More articles from Adult Brain
- Myelin and Axonal Damage in Normal-Appearing White Matter in Patients with Moyamoya Disease
Eighteen patients with Moyamoya disease (16–55 years of age) and 18 age- and sex-matched healthy controls were evaluated with myelin-sensitive MR imaging based on magnetization transfer saturation imaging and 2-shell diffusion MR imaging. The myelin volume fraction, which reflects the amount of myelin sheath; the g-ratio, which represents the ratio of the inner (axon) to the outer (axon plus myelin) diameter of the fiber; and the axon volume fraction, which reflects axonal components, were calculated and compared between the patients and controls. Compared with the healthy controls, the patients with Moyamoya disease showed a significant decrease in the myelin and axon volume fractions in many WM regions, while the increases in the g-ratio values were not statistically significant. Correlations with cognitive performance were most frequently observed with the axon volume fraction. The authors conclude that the relationship with cognitive performance might be stronger with axonal damage than with myelin damage.
- Black Dipole or White Dipole: Using Susceptibility Phase Imaging to Differentiate Cerebral Microbleeds from Intracranial Calcifications
The authors evaluated the diagnostic accuracy of differentiating cerebral microbleeds and calcifications from phase patterns in axial locations in 31 consecutive patients undergoing both CT and MR imaging for acute infarction and exhibiting dark spots in gradient-echo magnitude images. Six patients had additional quantitative susceptibility mapping images. To determine their susceptibility, 2 radiologists separately investigated the phase patterns in the border and central sections. Among 190 gradient-echo dark spots, 62 calcifications and 128 cerebral microbleeds were detected from CT. Interobserver reliability was higher for the border phase patterns than for the central phase patterns. The sensitivity and specificity of the border phase patterns in identifying calcifications were higher than those of the central phase patterns, particularly for lesions >2.5 mm in diameter and quantitative susceptibility mapping of dark spots. They conclude that the border phase patterns were more accurate than the central phase patterns in differentiating calcifications and cerebral microbleeds and were as accurate as quantitative susceptibility mapping.