title: k-TE generalized autocalibrating partially parallel acquisition (GRAPPA) for accelerated multiple gradient-recalled echo (MGRE) R2* mapping in the abdomen.
abstract: Multiple gradient-recalled echo (MGRE) methods are commonly used for abdominal R(2)* mapping. Accelerated MGRE acquisitions would offer the potential to shorten requisite breathhold times and/or increase spatial resolution and coverage. In both phantom and normal volunteer studies, view-sharing (VS) methods, generalized autocalibrating partially parallel acquisition (GRAPPA) methods, and newly proposed k-echo time (k-TE) GRAPPA methods were compared for the purpose of accelerating MGRE acquisitions. Utilization of water-selective spatial spectral excitation pulses reduced artifact levels for both VS and k-TE GRAPPA approaches. VS approaches were found to be highly sensitive to off-resonance effects, particularly at increasing acceleration rates. k-TE GRAPPA significantly reduced residual artifact levels compared to GRAPPA approaches while improving the accuracy of accelerated abdominal R(2)* measurements. These initial feasibility studies demonstrate that k-TE GRAPPA is an effective method to reduce scan times during abdominal R(2)*-mapping procedures.
authors.affiliation: Department of Radiology, Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Yin
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Larson
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology*; D000465:Algorithms; D002138:Calibration; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D006801:Humans; D007089:Image Enhancement / Q000379:methods / Q000592:standards; D007090:Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity