Inverse T-2 contrast at 1.5 tesla between gray matter and white matter in the occipital lobe of normal adult human brain

T-2 of cortical gray matter is generally assumed to be longer than that of white matter. It is shown here that this is not the case in the occipital l obe, but that this effect is often obscured at lower resolution and conceal ed in standard T-2-weighted images. Using a high-resolution (1 x 1.3 x 2 mm (3)) segmented EPI Carr-Purcell-Meiboom-Gill sequence, T-2 relaxation times of the brain were measured at 1.5 T for eight healthy adult volunteers. Th e average T-2 values of cortical gray and white matter were found to be 88 +/- 2 and 84 +/- 3 msec in the frontal lobe, 84 +/- 2 and 83 +/- 3 msec in the parietal lobe, and 79 +/- 1 and 87 +/- 3 msec in the occipital lobe, re spectively. This unexpected occipital T-2 contrast between gray and white m atter is attributed to regional differences in iron concentration. (C) 2001 Wiley-Liss, Inc.