Method for preparation of highly polarized nuclear spins containing samples and uses thereof for nmr and mri

Abstract

A method for the preparation of a highly polarized nuclear spins containing sample of an organic or inorganic material, containing H or OH groups or adsorbed water molecules. Such highly polarized nuclear spins containing samples can be subjected to nuclear magnetic resonance (NMR) measurement and/or can be thawed and immediately administered to an individual undergoing a magnetic resonance imaging (MRI) scan. The method is based on generating unstable radicals on the surface of the sample in the presence of ionized environment followed by cooling the sample to cryogenic temperatures. A device for carrying out a particular step of said method is also disclosed.

What is claimed is: 
     
         1 . A method for the preparation of a sample comprising highly polarized nuclear spins, said method comprising:
 (i) providing a sample comprising an organic or inorganic material, containing H or OH groups or adsorbed water molecules, in the form of a powdery solid, in a sealed vessel;   (ii) generating unstable radicals in said sample by subjecting said sample to ionizing radiation with an energy not less than 25 eV, wherein said unstable radicals are fixed to the solid and thus do not decay for tens of minutes and up to several days under moderate conditions;   (iii) cooling said sample to a cryogenic temperature; and   (iv) performing a dynamic nuclear polarization (DNP) process on the cooled sample so as to transfer spin polarization from the electron spins to the nuclear spins, thereby obtaining said sample comprising highly polarized nuclear spins.   
     
     
         2 . The method of  claim 1 , further comprising the step of setting a controlled pressure and composition gas environment in said vessel, prior to step (ii), during step (ii), or immediately after step (ii). 
     
     
         3 . The method of  claim 2 , wherein the step of setting a controlled pressure and composition gas environment in said vessel is carried out prior to step (ii). 
     
     
         4 . The method of  claim 2 , wherein the step of setting a controlled pressure and composition gas environment in said vessel is carried out by evacuating gas from said vessel leaving a reduced pressure in said vessel. 
     
     
         5 . The method of  claim 4 , wherein the gas is evacuated by a vacuum system. 
     
     
         6 . The method of  claim 5 , wherein said vacuum system maintains a moderate vacuum level of 1×10 −6  bar to 1×10 −3  bar. 
     
     
         7 . The method of  claim 2 , wherein the step of setting a controlled pressure and composition gas environment in said vessel is carried out by introducing a suitable gas into said vessel, and creating a pressure lower than the initial pressure in said vessel. 
     
     
         8 . The method of  claim 7 , wherein the suitable gas introduced into said vessel is a noble gas, oxygen, nitrogen, methane, a halogen, CO 2 , CO, a chlorofluorocarbon (CFC), or a combination thereof. 
     
     
         9 . The method of  claim 1 , wherein said ionizing radiation is X radiation or gamma radiation. 
     
     
         10 . The method of  claim 1 , wherein said cryogenic temperature is in the range of 0° K to 120° K. 
     
     
         11 . The method of  claim 1 , wherein the DNP process performed in step (iv) involves microwave irradiation at a frequency of either the sum or difference of the electron and nuclear Larmor frequencies, under an applied magnetic field. 
     
     
         12 . The method of  claim 1 , wherein the sample provided in step (i) comprises a material having no carbonyl groups. 
     
     
         13 . The method of  claim 1 , further comprising the step of subjecting the sample obtained in step (iv) to a nuclear magnetic resonance (NMR) measurement. 
     
     
         14 . The method of  claim 13 , wherein said NMR measurement is solid state NMR, magic-angle spinning (MAS)-NMR, a liquid state NMR measurement, or an NMR measurement for the investigation of a surface. 
     
     
         15 . The method of  claim 1 , wherein the sample provided in step (i) is a magnetic resonance imaging (MRI) contrast agent or a compound participating in a metabolic pathway occurring in the body of a subject undergoing an MRI scan, and said method further comprises the step of thawing the sample obtained in step (iv) and immediately administering said sample, in liquid or gaseous form, to said subject. 
     
     
         16 . The method of  claim 15 , wherein said MRI scan is metabolic MRI or functional MRI.