title: A pulse sequence for rapid in vivo spin-locked MRI.
abstract: OBJECTIVE
  To develop a novel pulse sequence called spin-locked echo planar imaging (EPI), or (SLEPI), to perform rapid T1rho-weighted MRI.
  
  
  METHODS
  SLEPI images were used to calculate T1rho maps in two healthy volunteers imaged on a 1.5-T Sonata Siemens MRI scanner. The head and extremity coils were used for imaging the brain and blood in the popliteal artery, respectively.
  
  
  RESULTS
  SLEPI-measured T1rho was 83 msec and 103 msec in white (WM) and gray matter (GM), respectively, 584 msec in cerebrospinal fluid (CSF), and was similar to values obtained with the less time-efficient sequence based on a turbo spin-echo readout. T1rho was 183 msec in arterial blood at a spin-lock (SL) amplitude of 500 Hz.
  
  
  CONCLUSIONS
  We demonstrate the feasibility of the SLEPI pulse sequence to perform rapid T1rho MRI. The sequence produced images of higher quality than a gradient-echo EPI sequence for the same contrast evolution times. We also discuss applications and limitations of the pulse sequence.
authors.affiliation: MMRRCC, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA. ari@mail.mmrrcc.upenn.edu
authors.forename: Arijitt
authors.initials: A
authors.lastname: Borthakur
authors.forename: Justin
authors.initials: J
authors.lastname: Hulvershorn
authors.forename: Eugene
authors.initials: E
authors.lastname: Gualtieri
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wheaton
authors.forename: Sridhar
authors.initials: S
authors.lastname: Charagundla
authors.forename: Mark A
authors.initials: MA
authors.lastname: Elliott
authors.forename: Ravinder
authors.initials: R
authors.lastname: Reddy
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D011150:Popliteal Artery / Q000033:anatomy & histology*