Performance characteristics of scintigraphic colon transit measurement in health and irritable bowel syndrome and relationship to bowel functions

Colonic transit time (CTT) refers to the time taken for chyme to pass through the colon. Measurement of CTT is frequently performed in clinical practice to identify colonic motor function abnormalities, for example, in patients with irritable bowel syndrome (IBS) [1] or constipation [2–4]. This method is also used to investigate pathophysiological mechanisms that lead to symptoms or syndromes [5, 6] and to evaluate the effect of treatment [7, 8]. The most widely applied techniques evaluate movement of radiopaque markers through the gut [3, 9] or appearing in stool [10]. A less commonly used method involves scintigraphy, which is valuable for the assessment of gastrointestinal function in humans [11]. Both provide noninvasive and quantitative assessments of colonic transit. In the most commonly applied radiopaque marker transit technique, subjects ingest radiopaque markers on three [9] or six [12] consecutive days, and a single abdominal x-ray is obtained on the subsequent day and, if necessary, on one or more days later [13]. With the most widely used and published scintigraphic method, radiolabeled charcoal particles [14] are delivered to the colon in a delayed-release, methacrylate-coated capsule [15], and gamma camera images are acquired at specified times during a 48-hour period. Regardless of the method, there is considerable intra-subject variation in colonic transit [16–19], possibly because some studies administered the radiolabel in the meal rather than in a delayed-release capsule which delivers radiolabeled solid particles to the ileocolonic junction. Moreover, intra-subject variation has been studied mainly in healthy volunteers [20–23], with only 2 studies having evaluated the reproducibility of radiopaque marker CTT in disease states. Thus, Nam et al [4]reported an acceptable reproducibility in 22 patients with idiopathic constipation, but poor reproducibility in patients with colonic inertia or paradoxical puborectalis contraction. In another study by Bouchoucha et al [24] which included 30 healthy volunteers and 43 patients with IBS, 16 subjects underwent repeat colonic transit testing with radiopaque markers and, therefore, there are data on the reproducibility of radiopaque marker transit in some IBS patients. No significant differences were found between the two test results, but it is not clear whether these subjects were healthy controls or IBS patients. Thus, the reproducibility of CTT measurements in disease states remains unclear. The aim of this study was to assess the inter- and intra-subject variations of scintigraphic colonic transit parameters in patients with IBS and healthy participants. A secondary aim was to quantify the relationship between colonic transit measurement and bowel functions. For the purpose of the current study in which the focus was on variation in IBS patients, we excluded the previously reported performance characteristics in 37 healthy participants [20].