Neck CT angiogram is a method of radiation diagnostics that allows to obtain cross sections (tomograms) of extracranial vessels and conduct two- and three-dimensional computer reconstruction of the vascular basin. The study in angiographic mode is carried out with intravenous bolus injection of contrast. Subclavian, carotid and vertebral arteries, jugular veins fall into the scanning area. CT has proven informative value in detecting atherosclerotic lesions, aneurysms, vasculitis, vascular malformations, stenoses and occlusions of the main arteries and veins of the neck.
Indications
Contrast computed tomography of the blood vessels of the neck is indicated for traumatic injuries of the cervical spine, pathologies of arteries and veins (aneurysms, malformations, kinking syndrome), atherosclerosis of the carotid artery, intravascular thrombus formation, rheumatic vasculitis, vascular pathologies accompanied by insomnia, headache, impaired attention and memory. Neck CT angiogram is also indicated for edema, soreness of this area and suspected benign or malignant neoplasms.
Contraindications
Contrast CT is contraindicated in pregnant patients. In other cases, limitations in the use of computed tomography are associated with allergic reactions to the components of the contrast agent or functional disorders. It can be anaphylactic shock, sudden dysfunction of the cardiovascular or respiratory system. Computed tomography is also undesirable for patients with bronchial asthma, hyperthyroidism, acute and chronic renal failure. During lactation, CT with contrast is acceptable if the patient subsequently refrains from feeding for 2 days.
Methodology of conducting
The CT procedure is preceded by the collection of anamnestic data, including the presence of contraindications to the administration of contrast agents. Neck CT angiogram is performed after intravenous infusion of iodine-containing drugs, therefore, a specialist should assess the functional state of the kidneys and perform a skin test to exclude an allergic reaction. The main preparation of the patient for CT angiography of the vessels of the neck consists in intravenous administration of a contrast agent. In this case, the contrast agent is infused in such a way that its high concentration (bolus) remains as long as possible before dilution in the small circle of blood circulation. In this regard, the rate of contrast injection should be 2-6 ml/s. The maximum possible injection comfort is achieved by placing intravenous cannulas.
Before the examination, the patient removes all metal jewelry from himself and is placed in a horizontal position on a special mobile table. CT diagnostics does not require prior medical preparation, it is only necessary to inject a contrast agent into the subclavian artery. At the same time, the arch of the device is located in the neck area. Then the table with the patient begins to move slowly, and the scanned ring rotates around its axis. At this moment, the patient may feel slight discomfort, which is associated with a soft noise and crackling of the device.
During the procedure, the doctor or laboratory assistant is in the next room and watches what is happening through the glass. Communication with the patient is provided by means of a microphone and a speaker located in the arch of the device. In most cases, the duration of the procedure does not exceed 5-10 minutes. During the study, the patient should remain motionless. The arterial stage of the diagnostic procedure begins 18-25 seconds after the injection, and the pathology of the venous system is determined after another 25 seconds. The key to the accuracy of the examination is the X-ray diagnostics at the maximum concentration of contrast in the study area. To determine the exact moment of intravenous administration of a contrast agent, the technique of automatic starting of tomography by the bolus trigger allows. With neck CT angiogram, it is necessary to strictly observe the time frame of the examination, since the contrast agent is prone to rapid excretion from the body.
Interpretation of results
The patient receives the results of the study in the form of a series of images and in digital form. The patient is also given a detailed description of the functional state of the vascular basin of the neck. All the images on the CT diagrams are in a gray range of colors. Gas or air has a black tint, and bone tissue is white. The colors of all other structures are located in between these shades. The pattern of the vascular network in this case is clearly manifested due to the contrast agent in the arteries and veins. The image on the monitor screen is represented by a two-dimensional picture and a 3D model, which contain data on the average absorption of X-ray radiation by organs.
Reading the results of the diagnostic procedure consists in studying the facts of violation of the natural density of tissue in the area of the vascular bed. At the same time, it is taken into account that the density level of recently clotted blood is 30 units higher than that of fresh blood. CT data is displayed in several windows, which allows you to achieve maximum informative images of blood vessels. Many specialists pay attention to the fact that density indicators largely have individual values in different patients. This fact has a significant impact on the interpretation of the results of contrast computed tomography.
Advantages
The advantages of neck CT angiogram include the availability and relatively low price with high information content of the procedure and the possibility of building a 3D model of the area under study. Computed tomography is a universal tool for assessing the condition of arteries and veins. Due to the high speed of CT examination, it is considered a key method of emergency diagnosis of vascular pathology. The list of disadvantages of the technique includes the need to use X-rays and intravenous administration of iodine-containing drugs.
Ultrasound examination, like computed tomography, is absolutely painless, but has less informative and accurate diagnosis of vascular pathologies. Unlike neck CT angiogram, magnetic resonance imaging is not associated with the radiation load of the patient, but requires the use of expensive equipment, which increases the cost of the procedure.
