CT scan of eye and orbital area

CT examination of the eye and temporal region is a method of examining the eye and temporal region by CT. The CT scan provides a high-resolution, cut-off image and gray-scale eye image that displays the human-level image with X-rays as an energy source. At present, CT has become very popular, providing a superior examination method for the diagnosis of ophthalmic diseases. However, for various reasons, there are still many problems in CT analysis and diagnosis of ocular lesions. Diagnostic ultrasound for intraocular disease is superior to CT, and CT is superior to ultrasound in the diagnosis of orbital lesions. This article discusses some of the problems in CT diagnosis of orbital lesions, and introduces the basic knowledge of CT related to diagnosis, which is very important for comprehensive analysis of ocular CT films. Basic Information Specialist classification: growth and development check classification: CT Applicable gender: whether men and women apply fasting: fasting Tips: Pay attention to the hygienic care around the eyes. Normal value Can help check out: Intraorbital tumor (1) Primary (good, malignant) tumors in the sac. (2) Secondary tumors in the sac. (3) Eye tumors include primary and metastatic tumors. 2. Inflammatory lesions in the sputum (1) Non-specific inflammation, (2) Intrauterine infection. 3. Hyperthyroidism. 4. Vascular diseases. 5. Damage and foreign bodies. Clinical significance 1. It can display the location, shape, size and extent of various tumors, and some tumors can also determine their properties. 2. It can clearly display metal and non-metal foreign objects and can be accurately positioned. CT signs of common intraorbital lesions 1. Benign tumors: CT scans of benign tumors in the sputum are mostly round, round, and elliptical high-density space-occupying lesions with clear boundaries and uniform internal density (referring to the uniform density of tumors on CT slices), such as sponges. Hemangioma, schwannomas, benign pleomorphic adenoma of lacrimal gland. Long-term slow growth of the tumor can cause an increase in intra-orbital pressure, and CT can show a general or partial enlargement of the sacral cavity. 2. Malignant tumors: malignant tumors show invasive growth. CT scans often show that the tumor boundaries are unclear, irregular in shape, and often associated with bone destruction, such as parasitic sinus cancer. However, some intracranial malignant tumors show CT signs similar to benign tumors, such as rounded shape, clear boundary, uniform internal density, no obvious bone destruction, etc. Common include rhabdomyosarcoma, lymphoma, adenoid cystic carcinoma of the lacrimal gland, etc. . 3. Inflammatory pseudotumor: Inflammatory pseudotumor is a common intraorbital lesion. CT shows that the lesion is mostly located in the front of the ankle and attached to or wrapped in normal structures such as the eyeball, extraocular muscle or optic nerve. The shape of the lesion is irregular and the boundary is unclear. Part of the diffuse inflammatory pseudotumor can affect all structures in the sputum, and the diffuse density of the sacral cavity is increased, and the normal structures in the sputum are covered. 4. Vascular malformations: The common intra-orbital vascular malformation is venous vascular malformation, also known as venous hemangioma. Because the range of lesions is often extensive, CT shows that the lesions in the sacral lesions have clear boundaries, irregular shapes, and a wide range of high-density space-occupying lesions, but there are also individual vascular malformations. The veins are often combined with venous stones, which is very helpful for diagnosis. 5. Bone hyperplasia: bone hyperplasia is bone hypertrophy. The lesions that cause bone hyperplasia in the sputum mainly include sphenoid ridge meningioma and dysplasia of bone fibers. The former CT showed hypertrophy of the sphenoid ridge (the outer wall of the iliac crest), and there were soft tissue shadows in the adjacent iliac crest or intracranial. The latter is extensive bone hyperplasia, often involving the frontal bone, iliac crest, ethmoid, dome, maxilla, etc., the boundary of the lesion is unclear, there is no soft tissue shadow in the sac or intracranial. 6. Bone destruction: generally seen in malignant tumors, metastatic cancer, also seen in granulomatous lesions. CT showed irregular bone defects in the bone wall, or worm-like, honeycomb-like, with soft tissue shadows adjacent to the bone destruction. 7. Calcification: Although calcification is rare in intraorbital tumors, it has a characteristic diagnostic significance. Calcification is divided into two types of intravascular calcification, because it is round, also known as venous stone, mainly seen in venous hemangioma, varicose veins, rare in cavernous hemangioma and other diseases. The other is irregular calcification, found in meningiomas, lacrimal gland epithelial malignancies, schwannomas, and the like. 8. Bone deficiency: It is generally caused by a certain congenital lesion causing bone dysplasia. For example, the outer wall of the iliac crest or the apical bone of the neurofibromatosis is obviously enlarged. CT showed that the boundary of the bone defect was clear and smooth, and there was generally no soft tissue block around it. 9. Fracture: CT is easier to diagnose. However, please note that sometimes the sieving board and the inferior wall of the sacral wall are not affected by the bone fracture due to the bone wall of the sputum. Clinically common include bursts of various types of orbital and iliac crest, and severe external iliac crest, zygomatic arch, and maxillary fracture. When analyzing the orbital burst fracture, attention should be paid to the size of the fracture area (the larger the fracture area, the more opportunities for eyeball retraction. The fracture area is small, it is not easy to cause eyeball retraction, but it can lead to double vision), whether there is soft tissue inside the eye, or outside the eye. Muscle spasms or caulking. 10. Thyroid-related eye disease: Thyroid-associated eye disease, also known as Graves' disease, is the most common cause of unilateral and bilateral ocular protrusion. Clinically, there are some typical signs such as eyelid retraction and late onset. CT showed different morphological changes in different periods of the disease. The main CT signs included eyeball protrusion, extraocular muscle hypertrophy, and fat pad enlargement. Among them, extraocular muscle hypertrophy was the most common. The frequency of involvement is inferior rectus muscle, medial rectus muscle, superior rectus muscle and lateral rectus muscle, and the superior levator palpebral muscle and upper oblique muscle are hypertrophied. The extraocular muscle hypertrophy of thyroid-associated ophthalmopathy is characterized by muscle-bellied hypertrophy and clear borders. However, when the lower rectus hypertrophy is performed by horizontal CT scan, it is easy to be misdiagnosed as intraorbital tumor. At this time, coronary CT should be identified. 11. Other secondary changes: (1) enlargement of the sacral cavity Any long-term sacral space-occupying lesion can cause a general or partial enlargement of the sacral cavity. Adults have a history of more than one year, and the enlargement of the sacral cavity can occur in children with a lesion within 3 months. (2) Deformation of the eyeball The internal hard lesion or the fast-growing mass can be deformed to the eye wall close to the lesion, even in a tent form. (3) The normal structure of the iliac crest can expand the extraocular muscle and optic nerve. 12. The thickening or enlargement of the normal structure of the sputum. Some normal structures in the sputum may be thickened or swollen for some reason, such as extraocular muscles, optic nerves, and post-ball fat. These lesions are also a common cause of eyeball protrusion, but are often overlooked by clinicians. 13. Extraocular muscle hypertrophy Extraocular muscle hypertrophy is more common in ocular CT, mainly including thyroid-related eye disease (Graves' disease), inflammatory pseudotumor, trauma, parasitic and other diseases. 14. Optic nerve thickening optic nerve can be thickened due to diseases such as tumor, inflammation and oppression. 15. After the ball fat pad thickening, this disease is easy to ignore, clinically often due to eyeball protrusion and CT examination. However, CT only shows that the eyeball is prominent, and there are no other signs such as lesions, muscle thickening, etc. Actually, this is the thickening of the fat pad after the ball. Although this sign has no special significance, it is common in thyroid-related eye diseases, mild chronic inflammation in the sputum and other diseases. Precautions 1. The CT signs of most tumors in the sputum lack features, and qualitative diagnosis is more difficult. The differential diagnosis between intraorbital tumors and inflammatory pseudotumors and hyperthyroidism is often difficult. 2, CT examination of intraocular and intraorbital vascular diseases is not as valuable as ocular venography and internal carotid angiography (eye angiography). Inspection process Refer to CT routines. Not suitable for the crowd 1. Serious heart, liver and kidney dysfunction. 2. Allergic to iodine contrast agents. 3. The condition is seriously difficult to cooperate with. Adverse reactions and risks An allergic reaction may occur.