Computed tomography of supratentorial astrocytoma.

In a group of 40 astrocytomas the C.T. appearance was correlated with the grade of malignancy. On the plain scan the majority presented an irregular, nonhomogeneous low density lesion, better demarcatable in high than in low grade astrocytomas. Contrast enhancement was seen in 28 of the 32 high grade astrocytomas, 50% of the annular, 25% of the nodular and 25% of the mixed type. Six of the 8 low grade astrocytomas showed no contrast enhancement and 1 showed an annular type lesion. A relationship was found between the degree of contrast enhancement and the vascularity. Mass effect was observed in all but 1 patient, but more pronounced in high grade astrocytomas. At the first interpretation 98% were recognized as a lesion, 93% as a tumor and 68% as an astrocytoma. One false negative and no false postive C.T.scans were obtained. In review, high and low grade malignancies were correctly differentiated in 90%. As a screening method, the combination of EEG and echo equalled C.T.; in establishing a definite diagnosis angiography was inferior to C.T. Solely on the basis of the C.T. appearance, astrocytomas can hardly be differentiated from the other malignant brain tumors, but the grade of malignancy can be predicted reliably.