It is clear form the above discussion that the practitioner has many options available when attempting to optimise colonic distension prior to scan acquisition. While some techniques have an established evidence-base, others are largely a matter of personal preference. Whatever regime is chosen, it is clear that good distension is absolutely pivotal to the success of any CTC examination. The follow section will provide the reader with details of the authors' preferred methods.
Written patient information is provided and posted to the patient along with the bowel preparation approximately two weeks prior to examination. On the day of the examination, the radiologist or radiology resident greets the patient, checks they have understood what the procedure involves, they have no contraindications to hyoscine butylbromide or intravenous contrast and are happy to proceed. They are asked to evacuate the rectum just prior to entering the scanner room. In an attempt to improve compliance, patients are routinely warned that they will experience abdominal bloating and mild discomfort and the importance of good colonic distension for the accurate interpretation of their scan is stressed.
The authors favour carbon dioxide as the distension agent and in the past have slowly administered this via gentle compression of a filled enema bag as described in the section above. However, we now utilize an automated insufflator delivering carbon dioxide via a narrow calibre catheter, reserving a balloon catheter for the very occasional patient with anal incontinence. The patient is asked to lie supine initially so that an intravenous catheter can be sited if intravenous contrast is to be used, and for administration of Buscopan if not contraindicated. The patient is then asked to lie in the left lateral decubi-tus position and a lubricated rectal catheter, already attached to the insufflation device, is inserted. For all patients the maximum pressure shutdown dial is set initially at 25 mm Hg. Insufflation is commenced and after approximately 1.5 L have been introduced, the patient is turned into the supine position. Distension is then continued, titrated to patient tolerance, and sustained if rectal pressure remains low (i.e. below 15 mm Hg), providing the patient does not complain of undue abdominal discomfort. Once either the patient is mildly uncomfortable or intraluminal pressure consistently remains above 25 mm Hg (such that further insufflation is automatically prevented, which usually occurs following administration of 24 L of gas), a first CT scout image is acquired. If distension is deemed optimal by the supervising radiologist, then the full supine scan is acquired in a single breathhold. As long as the patient is comfortable the authors prefer to leave the insufflator device switched on during scanning, but turn down the pressure limit to 15 mm Hg so that this minimal rectal pressure is maintained. If the patient is uncomfortable, the device is paused to ensure that no further gas is insufflated until such time as the patient is happy for it to be recommenced. If distension is suboptimal despite the device recording rectal pressures exceeding 25 mm Hg, the catheter is checked and repositioned because it may be that its tip is occluded against the rectal wall. If unsuccessful, we will either then reposition the patient (e.g. prone) or gently manually palpate the abdomen to encourage redistribution of gas.
Once the supine study has been acquired, the rectal catheter is left in situ and the patient asked to turn prone. A second scout is performed and if distension is deemed suboptimal, the pressure limit will be increased to 25 mm Hg to encourage further gas insufflation. A further scout is performed and when this demonstrates optimal insufflation, the second study is acquired. The examination is then complete and the rectal catheter removed. The patient is reassured that much of the insufflated gas will be absorbed (rather than expelled), and that any abdominal cramping should ease within a few minutes.
There are several strategies available to the practitioner for optimising colonic distension and, if used appropriately, the time and effort invested will be rewarded by easier and more accurate interpretation. The authors recommend ongoing quality assurance measures are adopted by all departments performing CT colonography in order to minimise failure rates due to inadequate distension. Finally, safety concerns about CT colonography will likely diminish with more judicious use of rectal balloon catheters.
Barish MA, Soto JA, Ferrucci JT (2005) Consensus on current clinical practice of virtual colonoscopy. AJR 184:786-792 Blakeborough A, Sheridan MB, Chapman AH (1997) Retention balloon catheters and barium enemas: attitudes, current practice and relative safety in the UK. Clin Radiol 52:62-64
Bova JG, Jurdi RA, Bennett WF (1993) Antispasmodic drugs to reduce discomfort and colonic spasmduring barium enemas: comparison of oral hyoscyamine, i.v. glucagon and no drug. AJR 161:965-968 Bowles CJ, Leicester R, Romaya C et al. (2004) A prospective study of colonoscopy practice in the UK today: are we adequately prepared for national colorectal cancer screening tomorrow? Gut 53:277-283 Bruzzi JF, Moss AC, Brennan DD et al. (2003) Efficacy of IV Buscopan as a muscle relaxant in CT colonography. Eur Radiol 13:2264-2270 Burling D, Taylor SA, Halligan S et al. (2005) Automated colonic insufflation for Multi-Detector Row CT colonography: distension and patient experience in comparison to manual carbon dioxide insufflation. AJR (in press) Chen SC, Lu D, Hecht JR et al. (1999) CT colonography: value of scanning in both the supine and prone positions. AJR 172:595-599
Church J, Delaney C (2003) Randomized controlled trial of carbon dioxide insufflation during colonoscopy. Dis Colon Rectum 46:322-326 Coady-Fariborzian L, Angel LP, Procaccino JA (2004) Perforated colon secondary to virtual colonoscopy: report of a case. Dis Colon Rectum 47:1247-1249 Fenlon HM (2002) CT colonography:pitfalls and interpretation. Abdom Imaging. 27:284-291 Fletcher JG, Johnson CD, Maccarty RL, Welch TJ, Reed J, Hara AK (1999) CT colonography: potential pitfalls and problem solving techniques. AJR 172:1271-1278 Fletcher JG, Johnson CD, Welch TJ et al. (2000) Optimization of CT colonography technique: prospective trial in 180 patients. Radiology 216:704-711 Ghahremani G (2000) Iatrogenic gastrointestinal disorders. In: Gore RM, Levine MS (eds) Textbook of gastrointestinal radiology, 2nd edn. W.B Saunders Co., Philadelphia, pp 2228-2242
Gluecker T, Johnson D, Harmsen W et al. (2003) Colorectal cancer screening with CT colonography, colonoscopy, and double contrast barium enema examination: prospective assessment of patient perceptions and preferences. Radiology 227:378-384 Goei R, Nix M, Kessels AH et al. (1995) Use of antispasmodic drugs in double contrast barium enema examination: glu-cagon or buscopan? Clin Radiol 50:553-557 Grant DS, Bartram CI, Heron CW (1986) A preliminary study of the possible benefits of using carbon dioxide insufflation during double contrast barium enema. Br J Radiol 59(698):190-191 Gryspeerdt SS, Herman MJ, Baekelandt MA (2004) Supine/left decubitus scanning: a valuable alternative to supine/prone scanning in CT colonography. Eur Radiol 14:768-777 Hara AK, Johnson CD, MacCarty RL et al. (2001) CT colonography: single versus multi-detector row imaging. Radiology 219:461-465 Iafrate F, Laghi A, Paolantonio P et al. 2004 Colonic distension using mechanical CO2 insufflator versus manual air distension. In Radiological Society of North America scientific assembly and annual meeting program. Oak Brook, Ill: Radiological Society of North America, p 432 Kamar M, Portnoy O, Bar-Dayan A, Amitai M, Munz Y, Ayalon A, Zmora O (2004) Actual colonic perforation in virtual colonoscopy: report of a case. Dis Colon Rectum 47:12421244
Macari M (2004) Techniques for CT colonography. In: 5th International Symposium Virtual Colonoscopy course handbook, Boston, pp 45-48 Macari M, Megibow AJ (2001) Pitfalls of using 3D CT colonography with 2D imaging correlation. AJR 176:137-143 Morrin M, Farrell R, Keogan M et al. (2002) CT colonography: colonic distension improved by dual positioning but not intravenous glucagons. Eur Radiol 12:525-530 Muhldorfer SM, Kekos G, Hahn et al. (1992) Complications of therapeutic gastrointestinal endoscopy. Endoscopy 24:276-283
Paulson EK, Foster WL, Thonpson WM et al. (2004) Causes of errors in CT Colonography (CTC) and Air Contrast Barium Enema (ACBE) in detection of colonic lesions 1 cm or larger (abstr). In: Radiological Society of North America scientific assembly and annual meeting program. Oak Brook, Ill: Radiological Society of North America, p 618 Pickhardt PJ (2004) Differential diagnosis of polypoid lesions seen at CT colonography (virtual colonoscopy). Radio-graphics 24:1535-1556 Pickhardt PJ, Choi JR, Hwang I et al. (2003) Computed tomo-graphic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. NEJM 349:2191-2200 Ristvedt S, McFarland E, Weinstock L et al. (2003) Patient preferences for CT colonography, conventional colonoscopy, and bowel preparation. Am J Gastroenterol 98:578-585 Rockey DC, Paulson EK, Niedzwiecki D et al. (2005) Analysis of air contrast barium enema, computed tomographic colonography, and colonoscopy: prospective comparison. Lancet 365:305-311 Rogalla P, Bauknecht HC, Hein PA et al. (2004a) Pressure-controlled colonic insufflation for CT colonography. In: Radiological Society of North America scientific assembly and annual meeting program (abstr). Oak Brook, Ill: Radiological Society of North America, p 432 Rogalla P, Lembcke A, Hein PA et al. (2004b) Spasmolysis with butyl scopolamine versus glucagon in CT colonography. In: Radiological Society of North America scientific assembly and annual meeting program (abstr). Oak Brook, Ill: Radiological Society of North America, p 433 Rubesin S, Levine MS, Laufer I et al. (2000) Double-contrast barium enema examination technique. Radiology 215:642650
Sosna J, Bar-Meir E, Amitai M, Blachar A, Peled N (2004) Assessment of the risk of perforation at CT colongraphy (abstr). In: Radiological Society of North America scientific assembly and annual meeting program (abstr), Oak Brook, Ill. Radiological Society of North America, p 280 Svensson MH, Svensson E, Lasson A et al. (2002) Patient acceptance of CT colonography and conventional colonoscopy: prospective comparative study in patients with or suspected of having colorectal disease. Radiology 222:337-345 Taylor SA, Halligan S, Goh V et al. (2003) Optimizing colonic distension for multi-detector row CT colonography: effect of hyoscine hydrobromide and rectal balloon catheter. Radiology 229:99-108 Vallera R, Bailie J (1996) Complications of endoscopy. Endoscopy 28:187-204 Vos F, Van Gelder R, Serlie I et al. (2003) Three dimensional display modes for CT colonography: conventional 3D virtual colonoscopy versus unfolded cube projection. Radiology 228:878-885 Waye JD, Lewis BS, Yessayan S (1992) Colonoscopy: a prospective report of complications. J Clin Gastroenterol 15:347351
Yee J, Hung RK, Akerkar GA et al. (1999) The usefulness of glu-cagon hydrochloride for colonic distension in CT colonog-raphy. AJR 173:169-172 Yee J, Galdino G, Kumar N et al. (2002) Comparison of colonic distention using electronic CO2 insufflation and manual atmospheric insufflation on CT colonography (abstr). In: RSNA Scientific Assembly and Annual Meeting program Yee J, Kumar N, Hung R et al. (2003) Comparison of supine and prone scanning separately and in combination at CT colonography. Radiology 226:653-661
Was this article helpful?
Stop The Pain. Manage Your Diverticular Disease And Live A Pain Free Life. No Pain, No Fear, Full Control Normal Life Again. Diverticular Disease can stop you from doing all the things you love. Seeing friends, playing with the kids... even trying to watch your favorite television shows.