The Value of the X-Ray Examination of the Sella Turcica in the Sagittal Positions

IN June, 1937, we presented before the Internal Medical Society of Havana, “Estudios Clinicos,” a paper related to the x-ray examination of the sella turcica in the sagittal projections, describing a new technic. Although it is true that we have attained precision in the diagnosis of the alterations of the sella turcica as observed in lateral films of the skull, we believe that the sagittal views of the sella—antero-posterior and postero-anterior—add many interesting details of great value to the diagnosis. To the description of the technic and the information obtained in the examination of the sella turcica in these positions, we shall refer in this article. When an anteroposterior film of the head is taken so that the central ray is parallel to a plane passing the frontal protuberance and the external auditory canal, the sella turcica will be projected in the foramen magnum (Fig. 1). In this film we can see the anterior clinoid processes, the upper part of the sphenoidal sinuses, and the dorsum sella with the posterior clinoid processes (Fig. 2). When the postero-anterior film is taken so that the central ray is parallel to a plane passing through the external auditory canal and the frontal protuberance, we have the occipital projection (Fig. 3). In a film thus obtained, we can see the posterior clinoid processes, the dorsum sella, and the petrous portion of the temporal bone (Fig. 4). The lateral view of the head, taken routinely before the sagittal positions, will help us to find the point of election on the frontal bone through which the central ray should pass. We may draw a line on the film crossing the external auditory canal, the sella turcica, and the foramen magnum, that will leave the frontal bone at the point of election (Fig. 5). The point thus selected at the frontal bone will vary according to the type of head. In the platybasia type it will be lower than in the normal head, while in the basal kyphosis it will be higher (Fig. 6). In order to obtain a diagnostic film, careful centering is necessary so that the view may be symmetrical. Also, the technical detail, such as a fine focus tube, long cone, and Bucky diaphragm, must be taken into consideration. A rod fastened to the cone shows the direction of the central ray, thus allowing the technician to change the inclination of the head, to make certain that the central ray is directed parallel to a plane that passes by the frontal protuberance and the external auditory canal. We are now using 100 milliampere-seconds with the fine focus of the rotating anode tube, 80 kv.p., at 40 inches distance, changing the kilovoltage according to the size of the head. The transverse diameter of the sella turcica may be easily measured on the films taken in the sagittal projections, thus adding a new measurement to antero-posterior and vertical diameters of the sella obtained in the lateral view of the head.