What are the indications of ophthalmic CT and MRI?

CT, also known as computed tomography, uses X-rays, ultrasound, isotopes and other energy sources, scans the examined parts and reconstructs them by computer to obtain tomographic images.

MRI, called magnetic resonance imaging in Chinese, was originally called nuclear magnetic resonance. Because "nuclear"

Medical doubts about its instability and radioactivity, so in recent years it has been collectively called magnetic resonance imaging. It is based on the principle of magnetic resonance (when the nucleus placed in a strong magnetic field is excited by electromagnetic waves with a specific frequency, it absorbs energy and jumps from a low energy level to a high energy level, which is called magnetic resonance, and then the excited nucleus will return to its original state and release energy at the same time). The energy released by the hydrogen nucleus of human body is detected in the form of electromagnetic waves, and then input into the electronic computer. After processing, the tomographic image of human body is obtained.

Like CT, MRI has the advantages of painless, no danger and high sensitivity, which is of great significance to the diagnosis of tumor and neurology and the formulation of treatment plan. At the same time, MRI contains unique chemical structure information, which is considered to have greater potential advantages than ultrasound and CT, but it is difficult to show calcification in soft tissue, nor can it directly show fracture lines and bone destruction.

CT and MRI are suitable for the following eye diseases.

(1) exophthalmos.

(2) Progressive visual impairment and visual field defect.

(3) Unexplained ophthalmoplegia.

(4) Abnormal eye movements with nystagmus.

(5) optic disc edema.

(6) Optic atrophy.

(7) Post-traumatic vision and visual field disorder, foreign body examination.

(8) Intraocular tumors.

(9) Study on the etiology of strabismus and amblyopia.

Bone lesions around the orbit were found on (10)X-ray film.

(1 1) Ultrasound examination suspected extraocular lesions.

(12) Headache, orbital pain and hemifacial spasm.