Physiology of the small bowel: A new approach using MRI and proposal for a new metric of function Andoni P. Toms a,⇑ , Aser Farghal a , Bahman Kasmai b , Anthony Bagnall c , Paul N. Malcolm b a Norwich Radiology Academy, Cotman Centre, Colney Lane, Norwich, Norfolk NR4 7UB, UK b Department of Radiology, Norfolk and Norwich University Hospital, Colney Lane, Norwich, Norfolk NR4 7UY, UK c Department of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, UK article info Article history: Received 11 November 2010 Accepted 14 February 2011 abstract Background: The mechanics of small bowel motility are extremely complex. Routine clinical access to small bowel has been restricted to radiological enteric contrast studies which have not contributed sig- nificantly to the understanding of small bowel physiology. Small bowel mechanics are understood within a framework of individual visible or measurable elements such as peristaltic wave formation, intra-lumi- nal pressure gradients and transit times. There are no global measures of small bowel function that can be readily obtained in vivo in humans. Magnetic resonance imaging (MRI) is playing an increasingly impor- tant role in radiological diagnosis of small bowel disease and dynamic MRI offers the possibility of cap- turing small bowel movement in three-dimensional cinematic datasets. The metrics that are used to describe small bowel mechanics, typically anatomical measures in isolated segments, are not suited to analysing these large dynamic datasets. The proposal in this paper is to leave behind all previously described anatomical metrics and to describe anew the mechanics of small bowel movement in mathe- matical terms derived from changes in pixel intensity within dynamic MRI datasets so that global small bowel activity might be summarised in a single novel metric. Hypothesis: The hypothesis of this paper is that global small bowel activity can be quantified by a new dynamic MR based metric. Evaluation: A proposed strategy for evaluation includes a progression through feasibility, optimisation, reliability and validation studies. Thereafter normal volunteers would be required in order to define nor- mal ranges for the new metric. These ranges would describe small bowel activity during fasting or after ingestion of fluids and standard meals. Mathematical modelling of the data could follow a two stage approach. The first stage could be to study segmentation or extraction techniques by which the small bowel activity could be isolated from MRI signal generated by the rest of the abdomen. The second stage would be to apply a number of data mining techniques that would identify significant features within the datasets. Conclusion: If this approach proves to be a useful model for studying small bowel physiology in humans, it would afford significant new avenues of research and treatment particularly in areas such as enteric drug delivery, the ageing gut, and nutrition. Ó 2011 Elsevier Ltd. All rights reserved. Introduction Small bowel is a notoriously difficult organ to investigate. It is out of reach of endoscopes and for many years has only yielded its secrets in animal studies or invasive human studies. Conse- quently the understanding of gastric and colonic physiology is dec- ades ahead of that for small bowel. Modern applications of cross- sectional imaging techniques such as ultrasound, computed tomography and magnetic resonance imaging (MRI), along with capsule endoscopy, are now allowing us to probe the function of small bowel. In particular MRI offers the potential for significant advances in our understanding of how small bowel works. This is important because the role that the small bowel plays in delivering nutrition and absorbing enteric drugs is still poorly understood at a time when obesity and pharmaceuticals are major healthcare costs in developed nations. While MRI is showing promise as a non-inva- sive well-tolerated tool for in vivo human studies there are limita- tions to the current approaches being taken in analysing small bowel motility. The aim of this paper is to suggest a new approach that might redefine the way in which small bowel function is de- scribed and analysed and one that might produce new metrics for quantifying small bowel function that might reveal new ave- nues of clinical investigation and research. 0306-9877/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.mehy.2011.02.031 ⇑ Corresponding author. Tel.: +44 (0) 1603 286143; fax: +44 (0) 1603 286077. E-mail address: andoni.toms@nnuh.nhs.uk (A.P. Toms). Medical Hypotheses 76 (2011) 834–839 Contents lists available at ScienceDirect Medical Hypotheses journal homepage: www.elsevier.com/locate/mehy