The procedure of facial computed tomography with 3D rendering with contrast injection

This is an automatically translated article.

The article is expertly consulted by Master, Doctor Nguyen Thi Mai Anh - Doctor of Radiology - Department of Diagnostic Imaging and Nuclear Medicine - Vinmec Times City International General Hospital.
Maxillofacial computed tomography with 3D imaging with contrast injection today is widely used, helping doctors diagnose, plan treatment and monitor pathologies in the maxillofacial region.

1. What is 3D computed tomography of the face with contrast injection?

Maxillofacial computed tomography with 3D rendering using contrast agent for the purpose of examining maxillofacial pathology, rendering in three-dimensional planes to help diagnose and monitor disease progression . In particular, the use of contrast agents helps to clarify the lesions and related blood vessels in the maxillofacial region.
Computed tomography of the face with 3D rendering is also applied in plastic surgery, shaping the maxillofacial region. Patients due to trauma or congenital abnormalities have abnormal facial structure, making it difficult for patients in daily activities and affecting aesthetics. 3D imaging and imaging can detect abnormal anatomical images of the maxillofacial region, thereby planning appropriate treatment.

2. Indications, contraindications to 3D computed tomography with contrast injection

Indications for computed tomography 3D reconstruction:
Trauma to the maxillofacial region Congenital abnormalities of the maxillofacial region. Diseases of the maxillary sinuses. Inflammatory lesions Infectious lesions of blood vessels, nerves, tumors of the maxillofacial region. Contraindications:
Relative contraindications: Pregnant women, young children. Pregnant women must use a lead shirt to cover the abdomen if taking pictures. Absolutely contraindicated in cases with contraindications to contrast agents such as: Patients with renal failure, liver failure, severe heart failure, history of allergy to contrast agents, chronic diabetes mellitus, bronchial asthma, uncontrolled hyperthyroidism.

3. The procedure of facial computed tomography with 3D rendering without contrast injection

3.1 Preparation

Performer: To take computed tomography film of the maxillofacial region, it is necessary to have a team of doctors and technicians specializing in imaging.
Means used for computed tomography of the maxillofacial region include:
Multi-segment computed tomography machine and specialized electric injection pump. Film, photo printer and image storage system. Contrast: Use water-soluble iodinated contrast agent. General medical supplies. Anti-shock box, medicine and necessary tools to manage complications in case of abnormality when the patient injects contrast agent. Patient:
The patient is clearly explained how to take the film and some possible complications when taking pictures to coordinate with the photographer. Remove objects that cause image noise and affect image quality such as earrings, necklaces, hairpins... (if any).

You need to fast and drink 4 hours before the scan. You can drink water but not more than 50ml. Patients who are too excited, do not cooperate when taking pictures: Give sedatives as prescribed by the treating doctor before taking pictures.

2.2 Steps to take

Step 1: Take a cross-sectional scan before contrast injection
Patient position: The patient lies supine on the imaging bed, head still. Positioning is performed, the shooting plane is parallel to the hard palate. Image taken in the horizontal direction from the position of the lower border of the mandible to the superior border of the orbit. The thickness of each slice is 3mm. Spiral capture is intended for directional shaping and 3D rendering. Step 2: After shooting in the cross-sectional direction, proceed to reproduce the image in the horizontal direction but ensure the same good image quality as in the cross-sectional direction. From there, 3D reconstruction and rendering.
Step 3: Inject contrast, with an average dose of 1-2ml/kg body weight, depending on each case.
Step 4: Carry out taking cross-sectional scans after contrast injection. The program and method of imaging are similar to those without contrast injection.
Step 5: Reconstruct the image in different directions from the cross-sectional direction after contrast injection and 3D rendering.
Step 4: Determine the standard image and print the results in both cross-sectional and horizontal reconstruction directions, 3D reconstruction before and after contrast injection according to both bone and software windows.

2.3 Evaluation of results

The doctor reads the results, describes the lesion: Location, structure of the lesion, size, extent of spread of the lesion... Compare computed tomography and clinical images. Provide diagnostic guidelines. At the same time, if necessary, other examinations can be suggested to coordinate, in order to clarify the diagnosis. The doctor can give more professional advice to the patient if required.

4. Accidents and how to handle accidents when shooting

Complications that may occur due to contrast agents:
Anaphylaxis: Occurrence of symptoms such as nausea, vomiting, skin rash. The severity of urticaria appears faster and more severe, angioedema causes shortness of breath, vomiting, abdominal pain, blood pressure has not changed or increased, there is no manifestation of consciousness disorder ... Contrast-induced renal failure:

Thyroid storm: Manifestations of increased temperature, tachycardia, emotional disturbances, if not detected and treated, more severe manifestations of pulmonary edema, heart failure, coma... This condition appears on patients with hyperthyroidism. Pregnant women need to consider carefully before taking pictures and when taking pictures often have lead clothes to protect. Master, Doctor Nguyen Thi Mai Anh has nearly 10 years of experience in the field of diagnostic imaging, especially in imaging breast and thyroid cancer. Received formal training at Thai Binh Medical University and specialized postgraduate training at Hanoi Medical University. Currently, the doctor is a radiologist at Vinmec Times City International General Hospital.
To register for examination and treatment at Vinmec International General Hospital, you can contact Vinmec Health System nationwide, or register online HERE.

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