Lückenschädel, scalloping of the posterior surface of the petrous pyramids, falx hypoplasia, falx fenestration, and tentorial hypoplasia with wide incisura and tiny posterior fossa are readily identified by computed tomography (CT) in patients with Chiari II malformation. Enlargement of the foramen magnum may be appreciated on axial section CT in some cases. None of these findings is pathognomonic and each may be observed in some patients with other conditions. In the aggregate, however, these findings strongly suggest the presence of Chiari II malformation.

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In patients with Chiari II malformations, the fourth ventricle is usually not visualized or appears small; the third ventricle is relatively small, typically has a large massa intermedia, and only occasionally exhibits parasellar and/or posterior third ventricular diverticula. The lateral ventricles are usually asymmetrically dilated, show medial pointing of the floor of the body near the foramen of Monro, flattening of the superolateral angles, and frequent absence of the septum pellucidum. Prior to and after shunting, the interhemispheric fissure may be either obliterated, or widely open with serrations corresponding to the interdigitated gyri of the cerebral hemispheres. Prominent confluent cisterns at the hind end of the third ventricle in patients with ventricular collapse may represent the CT equivalent of the dilated pericallosal, ambient and retropulvinaric cisterns seen in patients with hydrocephalus and poor ventricular filling at pneumography.

Five hundred celiac angiograms were reviewed to evaluate the frequency of clinically significant variations in the origin of the left gastric artery. In 13 of 500 cases, the left gastric artery arose anomalously most often as a direct branch of the aorta; in 14 of 500 cases, the left gastric artery primarily supplied the liver with only minor contributions to the stomach. An aberrant origin of the left gastric artery necessarily influences the angiographic diagnosis and therapy of gastrointestinal hemorrhage.

Flattening of the epiphysis of the long bones is seen in several bone dysplasias. It is the hallmark of multiple epiphyseal dysplasia and is an important sign in the diagnosis of spondyloepiphyseal dysplasias, diastrophic dysplasia, and pseudoachondroplastic dysplasia. The goal of this study was to determine norms for the height of the distal femoral epiphysis and to apply these standards to patients with bone dysplasias. Ratios of the distal femoral epiphysis height to both the distal femoral metaphysis width and the distal femoral epiphysis width were obtained from 640 radiographs of healthy children of different ages. Application of these standards to 41 patients with the bone dysplasias mentioned above proved useful in ascertaining decreased height of the distal femoral epiphysis. These standards are of particular value in subtle or early cases in which the thinning of the epiphysis may not be apparent upon simple observation. Obtaining three simple measurements from the anteroposterior knee radiographs allows determination of the presence or absence of flattening of the epiphysis.

In the Chiari II deformity, the following defects can be visualized by computed tomography: partial or complete fusion of the corpora quadrigemina into a tectal beak or spur and invagination of the midline cerebellum to receive this spur; marked upward, transincisural growth of the cerebellum to produce a supratentorial, "extra-axial" mass effect (especially after shunting); enlargement of the pericerebellar cistern about the "towering" cerebellum, and infolding of the anterior border of the towering cerebellum to overlap the vermis and the more caudal portions of the cerebellum. Growth of the cerebellar hemispheres around the brain stem results in (a) overlapping of more of the cerebral peduncles than usual, which sometimes separates the midbrain from the hippocampus; (b) overlapping of more of the lateral aspect of the pons than usual, causing partial filling in of the cerebellopontine angle (CPA) cisterns, presenting as bilateral CPA masses, and (c) wedging of the cerebellar margin between the lateral aspect of the brain stem and the adjacent free tentorial margin, so that the cerebellar hemispheres acquire an anteriorly pointed configuration.

Ultrasound was used to study 10 patients with subacute thyroiditis. With gray-scale technique, a "washed-out" appearance was seen during the active phase of the active phase of the illness. Clinical migration of the inflammation was accompanied by migration of the sonographic abnormality. Ultrasound can be especially helpful in the diagnosis of unilateral subacute thyroiditis and the differentiation of true cysts from hemorrhagic degeneration of goiter.

Bands of increased density representing the free edges and lateral margins of the tentorium were routinely identified on 100 sequential, normal, contrast-enhanced axial CT scans of good quality. Because the tentorium has a complex shape, the exact configuration of these bands varies with the level and the angle of the CT section. Comparison of CT scans with anatomic specimens permits an understanding of these varying configurations, and provides a means to estimate the position of the tentorium on non-contrast CT studies. The CT manifestations of diverse non-neoplastic diseases including subarachnoid hemorrhage, arteriovenous malformation, venous sinus thrombosis and Dandy-Walker malformation may be understood, in part, in terms of the configuration and density of these tentorial bands.