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Virtual
colonoscopy/CT of the colon
1.
Do you know of any sites routinely administering IV contrast for CT
colonography? Any contacts you could provide (or papers on the topic)
would be very much appreciated. I hear equally good arguments for and
against.
| Answer:
We do not routinely use IV contrast. One or 2 published articles
did and found interpretation easier. I definitely agree, but we
are currently not routinely using IV contrast for Virtual Colonoscopy.
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2.
Could you please tell me of what type of catheter you are currently
using for infusion of air at Virtual Colonography, including the manufacturer
and the name of the catheter.
| Answer:
We use a 24F Harris Flush tube (Kendall Healthcare). For inpatients
who have trouble retaining the air, we use a classic barium tip
with a balloon. |
3.
Our facility is considering doing VC's and I have been asked to research
the equipment needed and reimbursements. We currently have a Sensation
16 and a Leonardo workstation. I have received a price on the software
needed, but need to know how others are infusing the air. I need to
know how others are infusing the air. What types of air infusion systems
are people using?
| Answer:
We use the new colon package on the Leonardo and in my opinion it
makes the best fly-through images and is easy to learn. As for putting
air in the colon, we simply put a small catheter in the rectum and
use a small balloon to distend the colon. This works well. We tried
the CO2 pump without much success and returned it. The billing issue
is tricky. Many sites charge people out of pocket $1000 to $1200
dollars, while others bill an abdominal/pelvis CT code and add a
3D charge. |
4.
We have a new Siemens 16. Administration would like to start offering
VC. My only option for inserting CO2 seems to be inflating a barium
bag and pushing the air in from the bag. Should I have any concerns
with this?
| Answer:
We have never used it. One would recommend either a CO2 injector
or use a bulb. |
5.
What is now considered the optimal bowel prep for VC? What dietary advice
do you recommend if any?
| Answer:
One can use either Golytely or LoSo. We advise a low-fiber, liquid
diet and encourage fluids to avoid dehydration. |
6.
It seems from your Baltimore Conference that you used water as an oral
contrast with IV for most small bowel exams. This will enhance the wall,
fill the lumen, and is better for 3D imaging. Is this also the case
when pathology is questioned in the large bowel? And do you change the
amount of water (1000 cc) and timing approximately (20-30 min)?
| Answer:
The water works great for the small bowel, but p.o. will not work
for the colon. For the colon, you can use air in the virtual studies. |
7.
Do you advise using tagging agents for VC, and how often? Do you advise
after every meal (broth)?
| Answer:
Yes, we routinely use a tagging agent 1 day prior to the study.
We recommend drinking it with breakfast, lunch and dinner. |
References
Morrin MM, Farrell RJ, Kruskal JB, Reynolds K, McGee JB, Raptopoulous
V. Utility of IV administered contrast material at CT colonography Radiology
2000; 217: 765-771.
- Summary:
This study compared unenhanced supine colonography datasets to enhanced
prone acquisitions in 81 patients with colonoscopy or surgical correlation.
Results demonstrated significantly improved reader confidence for
evaluating bowel wall conspicuity and detectability of medium polyps
when IV contrast was administered.
Geenen RWF, Hussain SM, Cademartiri F et al. CT and MR colonography:
Scanning techniques, postprocessing, and emphasis on polyp detection.
Radiographics 2003; 24:e18. Published online only.
- Summary:
Both MR and CT acquisition and postprocessing techniques are addressed
in this online review. The authors include data from numerous studies
which have guided the development and improvement of protocols for
CT and MR colonography.
Lefere
PA, Gryspeerdt SS, Dewyspelaere J, Baekelandt M, Holsbeeck BG. Dietary
fecal tagging as a cleansing method before CT colonography: initial
results-polyp detection and patient acceptance. Radiology 2002; 224:
393-403.
- Summary:
One-hundred patients were included in this comparison of bowel preparation
with and without fecal tagging. The results showed that the fecal
tagging preparation resulted in more fecal residue; however, the differentiation
of polyps from residue was improved. Survey of the patients demonstrated
decreased discomfort and side effect with the fecal tagging protocol,
and the sensitivity for polyp detection was similar between the two
groups (88% FT and 85% non F-T).
Macari
M, Bini EJ, Jacobs SL, Lange N, Lui YW. Filling defects at CT colonography:
pseudo- and diminutive lesions (the good), polyps (the bad), flat lesions,
masses, and carcinomas (the ugly). RadioGraphics 2003; 23:1073-1091.
- Summary:
This educational exhibit reviews CT data acquisition, the roles of
2D and 3D displays, and CT findings which aid in the discrimination
and detection of polyps.
In the section on technique, the authors describe three different
bowel preparations.
With respect to air insufflation, a flexible rubber catheter was used
to administer room air. This review provides CME credit.
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