title: Improved receiver arrays and optimized parallel imaging accelerations applied to time-resolved 3D fluoroscopically tracked peripheral runoff CE-MRA.
abstract: OBJECTIVE
  Three-station stepping-table time-resolved 3D contrast-enhanced magnetic resonance angiography has conflicting demands in the need to limit acquisition time in proximal stations to match the speed of the advancing contrast bolus and in the distal-most station to avoid venous contamination while still providing clinically useful spatial resolution. This work describes improved receiver coil arrays which address this issue by allowing increased acceleration factors, providing increased spatial resolution per unit time.
  
  
  METHODS
  Receiver coil arrays were constructed for each station (pelvis, thigh, calf) and then integrated into a 48-element array for three-station peripheral CE-MRA. Coil element sizes and array configurations for these three stations were designed to improve SENSE-type parallel imaging taking advantage of an increase in coil count for all stations versus the previous 32 channel capability. At each station either acceleration apportionment or optimal CAIPIRINHA selection was used to choose the optimum acceleration parameters for each subject. Results were evaluated in both single- and multi-station studies.
  
  
  RESULTS
  Single-station studies showed that SENSE acceleration in the thigh station could be readily increased from R=8 to R=10, allowing reduction of the frame time from 2.5 to 2.1 s to better image the typically rapidly advancing bolus at this station. Similarly, the improved coil array for the calf station permitted acceleration increase from R=8 to R=12, providing a 4.0 vs. 5.2 s frame time. Results in three-station studies suggest an improved ability to track the contrast bolus in peripheral CE-MRA.
  
  
  CONCLUSIONS
  Modified receiver coil arrays and individualized parameter optimization have been used to provide improved acceleration at all stations in multi-station peripheral CE-MRA and provide high spatial resolution with frame times as short as 2.1 s.
authors.affiliation: Mayo Clinic MR Laboratory, 200 First Street Southwest, Rochester, Minnesota, 55905. Electronic address: weavers.paul@mayo.edu.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Weavers
authors.affiliation: Mayo Clinic MR Laboratory, 200 First Street Southwest, Rochester, Minnesota, 55905.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Borisch
authors.affiliation: Mayo Clinic MR Laboratory, 200 First Street Southwest, Rochester, Minnesota, 55905.
authors.forename: Tom C
authors.initials: TC
authors.lastname: Hulshizer
authors.affiliation: Mayo Clinic MR Laboratory, 200 First Street Southwest, Rochester, Minnesota, 55905.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Rossman
authors.affiliation: Department of Radiology, 200 First Street Southwest, Rochester, Minnesota, 55905.
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Young
authors.affiliation: University of Minnesota, 1200 Washington Ave S, Minneapolis, Minnesota 55415-1227.
authors.forename: Casey P
authors.initials: CP
authors.lastname: Johnson
authors.affiliation: University of Minnesota, 1200 Washington Ave S, Minneapolis, Minnesota 55415-1227.
authors.forename: Jessica
authors.initials: J
authors.lastname: McKay
authors.affiliation: University of Minnesota, 1200 Washington Ave S, Minneapolis, Minnesota 55415-1227.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Cline
authors.affiliation: Mayo Clinic MR Laboratory, 200 First Street Southwest, Rochester, Minnesota, 55905.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Riederer
mesh_terms: D000054:Acceleration; D000328:Adult; D000792:Angiography / Q000295:instrumentation*; D003287:Contrast Media / Q000737:chemistry; D004867:Equipment Design; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D009038:Motion; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging; D010388:Pelvis / Q000000981:diagnostic imaging; D059629:Signal-To-Noise Ratio; D013848:Thigh / Q000000981:diagnostic imaging; D055815:Young Adult
chemical_list: D003287:Contrast Media
keywords: Acceleration apportionment; CAIPIRINHA; CEMRA; Fluoroscopic tracking; Parallel imaging; Receiver coils