST: Non-Iterative Radial k-t BLAST Reconstruction for Real-Time Imaging.

Kretzler Madison M Hamilton Jesse J Griswold Mark M Seiberlich Nicole N

IEEE transactions on medical imaging 20180927 3

Non-Cartesian trajectories are advantageous in the collection and reconstruction of dynamic MR images. Like many other fast imaging methods, the reconstruction technique k-t broad-use linear acquisition speed-up technique (BLAST) has been extended to non-Cartesian k-t BLAST through a conjugate gradient-based approach. However, it is necessary to transform and grid the data to a Cartesian domain as part of the reconstruction, a process which can be time consuming and computationally intensive. In ...[more]

PMID: 30273146

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Project description:BackgroundFunctional assessments of the heart by dynamic cardiovascular magnetic resonance (CMR) commonly rely on (i) electrocardiographic (ECG) gating yielding pseudo real-time cine representations, (ii) balanced gradient-echo sequences referred to as steady-state free precession (SSFP), and (iii) breath holding or respiratory gating. Problems may therefore be due to the need for a robust ECG signal, the occurrence of arrhythmia and beat to beat variations, technical instabilities (e.g., SSFP "banding" artefacts), and limited patient compliance and comfort. Here we describe a new approach providing true real-time CMR with image acquisition times as short as 20 to 30 ms or rates of 30 to 50 frames per second.MethodsThe approach relies on a previously developed real-time MR method, which combines a strongly undersampled radial FLASH CMR sequence with image reconstruction by regularized nonlinear inversion. While iterative reconstructions are currently performed offline due to limited computer speed, online monitoring during scanning is accomplished using gridding reconstructions with a sliding window at the same frame rate but with lower image quality.ResultsScans of healthy young subjects were performed at 3 T without ECG gating and during free breathing. The resulting images yield T1 contrast (depending on flip angle) with an opposed-phase or in-phase condition for water and fat signals (depending on echo time). They completely avoid (i) susceptibility-induced artefacts due to the very short echo times, (ii) radiofrequency power limitations due to excitations with flip angles of 10 degrees or less, and (iii) the risk of peripheral nerve stimulation due to the use of normal gradient switching modes. For a section thickness of 8 mm, real-time images offer a spatial resolution and total acquisition time of 1.5 mm at 30 ms and 2.0 mm at 22 ms, respectively.ConclusionsThough awaiting thorough clinical evaluation, this work describes a robust and flexible acquisition and reconstruction technique for real-time CMR at the ultimate limit of this technology.

Dataset Information

A-f BLAST: Non-Iterative Radial k-t BLAST Reconstruction for Real-Time Imaging.

Publications

a-f BLAST: Non-Iterative Radial k-t BLAST Reconstruction for Real-Time Imaging.

Similar Datasets

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