Differential Diagnosis of the 4th Ventricular Tumors

PURPOSE: To determine by analysis of MR and CT findings the points of differentiation among 4th ventricular tumors, especially the change of shape of the 4th ventricle caused by the site at which 4th ventricular tumors originate. MATERIALS AND METHODS: The authors retrospectively analyzed and compared the CT(n=5) and MRI(n=12) findings of 13 pathologically proven 4th ventricular tumors comprising six medulloblastomas three ependymomas (4 cases) and three choroid plexus papillomas. RESULTS: On axial MRI medulloblastomas showed anterior and anterolateral CSF-clefts between the tumor mass and the 4th ventricular wall in one and five cases, respectivaly ; on sagittal MRI, anterior beaking of the upper 4th ventricle was seen. Two ependymomas showed posterolateral CSF-cleft on axial MRI and posterior beaking of the upper 4th ventricle on sagittal MRI. Two ependymomas and all choroid plexus papillomas showed anterior, posterior and lateral CSF-clefts on axial MRI, and anterior and posterior beakings of upper 4th ventricle on sagittal MRI. On Gd-DTPA enhanced T1WI, all medulloblastomas and ependymomas showed inhomogeneous enhancement, and all choroid plexus papillomas showed homogeneous enhancement. On CT, tow choroid plexus papillomas showed dense calcifications. CONCLUSION: The differential diagnosis of 4th ventricular tumors can be preoperatively suggested by analysis of findings such as a CSF-cleft between the tumor mass and the 4th ventricular wall on axial MR and CT images, the shape of the upper 4th ventricle on sagittal MRI, contrast enhancement pattern, necrosis and cyst, and CSF seeding.

Analysis of High Signal Intensities of Nontumorous Conditions of Corpus Callosum on Magnetic Resonance T2-Weighted Images

PURPOSE: To evaluate high signal intensity of nontumorous conditions of corpus callosum on T2-weighted MR images. MATERIALS AND METHODS: Fourty nine patients with nontumorous high signal intensities involving corpus callosum on sagittal T2-weighted image were restrospectively analyzed. Nontumorous condition of corpus callosum were diffuse axonal injury(DAI, 19 cases), cerebral infarctions(16 cases), multiple sclerosis(MS, 5 cases), Wilson's disease(2 cases) and hydrocephalus(7 cases) that were diagnosed by clinical and MR findings. Numbers, configuration, involved thickness and sites of high signal intensities of corpus callosum were analyzed. RESULTS: DAI and infarctions showed either single or multiple lesions. MS and hydrocephalus showed multiple lesions, but Wilson's diseases showed single lesion. In DAI, infarctions and MS the lesions involved any part of corpus callosum, splenium in WIIson's disease, and all parts of corpus callosum in hydrocephalus. Wilson's disease showed only partial thickness involvement, and others involved partial or full thickness of corpus callosum. Configuration of high signal intensity was linear in most cases of hydrocephalus, and oval in Wilson's disease, and oval and confluent in MS, and variable in DAI and infarctions. CONCLUSION: High signal intensities of nontumorous conditions of corpus callosum revealed variable findings, and therefore, analysis of nontumorous high signal intensities of corpus callosum is not made by only MR findings but by conjuction with clinical aspects.

The Role of IVIRI in Early Ankylosing Spondylitis: Emphasis on the Sacroiliac and Hip Joints

PURPOSE: In clinically suspected ankylosing spondylitis of sacroiliac (SIJ) and hip joints with normal or minimal secondary bone change in simple X-ray films, we evaluated the role of MRI in sacroiliac and hip joints. MATERIALS AND METHODS: Authors evaluated 11 cases (36 joints;SIJ 14, hip 22) confirmed as spondylitis by clinical, laboratory, and radiologic findings, and compared the detectability of involvement of joints by simple X-ray film and MRI. Authors analysed MR findings for the presence of pannus and its si, intensities (SI), change of articular cartilage, bony erosion and sclerosis, subchondral bone cysts,.~ osteophytosis, bone marrow edema, joint effusion, adjacent soft tissue change, and contrast enhancement ofi pannus. RESULTS: MRI detected not only 20 joints (SIJ 11, hip 9) detected in simple X-ray, but also additional 7 joints (SIJ 3, hip 4). MRI depicted simultaneous involvement of SIJ and hip joints in 5 of 11 cases (SIJ 10 joints, hip9 joints), and bilateral involvement of SIJ and hip joints in 4 among the 5 cases. MRI also demonstrated pannus, which were not detected in conventional films, as intermediate SI on T1WI and high SI on T2WI, in all 27 joints (SIJ 14, Hip 13). Gd-DTPA enhanced T1WI revealed enhancement of pannus in 7 cases (17 joints). CONCLUSION: MRI was a valuable modality in evaluation of clinically suspected ankylosing spondylitis of SIJ or hip joints with normal or minimal secondary bone change in simple X-ray. Simultaneous evaluation of SIJ and hip joints is suggested in clinically suspected ankylosing spondylitis or other joint diseases.