title: Externally calibrated parallel imaging for 3D multispectral imaging near metallic implants using broadband ultrashort echo time imaging.
abstract: To develop an externally calibrated parallel imaging technique for three-dimensional multispectral imaging (3D-MSI) in the presence of metallic implants.
  
  
  
  A fast, ultrashort echo time (UTE) calibration acquisition is proposed to enable externally calibrated parallel imaging techniques near metallic implants. The proposed calibration acquisition uses a broadband radiofrequency (RF) pulse to excite the off-resonance induced by the metallic implant, fully phase-encoded imaging to prevent in-plane distortions, and UTE to capture rapidly decaying signal. The performance of the externally calibrated parallel imaging reconstructions was assessed using phantoms and in vivo examples.
  
  
  
  Phantom and in vivo comparisons to self-calibrated parallel imaging acquisitions show that significant reductions in acquisition times can be achieved using externally calibrated parallel imaging with comparable image quality. Acquisition time reductions are particularly large for fully phase-encoded methods such as spectrally resolved fully phase-encoded three-dimensional (3D) fast spin-echo (SR-FPE), in which scan time reductions of up to 8 min were obtained.
  
  
  
  A fully phase-encoded acquisition with broadband excitation and UTE enabled externally calibrated parallel imaging for 3D-MSI, eliminating the need for repeated calibration regions at each frequency offset. Significant reductions in acquisition time can be achieved, particularly for fully phase-encoded methods like SR-FPE. Magn Reson Med 77:2303-2309, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Curtis N
authors.initials: CN
authors.lastname: Wiens
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.|Department of Diagnostic Imaging, St. Jude Children's St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Artz
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.|Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Hyungseok
authors.initials: H
authors.lastname: Jang
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Alan B
authors.initials: AB
authors.lastname: McMillan
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.|Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA.|Department of Biomedical Engineering, University of Wisconsin, Madison, Wisconsin, USA.|Department of Medicine, University of Wisconsin, Madison, Wisconsin, USA.|Dept. of Emergency Medicine, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Reeder
mesh_terms: D016477:Artifacts; D002138:Calibration; D007089:Image Enhancement / Q000379:methods / Q000592:standards; D007090:Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D021621:Imaging, Three-Dimensional / Q000379:methods* / Q000592:standards; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D008670:Metals; D019047:Phantoms, Imaging; D019736:Prostheses and Implants; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D008670:Metals
keywords: fully phase-encoded imaging; metallic implant; multispectral imaging; off-resonance; parallel imaging