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To estimate hemocirculation and proliferating activity of intraventricular tumor, we measured kinetic rate constants (k1, k2, k3) and glucose metabolic rate (kinetic-rCMRGl) using dynamic positron emission tomography (PET), as well as regional cerebral blood flow (rCBF), blood volume (rCBV), oxygen extraction fraction (rOEF), oxygen metabolic rate (rCMRO2) and autoradiographic rCMRGl (arg-rCMRGl), in patients with intraventricular tumor. The subjects included ten patients, five males and five females, aged from 13 to 53 years with a mean age of 32 years old. Eight tumors were located in the lateral ventricle and two extended into the third ventricle through the foramen of Monro. Another two tumors were located in the fourth ventricle. Histological diagnosis was as follows: five cases of central neurocytoma, one subependymal giant cell astrocytoma, one ependymoma, one choroid plexus carcinoma, one subependymoma, and one meningioma. Tumor lesion on the PET images was determined using CT or MRI, which was performed at levels equivalent to those for the PET scans. For quantitative analysis, regions of interest (ROI) on PET images were delineated on the tumor and the contralateral gray matter. Hemocirculation (rCBF, rCBV) of the tumor was similar to or higher than that of the contralateral gray matter, which corresponded to neuroradiological findings of abundant tumor vessels. Oxygen metabolic parameters (rOEF, rCMRO2) were significantly lower than those of the contralateral gray matter. Especially, low rOEF resulted in an excessive blood flow beyond oxygen demand of the tumor. The raised metabolic rate (rCMRO2/rCMRGl), as compared with that of meningiomas or malignant gliomas, suggested aerobic glycolysis. The kinetic rate constants of tracer transport from blood to brain (k1), reverse transport from brain to blood (k2), and phosphorylation (k3) were analyzed according to the three-compartment model of 18F-fluorodeoxyglucose (18FDG). Tumor k1 and k2 values were similar to or higher than those of the contralateral gray matter, suggesting high permeability due to lack of blood-brain barrier and an abundant blood supply. Tumor k3 value, an indicator of hexokinase activity, and kinetic-rCMRGl were lower in six of eight patients. These six patients have been free from tumor recurrence or regrowth, postoperatively. In the other two patients, tumor kinetic-rCMRGl was similar to or higher than that of the contralateral gray matter, suggesting high activity of proliferation. However, one patient received irradiation and has been followed up, and the other received total resection and has shown no recurrence. Functional information concerning intraventricular tumor is obtained by PET analysis, and kinetic analysis of the rate constants is useful for interpreting a detailed metabolic process of glucose, and provides additional information on intraventricular tumor aggressiveness.

In the first report, the clinical manifestations of 30 cases of the lateral ventricle tumor were reviewed. This report summarizes neuroradiological findings of the same 30 cases, in which 26 cases were examined by cerebral angiograms and 3 cases by CT scan. For the radiological analyses, the tumors of the lateral ventricle are classified into two groups, as follows: 1. Intraventricular tumors arise in the projection of the choroid plexus, the tela and the ependyma and grow in the lateral ventricle. 2. Paraventricular tumors arise from the wall of the neuroglia not only bulge into ventricle, but in addition infliltrate the substance of the surrounding brain. Following conclusions are obtained. (1) Unilateral hydrocephalus, which is shown clearly by vascular displacements in subependymal veins, is demonstrated in both tumors groups. (2) There are different findings on the feeding arteries, the draining veins and the tumor stains between two tumors groups. (3) In the intraventricular tumors groups, the anterior choroidal artery supplying the tumor is its the plexal segments and atrial segments. (4) On the other hand, the paraventricular tumors group, the anterior choroidal artery supplying the tumor is its the superior penetrating branch to the cerebral parenchyma. (5) Cerebral angiograms can reveal the definite signs of the intraventricular mass, but it is sometimes difficult to evaluate whether its space occupying lesions infiltrates the cerebral substance below the wall of the lateral ventricle, or not. (6) CT scan is useful neuroradiological method in the different diagnosis between two tumor groups, and CT scan provides and anantomical diagnosis rather than a histological one. (7) The accurate diagnosis of the tumors of the lateral ventricle can be demonstrated by both cerebral angiograms and CT scan.