RASER: A new ultrafast magnetic resonance imaging method

✍ Scribed by Ryan Chamberlain; Jang-Yeon Park; Curt Corum; Essa Yacoub; Kamil Ugurbil; Clifford R. Jack Jr; Michael Garwood

• Book ID: 102533861
• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 359 KB
• Volume: 58
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.21396

✦ Synopsis

Abstract

A new MRI method is described to acquire a T~2~‐weighted image from a single slice in a single shot. The technique is based on rapid acquisition by sequential excitation and refocusing (RASER). RASER avoids relaxation‐related blurring because the magnetization is sequentially refocused in a manner that effectively creates a series of spin echoes with a constant echo time. RASER uses the quadratic phase produced by a frequency‐swept chirp pulse to time‐encode one dimension of the image. In another implementation the pulse can be used to excite multiple slices with phase‐encoding and frequency‐encoding in the other two dimensions. The RASER imaging sequence is presented along with single‐shot and multislice images, and is compared to conventional spin‐echo and echo‐planar imaging sequences. A theoretical and empirical analysis of the spatial resolution is presented, and factors in choosing the spatial resolution for different applications are discussed. RASER produces high‐quality single‐shot images that are expected to be advantageous for a wide range of applications. Magn Reson Med 58:794–799, 2007. © 2007 Wiley‐Liss, Inc.