How to Perform and Interpret Functional Magnetic Resonance Imaging Studies in Functional Gastrointestinal Disorders

Central Regulation of Eating Behaviors in Humans: Evidence from Functional Neuroimaging Studies

Neuroimaging has great potential to provide insight into the neural response to food stimuli. Remarkable advances have been made in understanding the neural activity underlying food perception, not only in normal eating but also in obesity, eating disorders, and disorders of gut-brain interaction in recent decades. In addition to the abnormal brain function in patients with eating disorders compared to healthy controls, new therapies, such as neurofeedback and neurostimulation techniques, have been developed that target the malfunctioning brain regions in patients with eating disorders based on the results of neuroimaging studies. In this review, we present an overview of early and more recent research on the central processing and regulation of eating behavior in healthy and patient populations. In order to better understand the relationship between the gut and the brain as well as the neural mechanisms underlying abnormal ingestive behaviors, we also provide suggestions for future directions to enhance our current methods used in food-related neuroimaging studies.

Food, Eating, and the Gastrointestinal Tract

Food ingestion induces a metered response of the digestive system. Initially, the upper digestive system reacts to process and extract meal substrates. Later, meal residues not absorbed in the small bowel, pass into the colon and activate the metabolism of resident microbiota. Food consumption also induces sensations that arise before ingestion (e.g., anticipatory reward), during ingestion (e.g., gustation), and most importantly, after the meal (i.e., the postprandial experience). The postprandial experience involves homeostatic sensations (satiety, fullness) with a hedonic dimension (digestive well-being, mood). The factors that determine the postprandial experience are poorly understood, despite their potential role in personalized diets and healthy eating habits. Current data suggest that the characteristics of the meal (amount, palatability, composition), the activity of the digestive system (suited processing), and the receptivity of the eater (influenced by multiple conditioning factors) may be important in this context.

Magnetic resonance-guided radiation therapy: A review

Magnetic resonance-guided radiation therapy (MRgRT) is a promising approach to improving clinical outcomes for patients treated with radiation therapy. The roles of image guidance, adaptive planning and magnetic resonance imaging in radiation therapy have been increasing over the last two decades. Technical advances have led to the feasible combination of magnetic resonance imaging and radiation therapy technologies, leading to improved soft-tissue visualisation, assessment of inter- and intrafraction motion, motion management, online adaptive radiation therapy and the incorporation of functional information into treatment. MRgRT can potentially transform radiation oncology by improving tumour control and quality of life after radiation therapy and increasing convenience of treatment by shortening treatment courses for patients. Multiple groups have developed clinical implementations of MRgRT predominantly in the abdomen and pelvis, with patients having been treated since 2014. While studies of MRgRT have primarily been dosimetric so far, an increasing number of trials are underway examining the potential clinical benefits of MRgRT, with coordinated efforts to rigorously evaluate the benefits of the promising technology. This review discusses the current implementations, studies, potential benefits and challenges of MRgRT.

Effect and cerebral mechanism of acupuncture treatment for functional constipation: study protocol for a randomized controlled clinical trial

Background

Acupuncture is effective in functional constipation (FC) treatment, but the central mechanism has not been well investigated. This trial will combine functional magnetic resonance imaging (fMRI) and positron emission tomography-computed tomography (PET-CT) to investigate the potential central mechanism of acupuncture treatment for FC.

Methods

This is a multimodal neuroimaging randomized controlled trial. In total, 140 FC patients will be randomly allocated into four groups: the verum acupuncture group; the sham acupuncture group; the PEG 4000 group; and the waiting-list group. This trial will include a two-week baseline period and a two-week treatment period. Patients will receive 10 sessions of acupuncture, sham acupuncture, PEG 4000, or no intervention during the treatment period. The stool diary, Cleveland Constipation Score (CCS), Patient Assessment of Constipation Symptom (PAC-SYM), and Patient Assessment of Constipation Quality of Life Questionnaire (PAC-QoL) will be used to assess the clinical efficacy of different interventions. The MRI and PET-CT scans will be performed to detect cerebral functional changes in 15 patients in each group at baseline and at the end of treatment/waiting. Multimodal imaging data will be associated with clinical data to investigate possible correlation between brain activity changes elicited by different interventions and symptoms improvement.

Discussion

We hypothesize that acupuncture can treat FC through normalizing the pathological alteration of the cerebral activity. The results of this trial will allow us to re-testify the therapeutic effects of acupuncture treating for FC and to investigate the potential central mechanism of acupuncture treatment for FC from direct (cerebral glucose metabolism) and indirect (contrast of oxyhemoglobin and deoxyhemoglobin) approaches.

Trial registration

Chinese Clinical Trial Registry, ChiCTR1800016658. Registered on 14 June 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3410-8) contains supplementary material, which is available to authorized users.

Expression and clinical significance of 5-HT and 5-HT3R in the intestinal mucosa of patient with diarrhea-type irritable bowel syndrome

Expression levels and clinical significance of 5-HT and 5-HT₃R in the intestinal mucosa tissue of patients with diarrhea-type irritable bowel syndrome (D-IBS) were investigated. A retrospective analysis was performed on 46 tissue specimens (observation group) of the intestinal mucosa of patients with D-IBS, who were diagnosed in the Tongde Hospital of Zhejiang Province and received colonoscopy from March 2016 to December 2017, and 18 tissue specimens (control group) of the intestinal mucosa of healthy subjects who received physical examinations. The expression levels of 5-HT and 5-HT₃R in the intestinal mucosa tissue of patients in the observation and control group were detected by ELISA, and the relationship between 5-HT, 5-HT₃R and the clinicopathological parameters of patients with D-IBS was analyzed. Pearson's correlation analysis was used to analyze the correlation of 5-HT and 5-HT₃R in the intestinal mucosa tissue of patients with D-IBS. The expression levels of 5-HT and 5-HT₃R in the intestinal mucosa tissue of patients in the observation group were significantly higher than those of the patients in the control group (344.86±67.52 ng/ml and 13.04±8.34 pg/ml) (P<0.001). There was a positive correlation between the expression level of 5-HT and the expression level of 5-HT₃R in the intestinal mucosa tissue of patients with D-IBS (r=0.725, P<0.001). The expression levels of 5-HT and 5-HT₃R in the intestinal mucosa tissue of patients with D-IBS were both significantly higher than those of the healthy subjects. The expression levels of 5-HT and 5-HT₃R in patients with D-IBS were correlated with age, sex and the history of gastrointestinal infection. 5-HT and 5-HT₃R may be involved in the pathogenesis of D-IBS, and potentially used for clinical treatment.

Biogastronomy: Factors that determine the biological response to meal ingestion

BACKGROUND

The biological response to a meal includes physiological changes, primarily related to the digestive process, and a sensory experience, involving sensations related to the homeostatic control of food consumption, eg, satiety and fullness, with a hedonic dimension, ie associated with changes in digestive well-being and mood. The responses to a meal include a series of events before, during and after ingestion. While much attention has been paid to the events before and during ingestion, relatively little is known about the postprandial sensations, which are key to the gastronomical experience.

PURPOSE

The aim of this narrative review is to provide a comprehensive overview and to define the framework to investigate the factors that determine the postprandial experience. Based on a series of proof-of-concept studies and related information, we propose that the biological responses to a meal depend on the characteristics of the meal, primarily its palatability and composition, and the responsiveness of the guest, which may be influenced by multiple previous and concurrent conditioning factors. This information provides the scientific backbone to the development of personalized gastronomy.