It is an examination method using radionuclides.The basic principle of ECT imaging: radiopharmaceuticals are introduced into the human body, and after metabolism, differences in radioactivity concentration are formed between inside and outside the organ or between the lesion site and the normal tissues, which will be detected and re-imaged by computer processing.ECT imaging is a functional imaging and molecular imaging with high specificity. ECT imaging is a kind of functional imaging and molecular imaging with high specificity, in addition to displaying the structure, it focuses on providing the functional information of organs and endogenous tissues.ECT imaging is very flexible, and it can carry out planar imaging and tomographic imaging, static imaging and dynamic imaging, localized imaging and whole-body imaging. In addition, it can also provide various functional parameters of organs, such as time-radiation curves, etc., which can provide multi-faceted information for the diagnosis and treatment of tumors. It is mainly used for the examination of thyroid cancer, bone and other parts of the tumor, especially commonly used in the detection of bone metastatic tumors, which can be detected 3-6 months earlier than the ordinary X-ray film. Therefore, for some cancers that are more likely to have bone metastasis. Such as breast cancer, lung cancer, prostate cancer, esophageal cancer, etc., even if there is no bone pain, it can be used for preoperative or postoperative examination, with a view to early detection of metastatic foci. However, it must be noted that inflammation of bone, blood flow changes, fracture repair, joint degeneration, bone deformity and metabolic bone lesions can also show positive results, which should be distinguished.
ECT structure and work process: it has a special detection of nuclear radiation (γ-ray) probe, fixed probe and can be rotated in all directions of the bracket, equipped with the system program of the central console (can run at high speed and a large number of high-performance data processing and storage of electronic computers, 16 ~ 64-bit). Under the control of the acquisition program, the probe collects the γ-rays emitted from the target organ, the crystal light amplification (into visible light) directed to the cathode of the photomultiplier tube (P.M.T.) (matrix arrayed on the surface of the crystal on the photoconductive surface, often 50 to 107 branches), converted into electrical pulse signals, according to the position of the position translator specified position transported to the computer, the computer will be the signal by the analog/digital (A/D) into digital Stored. Under the control of the processing program, the computer will carry out digital / analog (D / A) conversion, according to the source of the signal pawn marking the orientation of the pixel (pixel) points on the screen projected into an image. This image is a single plane image (two-dimensional), information overlap, blurring, only for small organ imaging or dynamic imaging, for deep structure observation is more difficult. If the probe is rotated with the target organ as the center, multi-plane acquisition, then three-dimensional images can be obtained, the so-called ECT image. This kind of image according to a certain thickness of cut layer, can observe different orientation, different depth of the plane of the image agent distribution image.
ECT classification:
(1) SPECT, i.e., single photon emission tomography. It uses single-photon emitting nuclide drugs such as 99mTc, 133I, 67Ca, 153Sm, etc. The basic structure of SPECT is divided into 3 parts, i.e., the rotating probe device, the electronic circuit, the computer system for data processing and image reconstruction.In addition to displaying the tumor foci, SPECT can also show the changes in the function of the local organs, such as: the left cardiac function and renal function after chemotherapy. SPECT is a computerized system that can be used for the reconstruction of images of tumor lesions.
(2) PET is a positron emission tomography (PET) scanner. As the name implies, it is the use of positron-emitting nuclide drugs for examination. Common nuclides such as: 18F, 11C, 13N, 15O, etc. PET is mainly used for the study of glucose metabolism, protein generation and oxygen metabolism of lesion tissues, and is most widely used in the field of oncology. Currently, it is most used for early diagnosis of tumors and identification of residual masses after treatment. It is often difficult to identify residual masses after radiotherapy or chemotherapy for brain tumors and nasopharyngeal carcinoma, as well as lung and mediastinal masses, etc. However, it is very easy to differentiate the nature of these masses by using PET imaging with 18F, flurodeoxyglucose (18F, FDG). If 18F-FDG is taken from the lesion, it indicates that the lesion has residual viable cancer cells, suggesting recurrence; if the 18F-FDG examination is negative, it is fibrosis.
Methods and scope of application
Selecting methods according to clinical requirements, there are static and dynamic imaging; planar and tomographic imaging; localized and whole-body imaging; and motion and resting imaging. The respective methods and their scope of application are introduced:
Static imaging refers to the acquisition of images of the total distribution of radioactivity on an observation surface over a certain period of time. It is mostly used for small organ imaging and rough observation of the morphology, location, size and radioactive distribution of an organ, as well as the analysis of locoregional lesions. Such as: thyroid imaging, rib gland imaging, brain, lungs, heart, liver, pelvis, spleen, kidney static plane imaging, gastrointestinal hemorrhage localization, Meckel's diverticulum, lymph nodes, transplanted organs, pancreas, adrenal glands, testes, prostate and other organs imaging, because of its simple method, the scope of application of the broader.
Dynamic imaging refers to the continuous time-sharing acquisition of a certain observation surface of an organ to obtain dynamic planar images at different times, which can provide region of interest (ROI) information at different times, and can also be used to cinematographically display target organ activity. Due to the introduction of the "time-radioactivity curve", the concept is very suitable for the judgment of organ function. For example, functional indicators of thyroid, brain, heart, liver, kidney, gastric emptying, bone uptake, liver and gallbladder.
Cardiac blood pool gated circuit control R-wave triggering (referred to as gating) imaging also belongs to a dynamic imaging, that is, R-wave triggering acquisition of a cardiac cycle of different periods of radioactive information, with the Ribbon function synthesized by fitting the heart volume curve. From this curve, a series of indicators of systolic and diastolic function of the heart can be obtained separately. Recently, this method has been reported to be used in lung imaging to obtain pulmonary function maps during the respiratory cycle.
Planar imaging, or two-dimensional imaging, is the opposite of tomographic (three-dimensional) imaging, in which only one plane is observed at a time. Should include static plane, dynamic plane, local plane, motion plane and resting plane image, because at present can not carry out a one-time whole body tomography, so the whole body image is called "whole body XX" such as "whole body bone image" should not be called The whole body is called "whole body XX", such as "whole body bone image", not "whole body bone plane image".
Tomography, is the target organ 360 degrees (or 180 degrees) rotation collection of multi-planar information, computer image processing (reconstruction, cut layer, magnification, projection) to get a certain thickness of the different observation surface and depth of the cross-section image. This kind of image computer can combine them into a stereogram (rotated in different directions and rotated at different speeds for observation). It is most suitable for large organ imaging, such as: brain, heart, lungs, liver, etc., to analyze space-occupying lesions, blood supply, and organ volume measurement. Cerebral perfusion tomography diagnosis of cerebral ischemic disease and epilepsy has a unique superiority; myocardial perfusion tomography diagnosis of "coronary heart disease", myocardial infarction and prognosis judgment, is the closest to the catheterization of the effect of a non-invasive inspection method.
Local imaging, is relative to the whole body imaging, which includes a wide range of local plane imaging, where each organ respectively, a variety of inspection methods are called local imaging.
The whole-body imaging refers to the whole body after the imaging agent enters the body, the whole body to collect the distribution information of radioactivity, to obtain the whole body distribution image. Such as: whole-body bone imaging, whole-body blood pool imaging, whole-body lymphatic imaging, whole-body soft tissue imaging, whole-body tumor marker imaging and animal experiments in the whole-body distribution of drugs imaging and so on. Whole-body bone imaging is very valuable for finding metastases of malignant tumors. Whole-body bone imaging can detect metastases at an early stage in the cases of nasopharyngeal cancer, lung cancer, breast cancer, intestinal cancer, anterior fissure adenocarcinoma and other cases that are most likely to metastasize to the bone. It also plays an important role in the decision of surgical treatment (e.g. amputation).
Exercise (loading) imaging, or loading imaging, is like the "exercise test" of the electrocardiogram (ECG), and is a method of capturing information about the distribution of the nuclide imaging agent in the target organ (mainly the heart) during loading conditions. In the case of the heart, there are myocardial gated imaging and myocardial gated imaging; myocardial and myocardial pool tomography; and myocardial and myocardial pool gated control layer imaging. The latter due to the amount of information is too large, processing annoyance lock, data storage, some of the loss is not worth it, difficult to be widely used. At present, the most commonly used is "cardiac blood pool gated control plane imaging" and "myocardial perfusion tomography". These two groups of information plus exercise and resting control is already comprehensive enough, and some use drug control, can provide some effective parameters, such as myocardial infarction can be recovered cardiomyocytes (surviving myocardium) determination is very clinically valuable.
Resting imaging, which shows the uptake and distribution of nuclide imaging agents by the heart while the patient is at rest, is often used in conjunction with exercise imaging. It is often used in conjunction with exercise imaging.
What to pay attention to when receiving ECT:
1. Cerebral blood flow tomography: 1 or 2 days before the test, patients try to stop taking cerebral vascular expanding drugs, in order to increase the sensitivity of the test. 30-60 minutes before the injection of imaging agent should follow the doctor's instructions oral potassium perchlorate, in order to close the choroid plexus and the thyroid gland, to reduce interference. Before and after the injection 5-10 minutes, patients try to rest, reduce sound and light stimulation, bed rest to keep calm and wear eye masks and earplugs until about 10 minutes after the injection of the imaging agent. The head should not move during the examination to ensure the authenticity of the image.
2, myocardial perfusion imaging: the day before the examination should be discontinued nitroglycerin, easy Shun pulse, Dio cardiovascular and other drugs. If the exercise load test, it is best to stop the use of cardiac glycosides, cardioplegia, bethanechol, isobarbital, methoxyethanol and other drugs in the first two days. For myocardial drug loading test, drugs such as Pansentin, Dobutamine and Aminophylline should be discontinued 24 hours before the test. Breathing should be kept steady during the examination to minimize the interference of septal muscle movement on myocardial imaging. Those with cardiac pacemakers should inform their doctors for reference in image analysis.
3. Whole-body bone imaging: Try to drink more than 500ml of water within 2 hours after injection of imaging agent. The patient should empty the urine before the examination. If there is any urine contamination of clothing or skin, the skin should be scrubbed and the clothing should be changed before the examination. If you have implanted metal prostheses or breast implants, please inform the doctor of the implanted parts. You should not take barium meal or barium enema two days before the examination. The barium may be retained in the intestines and affect the image observation.
4, glomerular filtration rate measurement: three days before the test, stop using diuretics, such as dihydroketonuria, tachycardia, and so on. Drink about 300 ml of water 30 minutes before the test and empty the urine during the test.
5, esophageal motility imaging and gastric emptying: patients should be fasted for 6-12 hours before the examination and discontinue the use of atropine, cardiac painkillers, desipramine, spasmolytics, cimetidine, famotidine, and gastric stimulant drugs, such as morphine, Prevacid, and so on, according to the doctor's instructions.
6, thyroid imaging: stop using iodine-containing drugs and iodine-rich foods, such as kelp, seaweed, marine fish and shrimp, and stop using thyroid tablets. Those who use iodine contrast should wait at least three weeks before having the test.
In case of pediatric or uncooperative patients, sedatives can be used before the examination. Analgesics can be used beforehand if the patient is unable to cooperate with the examination due to pain. Before the examination should be removed from the examined part of the metal objects worn, such as jewelry, metal buttons, belts, keys, coins, etc..
Because most of the drugs used in ECT are excreted in the urine, drinking plenty of water after the test can speed up the elimination of the drugs.
If you think this entry needs to be improved, new content needs to be added, or incorrect content needs to be corrected, please edit the entry
References:
2. World Medical Devices
3. Nuclear Medicine Forum
Contributors (***2):
Sleeve swallowing Qiankun Xiaowuhou, yo immovable
This entry was mentioned in the following entries:
The Second Affiliated Hospital of Harbin Medical University
"ECT" in the English-Chinese dictionary (source:Baidu Dictionary):
ECT
abbr.
1. =electroconvulsive therapy Electroconvulsive therapy
Comments about this entry (***0 comments ): post a comment>>