Abstracts

Diffusion tensor imaging (DTI) provides information about magnitude (diffusivity) and directionality (anisotropy) of water diffusion. The uncinate fasciculus (UF), a pathway connecting temporal and frontal lobes, has been implicated in the retrieval of episodic memories. The purpose was to explore DTI measures of the UF in temporal lobe epilepsy (TLE) and their relationship to memory performance., DTI was performed in 13 TLE patients (7 left, 6 right) and 10 normal controls. Using DTI Task Card software (Massachusetts General Hospital), a region of interest (ROI) was outlined on two axial slices of the colorized fractional anisotropy (FA) map encompassing fibers of the UF. Fibers were reconstructed using an FA threshold of 0.2, and angular threshold of 50^[deg]. FA and diffusivity (ADC, apparent diffusion coefficient, in x 10 ^-5 mm²/s) measures in the entire UF were determined. Differences between left and right UF values among and between groups were assessed using t-tests. Correlations between DTI and memory measures in the TLE groups were examined., In the group, anisotropy values were significantly higher in the left compared to the right UF; ADC values were comparable. In the group, FA values were significantly lower and ADC values were significantly higher than the controls in the [italic]left UF[/italic]. No differences were found between the groups in the [italic]right UF[/italic]. In contrast, the group demonstrated significantly higher ADC values in both the [italic]left and right UF[/italic] compared to controls, but no differences in FA were observed.[table1]To explore the functional significance, correlations were computed between DTI values and memory scores. In patients, FA was significantly positively correlated with Auditory Immediate Memory in both the[italic] right and left UF[/italic]. ADC values in the [italic]left UF[/italic] were significantly negatively correlated with Auditory Delayed Memory. No significant correlations were found between DTI measures and memory scores in patients., Measures of diffusivity and ansiotropy and visualization of tracts allow better understanding of the pathological changes accompanying TLE. Abnormal diffusion measures of the UF ipsilateral to the epileptogenic zone may evidence damage secondary to seizure spread. Preliminary data suggest a correlation between DTI measures and reduced memory scores in patients with left TLE. Future studies with larger sample sizes are needed., (Supported by the CCF CIDA and Milken Familiy Foundation (BD).)