Hao Sun1, Jeffrey A Fessler1,2, Douglas C Noll2, Jon-Fredrik Nielsen3. 1. Departments of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, USA. 2. Departments of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA. 3. Departments of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA. jfnielse@umich.edu.
Abstract
PURPOSE: Develop a method for rapid three-dimensional inner-volume (IV), or reduced field-of-view, steady-state imaging. METHODS: Tailored radiofrequency pulses for exciting a three-dimensional IV were designed using a recently proposed algorithm and used in three different sequences: spoiled gradient echo, balanced steady-state free precession, and "small-tip fast recovery" (STFR) which uses a "tip-up" RF pulse after the readout to fast recover spins to the longitudinal axis. The inner- and outer-volume (OV) steady-state signals were analyzed. To demonstrate the potential utility of the proposed method, segmented stack-of-spirals reduced field-of-view images in a volunteer were acquired. RESULTS: For a given three-dimensional IV excitation pulse, STFR can achieve higher IV/OV signal ratio compared with spoiled gradient echo and balanced steady-state free precession. For spoiled gradient echo and balanced steady-state free precession, this ratio is significantly lower than that produced by a single IV excitation. For STFR, this ratio exceeds that produced by a single IV excitation, due to partial OV saturation produced by the nonspatially selective tip-up pulse. Reduced FOV STFR stack-of-spirals imaging with 2-fold under-sampling in both x-y and z is demonstrated. CONCLUSION: STFR provides an effective mechanism for OV suppression in steady-state IV imaging. The recently proposed joint pulse design method can be used in the STFR sequence to achieve fast reduced field-of-view imaging. Magn Reson Med 76:1217-1223, 2016.
PURPOSE: Develop a method for rapid three-dimensional inner-volume (IV), or reduced field-of-view, steady-state imaging. METHODS: Tailored radiofrequency pulses for exciting a three-dimensional IV were designed using a recently proposed algorithm and used in three different sequences: spoiled gradient echo, balanced steady-state free precession, and "small-tip fast recovery" (STFR) which uses a "tip-up" RF pulse after the readout to fast recover spins to the longitudinal axis. The inner- and outer-volume (OV) steady-state signals were analyzed. To demonstrate the potential utility of the proposed method, segmented stack-of-spirals reduced field-of-view images in a volunteer were acquired. RESULTS: For a given three-dimensional IV excitation pulse, STFR can achieve higher IV/OV signal ratio compared with spoiled gradient echo and balanced steady-state free precession. For spoiled gradient echo and balanced steady-state free precession, this ratio is significantly lower than that produced by a single IV excitation. For STFR, this ratio exceeds that produced by a single IV excitation, due to partial OV saturation produced by the nonspatially selective tip-up pulse. Reduced FOV STFR stack-of-spirals imaging with 2-fold under-sampling in both x-y and z is demonstrated. CONCLUSION: STFR provides an effective mechanism for OV suppression in steady-state IV imaging. The recently proposed joint pulse design method can be used in the STFR sequence to achieve fast reduced field-of-view imaging. Magn Reson Med 76:1217-1223, 2016.
Authors: Johannes T Schneider; Raffi Kalayciyan; Martin Haas; Sarah R Herrmann; Wolfgang Ruhm; Jürgen Hennig; Peter Ullmann Journal: Magn Reson Med Date: 2012-06-21 Impact factor: 4.668