MRI OF THE NORMAL BRAIN FROM EARLY-CHILDHOOD TO MIDDLE-AGE .2. AGE-DEPENDENCE OF SIGNAL INTENSITY CHANGES ON T2-WEIGHTED IMAGES

We examined 66 healthy volunteers aged 4 to 50 years by magnetic reson ance imaging (MRI) and the signal intensity was measured on T2-weighte d images in numerous sites and correlated with age and sex. Using dist illed water and cerebrospinal fluid (CSF) as references on each slice, we calculated the signal intensities of the brain structures. Calcula ted ratios between structures did not change with age, except for thos e of the globus pallidus and thalamus, in which the signal intensities decreased more rapidly. The signal intensities of other brain structu res changed equally but this could not be discerned visually and quant itative measurements were required. The signal intensities in the whit e and deep grey matter decreased rapidly in the first decade and then gradually to reach a plateau after the age of 18 years. Maturation of the brain thus seems to continue until near the end of the second deca de of life. No sex differences were found. Quantitative analysis requi res intensity references. The CSF in the tips of the frontal horns see ms to be as reliable as an external fluid reference for intensity, and can be used in routine examinations provided the frontal horns are la rge enough to avoid partial volume effect.