CT sella turcica is a targeted X-ray examination of the pituitary bone receptacle in the sphenoid bone of the skull with subsequent computer processing of the scans. Allows you to visualize in detail the area of the sella turcica and the intersection of the optic nerves (chiasm), allowing you to judge the presence of pathological processes in this area (empty sella turcica syndrome, pituitary adenoma, optic nerve intersection glioma, aneurysm, etc.). It is performed natively or with additional contrast. In the latter case, it is possible to clarify the nature of the tumor, its prevalence, features of blood supply and the relationship with the surrounding brain structures.
The main indications for CT sella turcica are clinical signs of pituitary lesion or optic nerve intersection. These include general malaise and emotional lability, hormonal imbalance (excessive prolactin synthesis, diabetes insipidus) and sexual dysfunction (erectile dysfunction in men, dysmenorrhea and infertility in women) of unclear etiology. Computed tomography is also used for headaches of a permanent nature without a clear localization, their combination with diplopia or a drop in visual acuity, anomalies in the development of the bones of the skull and skeleton (acromegaly, dwarfism), the “empty sella turcica” symptom complex.
An absolute contraindication to the procedure is pregnancy in any trimester. Relative contraindications include significant body weight (most tomographs are able to withstand a weight of up to 120-140 kg.), the inability of the patient to be in a static position (mental illness, hyperkinesis) and younger childhood. CT using intravenous contrast is contraindicated in allergic reactions to contrast, severe renal failure, myeloma, diabetes mellitus, thyroid diseases.
Native tomography does not require specific preparation. When using radiopaque substances, the excretory function of the kidneys is examined without fail and a test for sensitivity to the injected drug is performed. It is also recommended to refuse food 6-8 hours before the tomography.
Methodology of conducting
Computed tomography is performed in a separate specially equipped room. The study itself is performed using a tomograph – a device that is a large ring with a movable platform inside. Before starting the diagnosis, the patient is asked to take off all metal objects (jewelry, removable dentures and hearing aids), because they can “layer” on the pictures. Then the subject lies down on the platform and moves inside the tomograph. The radiologist goes to the next office, from which he controls the quality of the images received, monitors the patient’s condition and communicates with him. The duration of the native CT sella turcica is 20-30 minutes, during which it is necessary to lie still. At this time, the patient can hear clicks or background noise that the device makes. If it is necessary to use contrast, the drug is administered after receiving the first series of native images, and the study takes 30-50 minutes. The native procedure, as a rule, does not cause any complications or adverse reactions. With the introduction of radiopaque drugs, slight discomfort may occur, less often dizziness, nausea or headache.
Interpretation of results
In most clinics and diagnostic centers, you can get the result of a scan “on hand” already 40-60 minutes after the end of the study. Depending on the institution, the patient may be given a description of the images, the conclusion of the radiologist in handwritten or printed form, a CD with the results and / or a 3D model, printed copies. CT sella turcica allows you to identify pathologies such as benign or malignant neoplasms of the pituitary gland, chiasm and regional bone structures, hematomas (fresh or calcified), tuberculous meningitis, lesions of blood vessels and the “empty sella turcica” syndrome.
The presence of a pituitary tumor or an intersection of the optic nerves may be indicated by osteoporosis of the walls and wedge-shaped processes of the sella turcica, deformation of its contour, symptoms of “double walls” or “double bottom”. The last two signs, combined with the prolapse of the suprasellar cistern into the saddle cavity, may indicate the “empty sella turcica” syndrome. Hematomas on tomograms are manifested by formations of various structures and shapes in the area of the bottom or walls with uneven, but clear edges. Calcified vessels are visualized as linear high-intensity signals. Tuberculous meningitis has the appearance of small formations above the diaphragm of the sella turcica with areas of calcification. Osteomas are viewed in the form of darkening in the area of the bottom or walls, clearly connected with the wedge-shaped bone. The use of intravenous contrast makes it possible to study in more detail the structure of regional blood vessels, the nature of blood supply to tissues and the localization of pathological neoplasms.
Unlike radiography, CT sella turcica provides a layered image of all structures of this area and the formation of their three-dimensional image. Unlike MRI, computed tomography does not give a clear picture of soft tissues, however, it allows you to assess the condition of bones and blood vessels in more detail, as well as to identify hemorrhages. In addition, CT is an alternative to MRI in the presence of metal objects in the patient’s body. The informativeness of the study may vary depending on the functionality of a particular CT scanner, but in general, the volume and reliability of the data obtained make it possible to accurately establish the final diagnosis.