Development of a new method for small bowel transit study

Quantitative Analysis of Small Intestinal Motility in 3D Cine-MRI Using Centerline-Aware Motion Estimation

BACKGROUND

Currently available tools for noninvasive motility quantification of the small intestine are limited to dynamic 2D MRI scans, which are limited in their ability to differentiate between types of intestinal motility.

PURPOSE

To develop a method for quantification and characterization of small intestinal motility in 3D, capable of differentiating motile, non-motile and peristaltic motion patterns.

STUDY TYPE

Prospective.

SUBJECTS

Fourteen healthy volunteers (127 small intestinal segments) and 10 patients with Crohn's disease (87 small intestinal segments).

FIELD STRENGTH/SEQUENCE

3.0 T, 3D balanced fast field echo sequence, 1 volume per second.

ASSESSMENT

Using deformable image registration between subsequent volumes, the local velocity within the intestinal lumen was quantified. Average velocity and average absolute velocity along intestinal segments were used with linear classifiers to differentiate motile from non-motile intestines, as well as erratic motility from peristalsis. The mean absolute velocity of small intestinal content was compared between healthy volunteers and Crohn's disease patients, and the discriminative power of the proposed motility metrics for detecting motility and peristalsis was determined. The consensus of two observers was used as referenced standard.

STATISTICAL TESTS

Student's t-test to assess differences between groups; area under the receiver operating characteristic curve (AUC) to assess discriminative ability. P < 0.001 was considered significant.

RESULTS

A significant difference in the absolute velocity of intestinal content between Crohn's patients and healthy volunteers was observed (median [IQR] 1.06 [0.61, 1.56] mm/s vs. 1.84 [1.37, 2.43] mm/s), which was consistent with manual reference annotations of motile activity. The proposed method had a strong discriminative performance for detecting non-motile intestines (AUC 0.97) and discernible peristalsis (AUC 0.81).

DATA CONCLUSION

Analysis of 3D cine-MRI using centerline-aware motion estimation has the potential to allow noninvasive characterization of small intestinal motility and peristaltic motion in 3D.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Microbial communities in a dynamic in vitro model for the human ileum resemble the human ileal microbiota

The important role for the human small intestinal microbiota in health and disease has been widely acknowledged. However, the difficulties encountered in accessing the small intestine in a non-invasive way in healthy subjects have limited the possibilities to study its microbiota. In this study, a dynamic in vitro model that simulates the human ileum was developed, including its microbiota. Ileostomy effluent and fecal inocula were employed to cultivate microbial communities within the in vitro model. Microbial stability was repetitively achieved after 10 days of model operation with bacterial concentrations reaching on average 107 to 108 16S rRNA copy numbers/ml. High diversities similar to those observed in in vivo ileum samples were achieved at steady state using both fecal and ileostomy effluent inocula. Functional stability based on Short Chain Fatty Acid concentrations was reached after 10 days of operation using fecal inocula, but was not reached with ileostomy effluent as inoculum. Principal Components and cluster analysis of the phylogenetic profiles revealed that in vitro samples at steady state clustered closest to two samples obtained from the terminal ileum of healthy individuals, independent of the inoculum used, demonstrating that the in vitro microbiota at steady state resembles that of the human ileum.

Variation in small bowel transit time on capsule endoscopy

Background

Small bowel motility remains inadequately understood because of the complex and various functions as well as its anatomical position. The aimed of the study was to investigate the small bowel transit time (SBTT) of capsule endoscopy (CE) and to analyze the clinical factors affecting SBTT.

Methods

SBTT was analyzed in patients who underwent small bowel CE. Factors contributing to SBTT and CE retention were investigated.

Results

Among 397 patients enrolled in this study, 336 (84.6%) completed CE. The mean SBTT (± standard deviation) was 282.1±132.2 min. According to the univariate and multivariate analyses, aging and small bowel stenosis extended SBTT. In 38 patients who underwent multiple CE studies, considerable variation in SBTT were observed [mean of standard deviations (SDs) =97.97 min, SD of the SDs =81.99 min]. CE retention was observed in 61 patients (13.3%), and it was statistically associated to small bowel lesion.

Conclusions

Aging and small bowel stenosis were associated with longer SBTT. Furthermore, SBTT analyzed by CE should be interpreted carefully considering the intra-individual differences in SBTT.

Akkermansia muciniphila in the Human Gastrointestinal Tract: When, Where, and How?

Akkermansia muciniphila is a mucin-degrading bacterium of the phylum Verrucomicrobia. Its abundance in the human intestinal tract is inversely correlated to several disease states. A. muciniphila resides in the mucus layer of the large intestine, where it is involved in maintaining intestinal integrity. We explore the presence of Akkermansia-like spp. based on its 16S rRNA sequence and metagenomic signatures in the human body so as to understand its colonization pattern in time and space. A. muciniphila signatures were detected in colonic samples as early as a few weeks after birth and likely could be maintained throughout life. The sites where Akkermansia-like sequences (including Verrucomicrobia phylum and/or Akkermansia spp. sequences found in the literature) were detected apart from the colon included human milk, the oral cavity, the pancreas, the biliary system, the small intestine, and the appendix. The function of Akkermansia-like spp. in these sites may differ from that in the mucosal layer of the colon. A. muciniphila present in the appendix or in human milk could play a role in the re-colonization of the colon or breast-fed infants, respectively. In conclusion, even though A. muciniphila is most abundantly present in the colon, the presence of Akkermansia-like spp. along the digestive tract indicates that this bacterium might have more functions than those currently known.

Video Capsule Endoscopy: A Tool for the Assessment of Small Bowel Transit Time

Purpose

Video capsule endoscopy (VCE) is a procedure that uses a wireless camera to take pictures of the gastrointestinal (GI) tract. A wireless motility capsule (WMC) of a similar size has been developed, which measures pH, pressure, and temperature and can be used to assess regional and total GI transit times. VCE could also potentially be used as a tool for measuring small bowel transit time (SBTT).

Methods

This study was designed to obtain SBTT from VCE and compare it with historical data generated by WMC. Gastric transit time (GTT) was also measured. Patients were included if the indication for VCE was either iron deficiency anemia (IDA) or overt obscure GI bleed (OOGIB), and they did not have any known motility disorder. Results from VCE were also compared in diabetic vs. non-diabetic patients.

Results

There were a total of 147 VCE studies performed, including 42 for OOGIB and 105 for IDA. Median GTT and SBTT were 0.3 and 3.6 h, respectively. The overall median GTT and SBTT were 0.3 and 3.6 h, respectively, in the IDA group compared with 0.3 and 3.4 h in the OOGIB group. When compared with WMC, the GTT and SBTT were significantly faster in both groups (GTT: 3.6 h and SBTT: 4.6 h). The median GTT and SBTT were not significantly different in diabetics vs. non-diabetics [GTT: 17.5 vs. 18.0 min (P = 0.86) and SBTT: 3.9 h (237 min) vs. 3.8 h (230 min), respectively (P = 0.90)].

Conclusion

SBTT as measured using VCE is not significantly different in OOGIB compared with IDA. Both GTT and SBTT are significantly faster as assessed by VCE, which is initiated in the fasting state, compared with WMC measurement, which is initiated after a standard meal. In summary, VCE could potentially be used for measuring SBTT in the fasting state.

Fusion of gamma scintigraphic and magnetic resonance images improves the anatomical delineation of radiotracer for the assessment of gastrointestinal transit

OBJECTIVES

This paper describes the use of gamma scintigraphic and magnetic resonance (MR) fusion images for improving the anatomical delineation of orally administered radiotracers used in gastrointestinal (GI) transit investigations.

METHODS

Ten healthy volunteers ingested enteric-coated gelatin capsules containing 4.4 ± 1.1 MBq SmCl3-labelled resin. Four external body markers containing Sm and Gd-DTPA were placed on the left and right lower costal margins and iliac crests of each volunteer. Anterior and posterior planar images were acquired hourly for 9 h, followed by a final single photon emission computed tomography (SPECT) image and subsequent T1-weighted images using a 1.5 T MR system. Coronal scintigraphic images were fused with MR images and assessed for diagnostic information.

RESULTS

The fused images revealed a combination of the tissue and organ anatomy with an overlay of the distribution of the tracer. Compared with conventional scintigraphic imaging alone, SPECT-MR fused images improved the localization of spatial and temporal movements of the radiotracer throughout the GI tract.

CONCLUSION

Fusion of SPECT and MR images in conjunction with sequential scintigraphic images improved the assessment of segmental GI transit. These have the potential to provide more accurate diagnostic results and are visually powerful images that would have more widespread acceptance by nonspecialists.

Impaired gastric emptying and small bowel transit in children with mitochondrial disorders

OBJECTIVES

The primary aim of our study was to evaluate gastric emptying (GE) and intestinal transit time (ITT) in children with mitochondrial disorders (MD), and secondarily to evaluate the effect of prokinetics in those with prolonged GE.

METHODS

We enrolled subjects 3 to 18 years with MD and having any of the following gastrointestinal (GI) symptoms: abdominal pain, vomiting, constipation, diarrhea, or gastroesophageal reflux. Abdominal pain was scored by visual analog pain scale (1-10). Age-appropriate diet was labeled with radioactive technetium-99 sulfur colloid and its movement tracked along the GI tract. Delayed GE based on our institutional standards was defined as half emptying time >90 minutes for a solid and >60 minutes for a semisolid meal. Prolonged ITT was defined as >4 hours for the tracer to pass from mouth to cecum. A prokinetic was instituted to those with delayed GE, and the study was repeated if possible in 4 to 8 weeks.

RESULTS

Of the 26 subjects, 18 (69%) had delayed GE (median GE 99 minutes) and 12 (46%) had prolonged ITT. The study was repeated in 9 subjects after administering a prokinetic for >1 month. GE normalized in only 3 subjects (median GE on treatment 128 minutes). Mean abdominal pain score, which was 4.8 (max 10) in the 9 subjects, did not improve (5.6 after prokinetic therapy).

CONCLUSIONS

A high prevalence of delayed GE and prolonged ITT was seen in children with MD having GI symptoms, and these abnormalities were poorly responsive to prokinetic therapy.

Small intestinal motility

PURPOSE OF REVIEW

To review recently published studies presenting novel and relevant information on small intestinal motility.

RECENT FINDINGS

The reviewed studies covered a variety of topics with several themes emerging. Our understanding of the influence of systemic disorders, intestinal and extraintestinal infections and enteric bacteria on digestive motor function continues to involve. Elegant and important new studies have been published that better define the physiology of intestinal gas handling along with the genesis of symptoms commonly attributed to excessive intestinal gas. While interest in small intestinal bacterial overgrowth in irritable bowel syndrome continues, the utility and specificity of lactulose hydrogen breath testing is yet again questioned and further data are needed before the practice of routinely prescribing antibiotics to patients with irritable bowel syndrome can be endorsed.

SUMMARY

Small intestinal motility remains an understudied area. Recent publications provide additional new information related to physiology and pathophysiology of small bowel motility. These findings should be of interest to clinician and investigator alike.

Microbial communities in the human small intestine: coupling diversity to metagenomics

The gastrointestinal tract is the main site where the conversion and absorption of food components takes place. The host-derived physiological processes and the residing microorganisms, especially in the small intestine, contribute to this nutrient supply. To circumvent sampling problems of the small intestine, several model systems have been developed to study microbial diversity and functionality in the small intestine. In addition, metagenomics offers novel possibilities to gain insight into the genetic potential and functional properties of these microbial communities. Here, an overview is presented of the most recent insights into the diversity and functionality of the microorganisms in the human gastrointestinal tract, with a focus on the small intestine.

The inulin hydrogen breath test accurately reflects orocaecal transit time

BACKGROUND

The lactose[(13)C]ureide breath test ((13)C-LUBT) has been validated and established as a reliable, non-invasive test for the assessment of orocaecal transit time (OCTT). More recently, small studies have demonstrated that inulin could be an alternative substrate for H(2)-based breath testing of the small bowel transit (H(2)-INBT). We compared the performance of the H(2)-INBT with the (13)C-LUBT in an appropriate number of participants, determined by sample-size calculation.

DESIGN

Twenty-nine people underwent a combined (13)C-LUBT/H(2)-INBT. Five Hundred mg of lactoseureide was ingested on the day before the test to induce an adequate enzyme activity in colonic bacteria. For the test, they received 500 mg of lactose[(13)C]ureide and 5 g inulin, dissolved in 400 mL of a standard enteral liquid nutrition orally. Breath samples were collected every 30 min for 8 h and analysed for H(2)[ p.p.m.] and (13)CO(2)-enrichment [delta-(13)C]. For the (13)C-LUBT, the OCTT was defined as the interval with an increase of delta > 2.5SD above the running average of all previous points. The latter was defined as a rise of > 10ppm above baseline regarding the H(2)-INBT.

RESULTS

Breath tests produced evaluable data in 27/29 patients [93%]. Median OCTTs were 315 min (range 210-450 min) for the (13)C-LUBT and 300 min (180-420 min) for the H(2)-INBT (P = 0.15). The (13)C-LU-OCTT correlated well with the H(2)-IN-OCTT (r = 0.72). Bland-Altman blot showed that the mean H(2)-IN-OCTTs were approximately 30 min shorter than predicted with the (13)C-LUBT.

CONCLUSIONS

Inulin is a reliable and inexpensive substrate for a hydrogen-based assessment of the OCTT. In contrast to the (13)C-LUBT, the H(2)-INBT does not require patients to refrain from physical activity and may additionally increase its acceptance for clinical purposes.