BackgroundColonic transit tests are used to manage patients with Functional Gastrointestinal Disorders. Some tests used expose patients to ionizing radiation. The aim of this study was to compare novel magnetic resonance imaging (MRI) tests for measuring orocecal transit time (OCTT) and whole gut transit time (WGT), which also provide data on colonic volumes.Methods21 healthy volunteers participated. Study 1: OCTT was determined from the arrival of the head of a meal into the cecum using MRI and the Lactose Ureide breath test (LUBT), performed concurrently. Study 2: WGT was assessed using novel MRI marker capsules and radio-opaque markers (ROMs), taken on the same morning. Studies were repeated 1 week later.Key ResultsOCTT measured using MRI and LUBT was 225 min (IQR 180–270) and 225 min (IQR 165–278), respectively, correlation rs = 0.28 (ns). WGT measured using MRI marker capsules and ROMs was 28 h (IQR 4–50) and 31 h ± 3 (SEM), respectively, correlation rs = 0.85 (p < 0.0001). Repeatability assessed using the intraclass correlation coefficient (ICC) was 0.45 (p = 0.017) and 0.35 (p = 0.058) for MRI and LUBT OCTT tests. Better repeatability was observed for the WGT tests, ICC being 0.61 for the MRI marker capsules (p = 0.001) and 0.69 for the ROM method (p < 0.001) respectively.Conclusions & InferencesThe MRI WGT method is simple, convenient, does not use X-ray and compares well with the widely used ROM method. Both OCTT measurements showed modest reproducibility and the MRI method showed modest inter-observer agreement.

BackgroundMost methods of assessing colonic motility are poorly acceptable to patients. Magnetic resonance imaging (MRI) can monitor gastrointestinal motility and fluid distributions. We predicted that a dose of oral polyethylene glycol (PEG) and electrolyte solution would increase ileo-colonic inflow and stimulate colonic motility. We aimed to investigate the colonic response to distension by oral PEG electrolyte in healthy volunteers (HVs) and to evaluate the effect of single 2 L vs split (2 × 1 L) dosing.MethodsTwelve HVs received a split dose (1 L the evening before and 1 L on the study day) and another 12 HVs a single dose (2 L on the main study day) of PEG electrolyte. They underwent MRI scans, completed symptom questionnaires, and provided stool samples. Outcomes included small bowel water content, ascending colon motility index, and regional colonic volumes.Key ResultsSmall bowel water content increased fourfold from baseline after ingesting both split (p = 0.0010) and single dose (p = 0.0005). The total colonic volume increase from baseline was smaller for the split dose at 35 ± 8% than for the single dose at 102 ± 27%, p = 0.0332. The ascending colon motility index after treatment was twofold higher for the single dose group (p = 0.0103).Conclusions & InferencesIngestion of 1 and 2 L PEG electrolyte solution caused a rapid increase in the small bowel and colonic volumes and a robust rise in colonic motility. The increase in both volumes and motility was dose dependent. Such a challenge, being well-tolerated, could be a useful way of assessing colonic motility in future studies.

BackgroundFunctional constipation (FC) and irritable bowel syndrome with constipation (IBS‐C) share many symptoms but underlying mechanisms may be different. We have developed a magnetic resonance imaging (MRI) technique to measure intestinal volumes, transit, and motility in response to a laxative, Moviprep®. We aim to use these biomarkers to study the pathophysiology in IBS‐C and FC.MethodsTwenty‐four FC and 24 IBS‐C were studied. Transit was assessed using the weighted average position score (WAPS) of five MRI marker pills, taken 24 h before MRI scanning. Following baseline scan, participants ingested 1 L of Moviprep® followed by hourly scans. Magnetic resonance imaging parameters and bowel symptoms were scored from 0 to 4 h.Key ResultsWeighted average position score for FC was 3.6 (2.5–4.2), significantly greater than IBS‐C at 2.0 (1.5–3.2), p = 0.01, indicating slower transit for FC. Functional constipation showed greater fasting small bowel water content, 83 (63–142) mL vs 39 (15–70) mL in IBS‐C, p < 0.01 and greater ascending colon volume (AC), 314 (101) mL vs 226 (71) mL in IBS‐C, p < 0.01. FC motility index was lower at 0.055 (0.044) compared to IBS‐C, 0.107 (0.070), p < 0.01. Time to first bowel movement following ingestion of Moviprep® was greater for FC, being 295 (116–526) min, compared to IBS‐C at 84 (49–111) min, p < 0.01, and correlated with AC volume 2 h after Moviprep®, r = 0.44, p < 0.01. Using a cut‐off >230 min distinguishes FC from IBS‐C with low sensitivity of 55% but high specificity of 95%.Conclusion & InferencesOur objective MRI biomarkers allow a distinction between FC and IBS‐C.

OBJECTIVES:Non-invasive biomarkers which identify different mechanisms of disease in subgroups of irritable bowel syndrome (IBS) could be valuable. Our aim was to seek useful magnetic resonance imaging (MRI) parameters that could distinguish each IBS subtypes.METHODS:34 healthy volunteers (HV), 30 IBS with diarrhea (IBS-D), 16 IBS with constipation (IBS-C), and 11 IBS with mixed bowel habit (IBS-M) underwent whole-gut transit and small and large bowel volumes assessment with MRI scans from t=0 to t=360 min. Since the bowel frequency for IBS-M were similar to IBS-D, IBS-M and IBS-D were grouped together and labeled as IBS non-constipation group (IBS-nonC).RESULTS:Median (interquartile range): fasting small bowel water content in IBS-nonC was 21 (10–42), significantly less than HV at 44 ml (15–70), P<0.01 as was the postprandial area under the curve (AUC) P<0.01. The fasting transverse colon volumes in IBS-C were significantly larger at 253 (200–329) compared with HV, IBS-nonC whose values were 165 (117–255) and 198 (106–270) ml, respectively, P=0.02. Whole-gut transit time for IBS-C was prolonged at 69 (51–111), compared with HV at 34 (4–63) and IBS-D at 34 (17–78) h, P=0.03. Bloating score (VAS 0–10 cm) correlated with transverse colon volume at t=405 min, Spearman r=0.21, P=0.04.CONCLUSIONS:The constricted small bowel in IBS-nonC and the dilated transverse colon in IBS-C point to significant differences in underlying mechanisms of disease.

Gluten is a crucial functional component of bread, but the effect of increasing gluten content on gastrointestinal (GI) function remains uncertain. Our aim was to investigate the effect of increasing gluten content on GI function and symptoms in healthy participants using the unique capabilities of MRI. A total of twelve healthy participants completed this randomised, mechanistic, open-label, three-way crossover study. On days 1 and 2 they consumed either gluten-free bread (GFB), or normal gluten content bread (NGCB) or added gluten content bread (AGCB). The same bread was consumed on day 3, and MRI scans were performed every 60 min from fasting baseline up to 360 min after eating. The appearance of the gastric chime in the images was assessed using a visual heterogeneity score. Gastric volumes, the small bowel water content (SBWC), colonic volumes and colonic gas content and GI symptoms were measured. Fasting transverse colonic volume after the 2-d preload was significantly higher after GFB compared with NGCB and AGCB with a dose-dependent response (289 (SEM 96) v. 212 (SEM 74) v. 179 (SEM 87) ml, respectively; P = 0·02). The intragastric chyme heterogeneity score was higher for the bread with increased gluten (AGCB 6 (interquartile range (IQR) 0·5) compared with GFB 3 (IQR 0·5); P = 0·003). However, gastric half-emptying time was not different between breads nor were study day GI symptoms, postprandial SBWC, colonic volume and gas content. This MRI study showed novel mechanistic insights in the GI responses to different breads, which are poorly understood notwithstanding the importance of this staple food.Key words: MRI: Gluten-free bread: Gastric emptying: Colonic volumes: Bloating Bread is one of the most common food items consumed all around the world. In the UK the industrial sector represents 80 % of total production, with a market worth £3·4 billion (1) . The most commonly consumed bread in western countries is wheat bread, of which gluten is a crucial functional component. Gluten is a protein contained in flour that is key to the breadmaking process. Mixing with water causes the gluten to swell and develop a network that gives a viscoelastic dough with the ability to retain gas, a property vital to allow bread to rise (2) . Gluten is largely responsible for the unique texture of wheat bread. In the last few years gluten has gained much more attention because of the increasing phenomenon of people complaining of gastrointestinal (GI) symptoms (altered bowel habit, abdominal pain, bloating and nausea) when they eat wheat, despite not having coeliac disease (CD) (3) . However, little is known about the 'in vivo' effects of bread gluten content on GI physiology. MRI has unique capabilities when it comes to imaging complex food materials during their processing within the GI tract. In a recent study (4) , we compared the upper GI processing of a wholemeal bread (WMB) meal with an equienergetic rice pudding (RP) meal. The MRI appearance of the two study meals inside the stomach was markedly different,...