![]() NAA is one of the most abundant amino acids in the central nervous system. NAA is the largest signal in the normal adult brain spectrum, resonating at 2.01 ppm, with a small and usually unresolved contribution from N-acetylaspartylglutamate (NAAG) at 2.04 ppm ( 9, 10). The biological significance of the major compounds is discussed below. A summary of all compounds that have been detected in the human brain by proton MRS is given in Table 9.1, and a complete list of metabolite structures and their spectra can be found in ( 8). ![]() At short echo times (e.g., 35 ms or less) other compounds such as glutamate, glutamine, myo-inositol, as well as lipids and macromolecular resonances ( Fig. ![]() 9.1a), while compounds such as lactate, alanine, or others may be detectable in pathological conditions which increase their concentration ( 5– 7). At commonly used field strengths such as 1.5 or 3.0 T, only signals from choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) are observed in normal brain at long echo times (e.g., 140 or 280 ms) ( Fig. Information Content of Proton MR Spectra of the Brainīecause of its relatively low sensitivity, only small, mobile molecules which are present in millimolar quantities are generally detectable in an in vivo MR spectrum.
0 Comments
Leave a Reply. |