Medical examinations are complementary and their main purpose is to localize or qualitatively diagnose diseases. For cancer patients, PET-CT is a commonly used method for diagnosis, staging and re-staging, efficacy evaluation and prognosis evaluation, and you need to understand the precautions of its examination in advance.
1. What is PET-CT?
PET-CT is positron emission tomography and X-ray computed tomography imaging system, which is an all-in-one machine that integrates PET and CT (computed tomography) equipment and technology.
The two images are organically combined and complement each other to produce a 1+1 2 effect: the biological metabolic information of the lesion and the accurate anatomical positioning and structure are presented in front of the doctor at the same time, so that the doctor's judgment of the disease is earlier, faster, more complete and more accurate.
2. Which patients need PET-CT examination?
1.Determine tumor grade.
In addition to determining the primary lesion, it can also determine whether there are lesions in various tissues, organs, and bones in the whole body at the same time, which can help doctors determine the tumor stage more accurately and provide accurate puncture and biopsy sites.
2.High suspicion of metastatic disease.
Patients with multiple metastases are highly suspected clinically, especially those with lymphoma, lung cancer, breast cancer, liver cancer, bile duct cancer and other cancers, and PET-CT examination is required to evaluate whether metastasis has occurred.
3.Tumor markers are markedly elevated but lesions are detected on routine examination.
Some patients find that the tumor markers continue to rise after reexamination, but there are no corresponding metastasis symptoms, and no lesions are found after routine CT, magnetic resonance and other examinations, and further PET-CT examination is required to find out the cause.
4.Determine the extent of radiation therapy.
In some cases, it is difficult for radiotherapists to judge the boundaries of the tumor, and PET-CT is needed to determine the range of metabolically active lesions, so as to accurately determine the scope of radiotherapy and reduce the risk of radiotherapy
3. What are the precautions for PET-CT?
Before PET-CT sachets
Do not do strenuous exercise for 1-2 days before PET-CT examination, and avoid excessive uptake of imaging agent in local muscles caused by high-intensity exercise.
Fasting, no sugary drinks and no intravenous glucose infusion should be prohibited 6 hours before the examination, and a small amount of plain water can be drunk. Before fasting, it is advisable to choose high-protein, low-carbohydrate foods and appropriately reduce the intake of starchy foods.
Stop taking all unnecessary medications 4-6 hours before the testIf you do need to take certain medications such as antihypertensive drugs, hypoglycemic drugs or painkillers, you should bring them with you on the day of the examination, and confirm with your doctor the time and method of taking them.
Diabetic patients should determine the fasting time with the doctor before the examination, and take the initiative to inform the type, dosage and method of hypoglycemic drugs currently used. If the patient requires insulin injections, fluorodeoxyglucose injections should be delayed.
Those who have had a barium swallow test or barium enema within 7 days before the examinationBarium bowel clearance is required to be tested.
If you have had anti-tumor** within 2-3 weeks, difficulty urinating, incontinence, metal foreign bodies in the body, pregnancy and lactation, inability to lie flat, impaired consciousness, etc., you should take the initiative to explain to your doctor.
PET-CT examination
During PET-CT examination, patients are required to remove all metal objects from their body, including dentures, jewelry, etc. Women need to take it off**. The PET-CT examination takes about half an hour, during which time the patient is placed in a fixed position, avoiding talking and moving the body to prevent blurring of the vision. If you feel unwell during the examination, you should always instruct the doctor to stop the examination and wait for the symptoms to be relieved.
After PET-CT examination
Drink plenty of water after PET-CT to facilitate the discharge of contrast medium. Try to avoid contact with pregnant women and infants after the examination. You can eat more oranges, green tea, apples, kelp, etc., to reduce the damage caused by PET-CT radiation to the human body.
4. Who should be cautious about PET-CT examination?
Those who have a severe cough.
Mild cough will not affect the effectiveness of PET-CT examination, but severe and persistent cough will cause shaking of the lungs and entire abdomen and blur the image.
Claustrophobia.
Patients with claustrophobia will feel irritability and anxiety about enclosed spaces, and then experience palpitation, shortness of breath, sweating, muscle tension, fainting, etc. A certain amount of muscle relaxant, tranquilizer, or *** should be injected before the examination
Pregnant women and infants.
PET-CT scans produce a certain amount of radiation, which affects the growth and development of infants and fetuses.
People with high blood sugar. High blood glucose concentration will affect the distribution and intake of fluorodeoxyglucose injected during PET-CT examination, resulting in a decrease in the intake of fluorodeoxyglucose in tumors and brain tissues, thus affecting the examination effect. Try to keep your blood sugar at 11 before PET-CTWithin 1mmol L.
Although PET-CT has some radiation, for some patients with indications, the benefits of PET-CT significantly outweigh the risks of radiation. In order to ensure the accuracy of the inspection, please understand the relevant precautions in advance, so as not to affect the inspection effect and delay the opportunity.
5. Precautions after PET CT examination
It should be more after the examinationDrink water, urinate more, promote the timely discharge of the imaging agent with the urine, and reduce the retention time of the drug in the body. You can eat more vegetables and fruits, such as carrots, oranges, strawberries, etc., to supplement nutrition and improve autoimmune function.
Try to avoid contact with minors, pregnant women, and lactating women for 24 hours after the examination.
Collect the inspection report on time, the test result cannot be given on the day of PET CT examination, and it generally takes 1-2 working days.