Assessment Of Small Bowel Motility Research Articles

Assessment of Small Bowel Motility and SMA Blood Flow Studied with Transabdominal Ultrasound.

Purpose Gastrointestinal ultrasound (GIUS) is a noninvasive imaging technique that may be used to study physiological changes in the small bowel. The aim of the study was to investigate the feasibility of measuring blood flow (BF) in the superior mesenteric artery (SMA) and regional motility in the small bowel with GIUS before and after a test meal and to compare ultrasound parameters to demographic factors such as age, sex, height, weight, and smoking habits. Materials and Methods 122 healthy volunteers aged 20 to 80 were examined after an overnight fast. Small bowel motility was registered in the upper left and lower right quadrants (ULQ and LRQ) with TUS and BF in the SMA with pulsed wave Doppler. The first 23 volunteers also received a 300 Kcal test meal and were re-examined 30 min postprandial. Results The feasibility of measuring BF was 97% in fasting patients while motility could be detected in 52% and 62% in the ULQ and LRQ, respectively. Females had a lower resistive index (RI) and a higher mean velocity than males, while the overall BF correlated with height. The RI had a negative correlation with age. Healthy volunteers with motility in the ileum were on average younger than those without motility. After the test meal, motility could be detected in the ULQ and LRQ in 95% and 90%, respectively, and the mean number of contractions in the ULQ increased significantly. As expected, there was a clear increase in all BF-parameters postprandially. Conclusion Regional motility in the small bowel was easier to detect after a test meal. There were some associations between demographic parameters and ultrasound parameters but overall the effects were relatively small.

Assessment of fasted and fed gastrointestinal contraction frequencies in healthy subjects using continuously tagged MRI.

BackgroundContinuously tagged MRI during free breathing can assess bowel motility at frequencies as low as the slow wave, motility pattern range. This study aimed to evaluate noninvasive gastrointestinal‐tagged MRI for small bowel motility assessment and to observe the physiological response to a 300‐kcal meal challenge in healthy, overnight‐fasted volunteers.MethodsAfter overnight fasting, 16 healthy subjects (7 women, mean age 25.5, range 19‐37 years) underwent a free breathing, tagged MRI scan to capture small bowel motility. Each subject underwent a (a) baseline motility scan, (b) food challenge, (c) postchallenge scan, and (d) second postchallenge scan (after 20 minutes). Motility was quantified using a frequency analysis technique for measuring the spectral power of the strain, referred to as motility score. Motility score was assessed in 20 frequency intervals between 1 and 20 contractions per minute (cpm), and the data were analyzed with linear mixed‐effect models.Key ResultThe stimulation protocol demonstrated an immediate, food‐induced, motility response in the low‐frequency range (2‐10 cpm), which is consistent with the stomach and small bowel frequency range (3‐12 cpm).Conclusions and InferencesThis study shows that this MRI tagging technique is able to quantify the fasted‐to‐fed response to a 300‐kcal meal challenge within the specific small bowel motility frequency range in healthy subjects. The food provocation MRI protocol provides a tool to explore the gut's response to a stimulus in specific motility frequency ranges in patients with gastrointestinal dysmotility and functional disorders.

The assessment of small bowel motility with attentive deformable neural network

The small bowel is the longest part of the gastrointestinal tract and quick assessment of its motility using Cine-MRI is conducive to the diagnosis of gastroenteric diseases. Because of the complex shape changes that occur frequently in the small bowel, approaches involving human designed features and simple convolutional neural network (CNN) methods fail to achieve satisfactory performance on massive datasets. To meet the challenge of assessing small bowel motility automatically, we propose the integration of deformable convolutional networks into attentive encoder–decoder. With the help of deformable convolution, a tailored CNN can track small bowel segments in different shapes from each MR image of a Cine-MRI sequence. The proposed attentive encoder–decoder performed significantly better than conventional recurrent neural network (RNN) in the assessment of small bowel motility. Experimental results demonstrate that the proposed method not only automatically assesses small bowel motility correctly, but also outperforms state-of-the-art methods. Furthermore, it provides useful information about the physiology of small bowel motility patterns, which can be used in the diagnosis of gastroenteric diseases.

Dynamic MRI for bowel motility imaging–how fast and how long?

Objective:Dynamic imaging of small intestinal motility is an increasingly common research method to examine bowel physiology in health and disease. However, limited data exist to guide imaging protocols with respect to quantitative analysis. The purpose of this study is to define the required temporal resolution and scan duration in dynamic MRI for small bowel motility assessment.Methods:Six healthy volunteers underwent motility imaging with MR enterography using breath-hold protocol. A coronal two-dimensional balanced fast field echo sequence was used to acquire dynamic data at a high temporal resolution of 10 frames per second (fps). Motility was quantified by generating a registration-derived motility index for local and global regions of bowel. To evaluate temporal resolution and scan duration, the data were undersampled and the scan length was varied to determine the impact on motility index.Results:The mean motility index stabilizes at a temporal resolution of 1 fps (median absolute percentage change 1.4% for global and 1.9% for local regions of interest). The mean motility index appears to stabilize for scan durations of 15 s or more in breath-hold (median absolute % change 2.8% for global and 1.7% for local regions of interest).Conclusion:A temporal resolution of at least 1 fps and a scan duration of at least 15 s is necessary in breath-hold scans for consistent motility observations. The majority of small bowel motility studies to date are in line with these requirements.Advances in knowledge:This study suggests the minimum temporal resolution and scan duration required in breath-hold scans to obtain robust measurements of small bowel motility from MRI.

Su1567 - Assessment of Small Bowel Motility in Patients with Small Bowel Obstruction: A Newly Developed Measurement Technique for Monitoring Small Bowel Motility by Using an Ileus Tube

Su1567 - Assessment of Small Bowel Motility in Patients with Small Bowel Obstruction: A Newly Developed Measurement Technique for Monitoring Small Bowel Motility by Using an Ileus Tube

Small bowel motility assessment based on fully convolutional networks and long short-term memory

Assessment of small bowel’s motility plays an important role in the diagnosis of small bowel disease. Conventional assessment methods rely on hand-designed features or manual guide-line drawing, which results in difficult modeling and high time consumption, thus they are still inefficient and impractical for clinical uses. With the help of deep neural networks, we introduced a semi-automated approach, replacing hand-designed features with automatic feature extraction, and an automated approach, eliminating manual guide-line drawing, to assess small bowel motility by automatically marking cross-sectional diameters on small bowel images, measuring temporal fluctuation of diameter lengths, and evaluating contraction frequency. Experiment results show that proposed methods could estimate small bowel contraction frequency correctly. The difference between predicted diameter lengths and one manually labeled is within reasonable range, and estimated frequency is close to the groundtruth. Therefore, proposed methods can be utilized for diagnosis of small bowel disease, which will assist radiologist in decision-making.

Quantitative assessment of small bowel motility in patients with Crohn's disease using dynamic MRI.

Assessment of motility alterations by functional magnetic resonance imaging (MRI) contributes to improved evaluation of inflammatory bowel disease. The aim of the study was to quantify motility in inflammatory bowel segments and to compare motility alterations with MR-based parameters for activity of inflammation in Crohn's disease (CD). Thirty consecutive patients with CD underwent bowel MRI which included a dynamic sequence for automatic generation of parametric maps facilitating quantification of bowel motility. Mean motility score (MMS) of small bowel segments with signs of inflammation was measured and compared with MMS of the whole gastrointestinal tract (GI tract). MRI-based score of inflammatory activity and lesion length were correlated with the MMS ratio of inflammatory small bowel lesion and whole GI tract. Inflammatory bowel segments showed a mean value of MMSs of 1080, whereas the whole GI tract showed a mean value of MMSs of 2839 (p < 0.0001). Decrease in motility ranged between 20 and 87% in inflammatory bowel segments compared to the MMS of the whole GI tract. The MMS ratio of an inflammatory small bowel segment and whole GI tract showed negative correlation with MR activity score (r = -0.5921, p = 0.0003) and length of the lesion (r = -0.3495, p = 0.0462). Quantitative assessment of motility alterations by means of motility scoring in small bowel segments affected by CD provides additional information on inflammatory activity.

Assessment of Small Bowel Motility in Patients With Chronic Intestinal Pseudo-Obstruction Using Cine-MRI

Chronic intestinal pseudo-obstruction (CIPO) is a rare, serious motility disorder, with life-threatening complications over time. However, lack of an established, non-invasive diagnostic method has caused delays in the diagnosis of this intractable disease. Cine-magnetic resonance imaging (MRI) is an emerging technique, with a potential to evaluate the motility of the entire bowel. We compared small bowel motility in healthy volunteers, patients with irritable bowel syndrome (IBS), and those with CIPO, using cine-MRI, and evaluated the usefulness of cine-MRI as a novel diagnostic method for CIPO. Twelve healthy volunteers, IBS patients, and CIPO patients prospectively underwent cine-MRI at 1.5 T. Luminal diameter, contraction ratio, and contraction cycle were measured and compared between the groups. Cine-MRI provided sufficient dynamic images to assess the motility of the entire small bowel. Luminal diameter (mean±s.d.) in CIPO patients was significantly higher than that in healthy volunteers and IBS patients (43.4±14.1, 11.1±1.5, and 10.9±1.9 mm, respectively), and contraction ratio was significantly lower in CIPO patients than that in healthy volunteers and IBS patients (17.1±11.0%, 73.0±9.3%, and 74.6±9.4%, respectively). No significant differences were observed in the contraction cycle. This study is the first to assess the clinical utility of cine-MRI in CIPO patients. Cine-MRI clearly detected contractility impairments in CIPO patients. Cine-MRI is noninvasive, radiation-free, and can directly evaluate the entire small bowel peristalsis, and can detect the affected loops at a glance; therefore, it might be extremely useful for the diagnosis and follow-up of CIPO patients in clinical practice.

Quantified terminal ileal motility during MR enterography as a potential biomarker of Crohn’s disease activity: a preliminary study

To compare quantified terminal ileal (TI) motility during MR enterography (MRE) with histopathological severity of acute inflammation in Crohn's disease. A total of 28 Crohn's patients underwent MRE and endoscopic TI biopsy. Axial and coronal TrueFISP, HASTE and post-gadolinium VIBE images were supplemented by multiple coronal TrueFISP cine motility sequences through the small bowel volume. TI motility index (MI) was quantified using validated software; an acute inflammation score (eAIS; 0-6) was assigned to the biopsy. Two observers qualitatively scored mural thickness, T2 signal, contrast enhancement and perimural oedema (0-3) to produce an activity score (aMRIs) based on anatomical MRI. The association among the MI, eAIS and aMRIs was tested using Spearman's rank correlation. Wilcoxon rank sum test compared motility in subjects with and without histopathological inflammation. Mean MI and mean eAIS were 0.27 (range 0.06-0.55) and 1.5 (range 0-5), respectively. There was a significant difference in MI between non-inflamed (mean 0.37, range 0.13-0.55) and inflamed (mean 0.19, range 0.06-0.44) TI, P = 0.002, and a significant negative correlation between MI and both eAIS (Rho = -0.52, P = 0.005) and aMRIs (R = -0.7, P < 0.001). Quantified TI motility negatively correlates with histopathological measures of disease activity and existing anatomical MRI activity biomarkers. • Magnetic resonance imaging is increasingly used to assess Crohn's disease. • MRI measurements can provide a quantitative assessment of small bowel motility. • MR enterography can grade Crohn's disease. • Small bowel motility can be used as a marker of inflammatory activity.

Quantitative assessment of small bowel motility by nonrigid registration of dynamic MR images

Evaluation of small bowel motility from two-dimensional dynamic MRI is of increasing interest for the assessment of segmental diseases such as Crohn's disease. We propose to use nonrigid image registration for automated motility analysis. Registration is particularly difficult when localized intensity changes occur (e.g., due to intraluminal flow or through-plane motion). Therefore, displacements were extracted using a joint registration and modeling of intensity changes. Results were analyzed in 10 patients with known or suspected Crohn's disease. Bowel wall displacements were assessed by tracking bowel cross-sectional markers over time. Automated tracking with the proposed technique was in good agreement with manual tracking (similar bias, improved standard deviations). The ability to quantify different grades of bowel motility was investigated by comparing direct motion measures (i.e., changes in bowel cross-sectional diameter or area) and various parametric maps, e.g., based on the Jacobian of the measured displacements with expert grading. Among these measures, the standard deviation over time of the Jacobian was the best at predicting grades from 1 (moving normally) to 4 (not moving at all) in 50 bowel regions with normal and pathologically reduced motility, yielding 93% correct classification with a 1-class tolerance (i.e., same score as the expert ± 1).

Quantitative Assessment of the Small Bowel Motility with Negative Mutual Information in Cine-MRI Sequences

Cine-MRI provides a well tolerated non-invasive method for the quantitative assessment of small bowel motility. The quantitative assessment of the small bowel motility reveals important information for the functional analysis of the small bowel. Traditionally the quantitative assessment is accomplished by detecting the peristaltic frequency of a specific small bowel segment within MRI sequences. Negative mutual information is proposed to assess the small bowel motility. A simulation of the small bowel motility is implemented, which proves that the proposed method can be utilized for the quantitative assessment. Experimental results demonstrate the accuracy of proposed method.

MR imaging of the small bowel in Crohn's disease

MR and CT techniques optimized for small bowel imaging are playing an increasing role in the evaluation of small bowel disorders. Several studies have shown the advantage of these techniques over tradition barium fluoroscopic examinations secondary to improvements in spatial and temporal resolution combined with improved bowel distending agents. The preference of MR vs. CT has been geographical and based on expertise and public policy. With the increasing awareness of radiation exposure, there has been a more global interest in implementing techniques that either reduce or eliminate radiation exposure [Brenner DJ, Hall EJ. Computed tomography—an increasing source of radiation exposure. N Engl J Med 2007;357:2277–84]. This is especially important in patients with chronic diseases such as inflammatory bowel disease who may require multiple studies over a lifetime or in studies that require sequential imaging time points such as in assessment of gastrointestinal motility [Froehlich JM, Patak MA, von Weymarn C, Juli CF, Zollikofer CL, Wentz KU. Small bowel motility assessment with magnetic resonance imaging. J Magn Reson Imaging 2005;21:370–75]. A recent study showed that certain subgroups of patients with Crohn's disease may be exposed to higher doses of radiation; those diagnosed at an early age, those with upper tract inflammation, penetrating disease, requirement of intravenous steroids, infliximab or multiple surgeries [Desmond AN, O’Regan K, Curran C, et al. Crohn's disease: factors associated with exposure to high levels of diagnostic radiation. Gut 2008;57:1524–29]. Therefore it has been suggested that techniques that can reduce or eliminate radiation exposure should be considered for imaging [Brenner DJ, Hall EJ. Computed tomography—an increasing source of radiation exposure. N Engl J Med 2007;357:2277–84]. Owing to the excellent softtissue contrast, direct multiplanar imaging capabilities, new ultrafast breath-holding pulse sequences, lack of ionizing radiation and availability of a variety of oral contrast agents, MR is well suited to play a critical role in the imaging of small bowel disorders. In this article we will review the technical issues related to the performance of MR enterography and enteroclysis and discuss the role and controversies of using MR in the assessment of inflammatory bowel disease.

SLOW‐TRANSIT CONSTIPATION: EVALUATION AND TREATMENT

Slow-transit constipation is characterized by delay in transit of stool through the colon, caused by either myopathy or neuropathy. The severity of constipation is highly variable, but may be severe enough to result in complete cessation of spontaneous bowel motions. Diagnostic tests to assess colonic transit include radiopaque marker or radioisotope studies, and intraluminal tests (colonic and small bowel manometry). Most patients with functional constipation respond to laxatives, but a small proportion are resistant to this treatment. In some patients biofeedback is helpful although the mechanism by which this works is still uncertain. Other patients are resistant to all conservative modes of therapy and require surgical intervention. Extensive clinical and physiological preoperative assessment of patients with slow colonic transit is essential before considering surgery, including an assessment of small bowel motility and identification of coexistent obstructed defecation. The psychological state of the patient should always be taken into account. When surgery is indicated, subtotal colectomy and ileorectal anastomosis is the operation of choice. Segmental colonic resection has been reported in a few patients, but methods of identifying the affected segment need to be developed further. Less invasive and reversible surgical options include laparoscopic ileostomy, antegrade colonic enema and sacral nerve stimulation.

Small bowel motility assessment with magnetic resonance imaging

To assess primarily the feasibility of magnetic resonance imaging (MRI) as a tool to monitor small bowel peristaltic motion and secondarily to validate this technique by demonstrating drug-induced motility changes. After a standardized oral preparation of Ispaghula husk (Metamucil) and meglumine gadoterate (Gd-DOTA; Dotarem), 10 volunteers underwent dynamic MRI using a two-dimensional turbofast field echo (TFE) sequence with a slice repetition time of 500 msec. Intraluminal cross-sectional caliber changes over time were assessed allowing quantification of the peristaltic frequencies and amplitudes of the small gut on various regions of interest. Pharmacologically induced alterations of the peristaltic motion after spasmolytics and gastrokinetic motion enhancers were investigated. Small bowel diameter measurement resulted in a peristalsis of 10.96 (SD = +/-2.51) waves per minute, oscillating regularly with mean amplitudes of 6.65 mm (SD = +/-1.15 mm). Peristaltic frequency in normal individuals is consistent with that observed with other techniques. Intravenous administration of scopolamine butylbromide (= hyoscine butylbromide/Buscopan) resulted in small bowel paralysis within 21.3 seconds (SD = +/-2.8 seconds). Prokinetic effect of intravenous metoclopramide (Paspertin) after Buscopan paralysis was tested in one volunteer, characterized by a slow recovery of peristalsis, which propagated from the proximal to the distal segments and enhanced contraction amplitudes. Dynamic MRI allows observing and quantifying small bowel peristalsis, characterizing motion patterns, and monitoring the effects of interfering factors such as drugs.

PERISTALSIS, SEGMENTATION, AND THE MYENTERIC REFLEX

PERISTALSIS, SEGMENTATION, AND THE MYENTERIC REFLEX