Procedure of virtual endoscopic colonoscopy

This is an automatically translated article.

The article is expertly consulted by Master, Doctor Hoang Van Lan Duc - Doctor of Radiology - Department of Diagnostic Imaging and Nuclear Medicine - Vinmec Times City International General Hospital.

1. Overview of virtual colonoscopy endoscopic magnetic resonance imaging

1.1 Related concepts Anatomically, the colon (large intestine) is the last part of the digestive tract, has an inverted U shape, about 1.5 - 2m long. The colon is responsible for receiving undigested food such as fiber and some bacteria here can produce vitamins for the body, reabsorb water from food, form feces to be excreted. The colon consists of four parts: the cecum and appendix, the colon (including the ascending colon, the transverse colon, the descending colon and the sigmoid colon), the rectum, the anal canal, and the anus.
Magnetic resonance imaging (also known as MRI - stands for magnetic resonance imaging) is an imaging technique that uses magnetic fields and radio waves. When performing an MRI, under the influence of a magnetic field and radio waves, the Hydrogen atom in the body will absorb and release RF energy. Different body tissues absorb and release energy differently. The magnetic resonance imaging machine captures and processes the energy release and converts it into image signals.
Images obtained by magnetic resonance imaging technique have high contrast, detail, multi-section survey, 3D reconstruction ability, allowing doctors to observe more clearly and accurately. In particular, MRI has no side effects like X-rays, so it is increasingly widely used in the diagnosis of neurological, cardiovascular, abdominal, muscle - bone - joint diseases,...

1.2 What is a virtual colonoscopy? Virtual endoscopic colonoscopy is a non-invasive examination technique, performed by injecting contrast material into the colon lumen, creating images and then reconstructing the internal structure of the colon lumen. This method is very effective in diagnosing some diseases that occupy space in the colon lumen and in differential diagnosis with tumors originating from outside the colon.

2. Technical indications and contraindications

2.1 Indications Virtual endoscopic colonoscopy is indicated to examine and evaluate the pathology of masses occupying space in the colon lumen such as colon tumors or tumors compressing the colon.
2.2 Contraindications Absolute contraindications:
People with serious illnesses need to have resuscitation equipment on their side; Wearers of metal surgical forceps in the intracranial, vascular or orbital for less than 6 months; Patients with electronic devices on the body such as cochlear implants, pacemakers, anti-vibration machines, automatic drug pumping devices under the skin,... Relative contraindications:
Patients with surgical forceps metal surgery on humans for more than 6 months; The patient has a fear of the dark or a fear of being alone.

3. Virtual colonoscopy endoscopic magnetic resonance imaging procedure

3.1 Preparation of personnel to perform: Specialist doctors, nursing assistants and radiology technicians; Drugs: Including magnetic contrast agents, skin and mucosal antiseptics and sedatives; Technical facilities: Including resonance imaging machine of 1 Tesla or more and film, film printer and image storage system; Medical supplies: Including gloves, cotton, gauze, sterile adhesive bandages, physiological saline or distilled water, 10ml syringe, 18G intravenous catheter and medicine box, first aid equipment in case of drug accident contrast ; Patient: The procedure is explained in detail; checked for contraindications (metallic grafts, claustrophobia,...); fasting is required to clear the digestive tract; change the clothes of the magnetic resonance imaging room, remove the items in the list of contraindications; Prepare a request for a doctor's virtual colonoscopy MRI or have a full medical record if necessary, clean the digestive tract (using laxatives or enemas combined with enemas). 3.2 Perform an MRI scan Virtual endoscopic colonoscopy is usually performed in the morning with the following procedure:
Patient position: Lie prone on the scanning table, inject 20mg of scopolamine intravenously to reduce the need bowel movements. Next, the patient received an infusion containing contrast agent into the colonic framework through the anorectal route. Then, the doctor selects and positions the receiver coil, then moves the table into the magnetic field of the magnetic resonance imaging machine, locates the imaging area; Capture positioning on 3 horizontal, vertical and horizontal; Capture pulse sequences 1 - 2 - 3 - 4 according to specifications. Pulse series 1 - 2 taken before contrast injection, pulse series 3 - 4 after contrast injection; Perform data analysis on the original figure; Apply maximum intensity rendering technique; Multi-plane reconstruction; Virtual colonoscopy ; The doctor performs image analysis and makes a diagnosis.

3.3 Evaluation of MRI results. MRI technique can visualize the anatomical structures of the colon; After performing an MRI scan, the doctor detects the lesion and assesses the enhancement status of the lesion, if any. 3.4 Risk of adverse events and measures to be taken The patient may be frightened or agitated. In this case, medical staff should encourage and comfort the patient; For patients who are too nervous or afraid, the doctor can give the patient a sedative under the supervision of an anesthesiologist; Complications related to contrast agents such as urticaria, nausea, hypotension, anaphylaxis,... are very rare. If these complications are encountered, they should be treated according to the treatment regimen. Magnetic resonance imaging virtual colonoscopy is not too complicated procedure, needs good cooperation of the patient according to the doctor's instructions to obtain fast, accurate diagnosis results and limit the risk. unexpected risks occur.

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Master. Doctor Hoang Van Lan Duc was formally trained and graduated with a Master's degree from Hanoi Medical University. The doctor has more than 10 years of experience in the field of imaging, especially in diagnosing with emergency internal, surgical, abdominal, thoracic, musculoskeletal, neurological and thyroid, breast, ...

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