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NMR Microscopy. Stef VanGorden Joseph Hornak Rochester Institute of Technology. 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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NMR Microscopy Stef VanGorden Joseph Hornak Rochester Institute of Technology
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
Overview of my Presentation • Background • Experimental • Applications • Conclusions
n = g B g = 42.58 MHz/T E = hn = hgB Energy Level Diagram (Hornak 1997)
Gy Sample with a Uniform Field N HydrogenMolecules S (Hornak 1997)
Gy Sample with Increasing Gradient HydrogenMolecules n = g B = g x Gx (Hornak 1997)
Starting Point • Reproduction of previous 1-D and 2-D imaging results. • Slice Selective Sequence Evaluation
Slice Selective Sequence Gz Gy Gx Slice Selective Case (tomographic slice)
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
Applying Gradients THK = 2/(gGztw) 100% =50 G/cm Maximum 10% = 5 G/cm => 6 mm 60% = 30 G/cm => 1 mm
Feature Documentation In-plane Resolution Phantoms Slice Thickness Phantoms
In-plane Resolution 284 mm 112 mm Fishing line in capillarytubes Glass rods
In-plane Resolution 45 mm -- 112 mm object --- image 1 pixel = 23.7 mm
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°
Nylon Screw Phantom Images x x y y z y One or more rotations x x y y Less than one rotation
Cone Phantom Design Illustration of Cone Phantom
Cone Phantom Images Images with slice thickness of 1mm and .5 mm respectively. .711 mm
Analyzing Wedge Images .55mm 4° 4.25mm Portion of Sample Tube (profile of middle)
Celery Images Thick slice Thinner slice Thinnest slice Day 1: Images Two Weeks Later
Conclusion • Moved practical NMR microscopy at RIT closer to reality. • Current Capabilities slice thickness ~.5 mm in-plane resolution ~ 100 microns
y x The Next Step ... • Slice Selection Locator • SNR improvements • Further In-plane Resolution Evaluation Slice Selection Locator