Vadim Spektor MD, Presenter: Nothing to Disclose

James B. Golomb MD, Abstract Co-Author: Nothing to Disclose

Meng Law MD, Abstract Co-Author: Nothing to Disclose

Stanley Lu MD, Abstract Co-Author: Nothing to Disclose

Ajax E. George MD, Abstract Co-Author: Nothing to Disclose

We hypothesize that there is a correlation between clinical symptoms of Normal Pressure Hydrocephalus (NPH) and Diffusion Tensor MRI (DTI) measurements in motor tracts.

18 patients with clinical diagnosis of NPH were recruited for this study. In addition, 12 patients with the clinical diagnosis of Alzheimer’s disease (AD) and 2 patients without clinically apparent symptoms and with accidentally detected ventriculomegaly were also studied with the same imaging protocol. 20 patients were scanned on a 3 Tesla MR imager, 6 patients were scanned on a 1.5 Tesla unit and 6 patients were scanned on both units. Axial DTI data were positioned in the same manner as the FLAIR images and acquired with a pulsed gradient, double spin echo, echo planar imaging method (5300/74; 128x128 matrix; 220x220 mm FOV; twenty 5 mm contiguous slices; b = 1000 s/mm2 on a 3T magnet) in six directions. Multiple ROIs were placed within the motor tract areas. Measurements of fractional anisotropy (FA) and mean diffusivity (MD) were correlated with patient’s clinical symptoms. We also compared number of fibers in each ROI, FA and MD values, and the degree of gait disturbance.

Mean FA measured at the genu of internal capsule in NPH patients with significant gait disturbance was 0.66 ± 0.038, mean FA in AD patients was 0.74 ± 0.053 and mean FA in neurologically asymptomatic patients was 0.76 ± 0.057. In comparing NPH and AD patients, the results were statistically significant at the P < 0.003 level. Notably, NPH patients with only minimal gait disturbance have FA values in the same range as asymptomatic and AD patients. There is also a decrease in the number of fiber tracts visualized in the standardized ROI of maximal FA in the genu of the internal capsule in NPH patients with severe gait disturbance in comparison to NPH patients with similar degree of ventriculomegaly and minimal gait symptoms.

The degree of gait disturbance correlates with measurements of FA and MD and number of visible tracts in the motor areas. This may have implications for therapy and follow up for patients with NPH.Key Words: Normal Pressure Hydrocephalus, diffusion tensor imaging, fiber tractography.

Spektor, V, Golomb, J, Law, M, Lu, S, George, A, Diffusion Tensor Measurements and Fiber Tractography in Patients with NPH.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4408335.html