Distant Secondary Degeneration: Quantitative Evaluation of Neuron Density by 3 Tesla MRI and SPECT

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I-123 iomazenil has favorable characteristics for in vivo assessment of benzodiazepine receptors with single photon emission computed tomography (SPECT). Using this ligand, we studied the central benzodiazepine receptor distribution in the cerebral cortex in patients with unilateral basal ganglionic or thalamic hemorrhage. This study included fifteen patients (9 men, 6 women : mean age 67.8 yr) with hypertensive brain hemorrhage (10 and 5 patients with unilateral thalamic or basal ganglionic hemorrhage, respectively). SPECT images were obtained 12 to 21 days (mean : 13.7 days) after the onset of hemorrhage. We also performed diffusion tensor imaging to evaluate water diffusivity using 3 tesla MR imaging for 5 patients. Diffusion tensor imaging applied diffusion gradient encoding in six non-collinear directions. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in the anterior and posterior cerebral white matter.On SPECT images, we evaluated the ac … More cumulation of I-123 iomazenil qualitatively and quantitatively. The accumulation of I-123 iomazenil in the ipsilateral cerebral cortex of the hemorrhage tended to be decreased in comparison with that of the contralateral cerebral cortex. However, the radioactivity ratio of the ipsilateral to the contralateral cerebral cortex (I/C ratio) was not significantly decreased. On the diffusion tensor imaging, ADC values of the ipsilateral cerebral white matter tended to be higher than those of the contralateral cerebral white matter.FA values of the ipsilateral cerebral white matter tended to be lower than those of the contralateral white matter. However, these changes were not statistically significant. Central benzodiazepine receptor I-123 iomazenil binding was decreased in the ipsilateral cerebral cortex remote from the hemorrhage. On the diffusion tensor imaging, water diffusivity of the ipsilateral cerebral white matter was different from contralateral cerebral white matter. These results would suggest the potential damage of the cortical neurons remote from thalamic or basal ganglionic hemorrhage. Less