A method for imaging and spectroscopy using γ-rays and magnetic resonance.
Magnetic resonance imaging (MRI) provides fine spatial resolution, spectral sensitivity and a rich variety of contrast mechanisms for diagnostic medical applications. Nuclear imaging using γ-ray cameras offers the benefits of using small quantities of radioactive tracers that seek specific targets of interest within the body. Here we describe an imaging and spectroscopic modality that combines favourable aspects of both approaches. Spatial information is encoded into the spin orientations of tiny amounts of a polarized radioactive tracer using pulses of both radio-frequency electromagnetic radiation and magnetic-field gradients, as in MRI. However, rather than detecting weak radio-frequency signals, imaging information is obtained through the detection of γ-rays. A single γ-ray detector can be used to acquire an image; no γ-ray camera is needed. We demonstrate the feasibility of our technique by producing images and spectra from a glass cell containing only about 4 × 10(13) atoms (about 1 millicurie) of the metastable isomer (131m)Xe that were polarized using the laser technique of spin-exchange optical pumping. If the cell had instead been filled with water and imaged using conventional MRI, then it would have contained more than 10(24) water molecules. The high sensitivity of our modality expands the breadth of applications of magnetic resonance, and could lead to a new class of radioactive tracers.
Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA.
Yuan
Y
Zheng
Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia 22908, USA.
G Wilson
GW
Miller
Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA.
William A
WA
Tobias
Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA.|Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, Virginia 22908, USA.
Gordon D
GD
Cates
D005720:Gamma Rays; D008279:Magnetic Resonance Imaging; D057054:Molecular Imaging / Q000379:methods*; D011849:Radioactive Tracers; D013057:Spectrum Analysis / Q000379:methods*; D014979:Xenon Isotopes
D011849:Radioactive Tracers; D014979:Xenon Isotopes
Proc Natl Acad Sci U S A. 2001 Sep 11;98(19):10654-7
11535830
ACS Nano. 2013 Feb 26;7(2):1609-17
23350651
Nature. 1994 Jul 21;370(6486):199-201
8028666
Nature. 1948 May 22;161(4099):807-9
18938975
J Magn Reson. 2011 Dec;213(1):187-91
21974998
J Nucl Med. 1990 Apr;31(4):489-92
2324824
Phys Rev A. 1990 Sep 1;42(5):2774-2784
9904348
Magn Reson Med. 1999 Dec;42(6):1137-45
10571936
Clin Orthop Relat Res. 1989 Jul;(244):3-6
2663289
Magn Reson Med. 1990 Nov;16(2):192-225
2266841
Phys Rev Lett. 1985 Jan 21;54(3):174-177
10031432
Proc Natl Acad Sci U S A. 2005 Dec 20;102(51):18275-9
16344474
Phys Rev Lett. 1987 Sep 28;59(13):1480-1483
10035245
J Nucl Med. 1986 Sep;27(9):1436-41
3746445
J Magn Reson. 2014 Oct 17;249C:108-117
25462954
J Magn Reson Imaging. 2013 Feb;37(2):313-31
23355432
Phys Rev Lett. 1993 Feb 1;70(5):690-693
10054178