CT colonography: optimisation, diagnostic performance and patient acceptability of reduced-laxative regimens using barium-based faecal tagging

Abstract

To establish the optimum barium-based reduced-laxative tagging regimen prior to CT colonography (CTC). Ninety-five subjects underwent reduced-laxative (13 g senna/18 g magnesium citrate) CTC prior to same-day colonoscopy and were randomised to one of four tagging regimens using 20 ml 40%w/v barium sulphate: regimen A: four doses, B: three doses, C: three doses plus 220 ml 2.1% barium sulphate, or D: three doses plus 15 ml diatriazoate megluamine. Patient experience was assessed immediately after CTC and 1 week later. Two radiologists graded residual stool (1: none/scattered to 4: >50% circumference) and tagging efficacy for stool (1: untagged to 5: 100% tagged) and fluid (1: untagged, 2: layered, 3: tagged), noting the HU of tagged fluid. Preparation was good (76-94% segments graded 1), although best for regimen D (P=0.02). Across all regimens, stool tagging quality was high (mean 3.7-4.5) and not significantly different among regimens. The HU of layered tagged fluid was higher for regimens C/D than A/B (P=0.002). Detection of cancer (n=2), polyps ≥6 mm (n=21), and≤5 mm (n=72) was 100, 81 and 32% respectively, with only four false positives ≥6 mm. Reduced preparation was tolerated better than full endoscopic preparation by 61%. Reducedlaxative CTC with three doses of 20 ml 40% barium sulphate is as effective as more complex regimens, retaining adequate diagnostic accuracy.

Gas insufflation of minimal preparation CT of the colon reduces false-positives

“…This is surprising, and other studies using this technique have produced poor results [17]. Most practitioners using barium tagging would combine it with at least a reduced dose of laxatives [18,19].…”

Laxative-free CT colonography

“…Most practitioners using barium tagging would combine it with at least a reduced dose of laxatives [13]. Taylor et al [3] reported a reduced laxative CTC regimen using bariumbased tagging. This was tolerated better than full laxative bowel preparation and produced results comparable to Figure 1.…”

“…These were modified from a previous study by Taylor et al [3]. Patients completed the questionnaires while they waited for their CT examination.…”

An interview study analysing patients' experiences and perceptions of non-laxative or full-laxative preparation with faecal tagging prior to CT colonography

“…An interview topic guide was developed by three health psychology researchers, BLIND FOR REVIEW, following consultation with three radiologists (with experience of over 1000 CTC examinations each; BLIND FOR REVIEW) and literature review [7][8][9][10]14 . Open-ended questions were presented in a flexible order (see Table 1 for key questions).…”

“…However, many patients perceive laxative bowel preparation as the worst aspect of the test 4,5 and the addition of 'faecal tagging' may add additional burden. Quantitative studies of acceptability have found non-laxative preparation to be equivalent or superior to full-laxative preparation in terms of its acceptability [6][7][8][9][10] . However, although non-laxative CTC is likely to be better tolerated, its diagnostic accuracy compared to full-laxative studies is currently uncertain and so this preparation is generally reserved for patients considered unfit for full catharsis 11 .…”