Various Tumors in the 4th Ventricle in Adults: MRI Findings

Primary fourth ventricular neoplasms are common in children but rare in adults, and the disease categories encountered differ according to the patient's age. This study reviewed the records of patients aged 16 years or over, who underwent magnetic resonance (MR) imaging and were found to have fourth ventricular lesions. Most patients then underwent surgical resection, leading to specific pathologic diagnosis. The various fourth ventricular tumors encountered were ependymoma (n=8), subependymoma (n=1), choroid plexus papilloma (n=3), astrocytoma (n=3), medulloblastoma (n=1), lymphoma (n=2), epidermoid cyst (n=2), meningioma (n=1), melanoma (n=1), cavernous hemangioma (n=1) and metastasis (n=1). We describe the various tumors located mainly in the fourth ventricle and review their clinical presentation and the radiological findings, the majority of which were nonspecific. In some cases, however, specific signal intensity or the growth pattern of the tumors was useful for differential diagnosis.

Intracranial and Spinal Ependymomas: Review of MR Images in 61 Patients

OBJECTIVE: To compare the age distribution and characteristic MR imaging findings of ependymoma for each typical location within the neuraxis. MATERIALS AND METHODS: During a recent eleven-year period, MR images of 61 patients with histologically proven ependymomas were obtained and retrospectively reviewed in terms of incidence, peak age, location, size, signal intensity, the presence or absence of cyst and hemorrhage, enhancement pattern, and other associated findings. RESULTS: Among the 61 patients, tumor location was spinal in 35 (57%), infrartentorial in 19 (31%), and supratentorial in seven (12%). In four of these seven, the tumor was located in brain parenchyma, and in most cases developed between the third and fifth decade. Approximately half of the infratentorial tumors occurred during the first decade. The signal intensity of ependymomas was nonspecific, regardless of their location. A cystic component was seen in 71% (5/7) of supratentorial, 74% (14/19) of infratentorial, and 14% (5/35) of spinal cord tumors. Forty- nine percent (17/35) of those in the spinal cord were associated with rostral and/or caudal reactive cysts. Intratumoral hemorrhage occurred in 57% (4/7) of supratentorial, 32% (6/19) of infratentorial, and 9% (3/35) of spinal cord tumors. In 17% (6/35) of spinal ependymomas, a curvilinear low T2 signal, suggesting marginal hemorrhage, was seen at the upper and/or lower margins of the tumors. Peritumoral edema occurred in 57% (4/7) of supratentorial, 16% (3/19) of infratentorial and 23% (8/35) of spinal cord tumors. Seventy-two percent (5/7) of supratentorial and 95% (18/19) of infratentorial tumors showed heterogeneous enhancement, while in 50% (17/34) of spinal cord tumors, enhancement was homogeneous. CONCLUSION: Even though the MR imaging findings of ependymomas vary and are nonspecific, awareness of these findings, and of tumor distribution according to age, is helpful and increases the likelihood of correct preoperative clinical diagnosis.