Gastrointestinal ❯ Virtual Colonoscopy
CT Protocol for Virtual Colonoscopy
| Problem | CT evaluation of the colon for screening for polyp or tumor |
| Protocol | The CT protocol starts with prepping the patient prior to the study for a cleansing of the colon similar to what is done for a classic colonoscopy. The main difference is usually 24-36 hours prior to the study the patient also drinks a prep like a barium agent ( usually about 250 ML) in order to tag any remaining stool in the colon. What prep you use will depend on the imaging site you follow. If you do not have a prep go to the web and a number of sites ranging from the Mayo Clinic to Stanford to U of Wisconsin have the preps clearly presented. On the day of the study the patient is typically NPO. The colon is distended with CO2 which is absorbed very quickly and so patient has less discomfort. With room air the patient will be uncomfortable and the experience will not be a good one. The study is done will the colon distended and is done in both the supine and prone position. |
| Pearls | 1. The study review initially is of the whole abdomen and pelvis to look for any extra-colonic findings 2. The study is done in both supine and prone position. If the patient can not lie in the prone position a decubitus set of images can be done 3. The study review consists of axial and multiplanar views and well as fly-thru views with 3D imaging. The fly thru views have many unique features but it will vary depending on your vendor for the virtual colonoscopy 4. We recommended training with whatever software vendor you use as the software will have different features. Most vendors currently can do remote training (some will even do hands on if you ask nicely). Vendor software features will vary from stool tagging to automatic fly-thrus to polyp detection with AI. 5. The success of virtual colonoscopy will be most dependent on a good patient prep and then on good distension of the colon 6. Virtual colonoscopy is especially good for polyps over 1cm 7. The main advantage of classic colonoscopy is the ability to remove polyps during a single exam. However the disadvantages include patient sedation and potential trauma to the colon or even the spleen. |