1, lumbar intervertebral disc herniation, mistakenly do knee MRI: a patient hurriedly came to the examination, said bilateral leg pain, the local doctor let him come to do double knee MRI. The local doctor asked him to come to do the MRI of both knees. The MRI of both knees requires high cost, and after understanding that the patient is a farmer, he did not go to do the MRI directly. After checking and questioning the patient, it was found that the symptoms of the knee joints did not resemble the symptoms of the lumbar spine, which needed to be excluded first. Therefore, after explaining the situation to the patient, an MRI of the lumbar spine was performed, and it was found to be a severe herniated disc in the lumbar spine. The herniated lumbar disc caused the leg pain due to the narrowing of the spinal canal. If we did bilateral knee MRI, it would not only be costly, but also not be able to diagnose the disease clearly. 2. When ultrasound suspects liver hemangioma, it is incorrect to choose CT scanning examination to confirm it: because only CT scanning for liver hemangioma can not be diagnosed, and it is necessary to do enhancement of dynamic or delayed scanning at the same time, so the cost is higher, and at the same time, accept a certain amount of radiation, in terms of the value of the detection of this kind of hemangioma and the confirmation of the diagnosis, so that the patient can be said to be more than worth the cost. In fact, if the ultrasound is considered to be a typical hemangioma (e.g., a typical strong echogenic light mass), there is no need to do any other tests. If you are not sure, you can choose MRI scanning, which can usually clarify the diagnosis of hemangioma, and its cost is also less than CT scanning plus enhancement. 3. It is sometimes impossible to distinguish fresh or old vertebral fracture by CT: In acute trauma, CT can diagnose fresh vertebral fracture according to fracture lines or fragments, but when the fracture lines are not obvious, CT is unable to distinguish between fresh or old fracture. MRI can distinguish between fresh and old fractures based on the presence or absence of bone marrow edema within a certain period of time after the injury. Therefore, the first choice should be nuclear magnetic examination. 4, suspected early necrosis of the femoral head, strong spondylitis, inflammatory lesions of the spine or early vertebral tumors choose CT examination, the diagnosis is not more helpful: the early stage of the above lesions have common pathological changes: bone marrow edema, and CT on the bone marrow edema display is not as sensitive as the nuclear magnetic examination, so the early detection of the above diseases should be dependent on the nuclear magnetic examination. 5.Suspecting skull base fracture after trauma and choosing MRI: Obvious skull base fracture can be detected by MRI, which is mainly better than CT for brain damage, but CT should be the best for inconspicuous or subtle skull base fracture. Similarly for observing the accessory fractures of the spine, CT should also be used. 6, prostate cancer and prostate hyperplasia, preferred CT scanning plus enhancement examination for identification, not very correct: typical prostate cancer diagnosis is not difficult. Atypical prostate cancer is not difficult to diagnose, but it is not easy to distinguish from prostate hyperplasia. Ultrasonography has no further discriminatory value, and CT scanning is not valuable; it can be differentiated by the blood supply characteristics shown on CT enhancement scans, which are nonetheless singularly limited in their information. A more practical and effective method is MRI, of which T2WI, DWI, and multiphase dynamic enhancement are important and sensitive imaging methods. If conditions can be combined with MRS (magnetic resonance spectroscopy or spectrum), it is differentiated by detecting the content of metabolic substances in the lesion area (there is a significant difference between the metabolic substances of cancer and hyperplasia), so some people refer to MRS as a noninvasive biopsy. Therefore, at present, the best way to identify prostate cancer and prostate hyperplasia by imaging method is MRI (magnetic resonance imaging) plus MRS. 7, choking, difficulty in swallowing just do esophageal barium meal imaging, incorrect: encountering choking, difficulty in swallowing middle-aged and old people, it is necessary to see a laryngologist first, to check whether there is any lesion in the pharynx; or do esophageal barium meal imaging to observe whether there is any lesion such as diverticulum or tumor in the esophagus or esophagophagus; in addition, some nodes have been found in the esophagus and the esophagus, which is the most common cause of cancer. Or do a barium meal imaging of the esophagus or esophagopharynx to see if there are any lesions such as diverticula or tumors; in addition, similar symptoms can also appear when certain diseases of the hoof and neck tissues, such as dermatomyositis and scleroderma, involve the digestive tract. However, for people with symptoms of choking and dysphagia, especially the elderly, another important examination should not be neglected, i.e., nuclear magnetic resonance imaging (NMRI) of the brain, which is used to observe whether there is any infarction in the brainstem, especially small infarcts in the medulla oblongata, and the symptoms appear due to the infarcts affecting the nuclei of nerves that are in charge of swallowing. In other words, it is a symptom caused by cerebrovascular disease.