Virtual Endoscopy
Virtual endoscopy corresponds to the calculation of three-dimensional images from two-dimensional MRI or CT images. Accordingly, it is a non-invasive diagnostic procedure that represents body cavities.
What is a virtual endoscopy?
In endoscopy (endoscopy), doctors examine certain body cavities and hollow organs with only a minor surgical intervention. The minimally invasive procedure plays a role above all in the diagnosis of diseases. However, endoscopies can also become therapeutically relevant by being used to treat diagnosed diseases.
Virtual endoscopy is a radiological examination that simulates real endoscopy images. It is thus a simplified version of conventional endoscopy that extends imaging diagnostics. With this method, cavities of the human body can be displayed in three-dimensional images without an endoscope penetrating the patient. Two-dimensional cross-sectional images of the magnetic resonance or computer tomograph are converted into three-dimensional endoscopy images during virtual endoscopy. This is also referred to as 3D reconstruction methods.
Applications
In principle, virtual endoscopy can show 3D simulations of all body cavities, which can be imaged by MRI or CT. However, the method is mainly used for endoscopic imaging of the colon and is called virtual colonoscopy in this context.In principle, the indications for performing virtual colonoscopy correspond to the same indications that apply to the diagnostic performance of conventional colonoscopy. Screening colonoscopy, for example, takes place regularly from the age of 55. In familial forms of colorectal carcinoma, regular colonoscopy is recommended from the age of 20. In addition, blood in the stool or tarry stool may be an indication.
Endoscopy is also used in tumor search, for example after unclear weight loss or unclear bowel movements with persistent middle and lower abdominal complaints. Only in the case of inflammatory bowel diseases or the suspicion of inflammation of the colon, the use of virtual endoscopy is not suitable.
The most common indication for the procedure is with control examinations after colorectal cancer therapies and polypectomies in case of incomplete or impracticable colonoscopy.
Other areas of application of virtual endoscopy are examinations of the paranasal sinuses, the trachea and bronchi as well as the stomach. Unlike conventional endoscopy, the virtual variant is a pure diagnostic device.
Methods and procedures
In addition to virtual colonoscopy, the most common procedures of virtual endoscopy include virtual sinus copy of the paranasal sinuses, virtual bronchoscopy of the bronchial area and virtual gastroscopy of the stomach.
Common to all methods is the spatial representation of the lumina, which is carried out by the software-supported conversion of MRI or CT images into three-dimensional endoscopy images. Cross-sectional imaging methods provide location-accurate and non-overlapping images of the examined body cavities. A high contrast is required to calculate the surfaces to be displayed. Therefore, the method of virtual endoscopic imaging is particularly suitable for air-filled body cavities such as the lungs or various sections of the intestine.
Although fluid-filled body cavities can also be imaged using virtual endoscopy, the contrast to the surrounding tissue is extremely low in such areas.
What does the patient have to consider?
Virtual endoscopy is not an actual procedure. Therefore, the patient has to pay significantly less attention in advance than with invasive and minimally invasive diagnostic procedures. The simulated endoscopy is based on CT or MRI images. For these images, for example, fasting on the day of imaging is critical only when images of the gastrointestinal tract are involved.
For example, during colonoscopies , patients are given laxatives the day before to empty their bowels and are only allowed to drink water between the laxative administration and the imaging. In the case of virtual endoscopies of the bronchial or paranasal sinus region, no precautions usually need to be taken in advance. The patient experiences the actual stress during the virtual endoscopy due to the radiological procedures.
Radiological imaging such as MRI is usually performed with the administration of a contrast medium. Contrast agent administration is accompanied by some follow-up recommendations. To ensure that the magnetic agent leaves the body as quickly as possible and does not put a strain on the organs, the patients are asked to drink more fluids on the day of the examination. In addition, patients must remove all metal objects before the MRI. Any cardiac pacemakers or prostheses must be discussed in advance with the doctor or radiologist.
process and implementation
Virtual endoscopies are created in different stages. Computer tomographic or magnetic resonance tomographic examinations, which provide two-dimensional cross-sectional images of the examined body cavity, make the beginning. The finished cross-sectional images are transmitted via a network to a workstation where the virtual endoscopy images are calculated. The interface between the imaged lumina and the tissue is determined by threshold values or manual work.
The two-dimensional contours are then combined by software to form three-dimensional surfaces. The path to be covered by the simulated camera can then be defined on the screen. The software calculates several still images for each individual camera position. These still images are stitched together to create a video film that resembles a real endoscopy. Different computer processes supplement the surface with a virtual light source with shadows and reflections to create a spatial impression. In addition, the surface is given a texture that gives a realistic impression.
Who bears the costs?
The costs of the virtual endoscopy amount to between 500 and 1,000 euros, depending on the provider and the type and scope. The assumption of costs by private health insurance companies is one possibility.Statutory health insurance companies usually do not cover the costs for this type of service. Exceptions are made when there is a medical need.
If a colonoscopy is not possible for certain reasons, but the doctor needs the images of the colon for diagnostics or further therapy planning, the costs for a virtual colonoscopy are also covered by the statutory health insurance companies. In principle, the assumption of costs also applies to the representation of other body cavities if this is medically certified as unavoidable.
Risks and complications
Virtual endoscopy is a non-invasive procedure. This means that the patient’s body is not opened and for this reason there are few risks and side effects. Virtual colonoscopy in particular is more comfortable for patients and also takes less time than conventional colonoscopies. Neither painkillers nor sedatives are required.
Since radiological images are necessary for the conversion into three-dimensional images, there are the general risks and side effects of radiological procedures. Patients receive precise information on radiation exposure from the responsible radiologist. The actual radiation dose depends on the tissue, its size and the number of tomographic images. Side effects such as headaches are common with contrast imaging. In addition, contrast media put a strain on the detoxification organs.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.