Many people have experienced CT plain scan, which is simple, fast, and painless, but they don't know much about enhanced CT. Many patients may think that enhanced CT and plain scan are the same and do not require any preparation work, only that the doctor can see more clearly after the scan. Next, let's popularize enhanced CT and learn about the upgraded version of this regular CT.
What is Enhanced CT Examination?
CT enhanced scanning is one of the CT scanning techniques that uses intravascular contrast agents to scan and inject iodine containing organic compounds, also known as contrast agents, intravenously before performing CT examination. This imaging technique can increase the density difference between diseased tissue and adjacent normal tissue, improving the display rate of lesions.
What is iodine contrast agent?
It is a diagnostic medication mainly composed of iodine, which is opaque to X-rays. Therefore, it uses this characteristic to produce contrast in the body distribution, making blood vessels and soft tissues that are not usually visible on X-ray films clear and assisting doctors in making reliable diagnoses.
Why do we need to fast before enhanced CT examination?
Fasting is to prevent the body from vomiting after injection of contrast agents, which can cause some food in the gastrointestinal tract to enter the respiratory tract and cause suffocation, thereby endangering life.
It should also be noted that patients undergoing abdominal CT examination are fasting before the examination to avoid food residue in the gastrointestinal tract interfering with the imaging and affecting the doctor's diagnosis; In abdominal CT, due to the volume effect of hollow organs, there may be artifacts, so it is necessary to drink water appropriately to overcome the volume effect and avoid artifacts; The filling of the gastrointestinal tract can create good contrast in the image, which can better distinguish the stomach from other adjacent organs such as the liver and spleen; The structures such as pancreas and para aortic lymph nodes can also be better displayed.
Is it uncomfortable to do enhanced CT? Is there any danger?
During the enhanced CT examination, there may be varying degrees of adverse reactions. Some patients may have mild symptoms such as nausea, vomiting, headache, dizziness, and rash, while others may have more obvious symptoms such as chest tightness, shortness of breath, numbness in the mouth and tongue. Even a very small number of patients may experience allergic reactions, such as difficulty breathing, loss of consciousness, and shock. But don't worry, we are currently using non-ionic contrast agents, which have high safety and generally do not cause drug reactions. Only a very small number of patients have a low probability of experiencing adverse reactions due to special physical conditions or various unexpected situations. Therefore, please stay for 30 minutes after the inspection is completed.
Why does the doctor still need to perform an enhanced CT scan after a CT plain scan?
Simply put, plain CT scan is the most basic CT examination, and patients can directly lie in the machine for examination. Enhanced CT is a CT scan performed after intravenous injection of a certain dose of iodine contrast agent in patients. Contrast agents can make the differences between the lesion and the surrounding blood vessels and tissues more pronounced, helping to detect lesions that cannot be detected by plain CT or to display the scope and nature of the lesion more clearly. Taking chest lesions as an example: Plain CT scan can detect lung shadows, but to determine their nature, enhanced CT examination is required.
What are the special precautions for enhanced CT?
Injecting iodinated contrast agents may cause allergic reactions, therefore, medical staff need to conduct an evaluation, sign an informed consent form, and use a indwelling needle for venipuncture before examination. If there are any of the following situations, please inform the doctor in advance.
Individuals with hyperthyroidism, a history of asthma, those currently taking interleukin, and those who have previously been allergic to iodine contrast agents are prohibited from undergoing this examination.
2. Patients with diabetes who take metformin should be examined under the guidance of doctors.
If CT or MRI enhancement examination has been performed within 3.1 weeks, it is necessary to inform the doctor or nurse for evaluation before performing this examination again.
After the examination, it is necessary to observe in the waiting area for 30 minutes. If there is any discomfort, please inform the medical staff in a timely manner.
5. Drink plenty of water within 2 days after the examination to facilitate the excretion of contrast agents from the body.
Generally speaking, if a clear diagnosis can be made through regular CT, there is no need for enhanced CT, such as intracranial hemorrhage, common pulmonary inflammation, etc. But for some suspicious lesions that cannot be detected by ordinary CT, especially abdominal examinations such as liver cirrhosis that require exclusion of liver cancer, doctors will recommend further enhanced CT!
The above are some basic knowledge about enhanced CT that we have talked about today. Do you understand enhanced CT?