IVUS-based CFD

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Project 2 Part 1 Technology Development for MR
Assessment of Small Animal PhysiologyBrian
Rutt, PhD
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MR Gradient Coil Insert Design and
ConstructionAndrew Alejski, PhDCarl
Gazdzinski, BSc Yuteng Chen, MSc
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300 mT/m 3-layer rabbit coil (Rcoil)
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Micro-Imaging
7T, 3D Spin Echo 100 micron isotropic 7 hour scan
1.5T, 3D FIESTA 100 micron in-plane 200 micron
slices 30 minute scan
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Next Generation Insert Coil (Scoil)

• 18 cm inner diameter
• Designed specifically for ultra-high-performance
  mouse, rat, rabbit imaging using GE Signa Lx and
  EXCITE at 1.5T and 3T
• Gmax 500 mT/m, SlewRate 2400 T/m/s
• Completed manufacturing of three identical Scoil
  prototypes
• 1) GE-ASLW / Stanford Research Institute
• 2) GE-GRC / Albany Medical Center
• 3) Robarts

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Installation and Early Results from GE-ASLW /
SRIYuteng Chen, MScElfar Adalsteinsson,
PhDDolf Pfefferbaum, MD
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• Sunday
• Feb. 22 2004
• Cable cutting crimping

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Monday Feb. 23 2004 Twin switch installation
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Monday Feb. 23 2004 Twin filter installation
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• Tuesday Feb. 24 2004 Magnet room custom cable
  installation

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Wednesday Feb. 25 2004 Insert coil calibration
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Completed / Installed Scoil (3T _at_ GE-ASLW)
Clinical Insert Peak gradient 40 mT/m 500
mT/m Slew rate 150 T/m/s 2000 T/m/s Resolution 0.8
mm 50-100 microns
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Thursday Feb. 26 2004 First imaging by Dr.
Pfefferbaum
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Thiamine-deficiency induced lesion in rat thalamus
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Thermal Engineering of Gradient Insert
CoilsYuteng Chen, MSc
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Table 2 3D FIESTA heating experiment Table 2 3D FIESTA heating experiment Table 2 3D FIESTA heating experiment Table 2 3D FIESTA heating experiment Table 2 3D FIESTA heating experiment Table 2 3D FIESTA heating experiment
Read Axis IRMS (A) Power (W) Max. Temperature (oC) Max. Temperature (oC) RMS Error (oC)
Read Axis IRMS (A) Power (W) Estimate Actual RMS Error (oC)
X 68.6 9409 96 91 4.0
Y 57.5 6626 80 79 1.5
Z 69.8 9738 101 101 2.1
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Zigzap cooling line (copper tube) design
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Novel Design Concepts for Gradient CoilsCarl
Gazdzinski, BSc
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Concept The Harmonic Gradient Coil

• A multilayered gradient coil with each layer
  contributing a spatial harmonic of field
• Drive layers in variable proportions to obtain
  variable resulting fields/DSVs
• Amounts to a Fourier Series approximation of the
  desired field

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Continuously Variable DSVs
DSV 17cm G 80 mT/m
DSV 33cm G 39 mT/m
DSV 48cm G 29 mT/m
Coil Specs ID 40cm Inductance 300 ?H/layer Max
Current 300 Amps Unshielded
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Conclusions To Date

• High performance insertable gradient coils
  feasible on clinical 1.5T and 3T GE scanners
• 10 minute, simple switch-over
• Performance increase 10 - 20 fold over best
  whole-body gradients
• Spatial resolution lt 100µm isotropic
• Advanced clinical pulse sequences (eg. 3DFIESTA,
  FSE, DTI) immediately available
• Advanced hardware (eg. 8-16 fast receivers)
  immediately available