Colon wall motility: comparison of novel quantitative semi-automatic measurements using cine MRI

Background Recently, cine magnetic resonance imaging (MRI) has shown promise for visualizing movement of the colonic wall, although assessment of data has been subjective and observer dependent. This study aimed to develop an objective and semi-automatic imaging metric of ascending colonic wall movement, using image registration techniques. Methods Cine balanced turbo field echo MRI images of ascending colonic motility were acquired over 2 min from 23 healthy volunteers (HVs) at baseline and following two different macrogol stimulus drinks (11 HVs drank 1 L and 12 HVs drank 2 L). Motility metrics derived from large scale geometric and small scale pixel movement parameters following image registration were developed using the post ingestion data and compared to observer grading of wall motion. Inter and intra-observer variability in the highest correlating metric was assessed using Bland–Altman analysis calculated from two separate observations on a subset of data. Key Results All the metrics tested showed significant correlation with the observer rating scores. Line analysis (LA) produced the highest correlation coefficient of 0.74 (95% CI: 0.55–0.86), p < 0.001 (Spearman Rho). Bland–Altman analysis of the inter- and intra-observer variability for the LA metric, showed almost zero bias and small limits of agreement between observations (−0.039 to 0.052 intra-observer and −0.051 to 0.054 inter-observer, range of measurement 0–0.353). Conclusions & Inferences The LA index of colonic motility derived from cine MRI registered data provides a quick, accurate and non-invasive method to detect wall motion within the ascending colon following a colonic stimulus in the form of a macrogol drink

Evaluation of intestinal motility with Magnetic Resonance Enterography and computer post-processing

Small bowel motility is an essential, physiological process central to the processing of ingested food. The small bowel is however anatomically and functionally complex, varying greatly between individuals and located deep within the abdomen making it extremely difficult to access with instrumentation. As a consequence, and in spite of its known or suspected role in a range of diseases, there remain little in the way of objective tests to evaluate or even observe this process in vivo. This thesis details the validation and application of a novel computer post-processing technique that allows the quantification of Magnetic Resonance Enterography derived time-series image data. A background to small bowel physiology and existing techniques is first provided along with an introduction to the registration algorithm used throughout this thesis to quantify small bowel motility. The technique is then applied retrospectively to two Crohn’s disease patient cohorts to explore how this inflammatory bowel disease influences contractility. A prospective evaluation of segmental motility analysis is then presented drawing attention to large within subject variation, in a cohort of healthy volunteers, as a limitation for this technique. As an alternative, a global motility analysis approach is described and validated. Although global measures of motility appeared robust, factors influencing clinical application are further addressed by expanding the technique to allow motility analysis in free-breathing data. In the final piece of research presented, the application of the global technique to a cohort of Chronic Intestinal Pseudo-Obstruction patients is detailed. The thesis is concluded with a reflection of the results and a chapter dedicated to the commercial exploitation of the research to address the ongoing need for a robust test to quantise intestinal motility

MRI assessment of the postprandial gastrointestinal motility and peptide response in healthy humans

Background: Feeding triggers inter-related gastrointestinal (GI) motor, peptide and appetite responses. These are rarely studied together due to methodological limitations. Recent MRI advances allow pan-intestinal, non-invasive assessment of motility in the undisturbed gut. This study aimed to develop a methodology to assess pan-intestinal motility and transit in a single session using MRI and compare imaging findings to GI peptide responses to a test meal and symptoms in a healthy volunteer cohort. Methods: Fifteen healthy volunteers (29.3±2.7years and BMI 20.1±1.2Kg/m2) underwent baseline and postprandial MRI scans, symptom questionnaires and blood sampling (for subsequent GI peptide analysis, Glucagon-like peptide-1 (GLP-1), Polypeptide YY (PYY), Cholecystokinin (CCK)) at intervals for 270min following a 400g soup meal (204kcal, Heinz, UK). Gastric volume, gall bladder volume, small bowel water content, small bowel motility and whole gut transit were measured from the MRI scans. Key Results: (mean±SEM) Small bowel motility index increased from fasting 39±3 arbitrary units (a.u.) to a maximum of 87±7a.u. immediately after feeding. PYY increased from fasting 98±10pg/ml to 149±14pg/ml at 30min and GLP-1 from fasting 15±3µg/ml to 22±4µg/ml. CCK increased from fasting 0.40±0.06pmol/ml to 0.94±0.1pmol/ml. Gastric volumes declined with a T1/2 of 46±5min and the gallbladder contracted from a fasting volume of 19±2ml to 12±2ml. Small bowel water content increased from 39±2ml to 51±2ml postprandial. Fullness VAS score increased from 9±5mm to 41±6mm at 30min postprandial. Conclusions and Inferences: The test meal challenge was effective in inducing a change in MRI motility end-points which will improve understanding of the pathophysiological postprandial GI response

Aberrant Motility in Unaffected Small Bowel is Linked to Inflammatory Burden and Patient Symptoms in Crohn's Disease.

BACKGROUND: Inflammation-related enteric dysmotility has been postulated as a cause for abdominal symptoms in Crohn's disease (CD). We investigated the relationship between magnetic resonance imaging-quantified small bowel (SB) motility, inflammatory activity, and patient symptom burden. METHODS: The Harvey-Bradshaw index (HBI) and fecal calprotectin were prospectively measured in 53 patients with CD (median age, 35; range, 18-78 years) the day before magnetic resonance enterography, which included a dynamic (cine), breath-hold motility sequence, repeated to encompass the whole SB volume. A validated registration-based motility quantitation technique produced motility maps, and regions of interest were drawn to include all morphologically normal SB (i.e., excluding diseased bowel). Global SB motility was correlated with calprotectin, HBI, and symptom components (well-being, pain, and diarrhea). Adjustment for age, sex, smoking, and surgical history was made using multivariate linear regression. RESULTS: Median calprotectin was 336 (range, 0-1280). Median HBI, motility mean, and motility variance were 3 (range, 0-16), 0.33 (0.18-0.51), and 0.01 (0.0014-0.034), respectively. Motility variance was significantly negatively correlated with calprotectin (rho = -0.33, P = 0.015), total HBI (rho = -0.45, P 0.05). CONCLUSIONS: Reduced motility variance in morphologically normal SB is associated with patient symptoms and fecal calprotectin levels, supporting the hypothesis that inflammation-related enteric dysmotility may explain refractory abdominal symptoms in CD