What is the difference between X ray film CT MRI

X-ray, CT and MRI are all imaging methods, but also the main basis for diagnosing orthopedic diseases, many people do not understand their differences, only know that there is a high and low distinction in the **, people who do not understand the situation usually ask to check a cheaper X-ray when seeing a doctor, and feel that the effect is the same. In fact, they are so different in **, it is enough to show that there is a big difference between them, but not the more expensive the better, the focus of different examination methods is different, take cervical spine diseases as an example, X-ray, CT and MRI can not detect the lesions. What is the difference between X-ray, CT, and MRI?

1. Magnetic resonance imaging In the examination and diagnosis of neck diseases, if it is to understand the soft tissue diseases that make up the cervical spine (cervical spondylosis, cervical disc herniation, cervical tuberculosis, cervical space infection, cervical spine tumor, cervical spinal cord lesion, etc.), magnetic resonance examination is superior to other examination methods. 2. CT If it is to understand the bony structural lesions of the cervical spine (cervical spinal stenosis, ossification of the posterior longitudinal ligament, cervical fracture, congenital deformity of the cervical spine, cervical facet joint hyperplasia), the CT examination of the cervical spine is superior to other examination methods. 3. X-ray If the stability and physiological curvature of the cervical spine or the general examination of cervical spine diseases are understood, the X-ray examination of the cervical spine is preferred.

Through the above introduction, you can understand the difference between these three examination methods, so when you see a doctor, don't blindly ask for only X-rays, refuse the doctor's request to check CT or MRI, the doctor is after the physical examination, according to your signs and further choose the examination method, to believe the doctor, in order to find the root of the disease, as soon as possible**. Recommended reading: Self-test methods for different types of cervical spondylosis (**).

X-ray, B-ultrasound, CT, MRI, these differences are in ** 1

When you have certain diseases, you need to go to the hospital for examination, and for the diagnosis of certain diseases, you will use some necessary instruments and examination methods, such as CT and MRI examinations. But some friends can say that they can't tell the difference between the two kinds of examinations, so what is the difference between CT and MRI?

Difference 1: The image characteristics are different. The reaction of NMR is that the hydrogen proton resonance signal intensity in the tissue is different, and multiple parameters will be reflected due to multiple sequences, including t1 value and t2 value.

CT, on the other hand, reflects the difference in tissue density and reflects a single parameter, for example, the black part of the CT image represents the low-density tissue, while the white part of the image represents the high-density tissue.

Difference 2: The imaging principle is different. CT is the use of different tissues in the human body, there are different degrees of absorption of X-rays, and then the detector receives the remaining X-rays, and then it will be processed by the computer, so that the absorption coefficient of different tissues can be obtained, and then reflected into an image, and it has a certain degree of radiation, but it will be in a safe dose range, so don't worry.

Nuclear magnetic resonance (NMR) uses hydrogen protons in the human body to generate signals through the combined action of an external magnetic field and radio frequency pulses, and then reconstructs an image through a computer, which is not radioactive.

Although the three types are all radioactive substances for the detection of the human body, the effect and cost of the detection are different, and the places of inspection are also different, and the results of the examination will also be different and different.

That is, some of the contents they inspect are different, and some of the details of the inspection are also very different, although they are all inspection items, but the scope of responsibility is different.

MRI is magnetic

resnane

The abbreviation of iamge, Chinese for magnetic resonance imaging. MRI is to place the human body in a strong magnetic field, excite hydrogen protons in the human body through radiofrequency pulses, and then receive the nuclear magnetic resonance signal sent by the proton, through the gradient field three directions of positioning, and then through the computer calculation, constitute an image of all directions. Because the X-ray tube and detector rotate around a certain part of the human body, CT can only do cross-sectional scanning imaging of the human body, while MRI can do cross-sectional, sagittal, coronal and arbitrary section imaging.

MRI can form a variety of images from different scanning sequences, such as T1 weighted image, T2 weighted image, proton density image, etc., as well as water imaging, water inhibition imaging, fat inhibition, diffusion imaging, spectral imaging, functional imaging, etc., CT can only distinguish tissues with density difference, and the resolution of soft tissues is not high, while MRI has good resolution for soft tissues, such as muscle, fat, cartilage, fascia and other signals are different. Therefore, CT and MRI are completely different examination methods.

Can MRI replace CT? No. Despite its many advantages, MRI is a very different imaging method from CT, resulting in a very different image.

MRI can be multi-directional imaging, no harm to the human body, has good resolution of soft tissues, has a variety of imaging methods, not only the image reflects the anatomy of the human body, but also can provide physiological, pathological, biochemical information, is considered to be imaging at the molecular level and many other advantages, but in the hydrogen proton deficiency or little content of tissues such as dense bones, calcifications, gas-containing lungs, etc., can not be imaged. Due to the long MRI imaging time, patients in coma and agitation cannot obtain clear images, and of course, patients with metal foreign bodies in the body cannot enter the magnetic field, which is a contraindication. So MRI also has insurmountable shortcomings, it can't replace CT, of course CT can't replace MRI, the two should complement each other, that's why sometimes MRI has to be done, or CT has to be done and MRI is done.

Magnetic resonance imaging (MRI) is also known as magnetic resonance imaging. It is another major advance in medical imaging after CT. Since its application in the 80s, it has developed at a breakneck pace.

Its basic principle: it places the human body in a special magnetic field, and uses radio frequency pulses to excite the hydrogen nuclei in the human body, causing the hydrogen nuclei to resonate and absorb energy. After stopping the RF pulse, the hydrogen nucleus emits a radio signal at a specific frequency, and releases the absorbed energy, which is collected by a receiver in vitro and processed by an electronic computer to obtain an image, which is called MRI.

Nuclear magnetic resonance (NMR) is a physical phenomenon that was widely used as an analytical method in the fields of physics, chemistry and biology, and it was not until 1973 that it was used for medical clinical testing. To avoid confusion with radiological imaging in nuclear medicine, it is referred to as magnetic resonance imaging (MR).

MR is a kind of biomagnetic spin imaging technology, which uses the characteristics of the spin motion of the atomic nucleus, in the applied magnetic field, after being excited by radio frequency pulses, to generate a signal, detect it with a detector and input it into a computer, and display the image on the screen after processing and conversion.

MR not only provides more information than many other imaging procedures in medical imaging, but also differs from existing imaging procedures, so it has great potential advantages for the diagnosis of diseases. It can directly make cross-sectional, sagittal plane, coronal plane and various inclined plane body layer images, without producing artifacts in CT detection; No injection of contrast is required; There is no ionizing radiation, and there is no adverse effect on the body. MR is very effective in detecting common brain diseases such as intracerebral hematoma, extracerebral hematoma, brain tumor, intracranial aneurysm, arteriovenous vascular malformation, cerebral ischemia, neuraxial tumor, syringomyelia and hydromyelosis, as well as for the diagnosis of lumbar intervertebral disc protrusion and primary liver cancer.

MR also has shortcomings. Its spatial resolution is not as good as CT, and it is not possible to perform MR examination in patients with pacemakers or parts with certain metal foreign bodies, and it is more expensive.

Ask questions to check for tumor risk.

Answer: PET-MRI does not have any radiation damage to the human body, and reduces the radiation dose received by patients in addition to imaging drugs to a certain extent; At the same time, its soft tissue resolution is much higher than that of CT, which can better provide anatomical fine information. Therefore, PET MRI is currently the best health examination and cancer screening equipment.

CT is computer

The abbreviation of Tomography means Computed Tomography. It is a computer-controlled X-ray scan of the human body. It is used to compare the different densities of human tissues on X-rays for diagnostic purposes.

Magnetic resonance imaging (MRI) is an imaging technique that reconstructs images by collecting signals generated by magnetic resonance phenomena, so it is also called spin tomography and magnetic resonance CT. It is suitable for the examination of different diseases of almost all systems of the body, such as tumors, inflammation, trauma, degenerative diseases, and various congenital diseases. Findings of cranial, spine, and myelopathy are superior to CT.

It also has a soft tissue resolution several times higher than CT, and is sensitive to detect changes in water content in tissue composition, so it is often more effective and earlier than CT to detect lesions. MRI can clearly and comprehensively show the heart chambers, myocardium, pericardium and other small structures in the heart, which is a reliable method for diagnosing various heart diseases and cardiac function tests.

Compared with CT, it has unique advantages such as no radiation damage, no bony artifacts, multi-faceted and multi-parameter imaging, high soft tissue resolution, and no need to use contrast media to show vascular structures. It can visualize lesions that cannot be visualized by CT, which is another major development in the field of medical imaging.

Ask the doctor specifically, the MRI visibility is clear, and the cost is more.

For X-ray, CT, B-ultrasound, and magnetic resonance imaging (MRI), which are commonly used, it is not clear at all. Today, we will compare the body to food, and tell you in an easy-to-understand way how these tests work differently!

X-rays look like bread is flattened.

The X-ray will pass through the human body and encounter the occluded part, but it will not be ** on the negative, and this part will be white after the film is washed.

It's like a slice of bread or a piece of cotton, you can't see the fiber texture inside, but it will be clearer when you press it by hand. The biggest disadvantage of X-rays is that the images of the deep and shallow tissues overlap and hide each other, and sometimes it is necessary to take X-rays from multiple angles.

The CT image is that the X-ray will pass through the human body in layers, and then the computer will calculate and then take a second image.

It's like cutting a slice of bread into slices. The advantage is that it can be viewed hierarchically, and more organizational information can be displayed after calculation. The principle of B-ultrasound is to use ultrasound waves to penetrate the human body, and when the sound waves encounter human tissues, reflected waves will be generated, and the reflected waves will be imaged by calculating the reflected waves.

It's like picking a watermelon, knocking and looking at the lesion.

The magnetic field of the magnetic resonance machine uses a strong magnetic field to make the magnetic field of all water molecules in the human body consistent, and then the magnetic field of the magnetic resonance machine suddenly disappears, and the magnetic field line direction of the water molecules in the body suddenly returns to the original state of random arrangement. After repeated application of the magnetic field and then abruptly disappearing, the MRI machine will obtain sufficient data and calculate the image. To put it simply, it is equivalent to shaking it with your hand, letting the water molecules vibrate, and then calming down and feeling the vibrations inside.

Therefore, the MRI is also jokingly referred to as a shaky examination. During the visit, doctors often prescribe a variety of imaging tests: ultrasound, CT, MRI, ......Many patients will question the doctor's deliberate prescription.

In fact, doctors choose different imaging tests according to different conditions.

For all kinds of trauma, if it is suspected that the bone has been injured, X-ray** is preferred, and the examination results are quick and easy to obtain. For further observation, CT can be selected. Ultrasound and MRI are not very clear for the bone cortex and medulla, so they are generally not selected.

Intervertebral disc diseases such as cervical spondylosis and lumbar disc herniation require observation of the intervertebral disc and the corresponding nerve roots, and the best choice is MRI to better observe these soft tissues. Similarly, for joint, muscle, and adipose tissue examinations, MRI is also preferred.

CT belongs to density imaging, which is an image of the difference in density generated by the post-processing system after X-rays penetrate the human body, because the density of different tissues of the human body is different, the absorption rate of the rays is different. Radiation has certain harmful effects on the human body. The advantages are fast inspection speed and good density resolution.

2. Nuclear magnetic resonance is the imaging of water quality protons, which uses an external magnetic field to change the spin direction of electrons around water quality electrons, and then produces proton imaging through this principle. So far, no clear harm has been found in the MRI examination. MRI examination has unique advantages in nervous system, articular cartilage, soft tissue lesions, etc.; In the examination of abdominal organ lesions, the diagnostic effect is also better because of the richer changes in the signal.

The former examination is more detailed, and in order to make money, doctors generally ask you to do a CT first, and then say that you can't see clearly, you can't be sure, and you'd better do an MRI again, so as not to misdiagnose and delay your condition. In fact, they are all a means of making money, which is too dark!!

The price is not the same, MRI is more expensive than CT, MRI can see more clearly than CT, and it is better than CT.

It is recommended to follow the doctor's instructions on which examination to do, and some diseases can be diagnosed with CT as long as they are used.