System and method for metabolic mr imaging of a hyperpolarized agent

Abstract

A system and method for metabolic MR imaging of a hyperpolarized agent includes exciting a single metabolic species of a hyperpolarized agent injected into a subject of interest. MR signals are acquired from the excited single metabolic species and an image is reconstructed from the acquired MR signals.

What is claimed is: 
     
         1 . An MRI apparatus comprising:
 a magnetic resonance imaging (MRI) assembly having a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images; and   a system controller coupled to the MRI assembly, the system controller configured to:
 cause the RF coil assembly to excite a single metabolic species of a hyperpolarized agent injected into a subject of interest; 
 cause the RF transceiver system to acquire MR signals from the excited single metabolic species; and 
 reconstruct an image from the acquired MR signals. 
   
     
     
         2 . The MRI apparatus of  claim 1  wherein the excitation of the single metabolic species excites the single metabolic species only. 
     
     
         3 . The MRI apparatus of  claim 1  wherein the excited single metabolic species comprises a metabolite of the hyperpolarized agent injected into the subject of interest. 
     
     
         4 . The MRI apparatus of  claim 1  wherein the system controller is further configured to repeat the excitation and the acquisition for each single metabolic species of the hyperpolarized agent. 
     
     
         5 . The MRI apparatus of  claim 1  wherein the single metabolic species comprises a single metabolic species of 13C. 
     
     
         6 . A method of hyperpolarized agent MR imaging comprising the steps of:
 injecting a hyperpolarized agent into a subject of interest;   exciting only a first metabolic species of the hyperpolarized agent;   acquiring MR signals from the excited first metabolic species; and   reconstructing an image from the acquired MR signals.   
     
     
         7 . The method of  claim 6  wherein the excitation of only the first metabolic species does not excite other metabolic species of the hyperpolarized agent. 
     
     
         8 . The method of  claim 6  wherein the excitation of the first metabolic species comprises a metabolite of the hyperpolarized agent injected into the subject of interest. 
     
     
         9 . The method of  claim 6  wherein the step of exciting comprises:
 modifying a flip angle train according to a first low angle modulation pattern; and 
 applying a pulse sequence having the modified flip angle train to the first metabolic species. 
 
     
     
         10 . The method of  claim 9  wherein the step of modifying comprises modifying the flip angle train according to a constant amplitude low angle modulation pattern having amplitudes less than 2 degrees. 
     
     
         11 . The method of  claim 9  wherein the step of modifying comprises modifying the flip angle train according to a Gaussian modulated low angle modulation pattern. 
     
     
         12 . The method of  claim 9  wherein the step of modifying comprises modifying the flip angle train according to a sinc function modulated low angle modulation pattern. 
     
     
         13 . The method of  claim 9  further comprising the steps of:
 exciting only a second metabolic species of the hyperpolarized agent; and 
 acquiring MR signals from the excited second metabolic species. 
 
     
     
         14 . The method of  claim 13  wherein the step of exciting the second metabolic species comprises:
 modifying the flip angle train according to a second low angle modulation pattern distinct from the first low angle modulation pattern; and 
 applying a pulse sequence having the modified flip angle train according to the second low angle modulation pattern to the second metabolic species. 
 
     
     
         15 . A non-transitory computer readable storage medium having stored thereon a computer program comprising instructions which when executed by a computer, causes the computer to:
 modulate a plurality of flip angle train RF pulses of a pulse sequence;   excite, with the pulse sequence, a plurality of molecules of a single hyperpolarized metabolite within an object;   acquire MR data from the plurality of molecules; and   generate an image from the MR data.   
     
     
         16 . The computer readable storage medium of  claim 15  wherein the instructions, in exciting of the plurality of molecules of the single hyperpolarized metabolite with the pulse sequence, do not excite molecules of other hyperpolarized metabolites within the object.