Parasagittal Arachnoid Markings on the Inner Skull on Three-Dimensional CT: Relation between Hydrocephalus and Arachnoid Granules.

The purpose of the study was to evaluate the number and size of arachnoid markings on the inner plate of the skull on 3D-CT. The subjects included 16 hydrocephalus and 26 non-hydrocephalus cases. We evaluated the correlation between age and both the number and sizes of the arachnoid markings, and compared them between hydrocephalus and non-hydrocephalus cases. We also evaluated cases exhibiting a "smooth cranium" that had no arachnoid markings at all on the inner plate. There was a positive correlation between age and the number of the arachnoid markings. There were no statistically significant differences in arachnoid markings between hydrocephalus and non-hydrocephalus cases, while, there were statistically significant differences in the frequency of "smooth cranium" findings in the population under ten years old. The "smooth cranium" can only be seen in hydrocephalus cases. These findings may be a clue to the morphological or functional changes of the arachnoid villi in hydrocephalus cases.

Diffusion anisotropy and diffusivity of white matter tracts within the temporal stem in Alzheimer disease: evaluation of the "tract of interest" by diffusion tensor tractography.

PURPOSE: Our aim was to determine whether diffusion anisotropy and diffusivity of white matter tracts of the temporal stem in patients with Alzheimer (AD) can be evaluated independently by using diffusion tensor tractography. MATERIALS AND METHODS: Subjects included 15 patients with AD (11 women and 4 men; mean age, 74 years) and 15 age-matched control subjects (11 women and 4 men; mean age, 72 years). Diffusion tensor images were acquired by using echo-planar imaging. We drew tractographies of the uncinate fasciculus, inferior occipitofrontal fasciculus, and Meyer's loop, with diffusion tensor analysis software. We measured diffusion anisotropy, diffusivity, and the number of voxels along the "tracts of interest" and used the Student t test to compare results between patients with AD and controls. RESULTS: Values of diffusion anisotropy of the bilateral uncinate fasciculus and left inferior occipitofrontal fasciculus were significantly lower for patients with AD than for controls. Also, values of diffusivity in the bilateral uncinate fasciculus were significantly greater for patients with AD than for controls. There was no significant difference in diffusion anisotropy or diffusivity along Meyer's loop between the 2 groups. There was no significant difference in the number of voxels included in all constructed tracts between patients with AD and controls. CONCLUSION: White matter tracts of the temporal stem can be evaluated independently by using diffusion tensor tractography, which appears to be a promising technique for determining changes in white matter in degenerative diseases.

Development of a 1 MV field-emission transmission electron microscope.

We developed a 1 MV field-emission transmission electron microscope. This paper reports details and specifications of the instrument. The microscope was designed to obtain a bright and coherent electron beam by using the field emission gun equipped with a pre-accelerating magnetic lens and the high-voltage power supply with high stability (0.5 ppm min(-1)). Using this microscope, the brightness of 1.8 x 10(10) A cm(-2) sr(-1) and the lattice resolution of 49.8 pm were attained.