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Introduction ⬇

A CT scan of the head, also known as a cranial CT or brain CT, is a relatively simple x-ray examination done by means of a special scanning machine to evaluate for suspected intracranial lesions, aneurysms, bleeding, hydrocephalus, and stroke. The results form a cross-sectional picture of the anatomic structure of the head that includes the internal cranial structure, brain tissue, and surrounding CSF. This axial image of the head is similar to a view looking down through the top of the head. Additionally, a head CT can evaluate sinuses, the orbits of the eyes, internal auditory canals, and mastoid and facial bones, as well as assist with planning radiation therapy for brain cancer.

A CT of the neck is performed to identify abnormalities of the cervical vertebrae, upper airway, thyroid and parathyroid glands, and foreign body ingestion. Images also may determine abnormalities of the jawbone, mouth and tongue, pharynx, larynx, and vocal cords.

Procedure ⬆ ⬇

  1. Have the patient lie completely still on a motorized table with their head comfortably immobilized. The table is moved into a doughnut-shaped frame called a gantry. X-ray tubes situated within the gantry move around the patient in a circular fashion.

  2. Inject an iodinated radiopaque contrast substance if tissue density enhancement is desired because a questionable area needs further clarification. Some patients experience nausea and vomiting after receiving this contrast agent.

  3. Take additional images during contrast injection.

  4. During and after the IV injection, the patient may experience warmth, flushing of the face, salty taste, or nausea. Encourage the patient to breathe deeply. An emesis basin should be readily available.

  5. Watch for other untoward signs such as respiratory difficulty, diaphoresis, numbness, or palpitations.

  6. Follow guidelines in Chapter 1 for safe, effective, informed intratest care.

Clinical Implications ⬆ ⬇

Abnormal CT head and neck scan results may reveal the following conditions:

  1. Bony and soft tissue tumor masses such as meningiomas, astrocytomas, angiomas, abscesses, and cysts

  2. Intracranial bleeding or hematoma

  3. Aneurysm

  4. Infarction

  5. Infection

  6. Sinusitis

  7. Foreign bodies

  8. Herniated cervical disks

  9. Congenital spinal defects

  10. Enlarged lymph nodes or glands in the neck

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and procedure. Provide written instructions. Reinforce knowledge regarding possible adverse effects such as radiation exposure or allergy to iodine contrast media.

  2. Assess pregnancy status of female patients. If positive, advise the radiology department.

  3. Follow iodine contrast test precautions. A creatinine level may be required before the study.

  4. Generally, the patient should fast 2–3 hours before the test if a contrast study is planned. In most cases, prescribed medications can be taken before CT studies.

  5. Check for patient allergies. Nausea and vomiting, warmth, and flushing of the face may signal a possible iodine allergy.

  6. Reassure the patient who is prone to claustrophobia that claustrophobic fear of the scanner is common. Pictures of the scanner or introduction to the scanner may alleviate these fears.

  7. Administer analgesic agents and sedatives, especially to minimize pain and unnecessary movement.

  8. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Clinical Alert

  1. If the patient has diabetes and is taking metformin, special considerations may be necessary. Consult with the radiology department to determine whether this medication regimen must be discontinued the day of and several days after the study.

  2. Assess whether the patient is allergic to iodine or latex. If iodine contrast or latex allergies or sensitivities are known or suspected, inform the radiology department before study.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed.

  2. Determine whether an iodine contrast substance was used. If used, observe and record information about reactions if they occurred. Reactions may include hives, skin rashes, nausea, swelling of parotid glands, or, most serious of all, anaphylaxis.

  3. Notify the healthcare provider immediately if allergic reactions occur. Antihistamines may be necessary to treat symptoms.

  4. Documentation should include assessment of information needs, instructions given, time at which the examination was completed, patient response to the procedure, and any allergic reactions.

  5. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆ ⬇

  1. A false-negative CT scan can occur in the presence of hemorrhage. As hematomas age, their appearance on CT scans changes from high-intensity to low-intensity levels partly because older hematomas become more transparent to x-rays.

  2. Patient movements negatively affect image quality and accuracy.

Reference Values ⬆

Normal

No evidence of tumor, other pathology, or fracture

Typically, low-density tissue areas appear black, whereas higher density tissues appear as shades of gray; the lighter the shading, the higher the density of the tissue or structure.