Abnormal esophageal motility during a solid test meal in systemic sclerosis-detection even in very early disease and association with disease progression

OBJECTIVE

This study assessed whether high-resolution manometry (HRM) with a test meal can detect clinically relevant, abnormal motility already in very early systemic sclerosis (SSc) and whether this finding is associated with subsequent disease progression.

METHODS

This prospective, longitudinal cohort study recruited 68 consecutive SSc patients (group #1: 32 established disease (ACR, American College of Rheumatology /EULAR, The European League against Rheumatism 2013 and ACR 1980 criteria fulfilled); group #2: 24 early disease (only ACR/EULAR 2013 fulfilled); group #3: 12 very early disease (clinical expert diagnosis of SSc) and 72 healthy controls. HRM evaluated esophageal motility for water swallows and a solid test meal.

RESULTS

Systemic sclerosis patients had less frequent effective esophageal contractions during the test meal compared to healthy controls even in very early disease (0.15, 1.0, 2.1 per minute for groups #1, #2, and #3, vs 2.5 per minute in health; P < 0.001, P < 0.001, and P < 0.0085, respectively). Ineffective motility at HRM was associated with a higher modified Rodnan skin score at baseline. Moreover, at mean 18 (10-31) months of follow-up, the presence of ineffective motility at baseline was associated with progression of skin disease (P = 0.01). Cox proportional hazard regression analysis identified hypotensive peristalsis in the test meal (<15% effective solid swallows) and low distal contractile integral (DCI; <400 mm Hg·cm·s) as predictors for skin aggravation, but not for new organ involvement.

CONCLUSION

Ineffective motility during a test meal is present already in patients with very early SSc. Findings on HRM studies are associated with disease severity at baseline, and low percentage of effective swallows in test meal and low mean DCI are both predictors of skin progression during follow-up.

What to eat and drink in the festive season: a pan-European, observational, cross-sectional study

BACKGROUND

Digestive discomfort after meals is common in the community, especially during the festive season. It is uncertain whether this is related to intake of either high-calorie or high-fat foods or, alternatively, intake of specific foods. This prospective, cross-sectional study tested the hypothesis that the risk of reflux or dyspepsia is associated with the fat content of the meal independent of caloric load in a 'real-life' setting.

MATERIALS AND METHODS

Four festive meals were served to delegates attending a conference on four consecutive days. Test meals had the same volume, but varied in calorie and fat content. Study procedures and symptoms were monitored using a mobile application (SymTrack). The effect of alcoholic compared with nonalcoholic drinks was also assessed. Primary outcome was the occurrence of reflux or dyspeptic symptoms. Fullness was documented by a visual analogue scale.

RESULTS

A total of 84/120 (70%) delegates aged 22-69 years consented to participate. At screening, 22 (31%) participants reported at least mild symptoms on the Leuven Dyspepsia Questionnaire. Specific ingredients did not appear to impact on postprandial symptoms. All high-calorie dinners [British, German, Italian (with alcohol)] induced more symptoms than the low-fat, low-calorie Czech dinner [odds ratio: 2.6, 95% confidence interval (CI): 0.97-6.9 (P=0.058), 1.5 (0.3-3.8), and 2.8 (0.7-10.5), respectively]. Self-reported fullness after the high-fat, high-calorie British dinner was higher by 23/100 (95% CI: 4-42, P=0.016) with respect to low-fat, low-calorie Czech and German dinners.

CONCLUSION

Study participants tolerated a range of food and drink well. Reflux or dyspeptic symptoms were least likely after the low-fat, low-calorie meal. Fullness was increased after the high-fat, high-calorie dinner, but not low-fat meals. These results will help the public to make evidence-based dietary choices during the carnival season!

The Dynamics of Gastric Emptying and Self-Reported Feelings of Satiation Are Better Predictors Than Gastrointestinal Hormones of the Effects of Lipid Emulsion Structure on Fat Digestion in Healthy Adults-A Bayesian Inference Approach

Background: Limited information exists on the relation between fat emulsion structure and its effect on the release of gastrointestinal hormones and feelings of satiation.Objective: We investigated the impact of fat emulsion droplet size, gravitational and acid stability, and redispersibility on gastrointestinal responses and sought to deduce the relative importance of the hormones ghrelin, cholecystokinin, glucagon-like peptide-1, and peptide YY (PYY) in controlling fat emptying and related satiation.Methods: Within a randomized, double-blind, 4-armed crossover study, an extensive data set was generated by MRI of gastric function, analysis of hormone profiles, and ratings of satiation in healthy participants [10 women and 7 men with a mean ± SD age of 25 ± 7 y and body mass index (in kg/m²) of 22 ± 1] after intake of 4 different fat emulsions. Iterative Bayesian model averaging variable selection was used to investigate the influence of hormone profiles in controlling fat emulsion emptying and satiation.Results: The emulsion structure had a distinct effect on the gastric emptying (primary outcome), gastrointestinal hormone profiles, and ratings of satiation (secondary outcomes). Gravitational and acid stability were stronger modulators of fat emptying and hormone profiles than were emulsion droplet size or redispersibility. Cholecystokinin and PYY were most strongly affected by fat emulsion instability and droplet size. Although both hormones were relevant predictors of gastric emptying, only PYY was identified as a relevant predictor of satiation.Conclusions: This work indicates that evenly dispersed, stable, small-emulsion droplets within the stomach lead to prolonged gastric distension, longer ghrelin suppression, and accelerated fat sensing (cholecystokinin and PPY), triggering prolonged feelings of satiation. It suggests that the effects of emulsion instability and droplet size on energy consumption are best studied by assessing changes in gastric emptying and ratings of satiation rather than changes in venous hormone profiles. This trial was registered at clinicaltrials.gov as NCT01253005.

Relationship of body weight with gastrointestinal motor and sensory function: studies in anorexia nervosa and obesity

Background

Whether gastrointestinal motor and sensory function is primary cause or secondary effect of abnormal body weight is uncertain. Moreover, studies relating continuous postprandial sensations of satiation to measurable pathology are scarce. This work assessed postprandial gastrointestinal function and concurrent sensations of satiation across a wide range of body weight and after weight change.

Methods

Patients with anorexia nervosa (AN) and obesity (OB) were investigated in reference to normal weight controls (HC). AN were additionally investigated longitudinally. Gastric emptying, antral contractions and oro-cecal transit after ingestion of a solid meal were investigated by MRI and ¹³C-lactose-ureide breath test. The dependency of self-reported sensations of satiation on the varying degree of stomach filling during gastric emptying was compared between groups.

Results

24 AN (BMI 14.4 (11.9–16.0) kg/m²), 16 OB (34.9 (29.6–41.5) kg/m²) and 20 HC (21.9 (18.9–24.9) kg/m²) were studied. Gastric half-emptying time (t₅₀) was slower in AN than HC (p = 0.016) and OB (p = 0.007), and a negative association between t₅₀ and BMI was observed between BMI 12 and 25 kg/m² (p = 0.007). Antral contractions and oro-cecal transit were not different. For any given gastric content volume, self-reported postprandial fullness was greater in AN than in HC or OB (p < 0.001). After weight rehabilitation, t₅₀ in AN tended to become shorter (p = 0.09) and postprandial fullness was less marked (p < 0.01).

Conclusions

A relationship between body weight and gastric emptying as well as self-reported feelings of satiation is present. AN have slower gastric emptying and heightened visceral perception compared to HC and OB. Longitudinal follow-up after weight rehabilitation in AN suggests these abnormalities are not a primary feature, but secondary to other factors that determine abnormal body weight.

Trial registration

Registered July 20, 2009 at ClinicalTrials.gov (NCT00946816).

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-016-0560-y) contains supplementary material, which is available to authorized users.

Microgravity Simulated by the 6° Head-Down Tilt Bed Rest Test Increases Intestinal Motility but Fails to Induce Gastrointestinal Symptoms of Space Motion Sickness

BACKGROUND

Space motion sickness (SMS) is the most relevant medical problem during the first days in microgravity. Studies addressing pathophysiology in space face severe technical challenges and microgravity is frequently simulated using the 6° head-down tilt bed rest test (HDT).

AIM

We were aiming to test whether SMS could be simulated by HDT, identify related changes in gastrointestinal physiology and test for beneficial effects of exercise interventions.

METHODS

HDT was performed in ten healthy individuals. Each individual was tested in three study campaigns varying by a 30-min daily exercise intervention of either standing, an upright exercise regimen, or no intervention. Gastrointestinal symptoms, stool characteristics, gastric emptying time, and small intestinal transit were assessed using standardized questionnaires, (13)C octanoate breath test, and H2 lactulose breath test, respectively, before and at day 2 and 5 of HDT.

RESULTS

Individuals described no or minimal gastrointestinal symptoms during HDT. Gastric emptying remained unchanged relative to baseline data collection (BDC). At day 2 of HDT the H₂ peak of the lactulose test appeared earlier (mean ± standard error for BDC-1, HDT2, HDT5: 198 ± 7, 139 ± 18, 183 ± 10 min; p: 0.040), indicating accelerated small intestinal transit. Furthermore, during HDT, stool was softer and stool mass increased (BDC: 47 ± 6, HDT: 91 ± 12, recovery: 53 ± 8 g/day; p: 0.014), indicating accelerated colonic transit. Exercise interventions had no effect.

CONCLUSION

HDT did not induce symptoms of SMS. During HDT, gastric emptying remained unchanged, but small and large intestinal transit was accelerated.

On the validity of the (13) C-acetate breath test for comparing gastric emptying of different liquid test meals: a validation study using magnetic resonance imaging

BACKGROUND

(13) C-acetate breath testing (BT) is applied to assess and compare gastric emptying of liquid meals. Gastric half-emptying times (t50 ) from BT show offsets compared to t50 values from γ-scintigraphy and ultrasonography. Linear transformations have been proposed to correct these offsets. This investigation critically validates the BT for the assessment of liquid gastric emptying by using simultaneously recorded meal and total gastric content volume emptying data from magnetic resonance imaging (MRI).

METHODS

Data were collected during a recently published double-blind, randomized, cross-over MRI gastric emptying study of three (13) C-labeled enteral formulas differing in protein sources (PMID: 24699556). Breath testing-derived t50 was computed with the analysis methods commonly applied in gastric emptying research, i.e., the exponential-beta function and the Wagner-Nelson (WN) method, respectively.

KEY RESULTS

Breath testing t50 values from exponential-beta function and WN method showed a positive and negative offset to MRI data, respectively. Linear regression detected low concordance between MRI and both BT methods revealing meal specific and emptying rate-dependent offsets. The WN method showed worse agreement and correlation with MRI emptying data. Breath testing rather reflected meal volume than total gastric content volume emptying.

CONCLUSIONS & INFERENCES

This validation study indicates that the (13) C-acetate breath test may not be applied to compare gastric emptying of arbitrary liquid meals without prior validation by imaging methods. t50 values from BT are biased by (i) the properties of the meal and (ii) the selected method used for (13) CO2 exhalation analysis. No linear transformation common for all meals was applicable to correct the offsets between BT and MRI.

Volume, distribution and acidity of gastric secretion on and off proton pump inhibitor treatment: a randomized double-blind controlled study in patients with gastro-esophageal reflux disease (GERD) and healthy subjects

Background

Postprandial accumulation of gastric secretions in the proximal stomach above the meal adjacent to the esophagogastric junction (EGJ), referred to as the ‘acid pocket’, has been proposed as a pathophysiological factor in gastro-esophageal reflux disease (GERD) and as a target for GERD treatment. This study assessed the effect of proton pump inhibitor (PPI) therapy on the volume, distribution and acidity of gastric secretions in GERD and healthy subjects (HS).

Methods

A randomized, double blind, cross-over study in 12 HS and 12 GERD patients pre-treated with 40 mg pantoprazole (PPI) or placebo b.i.d. was performed. Postprandial secretion volume (SV), formation of a secretion layer and contact between the layer and the EGJ were quantified by Magnetic Resonance Imaging (MRI). Multi-channel pH-monitoring assessed intragastric pH.

Results

A distinct layer of undiluted acid secretion was present on top of gastric contents in almost all participants on and off high-dose acid suppression. PPI reduced SV (193 ml to 100 ml, in HS, 227 ml to 94 ml in GERD; p < 0.01) and thickness of the acid layer (26 mm to 7 mm, 36 mm to 9 mm respectively, p < 0.01). No differences in secretion volume or layer thickness were observed between groups; however, off treatment, contact time between the secretion layer and EGJ was 2.6 times longer in GERD compared to HS (p = 0.012). This was not the case on PPI.

Conclusions

MRI can visualize and quantify the volume and distribution dynamics of gastric secretions that form a layer in the proximal stomach after ingestion of a liquid meal. The secretion volume and the secretion layer on top of gastric contents is similar in GERD patients and HS; however contact between the layer of undiluted secretion and the EGJ is prolonged in patients. High dose PPI reduced secretion volume by about 50 % and reduced contact time between secretion and EGJ towards normal levels.

Trial registration

NCT01212614.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-015-0343-x) contains supplementary material, which is available to authorized users.

Assessment of Obstructive Defecation by High-Resolution Anorectal Manometry Compared With Magnetic Resonance Defecography

BACKGROUND & AIMS

Patients with obstructive defecation have abnormalities of anorectal function and/or structure. Conventional anorectal manometry (ARM) can identify abnormal function and behavior (dyssynergia); however, agreement between manometry and defecography is only fair. High-resolution (HR)-ARM may improve diagnostic agreement by differentiating pressure effects caused by dyssynergia and obstruction. We compared HR-ARM findings with magnetic resonance (MR) defecography in the clinical assessment of patients with symptoms of obstructive defecation defined by Rome III criteria.

METHODS

HR-ARM (Manoscan AR 360; Given Imaging, Yoqeam, Israel) assessed anal sphincter function and pressure during simulated defecation. Abnormal manometric findings were classified according to the Rao system and compared with MR defecography as the reference standard.

RESULTS

A total of 188 consecutive patients (155 women; age, 19-93 y) with obstructive defecation underwent a full investigation. Compared with patients with dyssynergia on MR imaging (n = 66), patients with structural pathology (n = 87) had lower resting (P < .003) and squeeze pressures (P < .011), but a higher rectoanal pressure gradient (P < .0001) on HR-ARM. High intrarectal pressure with a steep, positive pressure gradient consistent with outlet obstruction on HR-ARM was present in 24 patients with intra-anal intussusception on MR imaging. This pattern was not observed in other patients. Interobserver agreement was substantial for HR-ARM diagnoses (κ = 0.67; 95% confidence interval, 0.559-0.779). Diagnostic accuracy for dyssynergia was 82% compared with MR imaging (sensitivity, 77% [51 of 66]; specificity, 85% [104 of 122]).

CONCLUSIONS

The diagnostic agreement between anorectal HR-ARM and MR defecography is high and pressure measurements accurately identify recto-anal dyssynergia and intra-anal outlet obstruction by structural pathology as causes of obstructive defecation.

Imaging gastric structuring of lipid emulsions and its effect on gastrointestinal function: a randomized trial in healthy subjects

BACKGROUND

Efficient fat digestion requires fat processing within the stomach and fat sensing in the intestine. Both processes also control gastric emptying and gastrointestinal secretions.

OBJECTIVE

We aimed to visualize the influence of the intragastric stability of fat emulsions on their dynamics of gastric processing and structuring and to assess the effect this has on gastrointestinal motor and secretory functions.

DESIGN

Eighteen healthy subjects with normal body mass index (BMI) were studied on 4 separate occasions in a double-blind, randomized, crossover design. Magnetic resonance imaging (MRI) data of the gastrointestinal tract and blood triglycerides were recorded before and for 240 min after the consumption of the following 4 different fat emulsions: lipid emulsion 1 (LE1; acid stable, 0.33 μm), lipid emulsion 2 (LE2; acid stable, 52 μm), lipid emulsion 3 (LE3; acid unstable, solid fat, 0.32 μm), and lipid emulsion 4 (LE4; acid unstable, liquid fat, 0.38 μm).

RESULTS

Intragastric emulsion instability was associated with a change in gastric emptying. Acid-unstable emulsions exhibited biphasic and faster emptying profiles than did the 2 acid-stable emulsions (P ≤ 0.0001). When combined with solid fat (LE3), different dynamics of postprandial gallbladder volume were induced (P ≤ 0.001). For acid-stable emulsions, a reduction of droplet size by 2 orders of magnitude [LE1 (0.33 μm) compared with LE2 (52 μm)] delayed gastric emptying by 38 min. Although acid-stable (LE1 and LE2) and redispersible (LE4) emulsions caused a constant increase in blood triglycerides, no increase was detectable for LE3 (P < 0.0001). For LE3, MRI confirmed the generation of large fat particles during gastric processing, which emptied into and progressed through the small intestine.

CONCLUSIONS

MRI allows the detailed characterization of the in vivo fate of lipid emulsions. The acute effects of lipid emulsions on gastric emptying, gallbladder volume, and triglyceride absorption are dependent on microstructural changes undergone during consumption. Gastric peristalsis and secretion were effective at redispersing pools of liquid fat in the stomach. This trial was registered at clinicaltrials.gov as NCT01253005.

Effects of baclofen on the functional anatomy of the oesophago-gastric junction and proximal stomach in healthy volunteers and patients with GERD assessed by magnetic resonance imaging and high-resolution manometry: a randomised controlled double-blind study

BACKGROUND

The mechanism of reflux protection may involve a 'flap valve' at the oesophago-gastric junction (OGJ).

AIM

To assess the effects of baclofen, a gamma-aminobutyric acid receptor type-B (GABA-B) agonist known to suppress reflux events, on the 'functional anatomy' of the OGJ and proximal stomach after a large test meal.

METHODS

Twelve healthy volunteers (HVs) and 12 patients with gastro-oesophageal reflux disease (GERD); with erosive oesophagitis or pathological oesophageal acid exposure completed a randomised, double-blind, cross-over study. On 2 test days participants received 40-mg baclofen or placebo before ingestion of a large test meal. OGJ structure and function were assessed by high-resolution manometry (HRM) and magnetic resonance imaging (MRI) using validated methods. Measurements of the oesophago-gastric angle were derived from three-dimensional models reconstructed from anatomic MRI images. Cine-MRI and HRM identified postprandial reflux events. Mixed model analysis and Wilcoxon rank signed tests assessed differences between participant groups and treatment conditions.

RESULTS

In both HVs and GERD patients, baclofen reduced the frequency of postprandial reflux events. The oesophago-gastric insertion angle in GERD patients was reduced (-4.1 ± 1.8, P = 0.025), but was unchanged in healthy controls. In both study groups, baclofen augmented lower oesophageal sphincter (LES) pressure (HVs: +7.3 ± 1.8 mmHg, P < 0.0001, GERD: +4.50 ± 1.49 mmHg, P < 0.003) and increased LES length (HVs: +0.48 ± 0.11 cm, P < 0.0003, GERD: +0.35 ± 0.06 cm, P < 0.0001).

CONCLUSIONS

Baclofen inhibits transient LES relaxations and augments LES pressure and length. Additionally, baclofen has effects on the 'functional anatomy' of the OGJ and proximal stomach in GERD patients, which may suppress reflux by means of a 'flap valve' mechanism.

L-lysine dose dependently delays gastric emptying and increases intestinal fluid volume in humans and rats

BACKGROUND

Novel sensory inputs for the control of food intake and gastrointestinal (GI) function are of increasing interest due to the rapid increase in nutrition-related diseases. The essential amino acid L-lysine was demonstrated to have a selective impact on food intake, gastric emptying, and intestinal transit in rats, thus indicating a potential novel direct sensory input to assess dietary protein content and quality. The aim of this study was to assess translational aspects of this finding and to investigate the dose-dependent effect of L-lysine on human and rat GI function.

METHODS

L-lysine doses from 0-800 mg in rats and 0.5-7.5 g in humans were analyzed for their effect on gastric emptying and GI secretion. Human GI function was assessed non-invasively using magnetic resonance imaging (MRI), rat data were acquired using standard lethal measurement methods. L-lysine dose dependently delayed gastric emptying and stimulated GI secretion in rats as reflected by residual phenol red content and increased gastric wet weight.

KEY RESULTS

The dose-dependent delay in gastric emptying observed in rats was confirmed in humans with an increase in halftime of gastric emptying of 4 min/g L-lysine, p < 0.01. Moreover, a dose-dependent increase in intestinal fluid accumulation was observed (0.4 mL/min/g L-lysine, p < 0.0001). No effect on alkaline tide, glucose concentration, hematocrit, or visceral sensations was detected.

CONCLUSIONS & INFERENCES

This translational study demonstrates comparable dose-dependent effects of intragastric L-lysine on GI function in humans and rats and suggests a broader role for individual amino acids in the control of GI motility and secretion in vivo.

The effect of Helicobacter pylori infection and eradication in patients with gastro-oesophageal reflux disease: A parallel-group, double-blind, placebo-controlled multicentre study

OBJECTIVES

This study aimed to resolve controversy regarding the effects of Helicobacter pylori eradication therapy and H. pylori infection in gastro-oesophageal reflux disease.

DESIGN

A randomized, double-blind, multicentre trial was performed in patients presenting with reflux symptoms. H. pylori-positive patients were randomized to receive either antibiotics or placebo for 7 days. H. pylori-negative patient controls received placebo. All received esomeprazole 20 mg b.d. for 7 days, followed by 40 mg o.d. to complete an 8-week course, and were followed up for 32 weeks by telephone.

RESULTS

In this study, 198/589 (34%) patients were H. pylori-positive and 113 H. pylori-negative patients served as controls. Baseline endoscopy revealed 63% Los Angeles grade 0A and 37% Los Angeles grade BCD oesophagitis with no difference between patient groups. Symptom improvement on esomeprazole was seen in 89%. H. pylori eradication was successful in 82%. H. pylori eradication had no effect on symptomatic relapse (hazard ratio 1.15, 95% CI 0.74-1.8; p = 0.5). Overall, H. pylori-positive patients had a lower probability of relapse compared to H. pylori-negative controls (hazard ratio 0.6, 95% CI 0.43-0.85; p = 0.004). Relapse hazard was modulated also by oesophagitis grade (BCD vs. 0A, hazard ratio 2.1, 95% CI 1.5-3.0).

CONCLUSION

Relapse of gastro-oesophageal reflux disease symptoms after a course of high dose acid suppression took longer for H. pylori-positive patients than H. pylori-negative controls; however eradication therapy had no effect on the risk of relapse; ClincialTrials.gov number, NCT00574925.

Toward more accurate measurements of anorectal motor and sensory function in routine clinical practice: validation of high-resolution anorectal manometry and Rapid Barostat Bag measurements of rectal function

BACKGROUND

Measurements of anorectal function using high-resolution anorectal manometry (HR-ARM) and rectal barostat technology provide more reliable results than standard ARM with an elastic balloon; however, HR-ARM results have not been compared to ARM and standard barostat protocols are impractical in routine clinical practice. The aim of this study was to validate HR-ARM against standard ARM and standard barostat against a novel Rapid Barostat Bag (RBB) measurement and elastic balloon measurements of rectal function.

METHODS

Twenty-six healthy volunteers (15 female, 11 male, 19-52 years) were studied. Measurements of anal function and simulated defecation were compared for 12-sensor HR-ARM and 6-sensor standard ARM using line plots from the same recording. Rectal capacity, compliance, and sensation (volume threshold) were measured by elastic balloon, standard barostat, and RBB methods using stepwise inflation of a 700-mL polyethylene bag to 40 mmHg distension by electronic barostat and handheld syringe monitored by sphygmo-manometer, respectively. Results are reported as mean ± SD. Bland-Altman plots and correlation coefficients (r) for measurements were calculated.

KEY RESULTS

There was excellent agreement between HR- and standard ARM measurements (r > 0.86, <25 mmHg difference) and between standard barostat and RBB measurements of rectal capacity (r = 0.97, <25 mL difference). Correlation coefficients of threshold volumes for initial perception, urgency and discomfort were 0.37, 0.71, and 0.95, respectively. No significant correlation was present with elastic balloon measurements. Time to complete studies was shorter for HR-ARM than standard ARM and for RBB than standard barostat in historical controls.

CONCLUSIONS & INFERENCES

HR-ARM with RBB measurements of anorectal function provides quick and reasonably accurate measurements of continence function suitable for use in routine clinical practice (ClinicalTrial.gov NCT01456442).

Validation of a golden angle radial sequence (GOLD) for abdominal T1 mapping during free breathing: demonstrating clinical feasibility for quantifying gastric secretion and emptying

PURPOSE

To validate a magnetic resonance imaging sequence suitable for quantitative assessment of acid suppression by a proton pump inhibitor (PPI) on gastric secretion and emptying in clinical practice.

METHODS

A golden angle radial sequence (GOLD) was validated in a series of in vitro and in vivo experiments and clinical feasibility was shown in two studies. The impact of free breathing and image plane orientation on T1 values was evaluated in a controlled in vivo experiment. The free-breathing GOLD sequence was compared against a standard breath-hold gradient echo sequence for gastric half emptying time in 23 subjects during a gastric emptying study. Pilot data from five subjects assessed the sensitivity of the GOLD sequence to detect changes in acid secretion volume produced by PPI treatment.

RESULTS

The coronal free-breathing GOLD sequence and the axial breath-hold standard gradient echo sequence showed good agreement of the gastric half emptying time (6 ± 3 min, P = 0.053). The GOLD sequence demonstrated sensitivity to reduction of gastric secretion volumes induced by PPI treatment (55 ± 5 mL, P < 0.001).

CONCLUSION

The GOLD sequence allowed for free breathing, multislice, combined imaging and T1 mapping of the stomach content. GOLD presents a promising multipurpose, noninvasive imaging tool for monitoring gastric function in clinical studies.

Post-prandial reflux suppression by a raft-forming alginate (Gaviscon Advance) compared to a simple antacid documented by magnetic resonance imaging and pH-impedance monitoring: mechanistic assessment in healthy volunteers and randomised, controlled, double-blind study in reflux patients

BACKGROUND

Alginates form a raft above the gastric contents, which may suppress gastro-oesophageal reflux; however, inconsistent effects have been reported in mechanistic and clinical studies.

AIMS

To visualise reflux suppression by an alginate-antacid [Gaviscon Advance (GA), Reckitt Benckiser, UK] compared with a nonraft-forming antacid using magnetic resonance imaging (MRI), and to determine the feasibility of pH-impedance monitoring for assessment of reflux suppression by alginates.

METHODS

Two studies were performed: (i) GA and antacid (Alucol, Wander Ltd, Switzerland) were visualised in the stomach after ingestion in 12 healthy volunteers over 30 min after a meal by MRI, with reflux events documented by manometry. (ii) A randomised controlled, double-blind cross-over trial of post-prandial reflux suppression documented by pH-impedance in 20 patients randomised to GA or antacid (Milk of Magnesia; Boots, UK) after two meals taken 24 h apart.

RESULTS

MRI visualized a "mass" of GA form at the oesophago-gastric junction (OGJ); simple antacid sank to the distal stomach. The number of post-prandial common cavity reflux events was less with GA than antacid [median 2 (0-5) vs. 5 (1-11); P < 0.035]. Distal reflux events and acid exposure measured by pH-impedance were similar after GA and antacid. There was a trend to reduced proximal reflux events with GA compared with antacid [10.5 (8.9) vs. 13.9 (8.3); P = 0.070].

CONCLUSIONS

Gaviscon Advance forms a 'mass' close to the OGJ and significantly suppresses reflux compared with a nonraft-forming antacid. Standard pH-impedance monitoring is suitable for clinical studies of GA in gastro-oesophageal reflux disease patients where proximal reflux is the primary outcome.

The effect of standard compared to enhanced instruction and verbal feedback on anorectal manometry measurements

BACKGROUND

Guidelines recommend instruction and motivation during anorectal manometry; however, its impact on findings has not been reported. This study assessed the effects of standard versus enhanced instruction and verbal feedback on the results of anorectal manometry.

METHODS

High-resolution manometry was performed by a solid-state catheter with 10 circumferential sensors at 6 mm separation across the anal canal and two rectal sensors. Measurements were acquired first with standard instruction and then with enhanced instruction and verbal feedback. On both occasions, squeeze pressure and duration during three voluntary contractions and intra-rectal pressure and recto-anal pressure gradient (RAPG) during three attempts at simulated defecation were assessed.

KEY RESULTS

A total of 70 consecutive patients (54 female; age 25-82 years) referred for investigation of fecal incontinence (n = 31), constipation, and related disorders of defecation (n = 39) were studied. Enhanced instruction and verbal feedback increased maximum squeeze pressure (Δ10 ± 28.5 mmHg; P < 0.0038) and duration of contraction (Δ3 ± 4 s; P < 0.0001). During simulated defecation, it increased intra-rectal pressure (Δ12 ± 14 mmHg; P < 0.003) and RAPG (Δ11 ± 20 mmHg; P < 0.0001). Using standard diagnostic criteria, the intervention changed manometric findings from locally validated 'pathologic' to 'normal' values in 14/31 patients with incontinence and 12/39 with disorders of defecation.

CONCLUSIONS & INFERENCES

Enhanced instruction and verbal feedback significantly improved voluntary anorectal functions and resulted in a clinically relevant change of manometric diagnosis in some patients. Effective explanation of procedures and motivation during manometry is required to ensure consistent results and to provide an accurate representation of patient ability to retain continence and evacuate stool.

[Gastro-highlights 2012]

The annual Gastro Highlights training event, held at the university Hospital Zurich last autumn, also celebrated the 60th birthday of prof.Dr.med. Michael Fried, who initiated this widely recognized event 17 years ago. Featured at the symposium was a round up of the most important new discoveries in the field of gastroenterology and hepatology to be published during the course of the previous year or represented at the Digestive Disease Week (DDW). To mark the birthday of Prf. Dr. med. Michael Fried, two international experts made a special report on the key developments in the gastroenterology to emerge over the past decades.

Real-time multipoint gastrointestinal 19-fluorine catheter tracking

PURPOSE

To develop MR based real-time gastrointestinal 19-Fluorine (19F) catheter tracking and visualization allowing for real-time detection and feedback of 3D catheter shape and movement as well as catheter-driven adjustments of 1H imaging geometry parameters.

METHODS

Data were acquired on a 3T clinical system using 3D Golden Angle radial sampling. Two gastrointestinal catheters incorporating four fiducial 19F markers (65 or 50 µL marker volume) were tracked while being pulled through a gel phantom by an operator inside the MR room with velocities of 2-18 mm/s. During continuous acquisition, k-space profiles were transferred in real-time to an external computer for concurrent reconstruction of 3D 19F images and detection and visualization of marker positions. Based on αthe marker positions, automatic adjustments of 1H imaging planes to facilitate targeted anatomical scanning was implemented.

RESULTS

Mean tracking reliabilities were 94.5 and 83.6% (catheters 1 and 2) for temporal resolutions 185-740 ms. Reconstruction times of 196 ms were achieved. Real-time visual feedback allowed the operator to accurately control the catheter movement. Catheter-guidance for 1H imaging was reliable.

CONCLUSION

The presented real-time 19F MR based framework for the tracking of 19F labeled devices is applicable to combined 19F and 1H MRI guidance of gastrointestinal devices in vivo.

Gastric secretion does not affect the reliability of the 13C-acetate breath test: A validation of the 13C-acetate breath test by magnetic resonance imaging

BACKGROUND

(13)C-Acetate labeled meals are widely used to determine meal emptying by means of analyzing resulting (13)CO(2) exhalation dynamics. In contrast to the underlying metabolic processes, only few (13)C breath test meal emptying studies have focused on intragastric processes that may alter (13)CO(2) exhalation. This work assessed the effect of enhanced gastric secretion on the reliability of half emptying time (t50) measurements by (13)C-acetate breath test.

METHODS

(13)CO(2) exhalation data were acquired in a double-blind, randomized, cross-over gastric emptying study in 12 healthy volunteers receiving either pentagastrin or placebo intravenously. The standard method proposed by Ghoos et al. was applied to calculate t50 (t50_Ghoos) from (13)CO(2) exhalation data, which were compared and tested for agreement to meal half emptying times (t50_MV) from concurrent recorded MRI (magnetic resonance imaging) volume data. In addition, the accumulated gastric secretion volumes during infusion as detected by MRI (AUC_SV(60)) were correlated with the corresponding cumulative percent (13)C doses recovered (cPDR(60)).

KEY RESULTS

t50_Ghoos and t50_MV showed a linear correlation with a slope of 1.1 ± 0.3 (r(2) = 0.67), however, a positive offset of 136 min for t50_Ghoos. No correlation was detected between AUC_SV(60) and cPDR(60) (r(2) = 0.11). Both, breath test and MRI, revealed a prolonged t50 under pentagastrin infusion with median differences in t50_Ghoos of 45[28-84] min (P = 0.002) and t50_MV of 39[28-52] min (P = 0.002).

CONCLUSIONS & INFERENCES

This study suggests that (13)CO(2) exhalation after ingestion of a (13) C-labeled liquid test meal is not affected by stimulated gastric secretion, but is rather reflecting the dynamics of meal or caloric emptying from the stomach.

19F MR imaging golden angle-based capsule tracking for intestinal transit and catheter tracking: initial in vivo experience

PURPOSE

To combine fluorine 19 ((19)F) magnetic resonance (MR) imaging and golden angle radial acquisition and to assess the feasibility of (19)F MR imaging golden angle-based tracking for catheter tracking applications and simultaneous three-dimensional (3D) intestinal tracking of ingested (19)F-labeled capsules in vivo.

MATERIALS AND METHODS

Approval from the local ethical committee and informed consent from the subject were obtained. In vitro studies were performed to assess (19)F MR imaging golden angle-based tracking reliability with regard to temporal resolution and different tracking strategies (boundary condition-free tracking, composite image-based tracking, and model-based tracking). In vivo performance of the method was investigated in one healthy volunteer on 2 days. On study day 1, a duodenal catheter incorporating five (19)F-labeled capsules was administered nasally, and its 3D movement was tracked inside the stomach and esophagus. On study day 2, three (19)F-labeled capsules were swallowed, and intestinal movement was tracked.

RESULTS

Simultaneous in vivo 3D tracking of multiple (19)F-labeled capsules was successfully performed without incorporation of boundary conditions at a temporal resolution of 252 msec. Incorporation of boundary conditions with composite image-based tracking and model-based tracking increased tracking reliability and enabled temporal resolution as high as 108 msec.

CONCLUSION

Use of (19)F MR imaging golden angle-based capsule tracking enables in vivo tracking of (19)F-labeled capsules and catheters at high temporal resolution. The presented method is applicable to physioanatomic studies of the gastrointestinal tract and shows potential for real-time tracking in interventional radiology.

Measuring the interaction of meal and gastric secretion: a combined quantitative magnetic resonance imaging and pharmacokinetic modeling approach

BACKGROUND

The stimulation and intragastric accumulation of gastric secretion has been recognized as an important factor in gastroesophageal reflux disease. However, the interaction of gastric secretion and meal emptying has not been fully understood. Current methods to assess gastric secretion are either invasive or unable to provide information on its volume, distribution and dynamics. The aim of this study was to quantify the interaction between meal emptying and meal induced gastric secretion by using quantitative magnetic resonance imaging (MRI) and pharmacokinetic analysis.

METHODS

A chocolate test meal was developed which is secretion stimulating and MRI compatible. Meal emptying and gastric secretion were assessed in fourteen healthy volunteers using a validated quantitative MRI technique. A population based pharmacokinetic model was developed and applied to the extracted volume data, assessing the meal emptying rate, rate of secretion and their interaction.

KEY RESULTS

The test meal continuously induced gastric secretion in all subjects, which partly accumulated at the meal-air interface, forming a 'secretion layer' in the proximal stomach. Traditional fitting detected a significant correlation between meal emptying rate and rate of secretion. The pharmacokinetic model quantified this interaction and estimated a 2.3 ± 1 fold higher effect of meal on secretion than vice versa. The efficacy of the emptied meal to produce gastric secretion was 61%.

CONCLUSIONS & INFERENCES

The combined quantitative MRI and pharmacokinetic model approach allows for the quantification of gastric secretion volume and its interaction on meal emptying. The observed secretion layer might explain previous findings postulating the presence of an intragastric 'acid pocket'.

The gastro-esophageal reflux barrier: biophysical analysis on 3D models of anatomy from magnetic resonance imaging

BACKGROUND

The function and structure of the gastro-esophageal junction (GEJ) determine its efficacy as a reflux barrier. This study presents a novel methodology for the quantitative assessment of GEJ and proximal gastric morphology from magnetic resonance (MR) imaging. Based on this data we propose a new conceptualization of the hypothesis that a flap valve mechanism contributes to reflux protection.

METHODS

3D models of the GEJ and proximal stomach were reconstructed from MR images in 12 healthy volunteers during respiration and on eating a test meal to maximum satiation. A rotating plane analysis measured the gastro-esophageal insertion angle and span of contact. An ellipsoid fit provided quantitative assessment of gastric shape and orientation relative to a fixed anatomical reference point. Position of the esophageal insertion on the 'gastric ellipse' was noted. An ellipsoid-cylinder model was designed to analyze the relationships among parameters describing the GEJ morphology.

KEY RESULTS

The insertion angle became more acute on expiration, but did not change with meal ingestion. In contrast the span of contact did not vary with respiration, but increased with gastric filling. Changes in gastric morphology with distension further augmented the span of gastro-esophageal contact in almost 70% of the studies.

CONCLUSIONS & INFERENCES

Novel MR imaging and biophysical analysis of the GEJ and proximal stomach provide a quantitative description of structures contributing to the reflux barrier. Changes in these parameters during respiration and on eating support the hypothesis that structural components of a functional 'flap valve' like mechanism contribute to reflux protection.

Chicago classification criteria of esophageal motility disorders defined in high resolution esophageal pressure topography

BACKGROUND

The Chicago Classification of esophageal motility was developed to facilitate the interpretation of clinical high resolution esophageal pressure topography (EPT) studies, concurrent with the widespread adoption of this technology into clinical practice. The Chicago Classification has been an evolutionary process, molded first by published evidence pertinent to the clinical interpretation of high resolution manometry (HRM) studies and secondarily by group experience when suitable evidence is lacking.

PURPOSE

This publication summarizes the state of our knowledge as of the most recent meeting of the International High Resolution Manometry Working Group in Ascona, Switzerland in April 2011. The prior iteration of the Chicago Classification was updated through a process of literature analysis and discussion. The major changes in this document from the prior iteration are largely attributable to research studies published since the prior iteration, in many cases research conducted in response to prior deliberations of the International High Resolution Manometry Working Group. The classification now includes criteria for subtyping achalasia, EGJ outflow obstruction, motility disorders not observed in normal subjects (Distal esophageal spasm, Hypercontractile esophagus, and Absent peristalsis), and statistically defined peristaltic abnormalities (Weak peristalsis, Frequent failed peristalsis, Rapid contractions with normal latency, and Hypertensive peristalsis). The Chicago Classification is an algorithmic scheme for diagnosis of esophageal motility disorders from clinical EPT studies. Moving forward, we anticipate continuing this process with increased emphasis placed on natural history studies and outcome data based on the classification.

[Highlights in gastroenterology 2011]

«Gastro-Highlights», an annual symposium dedicated to continuing education, took place at the University Hospital Zürich for the sixteenth time this autumn. In this well-attended event, major new findings in the fields of gastroenterology and hepatology that were published in the past year or recently presented at the «Digestive Disease Week (DDW)» were summarized for practising gastroenterologists and internists.

Inter-observer reproducibility and analysis of gastric volume measurements and gastric emptying assessed with magnetic resonance imaging

BACKGROUND

Magnetic resonance (MR) imaging provides direct, non-invasive measurements of gastric function and emptying. The inter-observer variability (IOV) of MR volume measurements and the most appropriate analysis of MR data have not been established. To assess IOV of total gastric volume (TGV) and gastric content volume (GCV) measurements from MR images and the ability of standard power exponential (PowExp), and a novel linear exponential (LinExp) model to describe MR data.

METHODS

  Ten healthy volunteers received three different volumes of a liquid nutrient test meal (200-800 mL) on 3 days in a randomized order. Magnetic resonance scans were acquired using a 1.5T system every 1-5 min for 60 min. Total gastric volume and GCV were measured independently by three observers. Volume data were fitted by PowExp and LinExp models to assess postprandial volume change and gastric emptying half time (T(50) ).

KEY RESULTS

An initial rise in GCV and TGV was often observed after meal ingestion, thereafter GCV and TGV decreased in an approximately linear fashion. Inter-observer variability decreased with greater volumes from 12% at 200 mL to 6% at 600 and 800 mL. Inter-observer variability for T(50) was <5%. PowExp and LinExp models provided comparable estimates of T(50) ; however, only LinExp described dynamic volume change in the early postprandial period.

CONCLUSIONS & INFERENCES

Gastric MR provides quantitative measurements of postprandial volume change with low IOV, unless the stomach is nearly empty. The novel LinExp model describes the dynamic volume changes in the early postprandial period more accurately than the PowExp model used in existing gastric emptying studies.

Determinants of fecal continence in healthy, continent subjects: a comprehensive analysis by anal manometry, rectal barostat and a stool substitute retention test

BACKGROUND/AIMS

This study aimed to identify anal sphincter and rectal factors that determine anorectal filling sensations and continence during rectal filling in health.

METHODS

Measurements of anorectal physiology were collected from 42 continent healthy subjects participating in a prospective trial. Rectal function and capacity were assessed by barostat. Anal sphincter functions were assessed by manometry. A validated stool substitute retention test was performed in which a viscous suspension was infused into the rectum at 60 ml/min to 1,500 ml. Multivariate regression was applied to identify physiologic factors that determine anorectal sensation and continence during rectal filling.

RESULTS

The volume at which first awareness of rectal filling occurred associated with age (p < 0.03), rectal capacity (p < 0.06) and anal resting pressure (p < 0.003); urgency associated with rectal capacity (p < 0.0007), anal resting (p < 0.04) and squeeze pressure (p < 0.02); volume at first incontinence with rectal capacity (p < 0.0001) and squeeze pressure (p < 0.04) and the maximum volume retained were closely correlated with rectal capacity only (p < 0.0001).

CONCLUSION

Anorectal filling sensations and continence in health require a rectal reservoir of adequate capacity and effective voluntary anal sphincter function. Complementary associations between continence, motor and sensory function indicate the presence of an adaptive mechanism that enables timely, appropriate responses to events that threaten fecal continence.

Visualization and quantification of intestinal transit and motor function by real-time tracking of 19F labeled capsules in humans

A combined (19)F and (1)H MRI framework for the assessment of human intestinal transit and motor function is presented. This framework consists of silicone coated polychlorotrifluoroethylene capsules filled with perfluoro-[15]-crown-5-ether as (19)F marker, a flexible (19)F surface coil and a (19)F projection imaging sequence, allowing for real-time tracking of a single or multiple capsules. The capsules (length 11.5 mm, Ø 7.2 mm) contain 140 μL perfluoro-[15]-crown-5-ether and were tested for cytotoxicity and leakage prior to oral administration. A balanced SSFP projection sequence was implemented, yielding a temporal resolution of 133 ms. Optional multi-frequency excitation, allowing for interleaved tracking of differently labeled (19)F capsules, was incorporated. The passage of the (19)F capsules through intestinal sections was monitored in two healthy volunteers. Capsule coordinates were successfully coregistered with anatomical reference scans. Intestinal motility, residence times, lengths and forward velocities were determined. Simultaneous tracking of two capsules allowed for the assessment of peristaltic patterns with correction for respiratory motion. By providing the means for real-time multiple capsule tracking and high resolution anatomical imaging, the presented multinuclear imaging framework has the potential to provide important supplemental information for physiological and pharmaceutical research.

Effect on gastric function and symptoms of drinking wine, black tea, or schnapps with a Swiss cheese fondue: randomised controlled crossover trial

OBJECTIVE

To compare the effects of drinking white wine or black tea with Swiss cheese fondue followed by a shot of cherry schnapps on gastric emptying, appetite, and abdominal symptoms.

DESIGN

Randomised controlled crossover study.

PARTICIPANTS

20 healthy adults (14 men) aged 23-58.

INTERVENTIONS

Cheese fondue (3260 kJ, 32% fat) labelled with 150 mg sodium (13)Carbon-octanoate was consumed with 300 ml of white wine (13%, 40 g alcohol) or black tea in randomised order, followed by 20 ml schnapps (40%, 8 g alcohol) or water in randomised order.

MAIN OUTCOME MEASURES

Cumulative percentage dose of (13)C substrate recovered over four hours (higher values indicate faster gastric emptying) and appetite and dyspeptic symptoms (visual analogue scales).

RESULTS

Gastric emptying was significantly faster when fondue was consumed with tea or water than with wine or schnapps (cumulative percentage dose of (13)C recovered 18.1%, 95% confidence interval 15.2% to 20.9% v 7.4%, 4.6% to 10.3%; P<0.001). An inverse dose-response relation between alcohol intake and gastric emptying was evident. Appetite was similar with consumption of wine or tea (difference 0.11, -0.12 to 0.34; P=0.35), but reduced if both wine and schnapps were consumed (difference -0.40, -0.01 to -0.79; P<0.046). No difference in dyspeptic symptoms was present.

CONCLUSIONS

Gastric emptying after a Swiss cheese fondue is noticeably slower and appetite suppressed if consumed with higher doses of alcohol. This effect was not associated with dyspeptic symptoms.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00943696.

[Highlights in gastroenterology 2010]

This summer saw the fifteenth edition of «Gastro-Highlights», a well-attended symposium dedicated to continuing education that takes place each year at the University Hospital in Zurich. Major new findings in the fields of gastroenterology and hepatology that were achieved in the past year and were recently presented at the «Digestive Disease Week (DDW)» were summarized here for practising gastroenterologists and internists.

Effect of meal volume and calorie load on postprandial gastric function and emptying: studies under physiological conditions by combined fiber-optic pressure measurement and MRI

This study assessed the effects of meal volume (MV) and calorie load (CL) on gastric function. MRI and a minimally invasive fiber-optic recording system (FORS) provided simultaneous measurement of gastric volume and pressure changes during gastric filling and emptying of a liquid nutrient meal in physiological conditions. The gastric response to 12 iso-osmolar MV-CL combinations of a multinutrient drink (MV: 200, 400, 600, 800 ml; CL: 200, 300, 400 kcal) was tested in 16 healthy subjects according to a factorial design. Total gastric volume (TGV) and gastric content volume (GCV = MV + secretion) were measured by MRI during nasogastric meal infusion and gastric emptying over 60 min. Intragastric pressure was assessed at 1 Hz by FORS. The dynamic change in postprandial gastric volumes was described by a validated three-component linear exponential model. The stomach expanded with MV, but the ratio of GCV:MV at t(0) diminished with increasing MV (P < 0.01). Postprandial changes in TGV followed those of GCV. Intragastric pressure increased with MV, and this effect was augmented further by CL (P = 0.02); however, the absolute pressure rise was <4 mmHg. A further postprandial increase of gastric volumes was observed early on before any subsequent volume decrease. This "early" increase in GCV was greater for smaller than larger MV (P < 0.01), indicating faster initial gastric emptying of larger MV. In contrast, volume change during filling and in the early postprandial period were unaffected by CL. In the later postprandial period, gastric emptying rate continued to be more rapid with high MVs (P < 0.001); however, at any given volume, gastric emptying was slowed by higher CL (P < 0.001). GCV half-emptying time decreased with CL at 18 +/- 6 min for each additional 100-kcal load (P < 0.001). These findings indicate that gastric wall stress (passive strain and active tone) provides the driving force for gastric emptying, but distal resistance to gastric outflow regulates further passage of nutrients. The distinct early phase of gastric emptying with relatively rapid, uncontrolled passage of nutrients into the small bowel, modulated by meal volume but not nutrient composition, ensures that the delivery of nutrients in the later postprandial period is related to the overall calorie load of the meal.

Effects of postgastric 13C-acetate processing on measurement of gastric emptying: a systematic investigation in health

Uniform postgastric processing of the gastric emptying (GE) marker 13C-acetate (Ac) is an unverified assumption behind its widespread application to measure GE. This study assessed the postgastric processing of Ac administered by intraduodenal (i.d.) infusion simulating different physiological conditions. 13CO2 in breath was assessed in three groups of six volunteers after i.d. administration of A: Different caloric densities (0.75/1.5/3 kcal min(-1) in a 200 mL meal at constant 1 mg Ac min(-1) simulating a physiological range of nutrient delivery rates; B: different tracer delivery rates (0.5/1.0/2.5 mg Ac min(-1) simulating delayed, normal and increased GE; C1: a 500 mL meal resulting in same marker and caloric delivery compared to protocol A; C2: 50 mL water bolus injections of 12.5/25/50/100 mg Ac and C3 bolus injections of 50 mg Ac in 50/100/200 mL water in randomized order. A: 13CO2 excretion was independent of caloric load (P = 0.59). B: The dynamic of 13CO2 excretion was modulated by tracer elimination which was in turn dependent on the speed of tracer delivery, i.e. with faster deliveries resulting in lower 13CO2 recovery during infusion (P < 0.001). C: Increasing Ac doses resulted in decreased 13CO2 recovery (P < 0.001) over the first hour. 13CO2 recovery kinetics was independent of the volume delivered. This study shows 13C-acetate absorption and metabolism is independent of the volume and caloric delivery of test meals. The 'lag' in estimates of GE derived from 13CO2 breath tests is due to a postgastric, dose-dependent delay to 13CO2 elimination. This can be corrected for in analytical derivations of GE parameters based on 13C-acetate breath test measurements.

Effects of clonidine and sumatriptan on postprandial gastric volume response, antral contraction waves and emptying: an MRI study

Gastric emptying (GE) may be driven by tonic contraction of the stomach ('pressure pump') or antral contraction waves (ACW) ('peristaltic pump'). The mechanism underlying GE was studied by contrasting the effects of clonidine (alpha(2)-adrenergic agonist) and sumatriptan (5-HT(1) agonist) on gastric function. Magnetic resonance imaging provided non-invasive assessment of gastric volume responses, ACW and GE in nine healthy volunteers. Investigations were performed in the right decubitus position after ingestion of 500 mL of 10% glucose (200 kcal) under placebo [0.9% NaCl intravenous (IV) and subcutaneous (SC)], clonidine [0.01 mg min(-1) IV, max 0.1 mg (placebo SC)] or sumatriptan [6 mg SC (placebo IV)]. Total gastric volume (TGV) and gastric content volume (GCV) were assessed every 5 min for 90 min, interspersed with dynamic scan sequences to measure ACW activity. During gastric filling, TGV increased with GCV indicating that meal volume dictates initial relaxation. Gastric contents volume continued to increase over the early postprandial period due to gastric secretion surpassing initial gastric emptying. Clonidine diminished this early increase in GCV, reduced gastric relaxation, decreased ACW frequency compared with placebo. Gastric emptying (GE) rate increased. Sumatriptan had no effect on initial GCV, but prolonged gastric relaxation and disrupted ACW activity. Gastric emptying was delayed. There was a negative correlation between gastric relaxation and GE rate (r(2 )=49%, P < 0.001), whereas the association between ACW frequency and GE rate was inconsistent and weak (r2=15%, P = 0.05). These findings support the hypothesis that nutrient liquid emptying is primarily driven by the 'pressure pump' mechanism.

Characterization of gastric volume responses and liquid emptying in functional dyspepsia and health by MRI or barostat and simultaneous C-acetate breath test

The assessment of gastric accommodation and emptying by different methodologies provides inconsistent results. We aimed to compare magnetic resonance imaging (MRI), barostat and 13C-acetate breath test (BT) for the assessment of gastric volume responses and emptying in healthy controls (HC) and patients with functional dyspepsia (FD). Eight HC and eight FD patients underwent: (i) continuous BT with simultaneous MRI in the upright position after ingestion of isocaloric, 300 kcal, 200 and 800 mL meals, both labelled with 100 mg of (13)C-acetate; and (ii) BT with gastric barostat after ingestion of the 200 mL meal. MRI measured total gastric volume and gastric content volume (GCV) at baseline, after filling and during emptying. Meal emptying half-times (T(1/2)) for MRI and BT were calculated (mean +/- SD). We found: (i) Initial GCV was lower in FD than in HC (762 +/- 22 vs 810 +/- 52 mL, P < 0.04) after the 800 mL meal but not the 200 mL meal. T(1/2)(MRI) was shorter for the 800 mL than the 200 mL meal (P < 0.001), but similar in HC and FD (200 mL: HC 117 +/- 30 min vs FD 138 +/- 42 min, ns; 800 mL: HC 71 +/- 16 min vs FD 78 +/- 27 min, ns). In contrast, T(1/2)(BT) was similar between meals and groups (200 mL: HC 111 +/- 11 min vs FD 116 +/- 19 min; 800 mL: HC 114 +/- 14 min vs FD: 113 +/- 17 min). (ii) Barostat measurements showed similar postprandial volume increases between groups. We conclude that direct measurements by MRI provide a sensitive, non-invasive assessment of gastric accommodation and emptying after a meal. In contrast to MRI, BT did not detect faster emptying of high-volume compared to low-volume liquid nutrient meals in HC or FD.

The effect of gastric secretion on gastric physiology and emptying in the fasted and fed state assessed by magnetic resonance imaging

Conventional measurement of gastric secretion is invasive and cannot assess the intra-gastric distribution of gastric contents or the effects of secretion on gastric function. This study assessed the effect of gastric secretion on gastric volume responses and emptying (GE) using a validated fast T(1) mapping magnetic resonance imaging (MRI) technique. Twelve healthy participants were studied in the fasted state and after 200 kcal Gadolinium-DOTA labelled glucose meal during intravenous infusion of pentagastrin or placebo in double-blind, randomized order. Total gastric volume (TGV) and gastric content volume (GCV) was assessed by MRI volume scans and secretion by fast T(1) mapping. Data was described by the kappa-coefficient (volume change after meal ingestion), by GE half time (T(50)) and maximal GE rate (GER(max)) derived all from a GE model. Pentagastrin increased GCV and TGV compared to placebo [kappa(GCV):1.6 +/- 0.1 vs 0.6 +/- 0.1; kappa(TGV): 1.6 +/- 0.1 vs 0.7 +/- 0.1; P < 0.001]. T(1) maps revealed a secretion layer above the meal, the volume of which was associated with kappa (R(2) = 83%, P < 0.001). TGV and GCV change were similar in both conditions (kappa; P = ns). T(50) was higher for pentagastrin than for placebo (84 +/- 7 vs 56 +/- 4min, P < 0.001); however, GER(max) was similar (5.9 +/- 0.6 vs 4.9 +/- 0.4 mL min(-1), P = ns). This study shows volume and distribution of gastric secretion can be quantified in-vivo by non-invasive MRI T(1) mapping. Increased GCV drove TGV accommodation without evidence of a direct effect of pentagastrin or excess acid on gastric function. Secretion increases GCV thus prolongs GE as assessed by T(50); however, GE rate is unchanged.

Fast and optimized T1 mapping technique for the noninvasive quantification of gastric secretion

PURPOSE

To evaluate the noninvasive quantification of gastric secretion volume after administration of a labeled viscous glucose solution by fast T(1) mapping.

MATERIALS AND METHODS

T(1) values of a series of labeled and diluted glucose solutions were measured in vitro to characterize the interrelationship between T(1) and contrast agent concentration (C(Gd)) as well as the dependency of relaxivity and reference T(1) (T(10)) on the macromolecular concentration. Abdominal T(1) mapping in five healthy volunteers of different body mass index was performed after filling an intragastric balloon with a labeled and diluted glucose solution. In additional ex vivo experiments, T(1) values of gastric (GJ) and duodenal juice (DJ) and 0.1 N HCl solution were determined.

RESULTS

A linear relationship between relaxivity and macromolecular concentration and between T(10) and macromolecular concentration was found. The in vitro T(1)-C(Gd) calibration curve was successfully validated in all volunteers. T(1) values of GJ, DJ, and HCl (2939 msec vs. 2858 msec vs. 2760 msec) were close to the T(1) of water ( approximately 3000 msec).

CONCLUSION

The presented method allows one to noninvasively quantify the spatial distribution of gastric secretory products in the human stomach and provides a valuable tool for evaluating the efficacy of drugs to stimulate/inhibit gastric secretion.

Physiology of the oesophageal transition zone in the presence of chronic bolus retention: studies using concurrent high resolution manometry and digital fluoroscopy

Distinct contraction waves (CWs) exist above and below the transition zone (TZ) between the striated and smooth muscle oesophagus. We hypothesize that bolus transport is impaired in patients with abnormal spatio-temporal coordination and/or contractile pressure in the TZ. Concurrent high resolution manometry and digital fluoroscopy were performed in healthy subjects and patients with reflux oesophagitis; a condition associated with ineffective oesophageal contractility and clearance. A detailed analysis of space-time variations in bolus movement, intra-bolus and intra-luminal pressure was performed on 17 normal studies and nine studies in oesophagitis patients with impaired bolus transit using an interactive computer based system. Compared with normal controls, oesophagitis patients had greater spatial separation between the upper and lower CW tails [median 5.2 cm (range 4.4-5.6) vs 3.1 cm (2.2-3.7)], the average relative pressure within the TZ region (TZ strength) was lower [30.8 mmHg (28.3-36.5) vs 45.8 mmHg (36.1-55.7), P < 0.001], and the risk of bolus retention was higher (90%vs 12%; P < 0.01). The presence of bolus retention was associated with a wider spatial separation of the upper and lower CWs (>3 cm, the upper limit of normal; P < 0.002), independent of the presence of oesophagitis. We conclude that bolus retention in the TZ is associated with excessively wide spatial separation between the upper and lower CWs and lower TZ muscle squeeze. These findings provide a physio-mechanical basis for the occurrence of bolus retention at the level of the aortic arch, and may underlie impaired clearance with reflux oesophagitis.

Diffuse esophageal spasm

The purpose of this article is to review the clinical features, pathophysiology, diagnosis, and management of patients with diffuse esophageal spasm (DES). The PubMed database was searched with a focus on recent publications, using keywords "DES," plus "epidemiology," "prevalence," "diagnosis," "pathogenesis," "calcium channel blocker," "nitrates," "botulinum toxin," "antidepressants," "dilation," and "myotomy." The reference lists of papers identified in the initial PubMed search were reviewed for further relevant publications.

[Cross sectional imaging findings in ectopic pancreatitis]

Two patients with ectopic pancreas, associated with pancreas divisum are presented. In one of these patients MDCT examination showed an island of pancreatic parenchyma, isolated from the pancreatic head and located within the anterior wall of the duodenal bulb, where ectopic pancreas could be confirmed by endoscopy. The other patient suffered from acute pancreatitis according to the clinical and laboratory findings. However, MDCT showed a normal pancreas. Here the only abnormality on CT was found in an area of inflamed and infiltrated fatty tissue ventrally to the descending duodenum and the pancreatic head, which was clearly separated from pancreatic head. While these CT findings alone were non-specific, MRT allowed to identify an island of ectopic pancreas within this area of inflammation. Additionally both patient showed pancreas divisum. These two cases nicely demonstrate, that ectopic pancreas may be recognized by MDCT. However, familiarity with the embryology of the pancreas and knowledge about a probable association of pancreas divisum and ectopic pancreas may be helpful for the correct interpretation of imaging findings. Furthermore, in cases of ectopic pancreatitis CT may show only nonspecific extrapancreatic soft tissue inflammation and MRT may become necessary to identify the enclosed island of ectopic pancreatic tissue.

Clinical trial: the effects of adding ranitidine at night to twice daily omeprazole therapy on nocturnal acid breakthrough and acid reflux in patients with systemic sclerosis--a randomized controlled, cross-over trial

BACKGROUND

Gastro-oesophageal reflux disease (GERD) is an important problem in systemic sclerosis due to impaired salivation and oesophageal function.

AIM

To determine the efficacy of adding ranitidine at bedtime to control nocturnal acid breakthrough (NAB) and GERD in patients with systemic sclerosis already prescribed high-dose omeprazole.

METHODS

Patients with systemic sclerosis and GERD symptoms (n = 14) were treated with omeprazole 20 mg b.d. and either placebo or ranitidine 300 mg at bedtime for 6 weeks in a randomized, cross-over, placebo controlled study. At the end of each period a 24 h pH-study with intragastric and oesophageal pH measurement was performed.

RESULTS

Pathological acid reflux occurred in eight patients with omeprazole/placebo and in seven with omeprazole/ranitidine (P = ns) with technically adequate oesophageal pH-studies (n = 13). NAB was present in eight patients with omeprazole/placebo and six with omeprazole/ranitidine (P = ns) in whom technically adequate gastric pH-studies were obtained (n = 10). The addition of ranitidine had no consistent effect on patient symptoms or quality of life.

CONCLUSION

Many patients with systemic sclerosis experienced NAB and pathological oesophageal acid exposure despite high-dose acid suppression with omeprazole b.d. Adding ranitidine at bedtime did not improve NAB, GERD or quality of life in this population.

Intersubject and intrasubject variability of gastric volumes in response to isocaloric liquid meals in functional dyspepsia and health

Gastric emptying (GE) has a considerable variability, but data on reproducibility of gastric volume measurements are sparse. We aimed to study the reproducibility of postprandial gastric volume responses and GE using magnetic resonance imaging (MRI) in healthy controls (HC) and patients with functional dyspepsia (FD). Eight HC and eight FD patients underwent a MRI study on two occasions. MR images were acquired in seated position before and up to 120 min after liquid meal administration (200 mL, 300 kcal). Fasting (V0), initial postprandial stomach volumes (V1), volume changes (V1 - V0) and meal emptying half-times (T 1/2) were determined. Intersubject and intrasubject coefficients of variation (CV(inter), CV(intra)) and Pearson's correlation coefficients (r) were calculated. T 1/2 on both occasions were (mean +/- SD) 113 +/- 28 and 121 +/- 30 min in HC (ns) and 127 +/- 31 and 128 +/- 37 min in FD (ns), respectively. In HC, CV(inter), CV(intra), r were 31%, 23%, 0.49 for V0; 13%, 7%, 0.68 for V1; 10%, 4%, 0.71 for V1 - V0 and 25%, 7%, 0.90 for T 1/2. In FD these parameters were for V0: 42%, 41%, -0.06; for V1: 18%, 10%, 0.40; for V1 - V0: 20%, 14%, 0.74 and for T 1/2: 26%, 10%, 0.84. The stomach accommodates to a given meal volume, resulting in similar and reproducible postprandial volumes within- and between-subjects. MRI provides reproducible measurements of gastric volume responses in health and disease.

Quantification of distal antral contractile motility in healthy human stomach with magnetic resonance imaging

PURPOSE

To quantify healthy postprandial: 1) propagation, periodicity, geometry, and percentage occlusion by distal antral contraction waves (ACWs); and 2) changes in ACW activity in relationship to gastric emptying (GE).

MATERIALS AND METHODS

Using 1.5-T MR scanner, nine healthy fasted volunteers were examined in the right decubitus position after ingestion of 500 mL of 10% glucose (200 kcal) with 500 microM Gd-DOTA. Total gastric (TGV) and meal volumes (MV) were assessed every five minutes for 90 minutes, in and interspersed with dynamic scan sequences (duration: 2.78 minutes) providing detailed images of distal ACWs.

RESULTS

TGV increased by 738+/-38 mL after ingestion (t0), subsequently decreasing in parallel to GE. The mean GE rate and half-emptying time were 24+/-3 mL/5 minutes and 71+/-6 minutes, respectively. Accompanying ACWs reached a periodicity of 23+/-2 seconds at t35 and propagated at an unvarying speed of 0.27+/-0.01 cm/second. Their amplitude of 0.70+/-0.08 cm was constant, but the width decreased along the antral wall by 6+/-2%/cm (P=0.003). ACWs were nonocclusive (percentage occlusion 58.1+/-5.9%, t0 at the pylorus) with a reduction in occlusion away from the pylorus (P<0.001). No propagation and geometry characteristics of ACWs correlated with the changes of MV (mL/5 minutes; R2<0.05).

CONCLUSION

Our results indicate that ACWs are not imperative for emptying of liquids. This study provides a detailed quantitative reference for MRI inquiries into pharmacologically- and pathologically-altered gastric motility.

Contribution of sensitivity, volume and tone to visceral perception in the upper gastrointestinal tract in man: emphasis on testing

Upper gastrointestinal (GI) symptoms occur frequently in the general population, making them among the most common indications responsible for patients consulting the healthcare system. Consequently, understanding and characterization of the upper GI symptoms is important for the diagnosis and assessment of organ dysfunction. In practice, assessment of clinical symptoms is difficult and it is still to a large extent unclear how sensitivity, volume and tone contribute to visceral perception in the upper GI tract. The goal of advanced research in upper GI symptoms is to obtain a better understanding of the mechanisms involved in transduction, transmission, and perception under normal and pathophysiological conditions. An important step towards this goal is understanding the information provided by and the inherent limitations of the currently available measuring techniques. This article focuses on the sensory testing of the oesophagus, and methods and concepts used to assess the relation between gastric volumes or tone and upper GI symptoms. It also summarizes the contributions of these techniques towards identifying the components responsible for the generation of upper GI symptoms.

Optimized and combinedT1 andB1 mapping technique for fast and accurateT1 quantification in contrast-enhanced abdominal MRI

Fast T(1) mapping techniques are a valuable means of quantitatively assessing the distribution and dynamics of intravenously or orally applied paramagnetic contrast agents (CAs) by noninvasive imaging. In this study a fast T(1) mapping technique based on the variable flip angle (VFA) approach was optimized for accurate T(1) quantification in abdominal contrast-enhanced (CE) MRI. Optimization methods were developed to maximize the signal-to-noise ratio (SNR) and ensure effective RF and gradient spoiling, as well as a steady state, for a defined T(1) range of 100-800 ms and a limited acquisition time. We corrected B(1) field inhomogeneities by performing an additional measurement using an optimized fast B(1) mapping technique. High-precision in vitro and abdominal in vivo T(1) maps were successfully generated at a voxel size of 2.8 x 2.8 x 15 mm(3) and a temporal resolution of 2.3 s per T(1) map on 1.5T and 3T MRI systems. The application of the proposed fast T(1) mapping technique in abdominal CE-MRI enables noninvasive quantification of abdominal tissue perfusion and vascular permeability, and offers the possibility of quantitatively assessing dilution, distribution, and mixing processes of labeled solutions or drugs in the gastrointestinal tract.

The effect of macronutrients on gastric volume responses and gastric emptying in humans: A magnetic resonance imaging study

The effects of macronutrients on gastric volume changes, emptying, and gastrointestinal symptoms are incompletely understood. Three liquid meals of 500 ml (fat emulsion, 375 kcal; protein solution, 375 kcal; glucose solution, 400 kcal) were infused into the stomach of 12 healthy volunteers on three occasions. Studies were performed in seated body position using an open-configuration magnetic resonance imaging (MRI) system. MRI imaging sequences, assessing stomach and meal volumes, were performed prior to and at times t = 0, 3, 6, 9, 12, 15, 25, 35, 45, 60, 75, and 90 min after meal administration. Areas under the curve for the early emptying phase (0-15 and 0-45 min) were calculated, and characteristics of the volume curves were analyzed by a gastric emptying model. Gastrointestinal symptoms were assessed by a self-report scale. Initial (t = 0 min) and early postprandial gastric volumes were highest for glucose because of lower initial emptying. However, in the early emptying phase the characteristics of the volume curves for stomach and meal were uniform for all macronutrients. Perceptions of fullness and satiety were linearly associated with postprandial gastric volumes, but not with macronutrient composition. Isovolumic macronutrient meals modulate gastric volume response by initial meal emptying patterns. Macronutrient specific accommodation responses, as shown in barostat studies, are not reflected as gastric volume responses under noninvasive conditions.