Trauma can cause damage to any part or organ of the body. In some cases, subtle potential injuries or damage to the brain and internal organs that cannot be shown early or cannot be determined by ordinary tests require CT or MRI to clarify the diagnosis and help with treatment. CT can detect early and potential bleeding and provide timely treatment. In addition, sometimes there is bleeding in the ear canal and clear fluid coming out of the nasal cavity after head trauma, which should be examined by CT for skull base fracture. After abdominal trauma, rupture of parenchymal organs such as liver, spleen and kidney is suspected, and CT or MRI is also needed to make a clear diagnosis when it cannot be determined by some general examinations such as ultrasound. In addition, injuries to soft tissues such as muscles and joint ligaments are often undetectable by ordinary X-rays, and the superior resolution of CT and MRI on soft tissues allows timely and accurate detection of injuries. Since CT and MRI work on different principles and have their own advantages and disadvantages in imaging different parts of the body, it is important to choose the correct test to be performed after a trauma according to the condition. In general, CT is superior to MRI for the examination of bones, air-containing organs (e.g., lungs) and abdomen, and can be used for comprehensive examination of various intracranial lesions and cerebrovascular malformations, ophthalmology, ophthalmology, and major organs within the pleura. Compared with CT, MRI has the advantages of higher soft tissue density resolution than CT, better detail of anatomical structures, and the ability to image at any level, so it has a higher diagnostic value in the central nervous system and intra-articular injuries, and because MRI does not image bone and calcium-containing materials without bony artifacts, it is much superior to CT in the diagnosis of cranial fossa lesions.