Magnetic resonance imaging

Abstract

Methods for imaging the distribution of a marker compound in a sample using magnetic resonance imaging.

What is claimed is:  
     
         1 . A method for imaging the distribution of n-acetylaspartic acid (NAA) in mammalian neuronal tissue, said method comprising: 
 a) exciting said neuronal tissue to generate magnetic resonance signals, including signals corresponding to NAA; and    b) suppressing non-NAA magnetic resonance signals by a combination of band selective inversion with gradient dephasing, and chemical shift selective pre-excitation and dephasing.    
     
     
         2 . A method of    claim 1   , wherein said suppressing step (b) suppresses magnetic resonances down field from 2.5 ppm.  
     
     
         3 . A method of    claim 2   , wherein said chemical shift selective pre-excitation includes an excitation bandwidth of about 1.8 ppm to 2.5 ppm, said bandwidth including the water resonance.  
     
     
         4 . A method of    claim 2   , wherein said band selective inversion includes an excitation bandwidth of about 1.8 ppm to 2.5 ppm, and said dephasing produces a suppression band which includes the water resonance at about 4.7 ppm, the choline resonance at about 3.2 ppm, and the phosphocreatine resonance at about 3.0 ppm.  
     
     
         5 . A method of    claim 1   , further comprising, after the suppressing step (b), the step (c) of encoding the NAA signal with readout and phase encode gradients.  
     
     
         6 . A method of    claim 5   , further comprising, after the encoding step (c), the step (d) of reconstructing the image using two-dimensional Fourier transformation to obtain a NAA weighted image.  
     
     
         7 . A method of    claim 5   , wherein the encoding step (c) has a minimum imaging time of 96 seconds for a spatial encoding matrix of at least 256×64.  
     
     
         8 . A method of    claim 5   , wherein the encoding step (c) has a minimum imaging time of between 30 and 260 seconds for a spatial encoding matrix of 256×256.  
     
     
         9 . A method of    claim 1   , wherein said exciting step includes slice selective spin-echo excitation.  
     
     
         10 . A method of    claim 1   , wherein said exciting step (a) includes volume selective double spin-echo excitation.  
     
     
         11 . A method of    claim 10   , wherein said volume selective double spin-echo excitation includes orthogonal slice selection pulses in a double spin echo configuration (90°-180°-180°).  
     
     
         12 . A method of    claim 11   , wherein said volume selective double spin-echo excitation includes a STEAM localization configuration (90°-90°-90°).  
     
     
         13 . A method for imaging the distribution of a marker compound selected from n-acetyl aspartic acid, citrate, choline, phosphocreatine, and lactate in mammalian tissue, said method comprising: 
 i) exciting said tissue to generate magnetic resonance signals, including signals corresponding to said marker compound,    ii) suppressing non-marker compound magnetic resonance signals using band selective inversion with gradient dephasing and chemical shift selective pre-excitation, and    iii) encoding the remaining marker compound signal using conventional readout and phase encoding gradients.    
     
     
         14 . A method of    claim 13   , wherein said tissue is prostate tissue and said marker is citrate.  
     
     
         15 . A method of    claim 13   , wherein said marker is lactate, choline, or phosphocreatine.  
     
     
         16 . A method of    claim 13   , wherein said tissue is neuronal tissue and said marker is n-acetyl aspartic acid, choline, or phosphocreatine.