NMR Microscopy Stef Van Gorden Joseph Hornak Rochester

NMR Microscopy Stef Van. Gorden 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

BACKGROUND

Energy Level Diagram n=g. B g = 42. 58 MHz/T E = hn = hg. B (Hornak 1997)

Sample with a Uniform Field N Hydrogen Molecules S Gy (Hornak 1997)

Sample with Increasing Gradient Hydrogen Molecules Gy n = g B = g x Gx (Hornak 1997)

EXPERIMENTAL

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)

Timing Diagram for the Slice Selective NMR Microscope

Variables THK = 2/(g. Gztw) Thick Slice Thin Slice (From ~1 mm to ~10 mm) (From ~. 5 mm to ~1 mm) Width of 90° pulse = 80 µs tw (180°) =160 µs Amplitude attenuation = 20 d. B Width of 90° pulse = 157 µs tw (180°) = 314 µs Amplitude attenuation = 26 d. B

Applying Gradients THK = 2/(g. Gztw) 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

In-plane Resolution 284 mm 112 mm Fishing line in capillary tubes Glass rods

In-plane Resolution 1 pixel = 23. 7 mm 45 mm -- 112 mm object --- image

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 z y y x y One or more rotations x x y y Less than one rotation

Cone Phantom Design Illustration of Cone Phantom

Cone Phantom Images with slice thickness of 1 mm and. 5 mm respectively. . 711 mm

Analyzing Wedge Images. 55 mm 4° 4. 25 mm Portion of Sample Tube (profile of middle)

APPLICATIONS

Celery Images Thick slice Thinner slice Day 1: Images Thinnest slice Two Weeks Later

House Fly Image

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

The Next Step. . . • Slice Selection Locator • SNR improvements • Further In-plane Resolution Evaluation y x Slice Selection Locator