Multi-contrast imaging: a Novel Pulse Sequence for Simultaneous Acquisition of Proton Density, T1-Weighted, T2-Weighted and FLAIR Images

Abstract

Magnetic Resonance Imaging (MRI) is a widely used noninvasive clinical imaging modality. Unlike other medical imaging tools, such as X-rays or computed tomography (CT), the advantage of MRI is that it uses non-ionizing radiation. In addition, MRI can provide images with multiple contrasts by using different pulse sequences and protocols. However, image acquisition speed is known to be a major drawback of MRI and is a limitation in various MRI applications. To address speed limitations in acquisition of multiple contrasts images, we developed a new pulse sequence called Multi-contrast sequence that enables simultaneous acquisition of the four contrasts images, proton density (PD), T1-weighted, T2-weighted and FLAIR images, with a single scan in less than 6 min. Multi-contrast sequence is a combination of fast spin-echo (FSE) based imaging pulse sequences with inversion recovery (IR) acquisition and non- IR acquisition. From Multi-contrast sequence, two contrasts of fluid-attenuated images, PD images, and T2-weighted images are acquired at the same time and T1-weighted images are synthesized from the obtained images. Compared to conventional imaging sequences, the scan time is reduced by 50 %. Additionally, the new method generates both T1 maps and T2 maps that can be used for quantitative imaging. To demonstrate the effectiveness of our approach, phantom and in vivo experiments are performed. Then signal to noise ratio (SNR) of images from the proposed sequence and from the conventional sequences are compared. The method may have potentials as a rapid evaluation tool for clinical scans.