2, the industry's most profitable is the hospital followed by dealers, sales staff if the ability to be very strong also some gains.
3, the equipment is very expensive, the hospital into the equipment is the number of usual maintenance and product maintenance work is a long-term work.
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MRI
MRI is also known as magnetic **** vibration imaging, the full name of the English language is: Magnetic Resonance Imaging. in the beginning of the birth of this technology was known as the nuclear magnetic **** vibration imaging, to the early 1980s, as a new technology in medicine NMR imaging (NMR imaging) term increasingly familiar to the public. By the early 1980s, as a new medical technology, the term NMR imaging (NMR imaging) was becoming more familiar to the public. With the installation of large magnets, there was concern that the letter "N" might have a negative impact on the development of magnetic **** vibration imaging. In addition, the word "nuclear" tends to give hospital staff an image of another nuclear medicine department in the magneto*** vibration chamber. Therefore, in order to emphasize the advantages of this technique, which does not produce ionizing radiation, and to differentiate it from nuclear medicine, which uses radioactive elements, radiologists and equipment manufacturers have agreed to shorten the term "magnetic resonance imaging" to "magnetic resonance imaging (MRI)". ".
Catalog
Technical features
Principles of operation
Imaging principles
Medical uses
Instrumentation and equipment medical features
Indications for MRI examinations
Abbreviations for MRI examinations
History of magnetic **** vibration technique
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Technical features
Magnetic **** vibration imaging is a type of tomography, which uses the magnetic **** vibration phenomenon to obtain electromagnetic signals from the human body and reconstruct information about the human body.In 1946, Flelix Bloch of Stanford University and Edward Purcell of Harvard University each independently discovered the phenomenon of nuclear magnetic **** vibration. Magnetic **** vibration imaging is based on this physical phenomenon. 1972 Paul Lauterbur developed a method of spatial encoding of nuclear **** vibration signals, which can be used to reconstruct images of the human body.
MRI
Magnetic **** vibration imaging and other tomographic techniques (such as CT) have some **** the same point, for example, they can show the distribution of a certain physical quantities (such as density) in space; but also has its own characteristics, magnetic **** vibration imaging can be obtained in any direction of tomographic images, three-dimensional body images, and even can be obtained in the space of the - spectral distribution of four-dimensional images. -spectral distribution of the four-dimensional image.
Like PET and SPET, the magnetic **** vibration signal used for imaging comes directly from the object itself, and it can be said that magnetic **** vibration imaging is also a kind of emission tomography. However, unlike PET and SPET, magnetic **** vibration imaging does not require the injection of radioisotopes for imaging. This fact also makes the magnetic **** vibration imaging technique safer.
From the magnetic **** vibration image, we can get a variety of physical properties of the material parameters, such as proton density, spin-lattice relaxation time T1, spin-spin relaxation time T2, diffusion coefficient, magnetization coefficient, chemical shifts and so on. Compared with other imaging techniques (e.g. CT ultrasound PET, etc.), magnetic **** vibration imaging is more diverse, the imaging principle is more complex, and the information obtained is more abundant. Therefore, magnetic **** vibration imaging has become a popular research direction in medical imaging.
MRI also has shortcomings. Its spatial resolution is not as good as CT, patients with pacemakers or some metal foreign body parts can not be MRI examination, in addition to the price is more expensive.
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Working Principle
Nuclear magnetic **** vibration is a physical phenomenon, as a means of analysis is widely used in the field of physics, chemistry biology, etc., until 1973 it will be used for medical clinical testing. To avoid confusion with radiographic imaging in nuclear medicine, it is referred to as magnetic *** vibration imaging (MR).
MR is a biomagnetic spin imaging technology, it is the use of atomic nuclei spin motion characteristics, in the applied magnetic field, by radio frequency pulse excitation after the generation of signals, detected with a detector and input into the computer, after computer processing conversion on the screen to display images.
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Imaging principle
Nuclear magnetic **** vibration imaging principle: atomic nuclei are positively charged, and the nuclei of many elements, such as 1H, 19FT, and 31P, etc., undergo spin motion. Normally, the arrangement of the spin axis of the nucleus is irregular, but when placed in an applied magnetic field, the nuclear spin space orientation transitions from disorder to order. In this way, the spinning nucleus simultaneously spins around the vector direction of the applied magnetic field at an angle between the spin axis and the vector direction of the applied magnetic field; this spinning is called Larmor spinning, like the rotation of a spinning gyroscope under the gravity of the earth. The magnetization vector of the spin system grows gradually from zero, and when the system reaches equilibrium, the magnetization strength reaches a stable value. If the nuclear spin system is subject to external effects at this time, such as a certain frequency of radio frequency excitation of the nucleus can cause *** vibration effect. In this way, the spin nucleus but also in the direction of radio frequency spinning, this superposition of the spinning state is called chapter action. In the radio frequency pulse stops, the spin system has been excited nuclei, can not maintain this state, will return to the original arrangement of the magnetic field, while releasing a weak energy, become radio signals, the many signals detected, and make it can be spatially resolved, you get the distribution of atomic nuclei in the movement of the image. Atomic nuclei from the excited state back to the equilibrium arrangement of the process called relaxation process. The time required for it is called relaxation time. There are two types of relaxation time i.e. T1 and T2, T1 is spin-dot-dot or longitudinal relaxation time T2 and T2 is spin-spin or transverse relaxation time.
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Medical uses
The most commonly used nucleus for magnetic **** vibrations is the hydrogen nucleus proton (1H), as it has the strongest signal and is also widely found in human tissues. Factors affecting the magnetic **** vibration image include (a) the density of the proton; (b) the length of the relaxation time; (c) the flow of blood and cerebrospinal fluid; (d) paramagnetic substances (e) proteins. The gray scale of a magnetic **** vibration image is characterized by greater brightness the stronger the signal of magnetic **** vibration, and less brightness when the signal of magnetic **** vibration is weak, ranging from white, gray to black. Various tissue magnetic *** vibration image gray scale characteristics are as follows; adipose tissue, cancellous bone is white; cerebral spinal cord, bone marrow is whitish-gray; viscera, muscle is grayish-white; liquids, the normal rate of flow of blood is black; bone cortex, gas, air-containing lungs is black.
Nuclear magnetic **** vibration of another feature is the flow of liquid does not produce a signal called the flow effect or flow blanking effect. Thus blood vessels are grayish-white tubular structures, while blood is signal-less black. This makes the blood vessels easily soft tissue separated. The normal spinal cord is surrounded by cerebrospinal fluid, which is black, and has white dura mater lined with fat so that the spinal cord appears as a white, strong signal structure. MRI*** vibration has been applied to diagnostic imaging of systems throughout the body. The best results are the cranial brain, and its spinal cord, the heart large blood vessels, joints bones, soft tissues and pelvis. For cardiovascular disease can not only observe the anatomical changes of the chambers, great vessels and valves, but also make ventricular analysis, qualitative and semi-quantitative diagnosis, can be made for multiple cross-sectional maps, high spatial resolution, showing the whole picture of the heart and the lesion and its relationship with the surrounding structures, is superior to other X-ray imaging, two-dimensional ultrasound, nuclide and CT examination. Coronal, sagittal, and cross-sectional images can be made in the diagnosis of cerebrospinal lesions.
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Instrumentation medical characteristics
MR provides not only a greater amount of information than many other imaging techniques in medical imaging, but also different from existing imaging techniques, so it has a great deal of potential superiority for the diagnosis of disease. It can directly make cross-sectional, sagittal, coronal, and various oblique images, and will not produce the artifacts in CT detection; does not require injection of contrast media; no ionizing radiation, no adverse effects on the body.MR is very effective in detecting common cranio-cerebral disorders, such as intracerebral hematomas, extracerebral hematomas, brain tumors, intracranial aneurysms, arterio-venous vascular malformations, cerebral ischemia, intradural tumors, spinal cavernous disease, and hydrocephalus.
The test is also effective in the diagnosis of lumbar intervertebral disc posterior herniation, primary liver cancer and other diseases.
Examination purposes: cranial brain and spinal column, spinal cord lesions, pentacameral diseases, heart disease, mediastinal masses, bone and muscle lesions, uterus, ovaries, bladder, prostate, liver, kidney, pancreas and other parts of the lesions.
Advantages:
1. MRI has no ionizing radiation damage to the human body;
2. MRI can obtain native three-dimensional cross-sectional imaging without the need for reconstruction to obtain multi-directional images;
3. The soft tissue structure is clearly shown on the central nervous system, the bladder, rectum, uterus, vagina, joints, muscles, and other checks are better than the CT.
4. Multi-sequence Imaging, a variety of image types, to clarify the nature of the lesion to provide richer imaging information.
Disadvantages:
1. Like CT, MRI is also a diagnostic imaging, and many lesions are still difficult to diagnose by MRI alone, unlike endoscopy, which can obtain diagnosis of both imaging and pathology;
2. The examination of the lungs is not superior to X-ray or CT, and the examination of liver, pancreas, adrenal glands, and prostate gland is not superior to CT, but the cost is much higher;
3. lesions of the gastrointestinal tract are not as good as endoscopy;
4. diagnosis of bone fractures is not as sensitive as CT and X-ray radiographs;
5. people with metal objects in their bodies should not undergo MRI.
6. critically ill patients should not undergo it.
7. people in their third trimester of pregnancy are not recommended to undergo MRI unless it is necessary.
8. People with pacemakers should not undergo MRI or be near the MRI equipment
9. Most MRI equipment has a closed examination space, and some patients are unable to cooperate with the examination due to fear
10. The examination takes a long time
Cautions
Because of the strong magnetic fields in the MRI machine and MRI room, patients with pacemakers should not undergo MRI unless they have a pacemaker. Generally in hospitals, outside the door of the nuclear magnetic **** vibration examination room, there are red or yellow eye-catching signs indicate that absolutely strictly prohibit the nuclear magnetic **** vibration examination of the situation.
The body can not remove other metal foreign body, such as metal internal fixation, artificial joints, metal dentures, stents, silver clips, shrapnel and other metal deposits, for the examination of the relative contraindication, must be examined, it should be closely observed, in order to prevent the examination of the metal in a strong magnetic field in the movement of the neighboring blood vessels and important tissues, resulting in serious consequences, such as the absence of a special need to not accept the nuclear magnetism*** vibration examination. Vibration examination. The metal contraceptive ring and movable metal dentures must be taken out and then examined.
Sometimes, metallic iron ions left in the body may affect the quality of the image or even the correct diagnosis.
Before entering the nuclear magnetic **** vibration examination room, you should remove cell phones, pagers, magnetic cards, watches, coins, keys, lighters, metal belts, metal necklaces, metal earrings, metal buttons, and other metal jewelry or metal objects that you are carrying on your body. Otherwise, the uniformity of the magnetic field may be affected during the examination, resulting in interference with the image and the formation of artifacts, which is not conducive to the display of the lesion; and due to the strong magnetic field, metal objects may be sucked into the NMR*** vibration machine, thus causing damage to the very expensive NMR*** vibration machine; in addition, cell phones, pagers, magnetic cards, watches and other items may also be damaged by a strong magnetic field, which will result in the unnecessary loss of personal belongings.
Magnetic fields can also damage cell phones, pagers, magnetic cards, watches and other items, causing unnecessary loss of personal property.
MRI
In recent years, with the progress and development of science and technology, there are many orthopedic internal fixation, especially for the spine, began to be made of titanium alloy or titanium metal. Because titanium metal is not attracted by magnetic field, it will not move in the magnetic field. Therefore, patients with titanium internal fixations in their bodies are safe for MR*** vibration examinations; and titanium does not interfere with MR*** vibration images. This is valuable for patients with spinal disorders who require internal spinal fixation surgery. However, titanium alloys and internal fixation made of titanium metal are expensive, which affects its popularization to a certain extent.
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MRI examination indications
1, neurological lesions: cerebral infarction, brain tumors, inflammation, degenerative diseases, congenital malformations, trauma, etc., for the earliest application of the human body system, and has accumulated a wealth of experience in the localization of the lesions, qualitative diagnosis is more accurate and timely, can find early lesions.
2, cardiovascular system: can be used for heart disease, cardiomyopathy, pericardial tumors, pericardial effusion, and attached to the wall of thrombus, endothelial slice of the stripping and other diagnostic.
3, thoracic lesions: mediastinal masses, lymph nodes, and pleural lesions, etc., can show the relationship between the mass in the lungs and the larger airways and blood vessels, etc..
4, abdominal organs: diagnosis and differential diagnosis of hepatocellular carcinoma, hepatic hemangioma and hepatic cysts, diagnosis and differential diagnosis of intra-abdominal masses, especially retroperitoneal lesions.
5. Pelvic organs; uterine fibroids, other tumors of uterus, ovarian tumors, qualitative localization of pelvic masses, masses of rectum, prostate and bladder.
6, bone and joints: diagnosis of infection, tumor, trauma and lesion range in bone, especially for some subtle changes such as bone contusion, etc., have a greater value, intra-articular cartilage, ligament, meniscus, synovium, synovial bursa, etc., and bone marrow lesions have a higher diagnostic value.
7, the whole body soft tissue lesions: whether from the nerves, blood vessels, lymphatic vessels, muscles, connective tissue tumors, infections, degenerative lesions, etc., can make a more accurate localization, qualitative diagnosis.
MRI (Matz's Ruby Interpreter)
Standard Ruby implementation, standard Ruby interpreter
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MRI examination abbreviation
MRA
MR angiography, divided into those using a contrast agent and those not using a contrast agent.
MRCP
MR cholangiography, which shows the intra- and extrahepatic bile ducts and the gallbladder to determine the presence of stones and biliary dilatation.
MRU
MR urologic imaging, showing the ureters and bladder, to determine the presence of diseases such as dilatation and malformations of the urinary tract.
MRM
MR neuroimaging, which is primarily utilized in the diagnosis of peripheral nerve disease.
Disadvantages MR has its shortcomings. Its spatial resolution is not as good as CT, and patients with pacemakers or certain metal foreign bodies cannot be examined with MR. In addition, it is relatively expensive and takes a long time to scan
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History of MRM
History of MRM
In the 1930s, the physicist Isidore Labi discovered that the nuclei of atoms in a magnetic field would be arranged in a forward or reverse ordered parallel arrangement along the direction of the magnetic field, and that the spin direction of the nuclei flipped after the application of radio waves. This was the earliest human understanding of the interaction of atomic nuclei with magnetic fields and applied radiofrequency fields. For this research, Rabi was awarded the Nobel Prize in Physics in 1944.
In 1946, two U.S. scientists Bloch and Purcell found that the nucleus with an odd number of nuclei (including protons and neutrons) placed in a magnetic field, and then applied to a specific frequency of the radio frequency field, the nucleus will be absorbed by the phenomenon of the radio frequency field energy absorption, which is the initial understanding of the phenomenon of nuclear magnetic **** vibration. For this the two of them won the 1950 Nobel Prize in Physics.
People in the discovery of nuclear magnetic **** vibration phenomenon soon after the practical use of chemists to use the molecular structure of hydrogen atoms around the magnetic field generated by the development of nuclear magnetic **** vibration spectroscopy, used to analyze the structure of the molecule, over time, the nuclear magnetic **** vibration spectroscopy technology continues to evolve from the initial development of a one-dimensional hydrogen spectra to the 13C spectra, two-dimensional nuclear magnetic **** vibration spectra and other high-level spectroscopy. The ability of NMR*** vibration technology to analyze molecular structure is also getting stronger and stronger, and after entering the 1990s, people even developed the technique of relying on the NMR*** vibration information to determine the tertiary structure of protein molecules, which makes it possible to accurately determine the molecular structure of solution-phase proteins.
On the other hand, medical scientists have found that hydrogen atoms in water molecules can produce NMR*** vibration phenomenon, using this phenomenon to obtain information on the distribution of water molecules in the human body, so as to accurately map the internal structure of the human body, on the basis of the theory, in 1969, State University of New York, Southern Medical Center of the Medical Doctor Dharmadiyan through the measurement of the NMR*** vibration of the relaxation time of the mice will be successfully separated from normal tissue cells. Inspired by Damadian's new technique, Paul Lauterburgh, a physicist at the State University of New York at Stony Brook, developed an imaging technique based on the phenomenon of nuclear magnetic **** vibration (MRI) in 1973, and applied his equipment to successfully map the internal structure of a living clam. After Lauterpacht, MRI technology has become increasingly sophisticated and widely used as a routine medical test for the treatment and diagnosis of Parkinson's disease, multiple sclerosis and other brain and spinal lesions, as well as cancer. 2003, Paul Lauterpacht and Peter Mansfield, a professor at the University of Nottingham in the United Kingdom, were awarded the Nobel Prize in Physiology or Physiology in 2003 for their contributions to MR*** vibrational imaging. Nobel Prize in Physiology or Medicine that year.