Sonographic assessment of splanchnic arteries and the bowel wall

The diagnostic value of Doppler Resistive Index in the differential diagnosis of focal liver lesions

Aim

To investigate the diagnostic value of resistance index (RI) in differentiating focal liver lesions.

Patients and methods

In this retrospective study, a total of 576 patients with histologically confirmed focal liver lesions were included. Each patient underwent B-mode ultrasound examination and color Doppler ultrasound examination. The RI values of different focal liver lesions were recorded and compared.

Results

The mean RI value of benign lesions was significantly lower than that of malignant lesions (0.54 ± 0.10 vs. 0.71 ± 0.12) (p <0.05). In malignant lesions, the RI value of intrahepatic cholangiocarcinoma was significantly lower than that of hepatocellular carcinoma lesions. Furthermore, in hepatocellular carcinoma lesions, the RI of large lesions (group 4: >10 cm) was significantly lower than that of small lesions (group 1: ≤2 cm, group 2: 2-5 cm) (p <0.05). Taken RI of 0.615 as a cutoff value to differentiate malignant and benign lesions, the sensitivity, specificity, positive predictive value and negative predictive value were 82.80%, 81.00%, 81.34% and 82.48%, respectively.

Conclusion

Color Doppler ultrasound examination is a valuable imaging method in detecting blood flow signal within liver lesions. The RI parameter should be helpful in differentiating malignant and benign liver tumors.

Ultrasound evaluation of bowel vasculopathy in systemic sclerosis

BACKGROUND

Gastrointestinal (GI) manifestations are frequent in systemic sclerosis (SSc) with an impact on quality of life and morbidity. Bowel vasculopathy is a key pathogenetic factor responsible for GI involvement.

OBJECTIVES

To compare abdominal ultrasound (US) and Color Doppler Ultrasonography (CDU) features of splanchnic vessels of SSc patients with healthy controls.

METHODS

The charts of SSc patients who underwent an abdominal US and CDU study were retrospectively analyzed. For Superior Mesenteric Artery (SMA) and Inferior Mesenteric Artery (IMA) caliber, Peak Systolic Velocity (PSV), Reverse Velocity (RV), End-Diastolic Velocity (EDV), Mean Velocity (mV), Blood-flow, Resistive Index (RI) and Pulsatility Index (PI) were recorded.

RESULTS

28 SSc patients and 28 controls were enrolled. In SSc, caliber of SMA was significantly smaller than in controls (5.75 ± 0.62 mm vs. 6.45 ± 0.60 mm, p < 0.0001 - p adj =0.0002). The flow study of SMA and IMA showed a significant reduction of RV (SMA: 7.25 ± 6.37 cm/s vs. 18.52 ± 6.16 cm/s, p < 0.0001 - p adj <0.0001; IMA: 2.69 ± 6.10 cm/s vs. 17.06 ± 5.75 cm/s, p < 0.0001 - p adj <0.0001) and PI (SMA: 3.33 ± 0.75 vs. 4.53 ± 1.03, p < 0.0001 - p adj =0.0002; IMA: 3.54 ± 0.95 vs. 6.08 ± 1.53, p < 0.0001 - p adj <0.0001) in SSc patients than controls.

CONCLUSION

involvement of splanchnic vessels in SSc may be non-invasively investigated with abdominal US and CDU. Morphological and functional changes of Doppler parameters observed in SMA and IMA clearly demonstrate that these vessels are affected by SSc vasculopathy.

The Use of Transabdominal Ultrasound in Inflammatory Bowel Disease

Transabdominal ultrasound (TAUS) is useful in all aspects of lesion screening, monitoring activity, or treating/diagnosing any related complications of inflammatory bowel disease. Its ability to screen or diagnose complications is almost the same as that of other methods, such as CT or MRI. Moreover, its noninvasiveness makes it a first-line examination method. A TAUS image depicting ulcerative colitis will show large intestinal wall thickening that is continuous from the rectum, which is mainly due to mucosal layer thickening, while for Crohn’s disease, a TAUS image is characterized by a diversity in the areas affected, distribution, and layer structure. Indicators of activity monitoring include wall thickness, wall structure, and vascular tests that use Doppler ultrasound or contrast agents. While all of these have been reported to be useful, at this time, no single parameter has been established as superior to others; therefore, a comprehensive evaluation of these parameters is justified. In addition, evaluating the elasticity of lesions using elastography is particularly useful for distinguishing between fibrous and inflammatory stenoses. However, the lack of objectivity is the biggest drawback of using ultrasound. Standardizing and popularizing the ultrasound process will be necessary, including scanning methods, equipment settings, and image analysis.

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.

Ultrasound imaging for assessing functions of the GI tract

OBJECTIVE

In the following review we outline how ultrasound can be used to measure physiological processes in the gastrointestinal tract.

APPROACH

We have investigated the potential of ultrasound in assessing gastrointestinal physiology including original research regarding both basic methodology and clinical applications.

MAIN RESULTS

Our main findings show the use of ultrasound to study esophageal motility, measure volume and contractility of the stomach, assess motility, wall thickness, and perfusion of the small bowel, and evaluate wall vascularization and diameters of the large bowel.

SIGNIFICANCE

Ultrasound is a widely accessible technology that can be used for both scientific and clinical purposes. Being radiation-free and user friendly, the examination can be frequently repeated enabling longitudinal studies. Furthermore, it does not influence normal GI physiology, thus being useful to estimate motility and subtle changes in physiology. Accordingly, ultrasound scanning and physiological measurements may make a big difference for the scientist and the doctor; and for the patients who receive an efficient work-up.

Gastrointestinal Ultrasound (GIUS) in Intestinal Emergencies - An EFSUMB Position Paper

An interdisciplinary group of European experts summarizes the value of gastrointestinal ultrasound (GIUS) in the management of three time-critical causes of acute abdomen: bowel obstruction, gastrointestinal perforation and acute ischemic bowel disease. Based on an extensive literature review, statements for a targeted diagnostic strategy in these intestinal emergencies are presented. GIUS is best established in case of small bowel obstruction. Metanalyses and prospective studies showed a sensitivity and specificity comparable to that of computed tomography (CT) and superior to plain X-ray. GIUS may save time and radiation exposure and has the advantage of displaying bowel function directly. Gastrointestinal perforation is more challenging for less experienced investigators. Although GIUS in experienced hands has a relatively high sensitivity to establish a correct diagnosis, CT is the most sensitive method in this situation. The spectrum of intestinal ischemia ranges from self-limited ischemic colitis to fatal intestinal infarction. In acute arterial mesenteric ischemia, GIUS may provide information, but prompt CT angiography is the gold standard. On the other end of the spectrum, ischemic colitis shows typical ultrasound features that allow correct diagnosis. GIUS here has a diagnostic performance similar to CT and helps to differentiate mild from severe ischemic colitis.

Ultrasound in the evaluation of necrotic bowel in children: A pictorial essay

Necrotic bowel is a serious condition involving death of gastrointestinal tissue. The diagnosis is difficult to make clinically, and plain radiography is often inconclusive. Ultrasonography is an inexpensive, portable and readily available complementary diagnostic tool. In some cases, ultrasonography can detect features of necrotic bowel earlier than plain radiography or when plain radiography is equivocal and does not correlate with the clinical findings. This pictorial essay aims to compare the ultrasonography features of normal bowel and necrotic bowel in children. The role of ultrasonography and the ultrasonographic features of necrotic bowel will be illustrated by discussing some of the causes of necrotic bowel in children. Correlation with plain radiographs and pathological specimens is made. Frequent causes of necrotic bowel in neonates include necrotising enterocolitis, malrotation with small bowel volvulus and incarcerated inguinal hernias. Causes in older children include intussusception, complications of Meckel's diverticulum, post-surgical adhesions, internal hernias and vasculitic abnormalities. Ultrasonography features suggestive of necrotic bowel include persistently dilated loops of aperistaltic bowel, increase or decrease of bowel wall thickness, intramural or portal venous gas, loss of bowel wall perfusion, and free intraperitoneal gas and fluid. The diagnosis of necrotic bowel may be made earlier on ultrasonography than on abdominal radiographs alone. This pictorial essay will familiarise the reader with the role of ultrasonography and the ultrasonographic features of necrotic bowel through a wide range of conditions that may cause necrotic bowel in children. Familiarity with these findings will facilitate timely imaging diagnosis of necrotic bowel before complications develop.

Abdominal ultrasonography with color Doppler analysis in the assessment of ileal Crohn's disease: comparison with magnetic resonance enterography

Background/Aims

Consistently defining disease activity remains a critical challenge in the follow-up of patients with Crohn’s disease (CD). We investigated the potential applicability of abdominal ultrasonography with color Doppler (USCD) analysis for the detection of morphological alterations and inflammatory activity in CD.

Methods

Forty-three patients with CD ileitis/ileocolitis were evaluated using USCD analysis with measurements obtained on the terminal ileum and right colon. Sonographic parameters included wall thickening, stricture, hyperemia, presence of intra-abdominal mass, and fistulas. Patients were evaluated for the clinical activity (Harvey-Bradshaw Index [HBI]), fecal calprotectin (FC) and C-reactive protein (CRP). The USCD performance was assessed using magnetic resonance enterography (MRE) as a criterion standard.

Results

Most measurements obtained with USCD matched the data generated with MRE; however, the agreement improved in clinically active patients where sensitivity, positive predictive value, and accuracy were >80%, considering wall thickening and hyperemia. Complications such as intestinal wall thickening, stricture formation, and hyperemia, were detected in the USCD analysis with moderate agreement with MRE. The best agreement with the USCD analysis was obtained in regard to FC, where the sensitivity, positive predictive value, and accuracy were >70%. The overall performance of USCD was superior to that of HBI, FC and CRP levels, particularly when considering thickening, stricture, and hyperemia parameters.

Conclusions

USCD represents a practical noninvasive and low-cost tool for evaluating patients with ileal or ileocolonic disease, particularly in clinically active CD. Therefore, USCD might become a useful asset in the follow-up of patients with CD.

Duplex ultrasound in the early diagnosis of acute mesenteric ischemia: a longitudinal cohort multicentric study

OBJECTIVE

Acute mesenteric ischemia (AMI) is a life-threatening condition requiring time-dependent treatment; thus, early recognition may improve outcomes. We hypothesized that clinician-performed mesenteric vessels duplex ultrasound (DUS) could facilitate early identification of patients with AMI in high-risk patients presenting with abdominal pain.

METHODS

This was a single-operator, observational, prospective cohort study. Patients aged at least 65 presenting to Emergency Departments with acute abdominal pain and no clear diagnosis after an initial work-up were enrolled. All patients underwent multidetector computed tomography and these findings provided the reference standard in this study. DUS of the celiac artery and superior mesenteric artery (SMA) were obtained to measure the peak systolic velocity (PSV) and were performed within 24 h of admission. PSVs outside the normal range were considered to indicate AMI.

RESULTS

Of 49 patients identified, 47 were consented to enrollment and diagnostic images were obtained in 45 (96%). Fifteen patients (33%) had AMI (six occlusive, nine nonocclusive disease). Among these, 12 (80%) had abnormal DUS velocities. SMA PSV showed a sensitivity of 78.57% [95% confidence interval (CI): 49.2-95.34], a specificity of 64.52% (95% CI: 45.37-80.77), a positive predictive value of 50% (95% CI: 28.22-71.78), and a negative predictive value of 86.96% (95% CI: 66.41-97.22) for AMI. DUS had a sensitivity of 100%, a specificity of 64%, and a negative predictive value of 100% for occlusive AMI. Assessment of celiac artery PSV did not improve diagnostic performance.

CONCLUSION

In this single-operator pilot study, mesenteric vessel DUS was performed successfully in the Emergency Department, with a high proportion of diagnostic images obtained. A normal SMA PSV was associated with a low risk of occlusive AMI.

How to perform gastrointestinal ultrasound: Anatomy and normal findings

Gastrointestinal ultrasound is a practical, safe, cheap and reproducible diagnostic tool in inflammatory bowel disease gaining global prominence amongst clinicians. Understanding the embryological processes of the intestinal tract assists in the interpretation of abnormal sonographic findings. In general terms, the examination principally comprises interrogation of the colon, mesentery and small intestine using both low-frequency and high-frequency probes. Interpretation of findings on GIUS includes assessment of bowel wall thickness, symmetry of this thickness, evidence of transmural changes, assessment of vascularity using Doppler imaging and assessment of other specific features including lymph nodes, mesentery and luminal motility. In addition to B-mode imaging, transperineal ultrasonography, elastography and contrast-enhanced ultrasonography are useful adjuncts. This supplement expands upon these features in more depth.

Role of ultrasound in colorectal diseases

Ultrasound is an undervalued non-invasive examination in the diagnosis of colonic diseases. It has been replaced by the considerably more expensive magnetic resonance imaging and computed tomography, despite the fact that, as first examination, it can usefully supplement the diagnostic process. Transabdominal ultrasound can provide quick information about bowel status and help in the choice of adequate further examinations and treatment. Ultrasonography, as a screening imaging modality in asymptomatic patients can identify several colonic diseases such as diverticulosis, inflammatory bowel disease or cancer. In addition, it is widely available, cheap, non-invasive technique without the use of ionizing radiation, therefore it is safe to use in childhood or during pregnancy, and can be repeated at any time. New ultrasound techniques such as elastography, contrast enhanced and Doppler ultrasound, mini-probes rectal and transperineal ultrasonography have broadened the indication. It gives an overview of the methodology of various ultrasound examinations, presents the morphology of normal bowel wall and the typical changes in different colonic diseases. We will pay particular attention to rectal and transperineal ultrasound because of their outstanding significance in the diagnosis of rectal and perineal disorders. This article seeks to overview the diagnostic impact and correct indications of bowel ultrasound.

Impact of Continuous vs Bolus Feeding on Splanchnic Perfusion in Very Low Birth Weight Infants: A Randomized Trial

OBJECTIVE

To detect changes in splanchnic perfusion and oxygenation induced by 2 different feeding regimens in infants with intrauterine growth restriction (IUGR) and those without IUGR.

STUDY DESIGN

This was a randomized trial in 40 very low birth weight infants. When an enteral intake of 100 mL/kg/day was achieved, patients with IUGR and those without IUGR were randomized into 2 groups. Group A (n = 20) received a feed by bolus (in 10 minutes), then, after at least 3 hours, received the same amount of formula by continuous nutrition over 3 hours. Group B (n = 20) received a feed administered continuously over 3 hours, followed by a bolus administration (in 10 minutes) of the same amount of formula after at least 3 hours. On the day of randomization, intestinal and cerebral regional oximetry was measured via near-infrared spectroscopy and Doppler ultrasound (US) of the superior mesenteric artery was performed. Examinations were performed before the feed and at 30 minutes after the feed by bolus and before the feed, at 30 minutes after the start of the feed, and at 30 minutes after the end of the feed for the 3-hour continuous feed.

RESULTS

Superior mesenteric artery Doppler US showed significantly higher perfusion values after the bolus feeds than after the continuous feeds. Near-infrared spectroscopy values remained stable before and after feeds. Infants with IUGR and those without IUGR showed the same perfusion and oxygenation patterns.

CONCLUSION

According to our Doppler US results, bolus feeding is more effective than continuous feeding in increasing splanchnic perfusion.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01341236.

Particularities of Crohn's disease in pediatric patients: current status and perspectives regarding imaging modalities

A consensus on the best imaging modality evaluating inflammatory bowel disease in the pediatric population is lacking and it is often unclear which modality to choose in specific clinical circumstances. Children with inflammatory bowel disease are exposed to ionizing radiation from multiple imaging studies performed at initial diagnosis, throughout treatment and during the follow-up period. This paper discusses the value of different imaging techniques in pediatric patients with inflammatory bowel disease and gives a review of the literature. In addition, particular features of inflammatory bowel disease in children including the predilection of affected segments in the gastrointestinal tract are highlighted. Based on current literature knowledge, we encourage an integrative approach to the interpretation of clinical and imaging data for diagnosis and follow-up in daily clinical settings.

Intestinal ultrasonography in infants with moderate or severe hypoxic-ischemic encephalopathy receiving hypothermia

BACKGROUND

Infants with hypoxic-ischemic encephalopathy (HIE) may develop multiorgan dysfunction, but assessment of intestinal involvement is imprecise and based on nonspecific clinical signs that may occur several days later. Ultrasound imaging has been described as a helpful tool in assessing intestinal involvement in many gastrointestinal disorders.

OBJECTIVE

Describe abdominal ultrasonography findings in infants receiving therapeutic hypothermia and investigate its association with the severity of the hypoxic-ischemic insult and death.

MATERIALS AND METHODS

Studies were performed within the first 36 h of life to assess intestinal appearance (normal bowel, bowel wall echogenicity and thickness, and sloughed mucosa), free fluid, peristalsis and intramural perfusion. These findings were compared between infants with moderate and severe encephalopathy. Ultrasound findings were also categorized in three major groups and compared with markers of severity of the hypoxic-ischemic insult and with mortality.

RESULTS

Nineteen infants with moderate and 9 with severe HIE at admission were studied (17.7 ± 9.5 h of life). Major ultrasonography findings were increased bowel wall echogenicity (78%), free fluid (75%), decreased or absent peristalsis (50%) and sloughing of the intestinal mucosa (21%). Abnormal intestinal findings such as increased bowel wall echogenicity in all quadrants and presence of sloughed mucosa were associated with more severe hypoxic-ischemic insult. All 12 patients with normal bowel appearance or increased bowel wall echogenicity restricted to only one quadrant survived, whereas 7/15 (47%) patients with increased bowel wall echogenicity in all four quadrants died during hospitalization. The presence of sloughed mucosa was associated with increased mortality (P < 0.001).

CONCLUSION

In infants receiving therapeutic hypothermia, a high prevalence of intestinal involvement was noted by using ultrasonographic assessment. An association between intestinal findings and severity of hypoxic-ischemic insult was observed. The presence of sloughed mucosa is a potential ultrasonographic sign of severity.

Increased Hepato-Splanchnic Vasoconstriction in Diabetics during Regular Hemodialysis

Background and Objectives

Ultrafiltration (UF) of excess fluid activates numerous compensatory mechanisms during hemodialysis (HD). The increase of both total peripheral and splanchnic vascular resistance is considered essential in maintaining hemodynamic stability. The aim of this study was to evaluate the extent of UF-induced changes in hepato-splanchnic blood flow and resistance in a group of maintenance HD patients during regular dialysis.

Design, Setting, Participants, & Measurements

Hepato-splanchnic flow resistance index (RI) and hepato-splanchnic perfusion index (QI) were measured in 12 chronic HD patients using a modified, non-invasive Indocyaningreen (ICG) dilution method. During a midweek dialysis session we determined RI, QI, ICG disappearance rate (k_ICG), plasma volume (V_p), hematocrit (Hct), mean arterial blood pressure (MAP) and heart rate (HR) at four times in hourly intervals (t₁ to t₄). Dialysis settings were standardized and all patient studies were done in duplicate.

Results

In the whole study group mean UF volume was 1.86 ± 0.46 L, V_p dropped from 3.65 ± 0.77L at t₁ to 3.40 ± 0.78L at t₄, and all patients remained hemodynamically stable. In all patients RI significantly increased from 12.40 ± 4.21 mmHg∙s∙m²/mL at t₁ to 14.94 ± 6.36 mmHg∙s∙m²/mL at t₄ while QI significantly decreased from 0.61 ± 0.22 at t₁ to 0.52 ± 0.20 L/min/m² at t₄, indicating active vasoconstriction. In diabetic subjects, however, RI was significantly larger than in non-diabetics at all time points. QI was lower in diabetic subjects.

Conclusions

In chronic HD-patients hepato-splanchnic blood flow substantially decreases during moderate UF as a result of an active splanchnic vasoconstriction. Our data indicate that diabetic HD-patients are particularly prone to splanchnic ischemia and might therefore have an increased risk for bacterial translocation, endotoxemia and systemic inflammation.

Ultrasonography in gastroenterology

Ultrasonography (US) is a safe and available real-time, high-resolution imaging method, which during the last decades has been increasingly integrated as a clinical tool in gastroenterology. New US applications have emerged with enforced data software and new technical solutions, including strain evaluation, three-dimensional imaging and use of ultrasound contrast agents. Specific gastroenterologic applications have been developed by combining US with other diagnostic or therapeutic methods, such as endoscopy, manometry, puncture needles, diathermy and stents. US provides detailed structural information about visceral organs without hazard to the patients and can play an important clinical role by reducing the need for invasive procedures. This paper presents different aspects of US in gastroenterology, with a special emphasis on the contribution from Nordic scientists in developing clinical applications.

Ultrasonographic imaging of inflammatory bowel disease in pediatric patients

Inflammatory bowel disease (IBD) is one of the most common chronic gastrointestinal diseases in pediatric patients. Choosing the optimal imaging modality for the assessment of gastrointestinal disease in pediatric patients can be challenging. The invasiveness and patient acceptance, the radiation exposure and the quality performance of the diagnostic test need to be considered. By reviewing the literature regarding imaging in inflammatory bowel disease the value of ultrasound in the clinical management of pediatric patients is highlighted. Transabdominal ultrasound is a useful, noninvasive method for the initial diagnosis of IBD in children; it also provides guidance for therapeutic decisions and helps to characterize and predict the course of the disease in individual patients. Ultrasound techniques including color Doppler imaging and contrast-enhanced ultrasound are promising imaging tools to determine disease activity and complications. Comparative studies between different imaging methods are needed.

Gastrointestinal ultrasonography of normal Standardbred neonates and frequency of asymptomatic intussusceptions

Background

Ultrasonographic appearance of the gastrointestinal (GI) tract of equine neonates has not been completely described.

Objectives

To describe (1) sonographic characteristics of the GI segments in normal nonsedated equine neonates, (2) intra‐ and interobserver variation in wall thickness, and (3) the sonographic appearance of asymptomatic intussusceptions, and (4) to compare age and sonographic findings of foals with and without asymptomatic intussusceptions.

Animals

Eighteen healthy Standardbred foals ≤5 days of age.

Methods

Prospective, cross‐sectional blinded study. Gastrointestinal sonograms were performed stall‐side. Intraobserver variability in wall thickness measurements was determined by calculating the coefficient of variation (CV). The Bland–Altman method was used to assess interobserver bias. Student's t‐test and Fisher's exact test were used to test the association among presence of intussusceptions, age, and selected sonographic findings.

Results

The reference ranges (95% predictive interval) for wall thickness were 1.6–3.6 mm for the stomach, 1.9–3.2 mm for the duodenum, 1.9–3.1 mm for the jejunum, 1.3–2.2 mm for the colon, and 0.8–2.7 mm for the cecum. Intraobserver wall thickness CV ranged from 8 to 21% for the 2 observers for 5 gastrointestinal segments. The interobserver bias for wall thickness measurements was not significant except for the stomach (0.14 mm, P < .05) and duodenum (0.29 mm, P < .05). Diagnostic images of mural blood flow could not be obtained. Asymptomatic intussusceptions were found in 10/18 neonates. Associations between sonographic variables or age and the presence of intussusceptions were not found.

Conclusions and Clinical Importance

Sonographic characteristics of the GI tract of normal Standardbred neonates can be useful in evaluating ill foals. Asymptomatic small intestinal intussusceptions occur in normal Standardbred neonates.

Diagnosis of bowel diseases: The role of imaging and ultrasonography

Examinations with a visualisation of the anatomy and pathology of the gastrointestinal (GI) tract are often necessary for the diagnosis of GI diseases. Traditional radiology played a crucial role for many years. Endoscopy, despite some limitations, remains the main technique in the differential diagnosis and treatment of GI diseases. In the last decades, the introduction of, and advances in, non-invasive cross-sectional imaging modalities, including ultrasound (US), computed tomography (CT), positron-emission tomography (PET), and magnetic resonance imaging, as well as improvements in the resolution of imaging data, the acquisition of 3D images, and the introduction of contrast-enhancement, have modified the approach to the examination of the GI tract. Moreover, additional co-registration techniques, such as PET-CT and PET-MRI, allow multimodal data acquisition with better sensitivity and specificity in the study of tissue pathology. US has had a growing role in the development and application of the techniques for diagnosis and management of GI diseases because it is inexpensive, non-invasive, and more comfortable for the patient, and it has sufficient diagnostic accuracy to provide the clinician with image data of high temporal and spatial resolution. Moreover, Doppler and contrast-enhanced ultrasound (CEUS) add important information about blood flow. This article provides a general review of the current literature regarding imaging modalities used for the evaluation of bowel diseases, highlighting the role of US and recent developments in CEUS.

Crohn's disease activity assessed by Doppler sonography: the role of aortic flow parameters

OBJECTIVES

Intestinal neovascularization and abnormal abdominal arterial flow rates have been reported in Crohn's disease. The aim of this study was to evaluate Doppler sonography as a method for assessing Crohn's disease activity based on changes in splanchnic hemodynamics.

METHODS

Forty-eight patients with Crohn's disease, 22 healthy volunteers and 12 patients with irritable bowel syndrome were evaluated by Doppler ultrasound for flow parameters of the aorta and superior mesenteric artery. This evaluation included the cross-sectional area, maximum flow volume, peak systolic velocity, end diastolic velocity, resistance and the pulsatility index. Disease activity was classified according to the Crohn's disease activity index.

RESULTS

Most measurements in the aorta and superior mesenteric artery were significantly different between Crohn's disease patients and both control groups. Only the aortic maximum flow volume (CC = 0.37, p = 0.009) and aortic peak systolic velocity (CC = 0.30, p = 0.035) showed a significant positive correlation with the Crohn's disease activity index. The determination of cut-off points for the aortic maximum flow volume and peak systolic velocity measurements increased the sensitivity (80 and 75% for flow volume and velocity, respectively), specificity (57 and 75%), accuracy (67 and 75%) and positive (57 and 68%) and negative (80 and 81%) predictive values. These cut-off values permitted the correct classification of most of the patients with Crohn's disease with respect to disease activity. None of the superior mesenteric artery measurements were able to discriminate patients in relation to disease activity.

CONCLUSION

The aortic maximum flow volume and peak systolic velocity levels estimated by Doppler sonography reflected disease activity in Crohn's disease. Doppler sonography of the aorta is therefore a novel noninvasive adjunct method that may be useful in the clinical follow-up of patients with Crohn's disease.

Haemodynamic changes in the superior mesenteric artery induced by acupuncture stimulation on the lower limbs

Acupuncture is commonly performed on acupoints. A comparison of quantitative physiological alterations induced by stimulation on different acupoints has never been performed in the superior mesenteric artery (SMA) in humans. Therefore, we investigated changes in blood flow volume (BFV) in the SMA as an indicator of physiological effects induced by stimulation on 3 points. Thirty healthy participants aged 29 ± 10 years (mean ± SD) were enrolled. All participants underwent stimulations on 3 points located in the lower legs: ST36, LR3, and a non-acupoint. Control pertains to a condition with no-stimulation. Stimulation was performed bilaterally with manual rotation of the needles. BFV was measured by ultrasonography before insertion and 10, 20, 30, and 60 minutes after stimulation. Following acupuncture on ST36, BFV increased significantly 20 and 30 minutes after stimulation, compared to BFV before insertion (P < 0.05). Following stimulation on LR3 and the non-acupoint, no significant differences in BFV could be found. Relative to the no-stimulation group, stimulation on LR3, and the non-acupoint, stimulation on ST36 elicited a significant increase in BFV (P < 0.05). The results suggest that stimulation on the different points causes distinct physiological effects in BFV in the SMA.

Changes of blood flow volume in the superior mesenteric artery and brachial artery with abdominal thermal stimulation

In traditional Chinese medicine, moxibustion is a local thermal therapy that is used for several conditions. Quantifying the effects of moxibustion therapy has been difficult because the treatment temperature depends on the physician's experience, and the temperature distribution in the target area is not uniform. This prospective observational study aims to quantify the effect of local thermal stimulation to the abdomen. We developed a heat transfer control device (HTCD) for local thermal stimulation. Twenty-four healthy subjects were enrolled and they underwent abdominal thermal stimulation to the para-umbilical region with the device for 20 min. Blood flow volume in the superior mesenteric artery (SMA) and brachial artery (BA), the heart rate and the blood pressure were measured at rest, 15 min after starting thermal stimulation and 10, 20, 30 and 40 min after completing thermal stimulation. Blood flow parameters were measured by high-resolution ultrasound. In the SMA, blood flow volume was significantly increased during thermal stimulation (P < .01), as well as at 10 min (P < .01) and 20 min (P < .05) after stimulation. In the BA, blood flow volume decreased at 40 min after stimulation (P < .01). In conclusion we could quantify the effect of local thermal stimulation with an HTCD and high-resolution ultrasound. Thermal stimulation of the para-umbilical region increased blood flow in the SMA 20 min after stimulation in healthy subjects.

Imaging of perfusion using ultrasound

Ultrasound can be used to image perfusion in two ways: the traditional one using Doppler and the more recent using microbubble contrast agents. Doppler is simple to use and inexpensive but is limited to larger vessels with faster flow rates. It cannot interrogate the microvasculature because bulk tissue movement is faster than capillary flow. It has been used for liver and tumour flow. Contrast studies are much richer and can assess both the macro- and microcirculation. One approach analyses the time-intensity curves in a region of interest, e.g. a tumour, myocardium, brain, following bolus i.v. injection. Another approach measures the time taken for the microbubbles to cross a vascular bed of interest. These arrival times can be useful for the liver in both diffuse and focal diseases and for the kidney. Features derived from time-intensity curves following bolus i.v. injections of microbubbles form sensitive early indicators of the vascular response of tumours to antivascular drugs. This approach, known as dynamic contrast-enhanced ultrasound (DCE-US), has been accepted as a valid technique for monitoring tumour response by several authorities.

Color Duplex evaluation of the mesenteric artery()

Ischemic colitis is the most common form of intestinal ischemia. Diagnosis is made at clinical examination and endoscopy and completed by vascular imaging, but color Doppler US may become a first-line imaging technique for the evaluation of the mesenteric circulation.We present the case of an 80-year-old woman hospitalized for recurrent ischemic colitis of the sigmoid. At a previous hospitalization, color Doppler US examination showed medium to severe stenosis at the origin of the inferior mesenteric artery. However, CT angiography was negative and the condition was therefore misdiagnosed. Eight months later the patient was admitted again with abdominal pain and rectal hemorrhage. Rectosigmoidoscopy documented the presence of ischemia of the sigmoid mucosa. Angiography showed the presence of severe stenosis at the origin of the inferior mesenteric artery so revascularization was carried out by percutaneous transluminal angioplasty (PTA) during the same session. Follow-up showed normal patency of the inferior mesenteric artery after revascularization, and subsequent endoscopic evaluation documented gradual colonic mucosal ischemia resolution. Blood flow at the level of the inferior mesenteric artery was assessed using color Doppler US. The presented case confirms that color Doppler US is a valid first-line imaging technique in the assessment of ischemic intestinal lesions. It is reliable in the evaluation of the mesenteric arterial circulation, and it also allows assessment of blood flow alterations caused by stenosis and identification of localized hemodynamic stenosis which may be missed at CT-angiography or MR-angiography. Arteriography remains the examination of choice in case of discrepancy between first-and second-line imaging techniques and in all cases which offer the possibility of endovascular revascularization.

Diagnostic value and clinical utility of contrast enhanced ultrasound in intestinal diseases

Contrast enhanced ultrasound (CEUS) has recently gained increasing attention as it clearly improves the visualisation of perfusion in various tissues. The development of second generation contrast enhancing agents used in low-mechanical-index harmonic ultrasound has enabled real-time assessment of the microvascular circulation and quantification of bowel wall vascularity. For this review Medline was searched for clinical studies using CEUS to investigate the gastrointestinal tract. Many studies demonstrate that acute or chronic inflammation of the intestinal wall is accompanied by increased perfusion of the mesentery, which can be displayed semi-quantitatively using contrast enhanced ultrasound analyzing time intensity curves. In contrast, ischemia is characterized by hypoperfusion of the mesenteric arteries and the bowel wall. The most promising sonographic approach in assessing splanchnic arteries and the bowel wall is combining the analysis of superior and inferior mesenteric inflow by pulsed Doppler scanning (systolic and diastolic velocities, resistance index) with the end-organ vascularity by CEUS. CEUS at a preliminary stage has been described as clinically important in a variety of gastrointestinal disorders, particularly in patients with Crohn's disease. CEUS facilitates the detection of disease extent and activity, and its luminal and extraluminal complications.

Splanchnic arterial blood flow is significantly influenced by breathing-assessment by duplex-Doppler ultrasound

Duplex ultrasound is established for the assessment of mesenteric ischemia but potential influences of breathing on mesenteric arterial blood velocity have not been investigated so far. In 100 patients without abdominal diseases (39 men; age 59.4 ± 18.0 years), peak systolic (PSV), end diastolic velocity (EDV) and resistance index (RI) were assessed in the celiac trunk (CT) and the superior mesenteric artery (SMA) by Doppler ultrasound during expiration and deep inspiration. Expiratory PSVs in the CT and the SMA (153.4 ± 42.5 and 145.3 ± 39.5 cm/s) were significantly higher than inspiratory velocities (135.4 ± 36.8 and 131.9 ± 42.2 cm/s, p < 0.0001 and p = 0.0002), with expiratory PSVs exceeding inspiratory PSVs in more than 75% of patients. The mean percentage of PSV-variation was 21.5% ± 15.3% and 24.6% ± 19.1%, respectively. The study demonstrates that breathing may exert considerable periodic effects on splanchnic arterial hemodynamics. We, therefore, recommend that to prevent an underestimation of arterial stenosis, mesenteric Doppler ultrasound should be performed during expiration.

Chronic atherosclerotic mesenteric ischemia (CMI)

Chronic mesenteric ischemia (CMI) is most likely caused by atherosclerosis and less frequently by external compression and vasculitis. Symptomatic CMI is an uncommon, potentially under-diagnosed condition caused by fixed stenoses or occlusion of, in most conditions, at least two visceral arteries. If only one of the three major bowel-providing arteries — the celiac trunk, and the superior and inferior mesenteric arteries — is affected, the patient is usually asymptomatic due to a tight collateral network. The only exception is the celiac artery compression syndrome which represents primarily a compression syndrome of celiac plexus nerves by the arcuate ligament in conjunction with a compression of the celiac trunk. CMI of atherosclerotic origin is associated with a high morbidity and mortality. During the last decade, endovascular revascularization has replaced surgical revascularization as the therapy of choice in most centers. This article reviews the most relevant clinical aspects of the disease and the current practice of diagnosis and treatment of CMI.

Diagnosis and treatment of acute mesenteric artery ischemia: an analysis of 26 cases

AIM: To evaluate the diagnosis and treatment of acute mesenteric artery ischemia.

METHODS: A total of 26 patients with acute mesenteric artery ischemia were included in the study. The clinical features, diagnosis, treatment and prognosis of these patients were retrospectively analyzed.

RESULTS: Definite diagnosis was preoperatively established in 11 patients, of which 6 were diagnosed by color Doppler ultrasonography, 9 by spiral CT, and 6 by digital subtraction angiography (DSA). The remaining 15 patients with bloody ascites were diagnosed by exploratory laparotomy. Of all patients, 4 received systemic anticoagulation, 5 were subjected to Fogarty balloon catheterization for thrombus removal and completely recovered, 8 underwent partial small bowel resection, 7 underwent subtotal small bowel and right-sided colon resection, and 2 underwent second-look operation. Six patients died in six months after operation.

CONCLUSION: Ultrasound is considered as a first-line diagnostic technique for acute mesenteric artery ischemia. Exploratory laparotomy should be performed in patients with bloody ascites. Early diagnosis and treatment are key to decreasing the mortality and morbidity of acute mesenteric artery ischemia.

Contrast-enhanced sonography in the diagnosis of acute mesenteric ischemia: case report

Acute mesenteric ischemia is a serious condition associated with high mortality. Multislice CT and magnetic resonance angiography have proved accurate in diagnosing this pathology, which requires a prompt diagnosis to start appropriate therapy. We report the case of an 87-year-old woman with acute mesenteric ischemia, in whom contrast-enhanced sonography visualized the occluded superior mesenteric artery and the infarcted portion of the intestine.

Application of transabdominal ultrasound in the detection of inflammatory bowel disease

As the incidence of inflammatory bowel disease (IBD) increases in recent years, accurate diagnosis of the disease becomes much more important. Moreover, the wide use of new targeted drugs requires precise evaluation of their therapeutic effects. Transabdominal ultrasound, as a newly emerging noninvasive method, plays an important role in diagnosing IBD, evaluating disease activity, and observing therapeutic effects. In this article, we will review the application of transabdominal ultrasound in the detection of IBD.

Investigation of the thermal tissue effects of the argon plasma coagulation modes "pulsed" and "precise" on the porcine esophagus, ex vivo and in vivo

BACKGROUND

Argon plasma coagulation (APC) is a monopolar, noncontact, thermal procedure that is widely used in therapeutic endoscopy. Systematic investigations of the tissue damage ex vivo and in vivo with the new, second-generation APC modes are lacking.

OBJECTIVE

The aim of this study is to compare the tissue effects of the pulsed effect 2 and precise APC modes.

DESIGN AND SETTING

Ex vivo and in vivo animal model.

SUBJECTS

This study involved 3 explanted porcine esophagi and 8 pigs under general anesthesia.

INTERVENTION

APC application on 3 explanted esophagi and during esophagoscopy.

MAIN OUTCOME MEASUREMENTS

The tissue effect was subjected to histological and statistical investigation.

RESULTS

In vivo, a well known type of superficial tissue damage (type A) of the tunica mucosa and a new injury pattern (type B) limited to the tunica muscularis, were found. Ex vivo, only type A injuries were seen. Thermal injury of the tunica muscularis was significantly lower with precise APC compared with pulsed APC in vivo. The pulsed effect 2 shows a positive correlation between the penetration depth and the power (r = 0.38, P < .0002) or application time for the highest power setting used (40 W, r = 0.77, P < .0001). This correlation could not be detected with precise APC because of its very superficial tissue effect.

LIMITATIONS

This was an animal study. The distance of the APC probe to the esophagus may have varied between applications in vivo.

CONCLUSION

Thermal damage by APC of the esophageal tunica muscularis seems to be underestimated ex vivo. The extent of tissue injury was significantly lower with precise APC than with pulsed APC, indicating that precise APC may be suitable for the treatment of particularly thermosensitive, thin-wall anatomy.

Sonographic assessments of gastrointestinal and biliary functions

Ultrasound has been established as a routine work-up imaging method in abdominal diseases. It assesses the morphology of intra-abdominal organs and depicts the normal and pathological anatomy of the gastrointestinal tract as well as of the biliopancreatic system. Ultrasound is the method of choice for visualisation of motion sequences since it is, in contrast to other imaging methods, a real-time method. The non-invasiveness and the repeatability of the method are important advantages when performing investigations of functional processes. Therefore, ultrasound is most suited for functional studies. Up to now, functional ultrasound and its potential have been undervalued. Functional ultrasound provides a widely available method to increase our understanding of functional processes and motility. The authors review the options of functional ultrasound and discuss its practical relevance.

Magnetic resonance imaging of experimental inflammatory bowel disease: quantitative and qualitative analyses with histopathologic correlation in a rat model using the ultrasmall iron oxide SHU 555 C

OBJECTIVES

To quantitatively and qualitatively characterize the MR findings of inflammatory bowel disease in a rat model after i.v. injection of the reticuloendothelial system cell specific ultrasmall iron oxide SHU 555 C.

MATERIALS AND METHODS

Colitis was induced in 15 rats using dinitrobenzene sulfonic acid instillation. Five rats served as controls. T1- and T2-weighted spin-echo- and T2*-weighted gradient-echo-sequences were acquired at 2.4 Tesla before and immediately, 15, 45, 60, and 90 minutes, and 24 hours after i.v.-injection of SHU 555 C (0.1 mmol Fe/kg). MR images were evaluated quantitatively regarding thickness and signal-to-noise ratio (SNR) of the bowel wall and qualitatively regarding overall bowel wall signal intensity and the occurrence of bowel wall ulcerations. MR findings were correlated to histology.

RESULTS

The inflamed bowel wall was significantly thicker than the noninflamed bowel wall and 90 minutes after contrast injection it showed a significant reduction of SNR in T1- (94 +/- 27 vs. 61 +/- 29; P < 0.01), T2- (67 +/- 26 vs. 28 +/- 17; P < 0.05), and T2*- (92 +/- 57 vs. 10 +/- 7; P < 0.05) weighted images as compared with unenhanced images. At 24 hours, the respective SNR values remained significantly reduced. The signal loss was homogeneous in 12 and focal in 3 of the 15 rats with colitis. Nine rats showed colonic wall ulcerations. In all but one animal (missed focal ulceration) MR findings correlated to the histologic findings.

CONCLUSIONS

SHU 555 C leads to a significant signal intensity loss of the inflamed bowel wall in T1-, T2- and T2*-weighted images. SHU 555 C enhanced MRI findings correlate well with histologic findings.

Neonatal colour Doppler ultrasound study: normal values of abdominal blood flow velocities in the neonate during the first month of life

BACKGROUND

Doppler US to measure abdominal blood flow velocities (ABFV) is increasingly used to investigate intestinal haemodynamics in several clinical conditions in neonates. Studies that provide reference values of ABFV during the entire neonatal period are currently lacking.

OBJECTIVE

To make available normal reference values of ABFV and Doppler indices in the coeliac trunk and superior mesenteric artery during the first month of life in term and healthy preterm infants.

MATERIALS AND METHODS

ABFV were obtained with colour Doppler US in 69 neonates (12 term, 57 preterm) divided into four gestational age groups (25-28 weeks, 29-32 weeks, 33-36 weeks, and 37-41 weeks).

RESULTS

ABFV increased with increasing gestational and postnatal age. We also provide normal reference values of ABFV and Doppler indices to compare with measurements of abdominal blood flow changes during the neonatal period for diagnostic, therapeutic and prognostic purposes.

CONCLUSION

These longitudinal reference values provide a useful tool for assessing possible alteration in ABFV secondary to neonatal pathologies.

Single vessel abdominal arterial disease

The long-standing discussion concerning the mere existence of single vessel abdominal artery disease can be closed: chronic gastrointestinal ischaemia (CGI) due to single vessel abdominal artery stenosis exists, can be treated successfully and in a safe manner. The most common causes of single vessel CGI are the coeliac artery compression syndrome (CACS) in younger patients, and atherosclerotic disease in elderly patients. The clinical symptoms of single vessel CGI patients are postprandial and exercise-related pain, weight loss, and an abdominal bruit. The current diagnostic approach in patients suspected of single vessel CGI is gastrointestinal tonometry combined with radiological visualisation of the abdominal arteries to define possible arterial stenosis. Especially in single vessel abdominal artery stenosis, gastrointestinal tonometry plays a pivotal role in establishing the diagnosis CGI. First-choice treatment of single vessel CGI remains surgical revascularisation, especially in CACS. In elderly or selected patients endovascular stent placement therapy is an acceptable option.

Small bowel vascular disorders from arterial etiology and impaired venous drainage

Intestinal ischemia of the small bowel represents an important diagnostic question to answer in an emergency. Although some findings could be appreciated with basic imaging methods, the MDCT as a modern noninvasive imaging method could be effective in evaluating intestinal disease caused by superior mesenteric artery or vein occlusion and making a diagnosis of ischemia from low-flow states. Looking at the features of the parietal layers with knowledge of the pathologic mechanism underlying the changes from the "normality" could be helpful in making a correct, prompt, and effective diagnosis of intestinal ischemia or disease from impaired venous drainage.

Imaging in intestinal ischemic disorders

Intestinal ischemia and infarction are a heterogeneous group of diseases that have as their unifying theme hypoxia of the small bowel or colon. The incidence of bowel ischemia and infarction is on the rise for several reasons: the aging of the population, the ability of intensive care units to salvage critically ill patients, and heightened clinical awareness of these disorders. Improvements in diagnostic imaging techniques have greatly contributed to the earlier diagnosis of intestinal ischemia, which can have a positive influence on patient outcomes. In this article, role of radiology in the detection, differential diagnosis, and management of patients who have intestinal ischemia and infarction is discussed.

Recurrent small bowel infarction in a young man: polycythaemia or vasculitis?

A 29-year-old man presented with a 3 day history of right lower quadrant pain, nausea and vomiting. There was tenderness in the right lower quadrant. At surgery the appendix was normal but an infarcted terminal ileum segment was found and resected. Histopathological examination was suggestive of vasculitis. The patient was discharged in good condition and follow-up for the first year was unremarkable. Unfortunately he developed another episode of bowel ischaemia in the second year and underwent resection of a short segment of proximal ileum. An autoimmune profile was negative. However, subsequent blood tests confirmed polycythaemia. Small bowel infarction due to polycythaemia in a young patient is rare and may be difficult to diagnose on clinical grounds.