 The
mission of the CIA-MR is to
apply magnetic resonance technology to fundamental problems in
engineering and the physical sciences.
CIAMR HomeCIAMR PersonnelCIAMR FacilitiesMR-PET Scanner DevelopmentMagnetic LevitationMR Compatibility of Medical DevicesMR Analysis of Bioreactor Structure and FunctionIndustrial NMR ApplicationsMRI of Wood3D MRI of FoamTissue EngineeringMRI of KneesMicro NMR CoilsDepartment of RadiologyUniversity of Minnesota |
MR-PET Scanner Development CIA-MR Testing of lightguides for measuring the range of positrons in tissue equivalent material in a 5.0 Tesla NMR imaging system. Bar Graphs illustrating the effect of positron energy on FWHM and FWTM. Note that very little squeezing of positron range occurs for 22Na (Emax=0.54 MeV, Eave=0.21 MeV) as a function of Bo whereas 68Ga (Emax=1.8 MeV, Eave=0.8 MeV) shows a large effect. Bo most affects the FWTM because higher energy positron energies contribute to the FWTM. (Hammer, B.E., Christensen, N.L., "Use of Strong Magnetic Fields to Limit Positron Range in Matter," IEEE Transactions on Nuclear Science, IEEE Transactions on Nuclear Science, vol. 42, no. 4, 1371-1376, 1995.... Christensen, N.L., Hammer, B.E., Heil, B.G., Fetterly, K., "Positron Emission Tomography within a Magnetic Field Using Photomultiplier Tubes and Lightguides", Physics and Medicine in Biology, vol. 40, 691-697, 1995....Hammer, B.E., Christensen, N.L., Heil, B.G., "Use of a Magnetic Field to Increase the Spatial Resolution of Positron Emission Tomography," Medical Physics, vol. 21, no. 12, 1917 - 1920, 1994.)   To show the feasibility of obtaining PET images with sub-millimeter resolution we have constructed an MR compatable translation/rotation device. This device moves a PET-ring section inside the 5.0 T NMR magnet shown above. Four pairs of solid-state detectors oppossed to one another in the green paddles. The detectors translate in 1 mm increments to create a projection having a spatial resolution of 0.5 mm. The device then rotates 1 degree and translates to create another projection. A PET image is reconstructed from a series of projections. 
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