Design and Implementation of magnetic field gradient waveform for optimal sampling of Magnetic resonance imaging data

Abstract

Magnetic Resonance Imaging (MRI) is a well-established imaging modality, which provides soft tissue contrast at high resolution. It has therefore been extensively used in the diagnosis and/or prognosis of numerous pathological conditions without using harmful radiations. However, MR acquisition takes a long time as compared to other imaging modalities such as Computed Tomography (CT). To overcome this limitation, efforts have been made to use non-Cartesian based acquisition such as spiral, radial, rosette and so on to reduce the scan time. The goal of thisresearch work isto design and implement magnetic field gradient waveforms for optimal sampling of magnetic resonance imaging data. Developing new pulse sequencesand testing on the scanner requiresa lot of time and effort. This is the major challenge faced by the researchers as they are required to be familiar with vendor-specific programming languages. Pulseq-GPI is an open source framework which has been developed to provide a single platform for rapid prototyping of pulse sequences by integrating Pulseq with Graphical Programming Interface (GPI). Pulseq framework is used to design the pulse sequences and is written in MATLAB. GPI is written in Python and allows prototyping of MRI. The work demonstrates the use of Pulseq-GPI for three pulse sequences - gradient echo, Spin Echo (SE), and SE- Echo Planar Imaging (EPI). Pulseq-GPI was demonstrated on in vitro phantom and in vivo brain data. Rapid prOtotyping of 2D non-Cartesian K-space trajEcTories (ROCKET) aims to promote rapid development and testing of new MR methods for non-Cartesian based acquisition starting from pulse sequence design to image analysis. This was achieved by using Pulseq for pulse sequence design and GPI for image reconstruction and analysis. ROCKET was demonstrated on two 2D non-Cartesian k-space trajectories Free Induction Decay (FID) based radial and variable density spiral.