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The British Journal of Radiology, 85 (2012), 1085–1092 Evaluation of two minimal-preparation regimes for CTcolonography: optimising image quality and patientacceptability A POLLENTINE, MB Chir, FRCR, A MORTIMER, MB ChB, FRCR, P MCCOUBRIE, MB BS, FRCR andL ARCHER, MB ChB, FRCR Department of Radiology, Southmead Hospital, Westbury-on-Trym, Bristol, UK To compare a 2 day bowel preparation regime of barium, iodine and a mild stimulant laxative with a 1 day iodine-only regime for CT colonography (CTC).
Methods: 100 consecutive patients underwent CTC. The first 50 patients (Regime 1) ingested 1 bisacodyl tablet twice a day 3 days before CTC and 1 dose each of 50 ml ofbarium and 20 ml of iodinated contrast per day starting 2 days before CTC. The second50 patients (Regime 2) ingested 3 doses of iodinated contrast over 24 h prior to CTC.
Volumes of residual stool and fluid, and the effectiveness of stool and fluid tagging,were graded according to methods established by Taylor et al (Taylor S, Slaker A,Burling D, Tam E, Greenhalgh R, Gartner L, et al. CT colonography: optimisation,diagnostic performance and patient acceptability of reduced-laxative regimens usingbarium-based faecal tagging. Eur Radiol 2008; 18: 32–42). A 3 day low-residue diet wastaken by both cohorts. Questionnaires rating the side-effects and burden of the bowelpreparation were compared to a control cohort of patients undergoing barium enema.
Results: The proportion of colons producing none/scattered stool (score 1) was 90.3% Received 14 June 2011Revised 22 September with Regime 1 and 65.0% with Regime 2 (p,0.005). Any residual stool was significantly better tagged with Regime 1 (score 5), with 91.7% of Regime 1 exhibiting optimum tagging vs 71.3% of Regime 2 (p,0.05). No significant differences in side-effects between the bowel preparation regimes for CTC were elicited. Bowel preparation for barium enema was tolerated significantly worse than both of the CTC bowel preparation regimes.
Conclusion: Regime 1, containing a 3 day preparation of a mild laxative, barium and iodine, produced a significantly better prepared colon, with no difference in patient acceptability.
CT colonography (CTC) requires a well-prepared bowel to bowel preparation, it is imperative to ensure that residual to enable accurate detection and characterisation of color- material is thoroughly and homogeneously tagged, and ectal polyps and carcinomas. Bowel preparation regimes that this can be readily differentiated from normal and vary among different institutions. These encompass solely abnormal mucosa. Employing this technique enables a cathartic bowel preparation with agents used traditionally to reduction in the amount of bowel catharsis necessary to be prepare bowel for colonoscopy such as polyethylene glycol able to accurately identify mucosal anomalies, and thus or sodium phosphate [1, 2]. Full cathartic bowel preparation increase patient acceptability and willingness to undergo is associated with significant side-effects, including diar- rhoea, abdominal pain and disruption to activities of daily Tagging materials can consist of iodine- and/or living [3, 4], and in extreme cases even death [5]. Previous barium-based agents. Some authors believe that barium studies have shown that patients often regard such bowel predominately tags the more solid elements of the preparation for bowel investigation as the most burdensome retained colonic residue [18]. Hyperosmolar iodine-based part of the process [6, 7]. This has a significant impact in the contrast agents promote stool softening by inducing context of screening for bowel cancer as patient compliance colonic fluid secretion. This allows homogeneous tagging is central for a successful programme [8]. More recently of both solid and fluid residue, but can induce significant there has been a vogue towards using oral contrast medium diarrhoea when administered in large volumes.
to ‘‘tag’’ residual faeces and fluid with the use of fewer To date there remains no consensus on the optimum laxatives [9, 10], or even with oral contrast medium alone way to tag bowel residue—neither which contrast agent [11–15]. This approach means a less vigorous bowel nor the volumes or timing for administration, nor preparation can be used, as any residual matter can be whether additional laxatives are necessary.
accurately delineated from mucosal abnormalities on the The aim of this study was to compare primarily the basis of its higher attenuation. When adopting this approach image quality achieved and the patient acceptance oftwo different regimes encompassing different elements ofbowel preparation. The first used both iodine and barium Address correspondence to: Dr Adrian Pollentine, Department of as tagging agents with a mild laxative over 2 days (Regime Radiology, Southmead Hospital, Southmead Road, Westbury- 1) and the second was a minimal preparation regime, on-Trym, Bristol BS10 5NB, UK. E-mail: adrianpollentine@doctors.
org.uk using iodine alone over 24 h (Regime 2).
The British Journal of Radiology, August 2012 A Pollentine, A Mortimer, P McCoubrie and L Archer This study consists of two main parts. The first aim of Patients undergoing CTC in both preparation groups this study was to evaluate the technical performance of were asked to adhere to the same low-residue diet for two different bowel preparation regimes in terms of the volume of residual stool and fluid, and the quality of the The first consecutive 50 patients (Regime 1) were asked tagging of retained material. Indications for referral for to take a mild laxative, bisacodyl, 5 mg twice a day for the 3 CTC were (1) increased risk of colorectal cancer from days prior to CTC. In addition, they were asked to take one family or personal history in asymptomatic patients and 50 ml dose of MicrocatH (5% w/v barium sulphate; (2) recent onset of concerning symptoms (e.g. rectal Guerbet, Solihull, UK) mixed with 200 ml of water and bleeding, iron deficiency anaemia and change in bowel one 20 ml dose of GastrografinH (100 mg sodium diatrizo- ate and 660 mg meglumine diatrizoate per ml; Bayer, The first 50 patients undergoing CTC after January Newbury, UK) together in the morning for 2 days prior to 2009 at each of 2 different hospitals employing different CTC and a further dose of each on the morning of the faecal tagging regimes were selected and retrospectively examination. The Regime 1 group therefore ingested a analysed. The two hospitals belong to the same NHS total of 150 ml 5% w/v barium and 60 ml of Gastrografin trust and serve the same population. In total, 100 patients were included in this technical performance arm of the The second consecutive 50 patients (Regime 2) were study. Each patient had all 6 colonic segments included asked to take 3 aliquots of Gastrografin in the 24 h and analysed, totalling 600 colonic segments. Patients preceding examination: 35 ml of Gastrografin at lunch with prior personal history of colorectal carcinoma or and dinner the day before CTC and a further 30 ml on the previous colonic resection, as well as patients with a morning of the examination. The Regime 2 group therefore contraindication to iodine administration, were excluded ingested a total of 100 ml of Gastrografin for faecal tagging.
A summary of the bowel preparation regimes for CTC The second part of the study was a prospective evaluation by means of a questionnaire regarding the The control group of patients undergoing barium effects of the bowel preparation of three groups of enema ingested two sachets of Picolax (Ferring Pharma- patients. The first cohort underwent investigation using ceuticals Ltd, West, Drayton, UK; sodium picosulphate Regime 1 and included 57 patients. The second cohort 10.0 mg, magnesium oxide 3.5 g, citric acid 12.0 g) in the ingested Regime 2 for CTC and included 54 patients. A third cohort of 59 patients undergoing barium enemaexamination was used as a control group for analysis ofpatient tolerance to traditional cathartic bowel prepara- tion, which some centres continue to employ. Thequestionnaires were collected continuously until 50 CT was performed on a four-slice Marconi Mx8000 CT complete questionnaires had been acquired from each system (Philips Healthcare, Best, Netherlands) for the cohort. There were seven incomplete questionnaires Regime 1 group at a slice thickness of 1 mm, pitch 1.5, from Regime 1, four from Regime 2 and nine from the tube voltage 120 kV and tube current varied according to barium enema group. These were therefore excluded the patient’s body habitus. The Regime 2 group were and only the 50 completed questionnaires were used in examined on a 64-slice Siemens CT system (Siemens Medical Solutions, Forchheim, Germany) at a slice The patients used for both study components under- thickness of 0.6 mm, pitch 1.5, tube voltage 120 kV and took identical bowel preparation regimes and were tube current of 100 mAs. 3 mm axial slice reconstructions referred from the same catchment population of the were sent by both scanners to local picture archiving and two hospitals under the same referral criteria.
communications system (PACS) servers for assessment.
Ethics approval was waived for the first part as it was Patients were given 20 mg of intravenous butylscopola- a retrospective analysis of the technical performance of mine bromide (BuscopanH; Boehringer Ingelheim, Bracknell, the bowel preparation. Ethics approval was granted for UK) or 1 mg of glucagon hydrochloride if Buscopan was the questionnaire forming the second part of the study contraindicated to ensure bowel paralysis. For patients who by the trust’s clinical audit advisory committee.
ingested Regime 1, colonic distension was achieved by Table 1. Summary of bowel preparation regimes bd, twice daily; CTC, CT colonography.
The British Journal of Radiology, August 2012 Patient acceptance and image quality in two minimal-preparation regimes for CTC manual air insufflation by the supervising radiologist until preparation regime protocol. Patients were assured that adequate distension had been achieved or patient tolerance they would not be excluded from having their examina- allowed. Patients taking Regime 2 underwent automated tion if they had failed to adhere to the instructions or were CO2 insufflation. Patients were imaged in supine and unable to tolerate the preparation owing to side-effects.
prone positions (or lateral decubitus if patient could not The questionnaire was designed using questions previously used in evaluation of bowel preparation[20–22], using a Likert scale with seven points employedfor each question [23]. A variety of potential side-effects from the bowel preparation were interrogated as follows:general disruption to daily life, overall discomfort, Images were reviewed on a GE PACS RA 1000 abdominal pain, diarrhoea, anal irritation, thirst, hunger, workstation (GE Healthcare, Waukesha, WI) using a nausea and vomiting. Patients were asked to rate how primary two-dimensional technique by two experienced severe each symptom was, with 1 equalling no symp- radiologists. Each radiologist was blinded to the type of toms experienced and a score of 7 equalling extreme bowel preparation regime. No restriction was placed on symptoms. Patients were finally asked whether they windowing and the radiologist was encouraged to would take the bowel preparation again if required.
utilise the full range of processing tools as required.
The amount of residual faeces was graded according tocriteria established by Taylor et al [19], as illustrated inTable 2. These criteria were applied to the quality of the faecal tagging, as well as the volume of residual fluidand the quality of the tagging thereof. The evaluations For all statistical comparisons, any difference asso- were repeated for each of the colonic segments: caecum, ciated with a two-tailed p-value ,0.05 was considered ascending, transverse, descending, sigmoid and rectum.
statistically significant. Age and sex distributions The part of the segment that yielded the worst score (e.g.
between the groups were analysed using the Mann– the highest residual volume and lowest tagging quality Whitney U-test and x2 test, respectively.
scores) was used to allocate the score for that segment.
For the analysis of the volumes of residual stool and Examples of colons achieving the optimum preparation fluid, as well of the quality of tagging, we applied criteria and those that were poorly prepared are shown ordinal regression analysis and the generalised estimat- ing equation to allow for clustering and dependency of Colonoscopic correlation was not sought owing to the data (multiple segments per patient) and compared the relatively small number of positive findings in terms of groups using a non-parametric analysis of variation polyp or cancer detection and the fact that the study was not formally designed to investigate the accuracy of the Further scalar data including patient responses to CTC bowel preparation as an end point.
bowel preparation side-effects were analysed using theMann–Whitney U-test. The x2 test was applied to thequestion regarding whether the patient would take the Before undertaking their examination, consecutive patients were asked to complete a questionnairerelating to their experiences of the bowel preparation Patients were asked to declare whether they had taken The diagnostic arm sex breakdown was as follows: the all of the preparation components as detailed by the ratio of males to females was 17:33 for Regime 1 and Table 2. Criteria used to grade residual stool and fluid volumes and tagging quality Coating of ,25% of lumen diameter or circumferential film of ,2 mm Homogeneous tagging of single uniform density The British Journal of Radiology, August 2012 A Pollentine, A Mortimer, P McCoubrie and L Archer No statistical significance was reached between these Regime 1 produced 271/300 (90.3%) colonic segments with no or only scattered stool (grade 1). Regime 2yielded 195/300 (65.0%) colonic segments with the sameoptimal preparation (p,0.005).
There were 51/300 (17.0%) segments rated grades 3 or 4 (25–50% and .50% anteroposterior diameter ofstool) with Regime 2 and 8/300 (2.67%) with Regime 1(p,0.005). Figure 3 illustrates the stool volume scoresachieved by both regimes.
Per segment analysis between the two preparation regimes showed significantly reduced volumes (p,0.05)of stool in all colonic segments with Regime 1 except forthe rectum (p50.135).
Analysing for variability in residual stool volume between colonic segments prepared using Regime 1yielded statistically significant differences between the Figure 1. A 72-year-old male with change in bowel habit.
volume of residual stool in the sigmoid colon and the Axial CT colonographic image demonstrating no residual ascending and transverse colonic segments (p50.011 and stool (grade 1) with homogeneously tagged fluid (grade 3).
0.021, respectively). No such differences were shownbetween segments prepared using Regime 2.
16:34 for Regime 2. Mean ages for Regimes 1 and 2 were74 [standard deviation (SD) 13.5] and 71 (SD 12.1) yearsold, respectively.
The ratio of males to females for patients returning questionnaires was 21:29, 15:35 and 22:28 for Regime 1, The number of segments rated grade 5 (75–100% of Regime 2 and barium enema, respectively. Mean ages for stool tagged) was 275/300 (91.7%) and 214/300 (71.3%) Regimes 1, 2 and the barium enema group were 71 (SD for Regimes 1 and 2, respectively (p,0.05).
16.4), 68 (SD 13.5) and 65 (SD 12.8) years old, respectively.
There were 13/300 (4.33%) segments with stool tagging grades of 1–3 (none, 0–25% and 25–50% tagged)for Regime 1 compared with 62/300 (20.7%) for Regime 2(p,0.005). Figure 4 illustrates the stool tagging scoresachieved by both regimes.
Per segment analysis yielded statistically significantly superior stool tagging with Regime 1 across all colonicsegments compared with Regime 2, with the exception ofthe caecum (p50.106).
No significant difference in tagging quality existed between colonic segments prepared using Regime 1.
With Regime 2 there was significantly poorer taggingquality between the sigmoid and rectum and the moreproximal colonic segments (ascending/caecum vs sig-moid and rectum p,0.005), with more segments contain-ing completely untagged faeces (grade 1; 8/100 forsigmoid and rectum and only 1/100 for caecum andascending colon).
The number of colonic segments that exhibited the least retained fluid volume and thus the best prepara-tion (grade 1) was 56/300 and 18/300 (18.7% and 6%)for Regimes 1 and 2, respectively. The commonest score Figure 2. An 85-year-old male with rectal bleeding. Axial CT assigned to colonic segments was 2 (,25% anteropos- colonographic image demonstrating a large volume ofretained stool in the ascending colon (.50% anteroposterior terior diameter of residual fluid) and was found in diameter; grade 4) and untagged stool in the descending 180/300 and 218/300 segments for Regimes 1 and 2, The British Journal of Radiology, August 2012 Patient acceptance and image quality in two minimal-preparation regimes for CTC Figure 3. Residual stool volumegrades assigned to segments pro-duced by each CT colonographybowel preparation regime.
ANOVA analysis shows statistically lower fluid N Thirst: significantly less thirst was experienced by volume scores for Regime 1 across all colonic segments patients taking Regime 1 compared with barium (p50.008). Per segment analysis showed no significant enema preparation (p50.021). There was no difference difference in fluid volume scores except for the descend- N Hunger: significantly less hunger was experienced by patients taking Regime 2 compared with both Regime 1and the barium enema preparation (p50.0002 and p50.0013). No difference existed between Regime 1and barium enema.
Homogeneous tagging of residual fluid (grade 3) was N Headache: significantly more patients rated headache achieved in 94.7% of colon segments with Regime 1 and as a significant side effect with the barium enema 98.3% of colons with Regime 2. No statistical significance preparation compared with Regime 2 (p50.042), but existed between preparation regimes or between colonic no such significance existed compared with Regime 1 N No significant difference existed between the bowel preparations for the following side effects: nausea, vomiting, anal irritation and bloating.
N Refusal to take bowel preparation again: fewer Patients rated a variety of symptoms and side effects patients would refuse to take the bowel preparation relating to the bowel preparation for both CTC regimes again with Regime 2 (2/50) compared with Regime 1 and a cohort of patients undergoing barium enema (5/50) and the barium enema (8/50) preparation, but examination. The median score and interquartile ranges this was not statistically significant.
assigned to each side effect for each of the three bowelpreparations is shown in Table 3.
N Disruption to everyday life: no significant difference was shown between the CTC regimes. Significantlyworse for barium enema preparation (p,0.005 for We have shown that a simple bowel preparation regime incorporating a mild laxative and three doses of N General discomfort: no significant difference was each of iodinated contrast and barium taken over 2 days shown between the CTC regimes. Significantly worse prior to examination produces a very well-prepared for barium enema preparation (p,0.005 for both CTC colon that is well tolerated by patients.
Much work continues in attempting to establish a N Diarrhoea: barium enema preparation was rated bowel preparation regime that balances the need for a significantly more burdensome than either of the colon with as little residual material as possible for CTC preparations (p,0.0001 for both CTC regimes).
accurate and safe exclusion of colorectal neoplasia No difference existed between the CTC regimes.
and polyps with the smallest side effect profile to The British Journal of Radiology, August 2012 A Pollentine, A Mortimer, P McCoubrie and L Archer Figure 4. Stool tagging scoresassigned to colon segments pro-duced by each CT colonographybowel preparation regime.
ensure a high acceptability to patients, who are often should be simple and reproducible with small volumes of tagging agents and minimal side-effects.
The use of a low-residue diet is a simple and effective In our study, the proportion of colonic segments that way of reducing the volume of residual faecal material contained no residual stool was strikingly different [24], with no difference in patient acceptance [25]. The between the longer, mixed preparation regime and the exact timing of when to ask patients to commence a low- shorter 24 h regime consisting of only iodinated contrast residue diet has yet to be established [26, 27].
(90.3% vs 65.0%). The explanation of this is likely to be The use of tagging agents to increase the conspicuity of multifactorial and could be owing to the incorporation residual material is an established method of reducing the of a mild laxative with Regime 1 as well as the longer need for full cathartic bowel preparation. Several of the preparation period. This is borne out by the observation major studies undertaken to establish the accuracy of CTC that only 2.67% of segments exhibited stool occupying as a tool for polyp and cancer detection [8, 28] used full .25% of the luminal diameter with Regime 1 compared with 17.0% of segments with Regime 2.
in combination with both barium and iodine residue When tagging-only regimes are used for CTC it is important that there is thorough and homogeneous The optimum tagging agent is yet to be established incorporation of the tagging agent with the faeces, with proponents of both barium- and iodine-based without untagged faecal remnants. Inadequate tagging agents. Likewise, the optimal timing and volumes of could lead to an examination where detection and these agents remains to be optimised. Some authors have exclusion of mucosal pathology is difficult. In our study concluded that barium preferentially tags solid faecal there was a significantly higher number of colonic material, leaving appreciable volumes of colonic fluid segments containing faecal residue that was untagged untagged [18]. Larger volumes of administered barium or only partially (,25%) tagged: 3/300 (1.0%) for Regime seem to tag a greater proportion of colonic fluid, but 1 and 23/300 (7.7%) for Regime 2. The 24 h tagging-only with layering [19]. The hyperosomolar properties of regime showed a significant difference in tagging Gastrografin may to some degree allow liquidisation of homogeneity between the better tagged proximal colonic stool and more homogeneous incorporation of tagging segments and the distal colonic segments. This raises the agent. There is clearly complex interplay between the possibility that a 24 h preparation protocol is insufficient volumes, concentrations and timings of administered time in some patients to ensure homogeneous tagging in tagging agent with the volumes of ingested fluid and the more distal colonic segments where the majority of diet, and the ultimate appearance at CTC.
Minimal preparation regimes vary greatly. The term Both regimes showed thorough homogeneous tagging itself encompasses a wide range of differing practices of residual fluid. This is likely to be attributable to both across institutions in terms of the quantity of tagging regimes using iodinated contrast, which preferentially agents ingested by the patient, the timing and frequency tags fluid. There was a significant difference in the of their ingestion, and the addition of other laxatives and volume of residual fluid between the two tagging regimes.
implementation of dietary restrictions. The ideal regime The addition of a mild stimulant laxative to Regime 1, The British Journal of Radiology, August 2012 Patient acceptance and image quality in two minimal-preparation regimes for CTC Table 3. Patient questionnaire responses: median and interquartile ranges leading to lower residual colonic fluid volumes, presum- contrast and a mild laxative yielded colons that were significantly better prepared than a 24 h iodinated The side effects rated most burdensome by patients contrast-only regime, with no significant difference in undergoing CTC were diarrhoea and general disruption to daily life. Importantly, these were tolerated equallywell between the two regimes, with similar median scores and interquartile ranges. The addition of a mildlaxative to Regime 1 did not have a significant impact on 1. Buccicardi D, Grosso M, Caviglia I, Gastaldo A, Carbone S, the amount of diarrhoea experienced by patients, but is Neri E, et al. CT colonography: patient tolerance of laxativefree fecal tagging regimen versus traditional cathartic likely to have a positive effect on image quality in terms cleansing. Abdom Imaging 2011;36:532–7.
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