Many people can’t tell the difference between X-rays, CT, ultrasound, and MRI, which are commonly used imaging tests. Now, we compare the body to food and show you how these tests play different roles. X-rays, like flattening bread to see X-rays will pass through the body and encounter an obscured area that will not be exposed on the negative, and the area will be white after the film is washed. The biggest disadvantage of X-rays is that the images of deep and shallow tissues overlap and are hidden from each other, and sometimes it is necessary to take X-rays from multiple angles. CT, like slicing bread CT examination principle is that X-rays will pass through the body in layers, and then through computer calculations after the secondary imaging, like cutting a piece of bread into slices to see. The advantage is that it can be viewed in layers, and after calculation, more information about the tissue can be shown. Ultrasound, like picking a watermelon before knocking The principle of ultrasound is to use ultrasound to penetrate the body, when the sound waves meet the body tissue will produce reflected waves, through the calculation of reflected waves imaging. It is like picking a watermelon, knocking while looking at it to show the condition of the lesion. Nuclear magnetic resonance, shake and then look Nuclear magnetic resonance machine uses a more powerful magnetic field, so that the magnetic field of all water molecules in the body in the same direction of magnetic lines, when the magnetic field of the magnetic resonance machine suddenly disappears, the body of water molecules in the direction of magnetic lines, suddenly returned to the original random arrangement of the state. Simply put, it is equivalent to shaking your hand to make the water molecules vibrate, then calm down and feel the vibration inside. Therefore, MRI is also jokingly referred to as a shake and look examination. What kind of tests are each of the four modalities used for? During a visit, doctors often prescribe a variety of imaging tests: ultrasound, CT, MRI …… Many patients may question their doctors for intentionally prescribing high-priced tests. In fact, doctors choose different imaging tests according to different conditions. 1, traumatic bone coarse look at the X-ray film, a closer look at CT, MRI can not see a variety of trauma, if you suspect that the injury to the bone, the priority choice of X-ray photos, test results quickly and easily. If you want to further observation, you can choose CT. ultrasound, nuclear magnetic for the bone cortex medulla, etc. do not see very clear, generally do not choose. 2, cervical spine lumbar spine The best choice of MRI, the second choice of CT cervical spondylosis, lumbar disc herniation and other intervertebral disc disease need to observe the intervertebral disc and the corresponding nerve roots, to better observe these soft tissues, the optimal choice is nuclear magnetic. Similarly, for joint, muscle and fat tissue examination, MRI is also the first choice. 3, chest A cursory look at X-rays, a closer look at CT, look at the lungs do not choose MRI X-rays of the chest can be a cursory examination of the heart, aorta, lungs, pleura, ribs, etc., and can be checked for increased lung texture, calcified lung spots, calcified aortic nodes, etc. CT chest examination shows clearer structures, and its sensitivity and accuracy in detecting chest lesions are better than those of conventional X-ray chest films, especially for early lung cancer diagnosis. However, the radiation dose of CT examinations is higher than that of X-rays. The application of MRI for the diagnosis of lung diseases is very limited. 4.Abdominal pelvis Except for the intestines, general ultrasound can examine The abdominal organs are more affected by whistling, which in turn affects CT and MRI imaging, while ultrasound will not be affected by this. Meanwhile, ultrasound has a high diagnostic accuracy for organs such as liver, spleen, pancreas, kidney and pelvis. However, ultrasound is greatly interfered by gas, and the diagnostic accuracy of ultrasound will be reduced for organs containing more gas such as the intestine. 5.Heart Exclude coronary heart disease with CT, see the heart function with ultrasound Conventional heart structure and function examination, the information provided by cardiac ultrasound has been more adequate, and simple and easy to use. With CT, coronary arteries can be examined, but coronary CT examination has a large amount of radiation, which is not suitable for routine physical examination. Although MRI is free of electromagnetic radiation, it is not as good as CT for coronary artery observation, and cardiac MRI is the “gold standard” for evaluating the structure and function of the heart.