NMR Microscopy

1
NMR Microscopy

• Stef VanGorden
• Joseph Hornak
• Rochester Institute of Technology

2
Objective

• The main goal of this research was to create a
  NMR microscope capable of producing a 1 mm thick,
  approximately 112 micron in-plane resolution
  tomographic images.
• Bruker 300 DRX Spectrometer

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Overview of my Presentation

• Background
• Experimental
• Applications
• Conclusions

4
BACKGROUND
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Energy Level Diagram

• n g B
• g 42.58 MHz/T

(Hornak 1997)
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Sample with a Uniform Field
N
Hydrogen Molecules
S
(Hornak 1997)
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Sample with Increasing Gradient
Hydrogen Molecules
n g B g x Gx
(Hornak 1997)
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EXPERIMENTAL
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Starting Point

• Reproduction of previous 1-D and 2-D imaging
  results.
• Slice Selective Sequence Evaluation

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Slice Selective Sequence
Gz
Gy
Gx
Slice Selective Case (tomographic slice)
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Timing Diagram for the Slice Selective NMR
Microscope
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Variables
THK 2/(gGztw)
Thick Slice (From 1mm to 10 mm) Width of 90
pulse 80 µs tw (180) 160 µs Amplitude
attenuation 20 dB
Thin Slice (From .5 mm to 1 mm) Width of 90
pulse 157 µs tw (180) 314 µs Amplitude
attenuation 26 dB
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Applying Gradients
THK 2/(gGztw)
100 50 G/cm Maximum 10 5 G/cm gt 6 mm 60
30 G/cm gt 1 mm
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Feature Documentation
In-plane Resolution Phantoms Slice Thickness
Phantoms
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In-plane Resolution
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In-plane Resolution
284 mm
112 mm
Fishing line in capillary tubes
Glass rods
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In-plane Resolution
1 pixel 23.7 mm

• 45 mm -- 112 mm
• object --- image

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Slice Thickness Phantom
Screw phantom in sample tube
Signal from the screw phantom.
THK (f/360) (1/32 in/threads)(25.4 mm/in) THK
.8 mm for an angle of 360
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Nylon Screw Phantom Images
x
x
y
y
z
y
One or more rotations
x
x
y
y
Less than one rotation
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Cone Phantom Design
Illustration of Cone Phantom
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Cone Phantom Images
Images with slice thickness of 1mm and .5 mm
respectively.
.711 mm
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Analyzing Wedge Images
.55mm
4
4.25mm
Portion of Sample Tube (profile of middle)
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APPLICATIONS
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Celery Images
Thick slice
Thinner slice
Thinnest slice
Day 1 Images
Two Weeks Later
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House Fly Image
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Conclusion

• Moved practical NMR microscopy at RIT closer to
  reality.
• Current Capabilities slice thickness .5
  mm in-plane resolution 100 microns

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The Next Step ...

• Slice Selection Locator
• SNR improvements
• Further In-plane Resolution Evaluation

Slice Selection Locator