Colonic content: effect of diet, meals, and defecation

This is the peer reviewed version of the following article: Bendezú, Á., Mego, M., Monclús, E., Merino, X., Accarino, A., Malagelada, J., Navazo, I., Azpiroz, F. Colonic content: effect of diet, meals, and defecation. "Neurogastroenterology and motility", Febrer 2017, vol. 29, núm. 2, which has been published in final form at [http://onlinelibrary.wiley.com.recursos.biblioteca.upc.edu/doi/10.1111/nmo.12930/full]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The metabolic activity of colonic microbiota is influenced by diet; however, the relationship between metabolism and colonic content is not known. Our aim was to determine the effect of meals, defecation, and diet on colonic content. Methods: In 10 healthy subjects, two abdominal MRI scans were acquired during fasting, 1 week apart, and after 3 days on low- and high-residue diets, respectively. With each diet, daily fecal output and the number of daytime anal gas evacuations were measured. On the first study day, a second scan was acquired 4 hours after a test meal (n=6) or after 4 hours with nil ingestion (n=4). On the second study day, a scan was also acquired after a spontaneous bowel movement. Results: On the low-residue diet, daily fecal volume averaged 145 ± 15 mL; subjects passed 10.6 ± 1.6 daytime anal gas evacuations and, by the third day, non-gaseous colonic content was 479 ± 36 mL. The high-residue diet increased the three parameters to 16.5 ± 2.9 anal gas evacuations, 223 ± 19 mL fecal output, and 616 ± 55 mL non-gaseous colonic content (P<.05 vs low-residue diet for all). On the low-residue diet, non-gaseous content in the right colon had increased by 41 ± 11 mL, 4 hours after the test meal, whereas no significant change was observed after 4-hour fast (-15 ± 8 mL; P=.006 vs fed). Defecation significantly reduced the non-gaseous content in distal colonic segments. Conclusion & inferences: Colonic content exhibits physiologic variations with an approximate 1/3 daily turnover produced by meals and defecation, superimposed over diet-related day-to-day variations.Peer ReviewedPostprint (author's final draft

Quasi-automatic colon segmentation on T2-MRI images with low user effort

About 50% of the patients consulting a gastroenterology clinic report symptoms without detectable cause. Clinical researchers are interested in analyzing the volumetric evolution of colon segments under the effect of different diets and diseases. These studies require noninvasive abdominal MRI scans without using any contrast agent. In this work, we propose a colon segmentation framework designed to support T2-weighted abdominal MRI scans obtained from an unprepared colon. The segmentation process is based on an efficient and accurate quasiautomatic approach that drastically reduces the specialist interaction and effort with respect other state-of-the-art solutions, while decreasing the overall segmentation cost. The algorithm relies on a novel probabilistic tubularity filter, the detection of the colon medial line, probabilistic information extracted from a training set and a final unsupervised clustering. Experimental results presented show the benefits of our approach for clinical use.Peer ReviewedPostprint (author's final draft

Colonic content in health and its relation to functional gut symptoms

This is the peer reviewed version of the following article: Bendezú, R. A., Barba, E., Burri, E., Cisternas, D., Accarino, A., Quiroga, S., Monclus, E., Navazo, I., Malagelada, J.-R. and Azpiroz, F. (2016), Colonic content in health and its relation to functional gut symptoms. Neurogastroenterol. Motil., 28: 849–854, which has been published in final form at [doi:10.1111/nmo.12782]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingGut content may be determinant in the generation of digestive symptoms, particularly in patients with impaired gut function and hypersensitivity. Since the relation of intraluminal gas to symptoms is only partial, we hypothesized that non-gaseous component may play a decisive role. Methods: Abdominal computed tomography scans were evaluated in healthy subjects during fasting and after a meal (n = 15) and in patients with functional gut disorders during basal conditions (when they were feeling well) and during an episode of abdominal distension (n = 15). Colonic content and distribution were measured by an original analysis program. Key results: In healthy subjects both gaseous (87 ± 24 mL) and non-gaseous colonic content (714 ± 34 mL) were uniformly distributed along the colon. In the early postprandial period gas volume increased (by 46 ± 23 mL), but non-gaseous content did not, although a partial caudad displacement from the descending to the pelvic colon was observed. No differences in colonic content were detected between patients and healthy subjects. Symptoms were associated with discrete increments in gas volume. However, no consistent differences in non-gaseous content were detected in patients between asymptomatic periods and during episodes of abdominal distension. Conclusions & inferences: In patients with functional gut disorders, abdominal distension is not related to changes in non-gaseous colonic content. Hence, other factors, such as intestinal hypersensitivity and poor tolerance of small increases in luminal gas may be involved.Peer ReviewedPostprint (author's final draft

Semi-automatic colonic content analysis for diagnostic

The analysis of the morphology and content of the gut is necessary in order to understand metabolic and functional gut activity and for diagnostic purposes. Magnetic resonance imaging (MRI) has become an important modality technique since it is able to visualize soft tissues using no ionizing radiation, and hence removes the need for any contrast agents. In the last few years, MRI of gastrointestinal function has advanced substantially, although scarcely any publication has been devoted to the analysis of the colon content. This paper presents a semi-automatic segmentation tool for the quantitative assessment of the unprepared colon from MRI images. This application has allowed for the analysis of the colon content in various clinical experiments. The results of the assessment have contributed to a better understanding of the functionality of the colon under different diet conditions. The last experiment carried out by medical doctors showed a marked influence of diet on colonic content, accounting for about 30% of the volume variations.Peer ReviewedPostprint (published version

Effect of Resistant Dextrin on Intestinal Gas Homeostasis and Microbiota

Previous studies have shown that a resistant dextrin soluble fibre has prebiotic properties with related health benefits on blood glucose management and satiety. Our aim was to demonstrate the effects of continuous administration of resistant dextrin on intestinal gas production, digestive sensations, and gut microbiota metabolism and composition. Healthy subjects (n = 20) were given resistant dextrin (14 g/d NUTRIOSE ®, Roquette Frères, Lestrem, France) for four weeks. Outcomes were measured before, at the beginning, end, and two weeks after administration: anal evacuations of gas during daytime; digestive perception, girth, and gas production in response to a standard meal; sensory and digestive responses to a comfort meal; volume of colonic biomass by magnetic resonance; taxonomy and metabolic functions of fecal microbiota by shotgun sequencing; metabolomics in urine. Dextrin administration produced an initial increase in intestinal gas production and gas-related sensations, followed by a subsequent decrease, which magnified after discontinuation. Dextrin enlarged the volume of colonic biomass, inducing changes in microbial metabolism and composition with an increase in short chain fatty acids-producing species and modulation of bile acids and biotin metabolism. These data indicate that consumption of a soluble fibre induces an adaptative response of gut microbiota towards fermentative pathways with lower gas productio

Mecanismo de producción de los síntomas digestivos funcionales

En esta tesis se abordan los mecanismos que producen los síntomas digestivos funcionales haciendo uso de técnicas no invasivas como son la tomografía computarizada y la resonancia magnética nuclear. Para el análisis de las imágenes y estudio de su contenido se han diseñado softwares especiales en nuestro laboratorio. En el primer estudio, empleando una metodología original y técnicas de inteligencia artificial se ha estudiado una cohorte grande de sujetos sanos para establecer el patrón de normalidad en la distribución de gas dentro del tubo digestivo. Además se incluyeron 88 enfermos con síntomas atribuidos al gas intestinal, a quienes se les estudió en situación basal y durante un episodio de distensión máxima. Los volúmenes medidos cuando el paciente se encontraba asintomático fueron similares a los de la cohorte de voluntarios sanos, sin embargo durante los episodios sintomáticos algunos pacientes presentaron un patrón de gas en el tubo digestivo fuera del rango de la normalidad. En el segundo estudio se midió el componente no gaseoso a nivel del colon tanto en sujetos sanos como en enfermos con distensión abdominal, observándose que el contenido sólido presenta una distribución uniforme con variaciones en relación a la ingesta. Los síntomas abdominales funcionales no se relacionan con variaciones del contenido no gaseoso del colon. En el tercer estudio, haciendo uso de imágenes abdominales obtenidas por resonancia magnética nuclear, se obtuvo una valoración fiable del colon y su contenido. Es así que el contenido no gaseoso presenta variaciones circadianas con un recambio sustancial producidas por la ingesta y la defecación. La ingesta de residuos no absorbibles en la dieta tiene una influencia marcada sobre el contenido no gaseoso del colon.In this thesis we have studied the mechanisms that produce functional gastrointestinal symptoms using non-invasive techniques such as computed tomography and magnetic resonance imaging. For image analysis and study of its contents we created special softwares in our laboratory. In the first study, using an original methodology and techniques of artificial intelligence we have studied a large cohort of healthy subjects to establish the pattern of normality in the distribution of gas within the digestive tract. In addition, 88 patients with symptoms attributed to intestinal gas were studied at baseline and during an episode of maximum distension. Volumes measured when the patient was asymptomatic were similar to those of the cohort of healthy volunteers, however during symptomatic episodes some patients had a pattern of gas in the digestive tract outside the range of normal. In the second study the non-gaseous component in the colon in both healthy subjects and in patients with abdominal distention was measured, showing that the solid content has a uniform distribution with variations related to ingestion of meals. Functional abdominal symptoms not related to changes in non-gaseous contents of the colon. In the third study, using abdominal images obtained by nuclear magnetic resonance, a reliable assessment of the colon and its contents was obtained. Thus the non-gaseous content presents circadian variations with substantial parts produced by ingestion and defecation. Intake nonabsorbable residues in the diet has a marked influence on colon nongaseous content

Mecanismo de producción de los síntomas digestivos funcionales

En esta tesis se abordan los mecanismos que producen los síntomas digestivos funcionales haciendo uso de técnicas no invasivas como son la tomografía computarizada y la resonancia magnética nuclear. Para el análisis de las imágenes y estudio de su contenido se han diseñado softwares especiales en nuestro laboratorio. En el primer estudio, empleando una metodología original y técnicas de inteligencia artificial se ha estudiado una cohorte grande de sujetos sanos para establecer el patrón de normalidad en la distribución de gas dentro del tubo digestivo. Además se incluyeron 88 enfermos con síntomas atribuidos al gas intestinal, a quienes se les estudió en situación basal y durante un episodio de distensión máxima. Los volúmenes medidos cuando el paciente se encontraba asintomático fueron similares a los de la cohorte de voluntarios sanos, sin embargo durante los episodios sintomáticos algunos pacientes presentaron un patrón de gas en el tubo digestivo fuera del rango de la normalidad. En el segundo estudio se midió el componente no gaseoso a nivel del colon tanto en sujetos sanos como en enfermos con distensión abdominal, observándose que el contenido sólido presenta una distribución uniforme con variaciones en relación a la ingesta. Los síntomas abdominales funcionales no se relacionan con variaciones del contenido no gaseoso del colon. En el tercer estudio, haciendo uso de imágenes abdominales obtenidas por resonancia magnética nuclear, se obtuvo una valoración fiable del colon y su contenido. Es así que el contenido no gaseoso presenta variaciones circadianas con un recambio sustancial producidas por la ingesta y la defecación. La ingesta de residuos no absorbibles en la dieta tiene una influencia marcada sobre el contenido no gaseoso del colon.In this thesis we have studied the mechanisms that produce functional gastrointestinal symptoms using non-invasive techniques such as computed tomography and magnetic resonance imaging. For image analysis and study of its contents we created special softwares in our laboratory. In the first study, using an original methodology and techniques of artificial intelligence we have studied a large cohort of healthy subjects to establish the pattern of normality in the distribution of gas within the digestive tract. In addition, 88 patients with symptoms attributed to intestinal gas were studied at baseline and during an episode of maximum distension. Volumes measured when the patient was asymptomatic were similar to those of the cohort of healthy volunteers, however during symptomatic episodes some patients had a pattern of gas in the digestive tract outside the range of normal. In the second study the non-gaseous component in the colon in both healthy subjects and in patients with abdominal distention was measured, showing that the solid content has a uniform distribution with variations related to ingestion of meals. Functional abdominal symptoms not related to changes in non-gaseous contents of the colon. In the third study, using abdominal images obtained by nuclear magnetic resonance, a reliable assessment of the colon and its contents was obtained. Thus the non-gaseous content presents circadian variations with substantial parts produced by ingestion and defecation. Intake nonabsorbable residues in the diet has a marked influence on colon nongaseous content

Mecanismo de producción de los síntomas digestivos funcionales /

En esta tesis se abordan los mecanismos que producen los síntomas digestivos funcionales haciendo uso de técnicas no invasivas como son la tomografía computarizada y la resonancia magnética nuclear. Para el análisis de las imágenes y estudio de su contenido se han diseñado softwares especiales en nuestro laboratorio. En el primer estudio, empleando una metodología original y técnicas de inteligencia artificial se ha estudiado una cohorte grande de sujetos sanos para establecer el patrón de normalidad en la distribución de gas dentro del tubo digestivo. Además se incluyeron 88 enfermos con síntomas atribuidos al gas intestinal, a quienes se les estudió en situación basal y durante un episodio de distensión máxima. Los volúmenes medidos cuando el paciente se encontraba asintomático fueron similares a los de la cohorte de voluntarios sanos, sin embargo durante los episodios sintomáticos algunos pacientes presentaron un patrón de gas en el tubo digestivo fuera del rango de la normalidad. En el segundo estudio se midió el componente no gaseoso a nivel del colon tanto en sujetos sanos como en enfermos con distensión abdominal, observándose que el contenido sólido presenta una distribución uniforme con variaciones en relación a la ingesta. Los síntomas abdominales funcionales no se relacionan con variaciones del contenido no gaseoso del colon. En el tercer estudio, haciendo uso de imágenes abdominales obtenidas por resonancia magnética nuclear, se obtuvo una valoración fiable del colon y su contenido. Es así que el contenido no gaseoso presenta variaciones circadianas con un recambio sustancial producidas por la ingesta y la defecación. La ingesta de residuos no absorbibles en la dieta tiene una influencia marcada sobre el contenido no gaseoso del colon.In this thesis we have studied the mechanisms that produce functional gastrointestinal symptoms using non-invasive techniques such as computed tomography and magnetic resonance imaging. For image analysis and study of its contents we created special softwares in our laboratory. In the first study, using an original methodology and techniques of artificial intelligence we have studied a large cohort of healthy subjects to establish the pattern of normality in the distribution of gas within the digestive tract. In addition, 88 patients with symptoms attributed to intestinal gas were studied at baseline and during an episode of maximum distension. Volumes measured when the patient was asymptomatic were similar to those of the cohort of healthy volunteers, however during symptomatic episodes some patients had a pattern of gas in the digestive tract outside the range of normal. In the second study the non-gaseous component in the colon in both healthy subjects and in patients with abdominal distention was measured, showing that the solid content has a uniform distribution with variations related to ingestion of meals. Functional abdominal symptoms not related to changes in non-gaseous contents of the colon. In the third study, using abdominal images obtained by nuclear magnetic resonance, a reliable assessment of the colon and its contents was obtained. Thus the non-gaseous content presents circadian variations with substantial parts produced by ingestion and defecation. Intake nonabsorbable residues in the diet has a marked influence on colon nongaseous content

Quasi-automatic colon segmentation on T2-MRI images with low user effort

About 50% of the patients consulting a gastroenterology clinic report symptoms without detectable cause. Clinical researchers are interested in analyzing the volumetric evolution of colon segments under the effect of different diets and diseases. These studies require noninvasive abdominal MRI scans without using any contrast agent. In this work, we propose a colon segmentation framework designed to support T2-weighted abdominal MRI scans obtained from an unprepared colon. The segmentation process is based on an efficient and accurate quasiautomatic approach that drastically reduces the specialist interaction and effort with respect other state-of-the-art solutions, while decreasing the overall segmentation cost. The algorithm relies on a novel probabilistic tubularity filter, the detection of the colon medial line, probabilistic information extracted from a training set and a final unsupervised clustering. Experimental results presented show the benefits of our approach for clinical use.Peer Reviewe

A scalable approach to T2-MRI colon segmentation

The study of the colonic volume is a procedure with strong relevance to gastroenterologists. Depending on the clinical protocols, the volume analysis has to be performed on MRI of the unprepared colon without contrast administration. In such circumstances, existing measurement procedures are cumbersome and time-consuming for the specialists. The algorithm presented in this paper permits a quasi-automatic segmentation of the unprepared colon on T2-weighted MRI scans. The segmentation algorithm is organized as a three-stage pipeline. In the first stage, a custom tubularity filter is run to detect colon candidate areas. The specialists provide a list of points along the colon trajectory, which are combined with tubularity information to calculate an estimation of the colon medial path. In the second stage, we delimit the region of interest by applying custom segmentation algorithms to detect colon neighboring regions and the fat capsule containing abdominal organs. Finally, within the reduced search space, segmentation is performed via 3D graph-cuts in a three-stage multigrid approach. Our algorithm was tested on MRI abdominal scans, including different acquisition resolutions, and its results were compared to the colon ground truth segmentations provided by the specialists. The experiments proved the accuracy, efficiency, and usability of the algorithm, while the variability of the scan resolutions contributed to demonstrate the computational scalability of the multigrid architecture. The system is fully applicable to the colon measurement clinical routine, being a substantial step towards a fully automated segmentation.Postprint (author's final draft