An aneurysm of the vein of Galen can have a varied CT appearance in infancy. The classical picture is a spherical posterior third ventricular mass with the density of circulating blood contiguous with a dilated straight sinus and with uniform contrast enhancement. With varying degrees of thrombosis of the aneurysm which may occur in late infancy, the mass can change in density and the dilated straight sinus disappear. With total thrombosis, a precontrast hyperdense rim develops with a low density center. The rim enhances but the low density center does not change with contrast infusion. Our experience in three patients with this spectrum of CT findings will be demonstrated and correlated with clinical findings and angiography.

Pituitary tumors commonly produce suprasellar extension. We have found that in assessing lateral suprasellar extent, the pneumoencephalogram and arteriogram are least accurate. CT scanning significantly increases the accuracy, and it is recommended that all patients with pituitary tumors have an initial CT scan.

Computed tomography has proved to be the most effective mode of evaluating cerebral infarction in 143 documented cases. This was especially true when multiple focal infarcts were present. The incidence of contrast enhancement in acute infarcts was 88%. Concomitant acute and old infarcts were observed in 20% of cases. In the acute stage of stroke, radionuclide studies are preferable to contrast angiography since the latter may aggravate the pre-existing focal ischemia. Follow-up CT and radionuclide scans were extremely useful in confirming the diagnosis and demonstrating various postinfarction sequelae.

On the basis of myelographic findings, spinal adhesive arachnoiditis was classified into three types: type I (peripheral or marginal), type II (central), and type III (advanced). Depending on its location and extent, it may be divided into group A (lumbar), group B (thoracic), and group C (cervical). In view of the fact that intrathecal injection both of oily and of water-soluble contrast media tends to produce spinal arachnoiditis, we have been using radionuclides for pre- and postoperative myelography to evaluate arachnoiditis. Radionuclide myelography with 131I-HSA or 111In-DTPA is a safe modality which provides useful information regarding spinal arachnoiditis.