CT temporal bone is a method of obtaining layered sections of the structures of the pyramid, the tympanic cavity and the scaly part of the temporal bone. The study is performed in standard projections: axial, anterior semi-axial, anterior semi-coronary and coronary. Computed tomography of the temporal bones is indicated for traumatic injuries of the temporal region, infectious processes of the middle and inner ear, tumor lesions, developmental abnormalities, degenerative changes in bone structures, as well as in preparation for cochlear implantation. Contrast enhancement is used to evaluate soft tissues (muscles, tendons, blood vessels).
The diagnostic procedure is usually prescribed by neurosurgeons, traumatologists, maxillofacial surgeons and otolaryngologists. With the help of CT temporal bone, fractures, developmental anomalies, inflammatory and infectious processes of various genesis and localization (in the area of the inner and middle ear, mastoid process, etc.) are detected. The study is indicated if tumors of the temporal bones are suspected. The technique allows to determine the size, shape and prevalence of neoplasms (benign or malignant), to identify the presence of neoplasia metastases of other localization.
CT makes it possible to assess the severity of osteosclerosis, to confirm the presence and severity of destruction during the spread of purulent processes to bone structures, to determine the cause of discharge from the external auditory canal. With the help of CT temporal bone, nearby soft tissues are examined. The procedure is carried out at the stage of preoperative preparation for the installation of a cochlear implant.
Absolute contraindications to CT temporal bone are pregnancy due to the teratogenic effect of X-rays on the fetus and children under 14 years of age due to the possible negative effect of X-rays on the growing body. As an exception, situations are considered when the procedure is necessary for vital reasons (for example, severe TBI). Relative contraindications to CT are considered obesity (weight more than 150 kg), hyperkinesis and mental disorders accompanied by increased motor activity. CT temporal bone with contrast is not prescribed to patients suffering from severe renal and hepatic pathology, diabetes mellitus, diseases of the cardiovascular system. CT with contrast enhancement is not indicated for intolerance to iodine preparations.
Preparation for CT
Carrying out the procedure without contrast enhancement does not require preparation. When using contrast, the patient is recommended to fast for 6 hours before the start of CT. Before contrasting, a preliminary skin test is carried out for the tolerability of iodine preparations. Nursing mothers stop feeding on the day of the study and resume it only two days later, after the contrast is completely removed from the body.
If the result of the skin test is negative, the radiopaque substance is injected intravenously, wait for some time until the drug is evenly distributed in the tissues and highlights them. Contrast can be introduced 15 minutes before the CT scan or during the procedure, after a series of native images. Sometimes the administration of iodine preparations is carried out through a catheter, which can be left in a vein in case a permanent or repeated infusion of contrast is necessary.
Methodology of conducting
Tomography of the temporal bones takes from 5 to 30 minutes, depending on the volume of the scan, with contrasting the duration of the procedure increases. Processing scans on a computer makes it possible to obtain a 3D model of the temporal region.
The patient receives a description of the study and printed images an hour after the scan is completed, with a high load of the X-ray diagnostics doctor, the time for preparing the conclusion may increase. At the request of the patient, the scans are transferred to a digital medium or sent to an email address. The absence of changes is interpreted as the norm. If a pathology is detected, the patient turns to the attending physician with the results of the study. A specialist may prescribe an additional examination, develop an outpatient treatment plan, or issue a referral for hospitalization in a hospital (planned or emergency).