Who wouldn’t go to the hospital for the rest of their lives? When you go to the hospital, you will often be prescribed a variety of imaging tests, such as ultrasound, CT, MRI, and so on. You may be confused, of all the various types of tests, why do I have to choose this one? Is it just the more expensive the better? Because many people may have such doubts, so I am here to talk about common sense, I hope you will also be helpful. 1, a sentence to understand what should be done imaging examination how to choose, first to a concise version, not to go into the fine reasoning, but for practical: trauma bone: coarse look at the X-ray film, look at the CT, MRI can not see; cervical spine, lumbar spine: the best MRI, the second choice CT; brain, spinal cord: brain infarction to see MRI, bleeding to see CT, the rest including brain tumors mostly MRI best; chest: a general understanding of the X-ray film, detailed analysis to choose CT, look at the lungs not to choose MRI, heart. The abdomen and pelvis: in addition to the intestines, the organs can be generally ultrasound, CT and MRI have their own advantages; heart: patients with high-risk chest pain can choose CT to exclude coronary heart disease, look at the heart itself with ultrasound can be, MRI is better. After reading these lines, I believe that some of the doubts you may have during your consultation can be answered by yourself. If you are interested, let’s talk more about it together. 2, the mystery behind the examination First of all, I want to “boring” to introduce, these tests are what. The most common X-ray, similar to the “chest X-ray” often used in the past during medical examinations, is the use of X-rays to penetrate the human body and get the image. It is still widely used in clinical practice today. CT, which means X-ray computed tomography, uses X-rays to tomographically scan a part of the body to obtain a cross-section of the examined part of the body or to produce a three-dimensional image after processing. With a variety of techniques, CT examinations can provide clearer, multifaceted image information of human structures, including the widely used CT angiography. Unlike X-rays and CT, ultrasound examinations utilize the principle of ultrasound to produce echoes. ultrasound is 2-dimensional information that constitutes a flat graphic that reflects the structure of the human body. With the creation of color Doppler ultrasound technology, color ultrasound (color B-ultrasound) emerged, which is a black and white B-ultrasound with color Doppler, providing additional rich information on the hemodynamics in blood vessels. Ultrasound, both the basic techniques mentioned above and new developments such as 3D ultrasound and ultrasonography, use ultrasound as the theoretical basis, and are therefore completely free of radiation, very safe and even suitable for maternity examinations of pregnant women. MRI, or magnetic resonance, is a magnetic spin imaging technique. Unlike CT and X-rays, one of the advantages of MRI is that it is not damaging to the body and is free of ionizing radiation. Compared to CT’s tomography, MRI does not require computer reconstruction to obtain three-dimensional cross-sectional imaging in multiple directions, such as stereoscopic images of the brain and spinal cord. MRI can be used to cut a radish any way you want, but CT can only do cross-sectional imaging, that is, you can only cut the radish from one end to the other, and then indirectly reconstruct the three-dimensional image through computer technology. MRI is particularly accurate for the diagnosis of brain, spinal cord, pelvic organs, cardiac macrovascular lesions and myocardial infarction. However, MRI is strictly contraindicated in patients with metal implants in the body (such as pacemakers, mechanical heart valves, aneurysm clips, vascular stents, artificial joints, and metal internal fixation), unless their material instructions specifically state that they are acceptable for MRI. In addition, due to the long and noisy MRI examination, MRI should not be performed in patients who cannot cooperate (e.g., pediatric patients, patients with confusion, claustrophobia) without sedation measures. PET/CT, a new technique that combines positron emission tomography with conventional CT, evaluates the metabolic function of cells while examining the structure, combining the evaluation of structure and function in It is of great significance in the evaluation of myocardial survival and the localization of epileptic foci in the brain. In recent years, PET/CT has been widely used especially for tumor screening and localization, and has some advantages over CT and MRI. 3.How to choose these examinations After a serious introduction, how to choose so many examinations? For traumatic bone injuries, X-ray is the first choice because it is fast and easy to obtain; for further and more detailed observation, CT can be chosen. Ultrasound and MRI are not very clear for the bone cortex and medulla and are far less effective than X-ray and CT. For cervical, lumbar and muscular disc diseases (cervical spondylosis, lumbar disc herniation, etc.), the intervertebral disc and the corresponding nerve roots need to be observed, and to Similarly, MRI is also preferred for the examination of joints, muscles, and fatty tissues. For brain and spinal cord diseases, MRI has the strongest soft tissue resolution and can directly obtain clear three-dimensional images, using different sequences to obtain more comprehensive diagnostic information. However, for hemorrhagic stroke (e.g. “cerebral hemorrhage”), CT examination can be performed in emergency conditions to detect abnormalities at the earliest and obtain early diagnosis. In the case of ischemic stroke (infarction), MRI can detect abnormalities earlier than CT, so early CT alone without detecting abnormalities often cannot rule out an infarction. X-rays of chest diseases can cursorily examine the heart, aorta, lungs, pleura, ribs, etc. You can see, for example, enlarged heart shadow, increased lung texture, calcified lung spots, and calcified aortic nodes. Compared with X-ray, CT chest examination shows a clearer structure, and the sensitivity of detecting and accuracy of showing lesions in the chest are better than conventional X-ray chest film, especially for the confirmation of early lung cancer diagnosis chest CT has decisive significance. High-resolution CT further increases the resolution of lung observation, which is significant for certain diseases (e.g. interstitial lung disease). However, the radiation dose of CT examinations is significantly higher than that of X-rays. MRI has very limited application for the diagnosis of lung diseases. The diagnosis of abdominal and pelvic diseases gallbladder diseases is very dependent on ultrasound, which is superior to CT and MRI. this is mainly because, the abdominal organs are affected by respiration and have greater motion, which affects CT and MRI imaging, while ultrasound is not affected by this. Ultrasound is also more accurate for the liver, spleen, pancreas, kidneys, pelvic organs, etc. With experienced ultrasonographers, the accuracy is as good as CT and MRI, but ultrasound is greatly disturbed by gas, so for areas containing more gas, such as the intestines, the accuracy of ultrasound diagnosis is greatly reduced. Heart disease Finally, a word about the heart. Imaging of the heart is mainly to examine the coronary arteries, with the myocardium, pericardium and other structures. Coronary artery stenosis up to a certain limit is what we usually call “coronary heart disease”. The gold standard for coronary artery examination is inpatient arteriography, but for reasons of convenience and feasibility, CT may sometimes be used instead. CT is a good way to rule out coronary artery disease if no stenosis is found, but it is subject to more interference (e.g., calcification), especially in elderly patients, whose coronary arteries are more calcified, so the observed stenosis cannot be directly interpreted as a stenosis and requires further evaluation. Finally, it is important to mention that coronary CT is not suitable as a routine physical examination because of its high radiation exposure. MRI is the “gold standard” for evaluating the structure and function of the heart, although there is no electromagnetic radiation, but the observation of coronary arteries is far less than CT. When myocardial infarction occurs, cardiac MRI can not only accurately display the size of the atrioventricular cavity and the thickness of the ventricular wall, but can also comprehensively show the motion changes of the ventricular wall segments and identify post-infarction scar tissue. Also, cardiac MRI is superior to cardiac ultrasound for the diagnosis of various cardiomyopathies, such as dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and left ventricular myocardial densification insufficiency, which can be considered a unique advantage. For restrictive cardiomyopathy and constrictive pericarditis, which have similar clinical features and pathophysiological changes, the “one-stop” scan can provide relevant signs for diagnosis and differential diagnosis in terms of anatomy, function and histological characterization. For congenital heart disease, especially complex or compound malformations, cardiac MRI can effectively complement cardiovascular imaging, such as atrioventricular junction, ventricular aortic junction, and extracardiac malformations, and play an important role in postoperative follow-up. However, as a routine examination of cardiac structure and function, cardiac ultrasound provides more than adequate information and is simple and easy to perform, making it a more common method. After talking so much, I hope I have made two things clear: 1. the imaging methods used are different for different sites and different observation focus; 2. not the more expensive the test, the better it is for you.