RASER: A new ultrafast magnetic resonance imaging method

Ryan Chamberlain, Jang Yeon Park, Curt Corum, Essa Yacoub, Kamil Ugurbil, Clifford R. Jack, Michael Garwood

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


A new MRI method is described to acquire a T2-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.

Original languageEnglish (US)
Pages (from-to)794-799
Number of pages6
JournalMagnetic Resonance in Medicine
Issue number4
StatePublished - Oct 2007


  • Chirp
  • Frequency-swept pulse
  • MRI
  • Quadratic phase profile
  • Single-shot imaging
  • Spatial encoding
  • Time-encoding

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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