Automated method for measurement of cerebral cortical thickness for 3-D MR images

We have developed an automated method for measurement of the cortical thickness for three-dimensional (3D) MR images An brain region was segmented by use of a multiple gray level thresholding technique, and a white matter region was extracted based on a level set method. The cortical thickness was measured with normal vectors as a Euclian distance between white matter surface and cortical gray matter surface on a voxel-by-voxel basis. We applied the computerized method to high-resolution 3-D T1-weighted images of the whole brains from 21 clinically diagnosed Alzheimer's disease (AD) patients and 16 non-AD subjects. The average thicknesses in upper slices for AD patients and non-AD subjects were 3.4 and 3.7 mm, respectively, which indicated a significant difference (P < 0.005) by Student's t test, and the average thicknesses in lower thickness were 4.2 and 4.9 mm, which also indicated a significant difference (P < 0.001). Our preliminary results suggest that the MRI-based computerized measurement of gray matter atrophy is promising for detection of AD patients.