”Dr. Chen, can I not do enhanced CT? I have done plain CT before…” In clinical work, patients often ask such questions. Next, I will come to popular science, what is enhanced CT, and why the doctor will ask for enhanced CT after plain CT.
The enhancement is not the radiation dose
The Chinese name of CT (Computed Tomography) is electronic computer tomography, which uses X-ray beams to scan a certain part of the human body, and the scanned image is converted into digital signals by a computer for processing. At present, the clinical application of CT scans is mainly divided into two categories, one is plain scan CT, and the other is enhanced CT. The operation of plain scan CT is very simple. The patient lies flat on the CT machine, and the scan can be completed in a few seconds; enhanced CT is the same as ordinary CT, and the scan is also done, but the difference is that intravenous injection is required before the enhanced CT The contrast agent will be distributed to the various organs and tissues of the human body along with the blood flow, so that the X-ray absorption value of the area increases, the density of the tissue increases, and the imaging signal is enhanced. Therefore, it is more conducive to the imaging physicians’ Observation and diagnosis.
After intravenous injection of a contrast agent into the human body, the doctor can observe the specific blood flow of the patient’s diseased tissue in detail, and compare it with the surrounding normal tissues to accurately determine the nature of the disease. At the same time, it is also possible to judge whether the lesion is malignant or benign by whether the blood supply of the lesion is abundant, whether there is necrosis and bleeding, and whether the enhancement is uniform. Therefore, compared with plain scan CT, enhanced CT has higher accuracy and can obtain more valuable information, which is very beneficial to the development of clinical differential diagnosis and treatment. Compared with conventional CT, enhanced CT does not increase the radiation dose of radiation.
Enhanced CT screening for cancer has more advantages
Clinically, when a doctor initially suspects cancer through plain scan CT and other tests, he usually recommends that the patient do another enhanced CT. This is because:
1. A dynamic enhanced CT scan can help determine the enhancement strength and enhancement method of the lesion, and it can also Give qualitative judgments to typical cases.
2. The degree of evolution of cancer lesions and surrounding tissues is different, and the density of the two will be different. Therefore, some missed lesions can be found during enhanced CT examination, especially in the brain, liver, kidney and other substantial organs. Small lesions can well reduce the missed diagnosis rate.
3. Performing enhanced CT scans for diagnosed malignant tumors can improve the accuracy of tumor staging, thereby helping doctors judge the feasibility of tumor surgical resection and the selection and precautions of surgical methods.
4. Enhanced CT scan can distinguish cerebral blood vessels and some relatively small lymph nodes, so as to diagnose tumors more accurately.
Enhanced CT examination 3 attention
1. The need to do a skin test
because some people have allergic to the contrast agent, so do check before you do the skin test, in order to determine whether patients with allergic reactions. Patients should also explain to the medical staff according to the facts to facilitate the evaluation of indications and eliminate contraindications. For example, you have had food allergies or drug allergy symptoms before, including urticaria, bronchospasm, moderate hypotension, convulsions, pulmonary edema, heart failure and other allergies, or have a history of allergy to iodine-containing contrast agents; Renal failure; asthma attack period; taking biguanide hypoglycemic drugs; severe thyroid disease, myeloma, paraglobulinemia, myasthenia gravis, homocystinuria; eating various kinds of seafood, containing Iodine foods are allergic; in addition, pregnancy, breastfeeding, pregnancy, etc. should be clearly informed to the doctor to see if it is suitable for examination.
Most of the current contrast agents are non-ionic, which is actually very safe. In addition, some patients are not allergic, but related to the dose. However, the current enhanced CT is mostly “double low”, that is, the dose of the contrast agent is low, The X-ray dose is low.
2. Drink plenty of water
a contrast agent mainly excreted by the human body to the kidneys, so patients in pre- and post-enhanced CT to drink plenty of water, in order to speed up the rate of excretion of the contrast agent. Drinking water refers to drinking plenty of boiled water.
3. abdominal fasted prior to scanning
of the abdomen by CT scan embodiment, the scanning to fasted the night before the bowel evacuation, in order to reduce the influence of intestinal gas and fecal developed. In addition, during the scanning process, the patient should remove the metal and accessories from the clothing to avoid artifacts.