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'''Colonography''' refers to radiographic imaging of the large intestine. [[CT]] colonography is the modality most frequently used. [[Colonoscopy]] is used more often than colonography for evaluation of the large intestine, as it allows for taking biopsy samples and removing polyps during the same procedure.
'''Colonography''' refers to radiographic imaging of the large intestine. [[CT]] colonography is the modality most frequently used. [[Colonoscopy]] is used more often than colonography for evaluation of the large intestine, as it allows for taking biopsy samples and removing polyps during the same procedure.
CT colonography with insufflation of the large intestine with CO2 is also called '''virtual colonoscopy''' or '''CT colonoscopy'''. It avoids the uncomfortableness of a regular colonoscopy but does not allow for sampling or treatment.
Barium may be administered rectally, in which case the examination is called a '''barium enema'''.


== Indications ==
== Indications ==
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* [[Colonic polyps]]
* [[Colonic polyps]]


== Patient preparation ==
== Modalities ==
Emptying the bowel before colonography is essential. The patient must fast minimum 6 hours ahead and only consume clear fluids (water and thin drinks) the day before. A strong [[laxative]] must be given to empty the bowel completely.
 
== Interpretation ==
In cases of colorectal cancer which forms a stenosis, the apple core sign can be seen. This is an annular constriction of the colonic lumen which looks like an apple-core.
 
In case of colitis, the bowel wall is thickened and the bowel lumen is irregularly narrowed.


== Lesser used colonic studies ==
=== CT colonography ===
CT colonography with insufflation of the large intestine with CO2 is also called virtual colonoscopy or CT colonoscopy. It avoids the uncomfortableness of a regular colonoscopy but does not allow for sampling or treatment, and so colonoscopy is usually preferred instead.


=== Colonic transit study ===
=== Colonic transit study ===
A colonic transit study can be used to evaluate constipation. It involves the patient swallowing a capsule containing many small radiopaque markers. Serial radiographs are then taken, allowing one to visualise the movement of the markers over time.
A colonic transit study can be used to evaluate constipation. It involves the patient swallowing a capsule containing many small radiopaque markers. Serial radiographs are then taken, allowing one to visualise the movement of the markers over time.
=== Barium enema ===
Barium may be administered rectally, in which case the examination is called a barium enema. This is rarely performed.


=== Defecography ===
=== Defecography ===
Defecography is a rarely used procedure used to evaluate for constipation. The rectum is filled with barium paste, and the patient defecates during [[Fluoroscopy|fluoroscopic]] examination.
Defecography is a rarely used procedure used to evaluate for constipation. The rectum is filled with barium paste, and the patient defecates during [[Fluoroscopy|fluoroscopic]] examination.
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== Patient preparation ==
Emptying the bowel before colonography is essential. The patient must fast minimum 6 hours ahead and only consume clear fluids (water and thin drinks) the day before. A strong [[laxative]] must be given to empty the bowel completely.
 
== Interpretation ==
In cases of colorectal cancer which forms a stenosis, the apple core sign can be seen. This is an annular constriction of the colonic lumen which looks like an apple-core.
 
In case of colitis, the bowel wall is thickened and the bowel lumen is irregularly narrowed.<noinclude>
[[Category:Radiology]]
[[Category:Radiology]]
</noinclude>
</noinclude>