Clear-Cell Meningioma: CT and MR Imaging Findings in Two Cases Involving the Spinal Canal and Cerebellopontine Angle

Clear-cell meningioma is a rare subtype of meningioma which occurs at a younger age and has a higher recurrence rate than other subtypes. We report two cases of clear-cell meningioma, one in the thoracolumbar spinal canal and the other in the cerebellopontine angle. Though the CT and MR imaging findings were not different from those of ordinary meningioma, after surgical removal the condition recurred repeatedly in the patient with spinal canal involvement.

Functional MR Imaging Using Sensory and Motor Task in Brain Tumors and Other Focal Cerebral Lesions

PURPOSE: To determine the usefulness of the functional MRI (fMRI) using motor and sensory stimuli in patients with brain tumors or focal cerebral lesions. MATERIALS AND METHODS: This study involved five patients with brain tumors (n=2) or cerebral lesions [cysticercosis (n=1), arteriovenous malformation (n=1), focal infarction (n=1)] and seven normal controls. For MR examinations a 1.5T scanner was used, and during motor or sensory stimulation, the EPI BOLD technique was employed. For image postprocessing an SPM program was utilized. RESULTS: In volunteers, contralateral sensori-motor cortices were activated by both motor and sensory stimuli, while supplementary motor cortices were activated by motor stimuli and other sensory cortices by sensory stimuli. Preoperative evaluation of the relationship between lesions and important sensory and motor areas was possible, and subsequent surgery was thus successful, involving no severe complications. Activation of ipsilateral or other areas occurred in patients with destruction of a major sensory and/or motor area, suggesting compensatory reorganization. CONCLUSION: fMRI could be a useful supportive method for determining the best approach to surgery treatment in patients with brain tumors or focal cerebral lesions.

Functional MR Imaging of the Motor Cortex in Active and Passive Movement: Qualitative and Quantitative Changes

PURPOSE: To compare functional MR imaging of the motor cortex during active and passive movement. MATERIALS AND METHODS: Seven healthy, right-handed volunteers (M:F=6:1; age:25-30 years) were included in this study. A 1.5-T whole body scanner and the multislice EPI BOLD method were used. The motor paradigm was flexion-extension of a thumb against rest. In the active motion task, the thumb was flexed voluntarily once a second, while in the passive task, it was tied with a thread and pulled to flex and extend passively at the same interval and with the same intensity as in the active task. For image postprocessing, an SPM 96 program was used. The sites, numbers, and signal intensity of the activated pixels were determined, and the threshold for significance was set at p<0.001 to p<0.01. RESULTS: In the active motion task, strong activation at the contralateral side of the primary sensorimotor cortex and supplementary motor cortex occurred in all 14 examples in all seven volunteers. Additionally, the ipsilateral primary sensorimotor cortex and supplementary motor area were activated in 12/14 and 11/14 such tasks, respectively. During passive motion tasks, on the other hand, weak activation occurred at the contralateral side of the primary sensorimotor cortex in all cases, but in the contralateral supplementary motor cortex in only three. In the ipsilateral primary sensorimotor cortex and supplementary motor area, there was no activation. CONCLUSION: Compared with the active motion task, activation occurring in the contralateral primary sensorimotor cortex and supplementary cortex was weaker and less frequent during the passive task, and during this latter, the ipsilateral motor cortex remained inactive. These results may be useful for the clinical application of functional MR imaging in unconscious patients or in animal studies.