Espectroscopia multivoxel com tempo de eco curto: a raz？o colina/N-acetil-aspartato e a gradua？？o dos astrocitomas cerebrais

the choline/n-acetyl-aspartate (cho/naa) ratio, obtained by the multivoxel spectroscopy with short echo time (te), was evaluated, in the histological grading of the brain astrocytomas (grades i, ii and iii-iv) in comparison with the normal cerebral parenchyma. a significant increase (p<0.05) in the average ratios of cho/naa was observed in the three astrocytoma groups studied in relation to normal tissue, having a tendency to increase with the increase in grading, without any statistic significance, which corresponded to: 0.53±0.24 in the control group, 1.19±0.49 in grade i, 1.58±0.65 in grade ii and 5.13±8.12 in the high grade group (grades iii-iv), with variation in the values encountered. there was an increase in the cho/naa ratio in 4/5 (80%) in grade i, 5/6 (83%) in grade ii and 10/20 (50%) in grades iii and iv. we conclude that multivoxel spectroscopy with short te can be used in discriminating between normal parenchyma and neoplasm tissue. however, not all neoplasm tissue studied presented an increase in cho/naa, especially in the group with higher grade of malignancy.