Cranial: CT and MRI are the usual means of examination. plain films and ultrasound are not very useful. CT examination is preferred for traumatic brain injury. For minor cerebral infarction and early cerebral infarction, MRI is preferred, while for intracerebral hematoma MRI can determine its period. For brain tumors, MRI is also clearer than CT. In conclusion, CT is preferred for traumatic brain injury and unexplained brain emergencies, and NRI is preferred for the rest. Orbits: Ophthalmic ultrasound, CT, and MRI are available. Ultrasound can show intra-bulbar lesions, but the specificity is poor. CT has a clear diagnosis of calcifications and intraorbital foreign bodies, especially metallic foreign bodies, which are best localized with CT. For pediatric retinoblastoma the diagnostic value is greater. CT should be preferred for all diseases with calcification, and metallic foreign bodies MRI is of great diagnostic value for hemorrhagic diseases such as melanoma and retinal exfoliation. The thyroid gland can be solved by ultrasound in general, and CT and MRI are generally not needed unless difficult signs are present. Abdomen Ultrasound is preferred, and CT and MRI cannot be solved. Liver: MRI is stronger than CT in diagnosing hemangioma, and no contrast agent is needed. For isodense liver cancer MRI has its advantages. Kidney: For kidney stones CT shows better. The rest of MRI. renal pelvic venography can show renal function. Pancreas: Ultrasound shows poorly. CT shows fair. Pancreatitis, pancreatic cancer, etc. can be shown clearly. The chest: preferably plain film, with doubt CT. MRI is generally not used. Pelvis: preferably ultrasound, with doubt CT – MRI Female adnexal and uterine diseases preferably ultrasound, with doubt CT – MRI Male prostate: preferably ultrasound, preferably MRI Bone: preferably plain film, with doubt MRI, unless looking at bone destruction, generally do not use CT. Soft tissue lesions: generally use MRI. Heart: Ultrasound for valve disease, CTA or coronary angiography for coronary artery disease. The mammogram, ultrasound, infrared effect can be, MRI can also be, CT is of little value in general: [Movement system]: X-ray plain film is preferred for bones, CT and MRI when necessary. If bone metastases are considered, a whole-body bone scan is necessary. The first thing you need to do is to get a good idea of what you’re looking for. I feel that CT coronal scan is very intuitive for sinuses and paranasal sinuses [circulatory system]: ultrasound is preferred. If you are considering aortic coarctation you should give MRI a look [digestive system]: esophagus, stomach, small intestine, large intestine preferred gas-barium double contrast imaging; liver, gallbladder, spleen, pancreas, kidney ultrasound and CT are excellent, but ultrasound is inexpensive easy for patients to accept, high field strength MRI shows also very good and multi-parameter, multi-directional and other points in increasingly prominent. Neurological system] Brain tissue and spinal cord preferred MRI (MRI special imaging MRA, MRS, DWI, etc., if necessary) Brain hemorrhage patients and trauma patients preferred CT [urinary system]: urinary stones B ultrasound and flat films can be found, urinary lesions are more complex depending on the actual situation CT and MRI (including MRU, etc.) [reproductive system]: preferred ultrasound. Combine MRI and CT if necessary