Roentgen Demonstration of Displaced Intracranial Physiologic Calcification and Its Significance in the Diagnosis of Brain Tumors and Other Space-Occupying Diseases
The purpose of this paper is to re-emphasize the significance of displaced physiologic intracranial calcification in the diagnosis of space-occupying disease and thus stimulate greater interest in the demonstration and recognition of normally and abnormally located calcifications by roentgen study. Ever since the pineal was demonstrated by roentgen methods (Fig. 1A), its importance as an intracranial landmark has been appreciated. More than three decades ago Schüller (1) stated that a diagnosis of space-taking disease was indicated when roentgenograms revealed pineal displacement. In 1925, in order to determine in just what percentage of persons the pineal is calcified, Naffziger (2) studied roentgenograms of the skull obtained in 215 consecutive cases. He found roentgen evidence of calcification in 45 per cent and therefore advocated stereoscopic studies, especially in the anteroposterior projection, in the presence of increased intracranial pressure, as a means of ascertaining the position of the gland. He reported lateral displacement of the pineal in 2 patients with brain tumors. Excellent articles by Vastine and Kinney (3) and later by Dyke (4) and Fray (5) dealing with pineal position as determined by the lateral view, stimulated the adoption of a routine determination of pineal position by many radiologists. Vastine and Kinney established the normal pineal zone in relation to the anterior and posterior extremities of the cranium by measuring, on the lateral films of several hundred normal persons, the distance from the inner table of the frontal bone to the pineal and plotting this measurement against the anteroposterior dimension of the skull. The normal pineal zone in relation to the vertex and base was determined by plotting the distance from the inner table of the vault to the pineal against the vertex-base dimension (Fig. 1, B and C). By use of the Vastine-Kinney measurements and charts, it is easy to determine whether the pineal is in normal relation to the extremities of the cranium as measured on the lateral film. When the pineal is outside its normal zone, a space-occupying lesion is the usual cause. The approximate position of the lesion is determined by the direction of displacement of the pineal. Dyke (4) determined the position of the pineal in 3,000 consecutive skull examinations, using this method, and after carefully correlating the results with the clinical and other findings, concluded that they were reliable. He found the pineal slightly in front of the Vastine-Kinney zone in a number of normals, but otherwise his results were the same. A few years later Fray (5) advocated different methods of measurement on the lateral film which clearly indicate whether the pineal is in normal relation to the extremities of the cranium. His method yields good results and is preferred by some.