What is ECT? What is the harm to human body?

This is an inspection method using radionuclides. The basic principle of ECT imaging: radioactive drugs are introduced into human body, and after metabolism, radioactive concentration difference is formed inside and outside organs or between diseased parts and normal tissues. These differences will be detected by computer and re-imaged. ECT imaging is a highly specific functional imaging and molecular imaging, which not only displays the structure, but also pays more attention to providing functional information of organs and normal tissues. The imaging mode of ECT is very flexible, which can be used for plane imaging and tomography, static imaging and dynamic imaging, local imaging and whole body imaging. In addition, it can provide various functional parameters of organs, such as time-radiation curves, and provide multi-directional information for the diagnosis and treatment of tumors. It is mainly used for the examination of thyroid cancer, bone and other tumors, especially the detection of bone metastases, which can find lesions 3-6 months earlier than ordinary X-ray films. So for some cancers that are prone to bone metastasis. Such as breast cancer, lung cancer, prostate cancer and esophageal cancer. Even if there is no bone pain, it can be examined before or after operation in order to find metastasis early. However, we must pay attention to osteitis, blood flow changes, fracture repair, joint degeneration, bone deformity, metabolic bone lesions, etc., and we must distinguish them.

Structure and working process of ECT: It has a probe for detecting nuclear rays (gamma rays), a bracket for fixing the probe and rotating in all directions, and a central console with system programs (a high-performance electronic computer with 16 ~ 64 bits for high-speed operation and mass data processing and storage). Under the control of the acquisition program, the gamma rays emitted from the target organ are collected by the probe, amplified by crystal light (turned into visible light) and guided to the cathode of the photomultiplier tube (generally 50 ~ 107 in the matrix arranged on the light guide surface of the crystal surface), converted into electric pulse signals, and transmitted to the computer according to the position specified by the position decoder, and the computer converts the signals into analog-to-digital (A/D) signals. Under the control of the processing program, the computer will carry out D/A conversion and project an image on the screen according to the pixels in the direction of the signal source. This image is a single plane image (two-dimensional) with overlapping information and high ambiguity. It is only suitable for small organ imaging or dynamic imaging, and it is difficult to observe deep structures. If the probe rotates around the target organ and carries out multi-plane acquisition, a three-dimensional image, the so-called ECT image, can be obtained. This image is sliced according to a certain thickness, and the distribution images of the developer in different directions and different depth planes can be observed.

ECT classification:

(1)SPECT, that is, single photon emission computed tomography. It uses 99mTc, 133I, 67Ca, 153Sm and other single photon emission nuclide drugs for inspection. The basic structure of SPECT is divided into three parts, namely rotating probe device, electronic circuit and computer system for data processing and image reconstruction. SPECT can not only show the tumor focus, but also show the changes of local organ function, such as the changes of left heart function and renal function after chemotherapy.

(2)PET, namely positron emission computed tomography. As the name implies, check with radionuclide drugs that emit positrons. Common nuclides are: 18F, 1 1C, 13N, 15O, etc. PET is mainly used to study glucose metabolism, protein production orientation and oxygen metabolism in diseased tissues, and it is widely used in oncology. At present, the most widely used is the early diagnosis of tumor and the identification of residual mass after treatment. It is often difficult to distinguish brain tumor from residual tumor of nasopharyngeal carcinoma after radiotherapy or lymphoma chemotherapy from tumor of lung and mediastinum, but it is easy to distinguish its nature by using 18F and fluorooxyglucose (18F, FDG) as PET imaging. For example, if the lesion ingests 18F-FDG, it indicates that there are still living cancer cells in the lesion, suggesting recurrence; If 18F-FDG is negative, it is fibrosis.

Inspection method and scope of application

Select methods according to clinical needs, including static and dynamic imaging; Plane and fault imaging; Local and whole body imaging; Motion and rest imaging. Now introduce their methods and scope of application:

Static imaging refers to collecting the total radioactive distribution image of an observation surface in a certain period of time. It is mostly used for imaging small organs and roughly observing the shape, position, size, radioactive distribution and space-occupying lesions of an organ. Such as thyroid imaging, costal gland imaging, static plane imaging of brain, lung, heart, liver, pelvic cavity, spleen and kidney, location of gastrointestinal bleeding, imaging of Meckel's diverticulum, lymph nodes, transplanted organs, pancreas, adrenal gland, testis, prostate and other organs. Because of its simple method and wide application range.

Dynamic imaging refers to the continuous time-sharing acquisition of the observation surface of an organ in order to obtain dynamic plane images at different times. These images can provide information about the region of interest (ROI) at different times, and can also show the activities of target organs in movies. Due to the introduction of "time-radioactivity curve", this concept is very suitable for judging organ function. Such as: thyroid, brain, heart, liver, kidney, gastric emptying, bone uptake, liver and gallbladder and other functional indicators.

R-wave triggered imaging controlled by cardiac blood pool gate circuit is also a kind of dynamic imaging, that is, R-wave triggered imaging is used to collect radioactive information at different time points in a cardiac cycle, and Fourier function is used to fit the cardiac volume curve. From this curve, a series of indexes of cardiac systolic and diastolic function can be obtained respectively. Recently, it has been reported that this method is used in lung imaging to obtain the pulmonary function diagram of respiratory movement cycle.

Plane imaging, that is, two-dimensional imaging, can only observe one surface at a time, as opposed to tomography (three-dimensional). It should include static plane, dynamic plane, local plane, motion plane and static plane imaging. Because there is no one-time whole-body tomography at present, whole-body imaging is called "whole-body XX", such as "whole-body bone imaging" instead of "whole-body bone plane imaging".

Tomography is to rotate the target organ 360 degrees (or 180 degrees) to collect multi-plane information, and then process the image with a computer (reconstruction, slicing, magnification and projection) to obtain cross-sectional images with a certain thickness and different observation surfaces and depths. This kind of image computer can combine them into a stereoscopic image (rotating in different directions and at different speeds for observation). It is most suitable for imaging large organs, such as brain, heart, lung and liver, and analyzing occupying lesions, blood supply and organ volume measurement. Cerebral blood perfusion tomography has unique advantages in the diagnosis of cerebral ischemic diseases and epilepsy. Myocardial perfusion tomography is a noninvasive method for diagnosis of coronary heart disease, myocardial infarction and prognosis judgment, which is closest to the effect of catheterization.

Contrary to whole-body imaging, local imaging covers a wide range. Local plane imaging of each organ and various inspection methods are called local imaging.

Whole-body imaging refers to the whole-body collection of radioactive distribution information after the imaging agent enters the human body to obtain the whole-body distribution image. Such as: whole body bone imaging, whole body blood pool imaging, whole body lymph imaging, whole body soft tissue imaging, whole body tumor marker imaging and drug distribution imaging in animal experiments. "General survey" is very valuable for finding metastatic focus of malignant tumor. Whole-body bone imaging can find the metastatic focus in the early stage in the cases that are most prone to bone metastasis, such as nasopharyngeal carcinoma, lung cancer, breast cancer, intestinal cancer and flexion adenocarcinoma. It is also important for the decision-making of surgical treatment (such as amputation).

Exercise (stress) imaging, that is, exercise imaging, just like the "exercise test" of ECG, is an imaging method to collect the distribution information of radionuclide imaging agent in the target organ (mainly the heart) under load. As far as the heart is concerned, there are cardiac blood pool gated imaging and myocardial gated imaging; Myocardial and blood pool tomography; Control layer imaging of myocardium and blood pool. The latter is difficult to be widely used because of too much information, troublesome processing and large data storage, and some of them are not worth the candle. At present, the most commonly used are "gated planar imaging of cardiac blood pool" and "myocardial perfusion tomography". These two sets of data, combined with exercise and rest control, are comprehensive enough, and some of them use drug control, which can provide some effective parameters, such as the determination of recoverable myocardial cells (viable myocardium) after myocardial infarction, which is of great clinical value.

Still imaging shows the uptake and distribution of radionuclide imaging agent by the heart when the patient is still. It is usually used in combination with motion imaging.

What should I pay attention to when accepting ECT inspection:

1, cerebral blood flow tomography: 1 and 2 days before examination, patients should stop using cerebrovascular dilators as much as possible to increase the sensitivity of examination. Take potassium perchlorate orally 30-60 minutes before injection of imaging agent to seal choroid plexus and thyroid gland to reduce interference. 5- 10 minutes before and after the injection, the patient should rest as much as possible, reduce the sound and light stimulation, stay in bed, keep calm, and wear an eye mask and earplugs until about 10 minutes after the injection of the imaging agent. The head can't move during the inspection to ensure the authenticity of the image.

2. Myocardial perfusion imaging: Nitroglycerin, Yishunmai, Di 'ao Xinxuekang and other drugs should be stopped the day before examination. It is best to stop using propranolol, propafenone, betaloc, verapamil, metoclopramide and other drugs in the first two days. Those who carry out myocardial drug load test should stop using dipyridamole, dobutamine and aminophylline 24 hours ago. Breathing should be kept steady during the examination to reduce the interference of diaphragm movement on myocardial imaging. The person who installs a pacemaker should inform the doctor 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. Empty urine before examination. If urine stains clothes and skin, scrub skin and change clothes and pants before inspection. If there is a metal prosthesis or breast implant, the doctor should be informed of the implantation site. Barium meal and barium enema should not be done two days before examination. So as to prevent barium from staying in the intestine and affecting image observation.

4. Determination of glomerular filtration rate: Diuretics, such as hydrochlorothiazide and furosemide, should be stopped as much as possible in the first three days. Drink about 300ml of water 30 minutes before the examination, and empty urine during the examination.

5. Imaging of esophageal motor function and determination of gastric emptying: Before the examination, the patient should fast for 6- 12 hours, and stop using atropine, propranolol, desshute, Ding Jingning, cimetidine, famotidine and gastric motility drugs such as motilin and prebos according to the doctor's advice.

6. Thyroid imaging: stop using iodine-containing drugs and foods rich in iodine, such as kelp, seaweed, seawater fish and shrimp, and stop using thyroid tablets according to the doctor's advice. Those who use iodine contrast media cannot be examined for at least three weeks.

In case of children or patients who do not cooperate with the examination, sedatives can be used before the examination. If you can't cooperate with the examination because of pain, you can use painkillers in advance. Before the inspection, the metal objects worn by the inspected parts, such as jewelry, metal buttons, belts, keys, coins, etc. , should be deleted.

Because most of the drugs used in ECT examination are excreted through urine, drinking more water after examination can accelerate the discharge of drugs.

If you think this entry needs improvement, adding new content or modifying wrong content, please edit it.

References:

1. nuclear medicine

2. World medical equipment

3. Nuclear Medicine Forum

Contributor (***2):

Little Wuhou who swallowed Gan Kun, didn't move.

This entry is mentioned in the following entries:

the second affiliated hospital of harbin medical university

The definition of "ECT" in English-Chinese dictionaries (source: Baidu Dictionary);

Electroconvulsive therapy

Abbreviations.

1. electroshock therapy

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