Medical imaging technique for colon

1. Virtual Colonoscopy
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2. What is virtual colonoscopy?
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Medical imaging procedure.
Also known as CT colonography.
Non invasive procedure.
uses x rays and computers.
2D and 3D images of rectum and entire colon.
display them on a screen.
can provide 3D reconstructed endoluminal
views of the bowel.
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3. What are the rectum and colon?
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4. Colon
 The colon is also called the large intestine
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5. Rectum
 Final straight portion of the large intestine.
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6. Why the Test is Performed
 Follow-up on colon cancer or polyps
 Look for the cause of:
• Abdominal pain, changes in bowel movements, or
weight loss
• anemia due to low iron
• Blood in the stool
• Screen for cancer of the colon
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7. Colon polyps
An abnormal growth of tissue projecting from
a mucous membrane
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8. How to Prepare for the Test
 Patient need to empty bowels before the exam
 patient will usually be asked to take laxatives or other
oral agents at home the day before the procedure to
clear stool from the colon.
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9. How the Test is Performed
 Patient is asked to lie on his/her left side on a
narrow table that is connected to an MRI or CT
scan machine.
 knees will be up towards the chest.
 A small, flexible tube will be inserted into rectum.
 Air is pumped through the tube to make the colon
bigger and easier to see.
After this is done, patient will be asked to lie in
supine position.
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11.  The table moves through the scanner to produce
a series of two-dimensional cross-sections along
the length of the colon.
 A computer program puts these images together
to create a three-dimensional picture that can be
viewed on the video screen .
 patient is asked to hold his/her breath during the
scan to avoid distortion on the images.
 The scan is then repeated with the patient lying
in a prone position .
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13. Direction of rotation
Rotating x ray
source
Motorized platform
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14. Advantages
 Virtual colonoscopy is less invasive, safer, and
takes less time than a regular colonoscopy.
 A thin tube to insert air into the colon is placed
in the rectum rather than a long flexible tube
that is moved up your colon.
 Patients do not require anesthesia or sedation
and can return home on their own or get back to
work immediately after the test.
 VC provides clearer, more detailed images
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15. Disadvantages
a radiologist cannot take tissue samples (biopsy) or
remove polyps during VC, so a
conventional colonoscopy must be performed if
abnormalities are found.
 may not show polyps smaller than 10 mm
 There is a slight risk that the CT scan can interfere
with implanted or external medical devices.
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16. Risks
The risks of virtual colonoscopy include
 exposure to radiation and
 perforation—a hole or tear in the
lining of the colon.
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17. Bibliography
 http://www.nlm.nih.gov/medlineplus/ency/ar
ticle/007253.htm
 http://digestive.niddk.nih.gov/ddiseases/pubs
/virtualcolonoscopy/
 http://en.wikipedia.org/wiki/Virtual_colonosc
opy
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