Rapid inner-volume imaging in the steady-state with 3D selective excitation and small-tip fast recovery imaging.
Develop a method for rapid three-dimensional inner-volume (IV), or reduced field-of-view, steady-state imaging.



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.



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.



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. © 2015 Wiley Periodicals, Inc.
Departments of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, USA.
Hao
H
Sun
Departments of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, USA.|Departments of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
Jeffrey A
JA
Fessler
Departments of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
Douglas C
DC
Noll
Departments of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA. jfnielse@umich.edu.
Jon-Fredrik
JF
Nielsen
D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
inner-volume imaging; multidimensional excitation; reduced FOV imaging; spatially tailored excitation; steady-state MRI