Role of contrast-enhanced ultrasound in evaluation of the bowel

Ultrasound Contrast Agents: Current Role in Adults and Children for Various Indications

Intravenous contrast-enhanced ultrasound (CEUS) is a rapidly evolving imaging technique that uses a microbubble contrast agent to enhance ultrasonographic images by augmenting characterization of blood vessels and organ perfusion. CEUS is considered as a useful problem-solving tool and as an indicated first-line imaging modality in select settings. CEUS technique has an inherent advantage over its predecessor B-mode and Doppler imaging. This article reviews different approved and off-label use of CEUS in the pediatric and adult population and also discusses Food and Drug Administration-approved contrast agents in the United States, their reported side effects, and ongoing efforts in the field.

The Current Role of Imaging in the Diagnosis of Inflammatory Bowel Disease and Detection of Its Complications: A Systematic Review

Inflammatory bowel disease (IBD) encompasses complex gastrointestinal (GI) conditions, primarily Crohn's disease (CD) and ulcerative colitis (UC), requiring precise imaging for effective diagnosis and management of complications. This systematic review aimed to evaluate the current role of imaging modalities in diagnosing IBD and detecting related complications. The review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We performed a literature search using text words and controlled vocabulary applying Boolean operators "AND," "OR," with various combinations on databases such as PubMed, Embase, and Cochrane Library. The search targeted open-access articles involving humans, with full-text available, and published in the English Language from 2005 to 2024. The quality of the included studies was assessed using the Cochrane Risk-of-Bias (RoB) checklist. Our search process identified 127 records from Cochrane (39), Embase (29), and PubMed (59). After removing 98 irrelevant records, 29 underwent further screening. Five were excluded as they involved irrelevant problems or outcomes, leaving us with 24 reports with full text, all of which were accessible. Following the eligibility assessment, two more reports were excluded due to inaccessibility, and 22 studies were included in the final analysis. The risk of bias and methodological quality assessment revealed that out of 22 studies analyzed, five (23%) had a high risk of bias, while 13 (59%) were classified as moderate risk, and four (18%) showed low risk. This distribution highlights a predominance of moderate-risk studies in research on imaging in IBD, emphasizing the need for enhanced study designs in future investigations. Our findings revealed the varying effectiveness of imaging modalities in diagnosing complications of CD and UC. Magnetic resonance enterography (MRE) stands out as the preferred method for CD due to its high sensitivity and noninvasive nature. In contrast, colonoscopy remains the gold standard for UC, providing direct visualization of mucosal lesions. While techniques like ultrasound and capsule endoscopy offer valuable insights, they have limitations that may affect their utility in certain cases.

A Comprehensive and Repeatable Contrast-Enhanced Ultrasound Quantification Approach for Clinical Evaluations of Tumor Blood Flow

OBJECTIVE

The aim of this study is to define a comprehensive and repeatable contrast-enhanced ultrasound (CEUS) imaging protocol and analysis method to quantitatively assess lesional blood flow. Easily repeatable CEUS evaluations are essential for longitudinal treatment monitoring. The quantification method described here aims to provide a structure for future clinical studies.

MATERIALS AND METHODS

This retrospective analysis study included liver CEUS studies in 80 patients, 40 of which contained lesions (primarily hepatocellular carcinoma, n = 28). Each patient was given at least 2 injections of a microbubble contrast agent, and 60-second continuous loops were acquired for each injection to enable evaluation of repeatability. For each bolus injection, 1.2 mL of contrast was delivered, whereas continuous, stationary scanning was performed. Automated respiratory gating and motion compensation algorithms dealt with breathing motion. Similar in size regions of interest were drawn around the lesion and liver parenchyma, and time-intensity curves (TICs) with linearized image data were generated. Four bolus transit parameters, rise time (RT), mean transit time (MTT), peak intensity (PI), and area under the curve (AUC), were extracted either directly from the actual TIC data or from a lognormal distribution curve fitted to the TIC. Interinjection repeatability for each parameter was evaluated with coefficient of variation. A 95% confidence interval was calculated for all fitted lognormal distribution curve coefficient of determination (R2) values, which serves as a data quality metric. One-sample t tests were performed between values obtained from injection pairs and between the fitted lognormal distribution curve and direct extraction from the TIC calculation methods to establish there were no significant differences between injections and measurement precision, respectively.

RESULTS

Average interinjection coefficient of variation with both the fitted curve and direct calculation of RT and MTT was less than 21%, whereas PI and AUC were less than 40% for lesion and parenchyma regions of interest. The 95% confidence interval for the R2 value of all fitted lognormal curves was [0.95, 0.96]. The 1-sample t test for interinjection value difference showed no significant differences, indicating there was no relationship between the order of the repeated bolus injections and the resulting parameters. The 1-sample t test between the values from the fitted lognormal distribution curve and the direct extraction from the TIC calculation found no statistically significant differences (α = 0.05) for all perfusion-related parameters except lesion and parenchyma PI and lesion MTT.

CONCLUSIONS

The scanning protocol and analysis method outlined and validated in this study provide easily repeatable quantitative evaluations of lesional blood flow with bolus transit parameters in CEUS data that were not available before. With vital features such as probe stabilization ideally performed with an articulated arm and an automated respiratory gating algorithm, we were able to achieve interinjection repeatability of blood flow parameters that are comparable or surpass levels currently established for clinical 2D CEUS scans. Similar values and interinjection repeatability were achieved between calculations from a fitted curve or directly from the data. This demonstrated not only the strength of the protocol to generate TICs with minimal noise, but also suggests that curve fitting might be avoided for a more standardized approach. Utilizing the imaging protocol and analysis method defined in this study, we aim for this methodology to potentially assist clinicians to assess true perfusion changes for treatment monitoring with CEUS in longitudinal studies.

Peak enhancement in contrast-enhanced ultrasound for assessing endoscopic disease activity in patients with Crohn's disease: a meta-analysis

BACKGROUND

Contrast-enhanced ultrasound (CEUS) has been proposed as a valuable tool for detecting disease activity in patients with Crohn's disease (CD). However, previous studies have utilized different parameters, leading to variation in clinical assessment of this technique.

PURPOSE

To assess the effectiveness of peak enhancement (PE) in CEUS for evaluating endoscopic disease activity in patients with CD.

MATERIAL AND METHODS

Articles were obtained by searching PubMed, Embase, Web of Science, Wanfang, and CNKI databases. Only studies that investigated the effectiveness of PE in CEUS to discriminate endoscopic disease activity in patients with CD were considered. Pooled sensitivity and specificity were then calculated using a random effects model.

RESULTS

Overall, seven studies were included. The endoscopic disease activity of CD was determined based on the simple endoscopic score for Crohn's disease and Crohn's Disease Endoscopic Index of Severity scores. Pooled results showed that a high PE was associated with increased detection efficacy for endoscopic disease activity in CD. Pooled sensitivity, specificity, and positive and negative likelihood ratios were 0.88 (95% confidence interval [CI] = 0.71-0.96), 0.88 (95% CI = 0.81-0.93), 7.60 (95% CI = 4.61-12.53), and 0.14 (95% CI = 0.05-0.35), respectively. The pooled receiver operating characteristic was 0.90 (95% CI = 0.87-0.92), suggesting a good discriminating efficacy of PE in CEUS for endoscopic disease activity of patients with CD.

CONCLUSIONS

A high PE in CEUS displayed substantial distinguishing accuracy for assessing endoscopic disease activity of patients with CD.

Ultrasound of the bowel with a focus on IBD: the new best practice

Inflammatory Bowel Disease (IBD) is a lifelong chronic disease affecting any part of the gastrointestinal tract with a predilection for the terminal ileum. IBD patients require repeat imaging throughout the course of their disease, necessitating a safe, noninvasive, available, and repeatable method. Imaging is required at diagnosis, routine surveillance, and acute exacerbation of disease. Ultrasound imaging meets these demands with a high degree of accuracy and wide patient acceptance. Ultrasound provides high-resolution imaging and is excellent for detailed evaluation of the bowel wall and surrounding soft tissues. Regular greyscale bowel evaluation and color Doppler imaging now have accepted standards for evaluating disease activity based on wall thickness, perienteric inflammatory fat, and blood flow, which is invaluable in staging and grading disease. High-resolution dynamic real-time imaging on ultrasound has the ability to show functional as well as morphologic detail, including dysfunctional peristalsis associated with bowel stricture and incomplete mechanical bowel obstruction. Fibrostenotic and penetrating complications of IBD may be associated with an acute or chronic presentation that is easily assessed using ultrasound. Newer software technologies for ultrasound, including Contrast-Enhanced ultrasound and Shear wave elastography, have transformed ultrasound from a basic preliminary imaging technique into a highly sophisticated modality that is now competitive with CT and MR enterography for managing IBD patients. Our long experience with ultrasound of the bowel suggests that the new best practice would include ultrasound as the first test for evaluation of the bowel at any stage of the disease.

Ultrasound imaging of bowel obstruction in infants and children

We review the etiologies of bowel obstruction in infants and children that can be identified on ultrasound (US) including perforated appendicitis, intussusception, foreign body ingestion, colonic volvulus, intra-abdominal mass lesions, internal hernia, and stricturing inflammatory bowel disease. US can potentially identify the cause of bowel obstruction in these age groups, without the need for additional cross-sectional imaging, and can aid in patient management including interventional and surgical planning. Hence, it is important to be familiar with the sonographic imaging findings of bowel obstruction in infants and children.

Contrast-enhanced ultrasound of polyp malignant transformation with multiple metastases in a patient with Peutz-Jeghers syndrome

Multi-systemic metastasis in patients with Peutz-Jeghers syndrome (PJS) is very rare, and there are nearly no relevant imaging reports, especially in contrast-enhanced ultrasound (CEUS). We present here a 40-year-old male patient who underwent several partial small bowel resections and endoscopic polypectomy for intestinal polyps. After reviewing the patient's clinical diagnosis and treatment process, CEUS with sulfur hexafluoride microbubbles (SonoVue, Bracco, Milan, Italy) in the liver and gastrointestinal tract was performed. We imaged multiple abnormal masses with sonographic features consistent with malignancies. Combined with other imaging examinations and 18 gauge core-needle puncture biopsy of liver masses, multiple metastases outside the gastrointestinal tract were considered. This case report suggests CEUS may be an easy, effective, and supplementary method for evaluating PJS patients with suspected multi-systemic malignant lesions including the gastrointestinal tract.

Current Developments and Role of Intestinal Ultrasound including the Advent of AI

Intestinal ultrasound is a non-invasive, safe, and cost-effective technique to study the small and large intestines. In addition to conventional B-mode and color doppler imaging, new US tools have been developed in more recent years that provide auxiliary data on many GI conditions, improving the diagnosis and assessment of relevant outcomes. We have reviewed the more recent literature (from 2010 onwards) on auxiliary tools in bowel ultrasound such as elastography techniques, CEUS, SICUS, and the potential contribution by artificial intelligence (AI) to overcome current intestinal ultrasound limitations. For this scoping review, we performed an extensive literature search on PubMed and EMBASE to identify studies published until December 2023 and investigating the application of elastography techniques, CEUS, SICUS, and AI in the ultrasonographic assessment of the small and large intestines. Multiparametric intestinal ultrasound shows promising capabilities in Crohn's disease, while less is known about the role in ulcerative colitis. Despite some evidence, the CEUS role as a point-of-care examination tool for rare conditions such as intestinal GvHD and ischemic small bowel disease seems promising, possibly avoiding the need to perform further cross-sectional imaging. The use of AI in intestinal ultrasound is still anecdotical and limited to acute appendicitis.

Performance of Ultrasonography in the Diagnosis of Acute Colonic Diverticulitis

OBJECTIVES

Computed tomography is regarded as the reference-standard imaging modality for the assessment of acute left-sided colonic diverticulitis (ALCD). However, its utility may be impaired by cost issues, limited availability, radiation exposure, and contrast-related adverse effects. Ultrasonography is increasingly advocated as an alternative technique for evaluating ALCD, although there is variation regarding its accuracy in disease diagnosis and staging and in determining alternative diagnoses. The aim of this study was to assess the performance of ultrasonography in diagnosing ALCD, differentiating complicated from non-complicated disease and defining alternative diseases related to left lower quadrant pain.

METHODS

Within a 2-year period, all consecutive adult patients with clinically suspected ALCD and available abdominal computed tomography were prospectively evaluated and planned to undergo an abdominal ultrasonographic examination, tailored to the assessment of left lower quadrant. Computed tomography (CT) was regarded as the reference standard.

RESULTS

A total of 132 patients (60 males, 72 females; mean age: 61.3 ± 11 years) were included. The sensitivity, specificity, and area under curve of ultrasonography for diagnosing ALCD were 88.6, 84.9, and 86.8%, with positive and negative predictive values of 89.7 and 83.3%, respectively. The method had sensitivity, specificity, and area under curve of 77.8, 100, and 88.9%, respectively, for defining complicated disease. The area under the curve for the identification of alternative diseases in patients with left lower quadrant pain was 90.9%.

CONCLUSIONS

Ultrasonography has high diagnostic accuracy for diagnosing ALCD, differentiating complicated from non-complicated disease and establishing alternative diagnoses related to left lower quadrant pain. A low threshold to get a CT should be maintained as not to miss cases that may mimic ALCD.

Abdominal perfusion in canine patients with pyometra and sepsis evaluated by Doppler and contrast-enhanced ultrasound

BACKGROUND

Sepsis is a condition characterized by organic dysfunction, leading to hemodynamic instability and high morbidity and mortality rates in humans and animals. Early identification of perfusion changes and appropriate management of sepsis are crucial for improving patient prognosis. Currently, the Systemic Inflammatory Response Syndrome (SIRS) and Sequential Organ Failure Assessment (SOFA) scores are widely studied for sepsis identification and evaluation of organ dysfunction. However, these scores do not assess gastrointestinal involvement, which is common in this condition. Contrast-enhanced ultrasound (CEUS) and Doppler have been considered promising diagnostic techniques for detecting changes in vascularization and microcirculation in a non-invasive and safe manner, particularly in the gastrointestinal system. This study aimed to evaluate duodenal perfusion using CEUS, as well as abdominal aortic and cranial mesenteric artery blood flow using Doppler ultrasound, and systolic arterial pressure (SAP) in 17 bitches with pyometra and in 10 healthy animals.

RESULTS

The variables were compared between the pyometra and control groups, as well between patients with and without sepsis determined by the SOFA or SIRS scores. Pyometra was found to cause a reduction in abdominal aortic blood flow volume, aortic peak systolic velocity, and resistivity index as evaluated by Doppler ultrasound. Patients with sepsis according to the SOFA criteria only presented lower SAP. In contrast, sepsis animals identified by the SIRS score exhibited lower SAP, aortic peak systolic velocity, aortic blood flow volume, and aortic resistivity index and additionally, higher peak intensity of contrast in the duodenal wall.

CONCLUSIONS

Pyometra causes a reduction in abdominal aortic blood flow, which is more pronounced in animals with sepsis identified by the SIRS criteria. These animals also exhibited a decrease in systolic blood pressure and an increase in duodenal perfusion, as evident by CEUS. However, these changes were not observed in patients with sepsis identified by the SOFA criteria. The alterations in intestinal perfusion observed in animals with sepsis indicate the presence of inflammation or dysfunction. In this regard, CEUS proves to be a valuable technique for detecting subtle changes in tissue hemodynamics that may not be apparent in conventional exams.

PET assessment of acute gastrointestinal graft versus host disease

Acute gastrointestinal graft versus host disease (GI-GVHD) is a common complication following allogeneic haematopoietic cell transplantation (HCT), and is characterised by severe morbidity, frequent treatment-refractoriness, and high mortality. Early, accurate identification of GI-GVHD could allow for therapeutic interventions to ameliorate its severity, improve response rates and survival; however, standard endoscopic biopsy is inadequately informative in terms of diagnostic sensitivity or outcome prediction. In an era where rapid technological and laboratory advances have dramatically expanded our understanding of GI-GVHD biology and potential therapeutic targets, there is substantial scope for novel investigations that can precisely guide GI-GVHD management. In particular, the combination of tissue-based biomarker assessment (plasma cytokines, faecal microbiome) and molecular imaging by positron emission tomography (PET) offers the potential for non-invasive, real-time in vivo assessment of donor:recipient immune activity within the GI tract for GI-GVHD prediction or diagnosis. In this article, we review the evidence regarding GI-GVHD diagnosis, and examine the potential roles and translational opportunities posed by these novel diagnostic tools, with a focus on the evolving role of PET.

Sonographic evaluation of a surgically created pouch

This manuscript focuses on a review of the normal and abnormal sonographic appearance of the surgically created pouch as part of an article series on the topic. It includes information regarding sonographic technique, normal anatomy, and commonly encounter diseases and complications.

Contrast-Enhanced Ultrasonography for the Evaluation of Crohn's Disease in Pediatric Patients

BACKGROUND

Contrast-enhanced ultrasonography (CEUS) of the bowel wall has been suggested as an alternative imaging modality for the follow-up of children with Crohn's disease. To demonstrate the feasibility and clinical usefulness of CEUS in the estimation of Crohn's disease activity in children with endoscopy as the reference standard.

METHOD

In this prospective study, 30 pediatric patients with Crohn's disease (24 males and 6 females; median age 14 years) underwent CEUS from December 2020 to August 2021. The simple endoscopic score for Crohn's disease, pediatric Crohn's disease activity index, serologic inflammatory markers, fecal calprotectin and CEUS perfusion parameters were assessed and compared between the inactive and active group based on endoscopic findings.

RESULTS

CEUS was performed successfully in all 30 patients. Two patients showed mild adverse side effects such as temporary dysosmia. The active Crohn's disease group showed higher erythrocyte sedimentation rate (mm/hr) (13.0 vs. 2.0, P = 0.003), C-reactive protein (mg/dL) (4.7 vs. 0.55, P = 0.018) and fecal calprotectin (mcg/g) (1,503 vs. 237.5, P = 0.005). Among the quantitative parameters for CEUS, the mean gradient to the peak value was higher in the active group (1.18 vs. 0.93, P = 0.034). The sensitivity and specificity of the mean gradient to the peak value for predicting active Crohn's disease was 55.6% and 83.3%, respectively, with a cut-off of 1.09 (P = 0.015).

CONCLUSION

CEUS can be a safe and specific diagnostic modality for Crohn's disease activity in children. Among quantitative CEUS parameters, the mean gradient to the peak value could be used to differentiate active and inactive Crohn's disease.

Dynamic contrast enhanced ultrasound in gastrointestinal diseases: A current trend or an indispensable tool?

Contrast enhanced ultrasound (CEUS) has been widely implemented in clinical practice because of the enormous quantity of information it provides, along with its low cost, reproducibility, minimal invasiveness, and safety of the second-generation ultrasound contrast agents. To overcome the limitation of CEUS given by the subjective evaluation of the contrast enhancement behaviour, quantitative analysis of contrast kinetics with generation of time-intensity curves has been introduced in recent years. The quantification of perfusion parameters [named as dynamic-CEUS (D-CEUS)] has several applications in gastrointestinal neoplastic and inflammatory disorders. However, the limited availability of large studies and the heterogeneity of the technologies employed have precluded the standardisation of D-CEUS, which potentially represents a valuable tool for clinical practice in management of gastrointestinal diseases. In this article, we reviewed the evidence exploring the application of D-CEUS in gastrointestinal diseases, with a special focus on liver, pancreas, and inflammatory bowel diseases.

The Utility of Contrast Enhanced Ultrasound and Elastography in the Early Detection of Fibro-Stenotic Ileal Strictures in Children with Crohn's Disease

Purpose

Crohn's disease (CD) is a chronic, idiopathic bowel disorder that can progress to partial or complete bowel obstruction. At present, there are no reliable diagnostic tests that can readily distinguish between acute inflammatory, purely fibrotic and mixed inflammatory and fibrotic. Our aim is to study the utility of contrast enhanced ultrasound (CEUS) in combination with shear wave elastography (SWE) to differentiate fibrotic from inflammatory strictures in children with obstructive CD of the terminal ileum.

Methods

Twenty-five (19 male) children between 2016-2021 with CD of the terminal ileum were recruited into the study. Among these patients, 22 had CEUS kinetic measurements of tissue perfusion, including wash-in slope (dB/sec), peak intensity (dB), time to peak intensity (sec), area under the curve (AUC) (dB sec), and SWE. In total, 11 patients required surgery due to bowel obstruction. Histopathologic analysis was performed by a pathologist who was blinded to the CEUS and SWE test results.

Results

Patients that underwent surgical resection had significantly higher mean area under the curve on CEUS compared to patients responsive to medical therapy (p=0.03). The AUC also correlated with the degree of hypertrophy and the percent fibrosis of the muscularis propria, as determined by histopathologic grading (p<0.01). There was no difference in the mean elastography measurements between these two patient groups.

Conclusion

CEUS is a useful radiological technique that can help identify pediatric patients with medically refractory obstructive fibrotic strictures of the terminal ileum that should be considered for early surgical resection.

Submucosal fat accumulation in Crohn's disease: evaluation with sonography

BACKGROUND/AIMS

The study objective is to investigate the ultrasound features that allow suspecting the presence of submucosal fat deposition, called the fat halo sign (FHS), in the intestinal wall of patients with Crohn's disease.

METHODS

Computed tomography (CT) examinations over a period of 10 years were reviewed for the presence of the FHS in the bowel wall. A measurement of less than -10 Hounsfield units was regarded as indicative of fat. We included only patients who had undergone ultrasound examinations 3 months before or after CT. The study cohort group comprised 68 patients. Wall and submucosal thickness were measured on longitudinal ultrasound sections. A receiver operating characteristic curve was constructed to determine the best cutoff of ultrasound submucosal wall thickness value for predicting FHS in the bowel wall determined on CT.

RESULTS

The FHS was present in 22 patients (31%) on CT. There were significant differences between submucosal thickness of patients with FHS and patients without FHS (4.19 mm vs. 2.41 mm). From the receiver operating characteristic curve, a threshold value of 3.1 mm of submucosal thickness had the best sensitivity and specificity to suspect FHS (95.5% and 89.1%, respectively; area under the curve, 0.962), with an odds ratio of 172. All of 16 patients with a submucosal thickness >3.9 mm had FHS.

CONCLUSIONS

FHS in patients with Crohn's disease can be suspected on ultrasound in cases with marked thickening of the submucosa layer. In these cases, the activity of the disease should be measured by other parameters such as the color Doppler.

Aptamer-Functionalized Microbubbles Targeted to P-selectin for Ultrasound Molecular Imaging of Murine Bowel Inflammation

PURPOSE

Our objectives were to develop a targeted microbubble with an anti-P-selectin aptamer and assess its ability to detect bowel inflammation in two murine models of acute colitis.

PROCEDURES

Lipid-shelled microbubbles were prepared using mechanical agitation. A rapid copper-free click chemistry approach (azide-DBCO) was used to conjugate the fluorescent anti-P-selectin aptamer (Fluor-P-Ap) to the microbubble surface. Bowel inflammation was chemically induced using 2,4,6-trinitrobenzenesulfonic acid (TNBS) in both Balb/C and interleukin-10-deficient (IL-10 KO) mice. Mouse bowels were imaged using non-linear contrast mode following an i.v. bolus of 1 × 10⁸ microbubbles. Each mouse received a bolus of aptamer-functionalized and non-targeted microbubbles. Mouse phenotypes and the presence of P-selectin were validated using histology and immunostaining, respectively.

RESULTS

Microbubble labelling of Fluor-P-Ap was complete after 20 min at 37 ̊C. We estimate approximately 300,000 Fluor-P-Ap per microbubble and confirmed fluorescence using confocal microscopy. There was a significant increase in ultrasound molecular imaging signal from both Balb/C (p = 0.003) and IL-10 KO (p = 0.02) mice with inflamed bowels using aptamer-functionalized microbubbles in comparison to non-targeted microbubbles. There was no signal in healthy mice (p = 0.4051) using either microbubble.

CONCLUSIONS

We constructed an aptamer-functionalized microbubble specific for P-selectin using a clinically relevant azide-DBCO click reaction, which could detect bowel inflammation in vivo. Aptamers have potential as a next generation targeting agent for developing cost-efficient and clinically translatable targeted microbubbles.

Intestinal Ultrasound in Inflammatory Bowel Disease: A Novel and Increasingly Important Tool

New and efficacious medical therapies have become available that have greatly enhanced clinicians' ability to manage inflammatory bowel diseases (IBDs). IBD activity should be assessed regularly in scheduled examinations as the part of a treat-to-target strategy for IBD care. The gold-standard approach to investigating IBD is colonoscopy, but this is an invasive procedure. Intestinal ultrasound (IUS) has played a crucial role in recent years regarding the assessment of IBD activity because it is noninvasive, safe, reproducible, and inexpensive. IUS findings could inform changes in therapeutic interventions for IBDs; this would necessitate fewer endoscopies and enable faster decision-making processes. Furthermore, patients are accepting and tolerant of IUS examinations. This review outlines the current evidence and gives indication regarding the use of IUS in the management of IBDs.

Focused Ultrasound and Ultrasound Stimulated Microbubbles in Radiotherapy Enhancement for Cancer Treatment

Radiation therapy (RT) has been the standard of care for treating a multitude of cancer types. However, ionizing radiation has adverse short and long-term side effects which have resulted in treatment complications for decades. Thus, advances in enhancing the effects of RT have been the primary focus of research in radiation oncology. To avoid the usage of high radiation doses, treatment modalities such as high-intensity focused ultrasound can be implemented to reduce the radiation doses required to destroy cancer cells. In the past few years, the use of focused ultrasound (FUS) has demonstrated immense success in a number of applications as it capitalizes on spatial specificity. It allows ultrasound energy to be delivered to a targeted focal area without harming the surrounding tissue. FUS combined with RT has specifically demonstrated experimental evidence in its application resulting in enhanced cell death and tumor cure. Ultrasound-stimulated microbubbles have recently proved to be a novel way of enhancing RT as a radioenhancing agent on its own, or as a delivery vector for radiosensitizing agents such as oxygen. In this mini-review article, we discuss the bio-effects of FUS and RT in various preclinical models and highlight the applicability of this combined therapy in clinical settings.

Multimodal ultrasound imaging with conventional B-mode, elastography, and parametric analysis of contrast-enhanced ultrasound (CEUS): A novel approach to assess small bowel manifestation in severe COVID-19 disease

The aim was to describe the small bowel morphology with conventional B-mode and elastography and additionally to evaluate dynamic effects of COVID-19 associated small bowel microvascularization using CEUS with color coded perfusion parameters.Thirteen patients with severe COVID-19 acute respiratory distress syndrome (ARDS) were investigated. 13 patients required intensive care treatment with mechanical ventilation. Five patients required extracorporeal membrane oxygenation (ECMO). Contrast-enhanced ultrasound (CEUS) was performed by an experienced investigator as a bolus injection of up to 2.4 ml sulfur hexafluoride microbubbles via a central venous catheter. In the parametric analysis of CEUS, the flare of microbubbles over time is visualized with colors. This is the first work using parametric analysis of CEUS to detect perfusion differences in the small bowel.Parametric analysis of CEUS in the intestinal phase was carried out, using DICOM loops for 20 seconds. In 5 patients, parametric analysis revealed intraindividual differences in contrast agent behavior in the small bowel region. Analogous to the computed tomography (CT) images parametric analysis showed regions of simultaneous hyper- and hypoperfusion of the small intestine in a subgroup of patients. In 5 patients, the parametric image of transmural global contrast enhancement was visualized.Our results using CEUS to investigate small bowel affection in COVID-19 suggest that in severe COVID-19 ARDS systemic inflammation and concomitant micro embolisms may lead to disruption of the epithelial barrier of the small intestine.This is the first study using parametric analysis of CEUS to evaluate the extent of small bowel involvement in severe COVID-19 disease and to detect microemboli. In summary, we show that in COVID-19 the small bowel may also be an important interaction site. This is in line with the fact that enterocytes have been shown to a plenitude of angiotensin converting enzyme (ACE)-2 receptors as entry sites of the virus.

Intestinal Ultrasound in the Assessment of Luminal Crohn’s Disease

Crohn’s disease is a chronic inflammatory disease affecting the gastrointestinal tract. Expert guidelines now recommend regular objective assessments as part of a treat-to-target approach. Intestinal ultrasound provides a noninvasive, patient-friendly modality for assessing Crohn’s disease without the risk of radiation exposure and does not require fasting or bowel preparation. Enhancement techniques, including oral and intravenous contrast, can improve disease-activity and complication detection. Due to its acceptability, intestinal ultrasound can be performed frequently, allowing for closer disease-activity monitoring and treatment adjustments. There have been significant advances in the utility of intestinal ultrasound; particularly for assessing disease activity during pregnancy and fibrosis detection utilising elastography. This review provides a comprehensive overview of performing intestinal ultrasound, the diagnostic accuracy, role in disease-activity monitoring, and recent advances in utilising ultrasound for the assessment of luminal Crohn’s disease.

Intestinal Ultrasound Early on in Treatment Follow-up Predicts Endoscopic Response to Anti-TNFα Treatment in Crohn's Disease

BACKGROUND

To assess treatment response, objective measures are superior to clinical improvement in Crohn's disease [CD]. Intestinal ultrasound [IUS] is an attractive, non-invasive alternative to endoscopy, demonstrating early transmural changes after treatment initiation. Therefore, we investigated IUS and contrast-enhanced ultrasound [CEUS] to predict [early] endoscopic treatment response.

METHODS

Consecutive patients with endoscopically active CD, starting anti-TNFα therapy, were included. Clinical, biochemical, IUS, and CEUS parameters at baseline [T0], after 4-8 weeks [T1] and 12-34 weeks [T2] were collected. The most severely inflamed segment at endoscopy (highest segmental Simplified Endoscopic Score for Crohn's Disease [SES-CD]) and IUS (highest segmental bowel wall thickness [BWT]) was identified. At T2, endoscopic response [decrease in SES-CD ≥ 50%] and remission [SES-CD = 0] were scored.

RESULTS

A total of 40 patients were included: 14 reached endoscopic remission and 17 endoscopic response. At T1 (3.1 mm [1.9-4.2] vs 5.3 mm [3.8-6.9], p = 0.005) and T2 (2.0 mm [1.8-3.1] vs 5.1 [3.0-6.3] mm, p = 0.002) BWT was lower in patients with endoscopic remission. At T1 and T2, 18% (area under the receiver operating curve [AUROC]: 0.77; odds ratio [OR]: 10.80, p = 0.012) and 29% [AUROC: 0.833; OR: 37.50, p = 0.006] BWT decrease predicted endoscopic response, respectively. To determine endoscopic remission, BWT 3.2 mm was most accurate [AUROC: 0.94; OR: 39.42, p < 0.0001] at T2. In addition, absence of colour Doppler signal [OR: 13.76, p = 0.03] and the CEUS parameter wash-out rate [OR: 0.76, p = 0.019] improved the prediction model.

CONCLUSIONS

Reduction in BWT, already after 4-8 weeks of follow-up, predicted endoscopic response and remission. CEUS parameters were of limited value. Furthermore, we have provided accurate cut-offs for BWT reflecting endoscopic response and remission at different time points.

Ultrasonographic scores for ileal Crohn's disease assessment: Better, worse or the same as contrast-enhanced ultrasound?

BACKGROUND

Intestinal ultrasound (IUS) is an increasingly used non-invasive tool to evaluate Crohn's disease (CD) activity. Recently, two IUS scores that evaluate inflammatory activity have emerged: the Simple Ultrasound Activity Score for CD (SUS-CD) and the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS). We aimed to compare the accuracy of SUS-CD, IBUS-SAS and contrast-enhanced ultrasound (CEUS) in predicting inflammatory activity in the terminal ileum in ileocolonoscopy in CD patients.

METHODS

Retrospective study including all consecutive CD patients submitted to IUS with CEUS directed to the terminal ileum performed by a single operator between April 2016 and March 2020. Segmental SUS-CD and IBUS-SAS were calculated. A time-intensity curve of the contrast bowel wall enhancement was created with measurement of peak intensity using CEUS. The CD endoscopic activity in ileocolonoscopy was graded by Simple Endoscopic Score for CD (SES-CD) as inactive (SES-CD < 7) or active (SES-CD ≥ 7).

RESULTS

Fifty patients were included, 54.0% were female, with mean age of 34 ± 12 years, and most had isolated ileal disease (60.0%), and a nonstricturing, nonpenetrating behaviour (44.0%). Most of the patients (60.0%) had active endoscopic disease (SES-CD ≥ 7). SUS-CD and IBUS-SAS were not different between patients with active or inactive endoscopic disease (p = 0.15; 0.57, respectively), having a poor accuracy to correlate endoscopic activity (area under de curve (AUC) 0.62; 0.55, respectively). Peak intensity in CEUS was significantly different in patients with active or inactive endoscopic disease (p = 0.004), having a good accuracy to correlate endoscopic activity (AUC 0.80).

CONCLUSION

Unlike CEUS, SUS-CD and IBUS-SAS were not able to accurately correlate endoscopic activity in terminal ileum in CD. Therefore, CEUS is a non-invasive emerging method that should be increasingly integrated in the ultrasonographic evaluation of CD patients.

Application of transabdominal ultrasound in Crohn's disease

Crohn's disease (CD), a chronic nonspecific intestinal inflammatory disorder of uncertain origin, is collectively referred to as inflammatory bowel disease with ulcerative colitis. In recent years, with the increasing incidence of CD, a greater demand has been put forward for disease diagnosis and inflammatory activity monitoring. With the development of ultrasound technology, transabdominal ultrasound has become more relevant for the diagnosis and follow-up of CD, providing an effective non-invasive examination tool for patients. This review summarizes several transabdominal ultrasound modalities and associated techniques that are presently being developed and utilized in clinical practice, describes the ultrasound manifestations of CD, and discusses the value and prospect of transabdominal ultrasonography in CD.

Contrast-Enhanced Ultrasound in Small Intestinal Ischemia: Proof of Concept

BACKGROUND

Small intestinal ischemia is a challenging diagnosis to make, even with the combination of imaging, laboratory analysis, and physical exam. This pilot study investigated the role of CEUS in evaluating small bowel wall vascularity in participants with suspected ischemia.

METHODS

In this IRB-approved pilot study, CEUS using perflutren lipid microspheres (DEFINITY®; Lantheus Medical Imaging Inc., N. Billerica, MA) was performed on participants determined by the clinical surgical team to have concerns for small intestinal ischemia. CEUS interpretations were performed at both the bedside and later by a blinded radiologist and compared to clinical imaging, surgical findings, or long-term clinical outcomes.

RESULTS

Fifteen CEUS examinations were performed on 14 participants. Five of the participants underwent exploratory laparotomy. Of these, one had small intestinal ischemia (without necrosis). Point of care CEUS demonstrated no evidence of bowel necrosis in any case, and delayed enhancement (indicative of intestinal ischemia) in three cases, resulting in a sensitivity of 100% (95% CI 2.5-100%) and specificity of 85.7% (95% CI 57.2-98.2%). CEUS correctly ruled out ischemia in 91.7% of cases with CT suspicion of small bowel obstruction and 60% of cases that underwent surgical intervention. Additionally, the rate of agreement between bedside interpretation and later radiologist read was high (93%).

CONCLUSIONS

CEUS is uniquely positioned for evaluating the small intestine, because of its high temporal resolution and immediacy of results. Combined with multi-sectional imaging for focal areas of ischemia and/or clinical suspicion for pan ischemia, CEUS may be a useful rule out test for small intestinal ischemia.

Contrast enhanced ultrasonography (CEUS) a novel tool to detect intestinal epithelial barrier dysfunction in severe COVID-19 disease

Ten patients with confirmed COVID-19 disease were studied. Nine patients required intensive care treatment, among them four needed extracorporeal membrane oxygenation (ECMO). Contrast enhanced ultrasonography (CEUS) was performed by one experienced investigator as a bolus injection of up to 2.4 ml of sulphur hexafluoride microbubbles via a central venous catheter. B-Mode evaluation and strain elastography showed mural edema of the small bowel with a thickness of up to 10 mm in all patients. We applied color coded Doppler sonography (CCDS) and power mode with flow-adapted parameters and early, dynamic capillary arterial contrast enhancement of bowel wall structures <10 s to assess perfusion of the small bowel. In all patients, reactive hyperemia was seen in the entire small bowel. In a subgroup of seven patients microbubbles translocated into the intestinal lumen. Thus, high-grade intestinal barrier disruption secondary to SARSCoV-2 infection can be postulated in these patients. This is the first description of perfusion changes and a disruption of the small bowel epithelial barrier in COVID-19 Patients using contrast ultrasonography and elastography.

Evaluation of Suspected Small Bowel Ischemia Using Contrast-Enhanced Ultrasound with Computed Tomography Fusion

Small bowel ischemia can lead to fatal complications such as necrosis, perforation, and sepsis. Clinical examinations and laboratory tests are usually inconclusive in critically ill patients. The need for surgical exploration is decided based on imaging, examination, and clinical judgment. The decision to operate is time-critical and can be lifesaving, but surgical intervention has the potential to cause additional morbidity, especially in unstable patients. Contrast-enhanced computed tomography (CECT) is the study of choice in suspected small bowel ischemia but has poor specificity. Contrast-enhanced ultrasound (CEUS) provides real-time visualization of the bowel wall vascularity. In this case report, we used a CEUS with CT fusion examination to rule out small bowel ischemia in a critically ill patient with suspected closed loop small bowel obstruction on CECT and in whom surgical exploration would have not been well tolerated. The patient's condition later improved, and an abdominal CT showed no evidence of obstruction.

Impact of intestinal ultrasound with a portable system in the management of Crohn's disease

Background

Intestinal ultrasound (IUS) is a valid cross-sectional imaging technique for the evaluation of Crohn’s disease (CD). With advancements in technology, portable ultrasound systems are becoming widely available, and the inevitable change to their use by non-radiologist clinicians would be a valuable contribution to improving patient care. This study aimed to investigate the diagnostic yield of IUS examination performed by a gastroenterologist with a portable system as an adjunct imaging modality in the routine care of CD patients.

Methods

A total of 117 CD patients were assessed by IUS imaging. Pre- and post-IUS clinical-management decisions were recorded. The primary outcome was to evaluate the change in the patients’ clinical-management decision following the IUS examination. The diagnostic accuracy was compared against the reference decision reached via a multidisiplinary meeting after the evaluation of all patient-related data. The endoscopic disease activity was determined using the simple endoscopic score for Crohn's disease (SES-CD).

Results

The initial clinical-management decision was changed in 47 patients (40.2%) after the IUS examination (P = 0.001). The accuracy of patient-management decisions improved from 63.2% to 90.6% in comparison to reference decisions (P < 0.001). After IUS examination, a further 13 cases (11.1%) were identified for urgent surgical/interventional procedures. The accuracy of colonoscopic (SES-CD ≥3) assessment was shown to be comparable to that of IUS (94% vs 91%). The sensitivity for disease presence was 95% with colonoscopy and 94% with the IUS assessment.

Conclusion

IUS examination with the use of a portable ultrasonography system significantly improves clinical-management decisions. With further supporting data, this practice would possibly become a requirement for CD management.

Use of contrast-enhanced ultrasound in pediatrics

Although contrast-enhanced ultrasound has been shown to provide considerable benefits, particularly in pediatric patients, it is still used relatively rarely in Brazil. It has proven to be a safe technique, and adverse effects are rare. In this review, we address the technique and main applications of contrast-enhanced ultrasound in the pediatric population, including the evaluation of focal liver lesions, abdominal trauma, kidney grafts, liver grafts, bowel loops, and vesicoureteral reflux. It is important for pediatric radiologists to be acquainted with this promising tool, understanding its applications and limitations.

Transmural healing as a therapeutic goal in Crohn's disease: a systematic review

Transmural healing is associated with substantial improvements in disease-related outcomes for patients with Crohn's disease, but there is no single validated definition of transmural healing to date. We did a systematic review to summarise the available definitions and to evaluate the effect of transmural healing on disease-related outcomes for patients with Crohn's disease by searching PubMed, Cochrane Library, and Web of Science for interventional and non-interventional studies. Seventeen studies were included, reporting rates of transmural healing in between 14·0% and 42·4% of patients. Transmural healing was assessed with magnetic resonance enterography, bowel sonography, or CT enterography. Most studies used bowel wall thickness, with 3 mm or less as the most frequent cutoff, to define transmural healing. Vascularisation assessed by doppler ultrasound and absence of complications or contrast enhancement were also used for this definition. Transmural healing was significantly associated with improvements in disease-related outcomes. In addition, there was a good correlation between transmural healing, mucosal healing, and selected biomarkers. We conclude that bowel wall thickness is the most frequently used item to evaluate transmural healing, which is associated with improvements in long-term outcomes of Crohn's disease and should be considered as a new treatment target.

Small bowel radiology

PURPOSE OF REVIEW

Recent advances in computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), and nuclear radiology have improved the diagnosis and characterization of small bowel pathology. Our purpose is to highlight the current status and recent advances in multimodality noninvasive imaging of the small bowel.

RECENT FINDINGS

CT and MR enterography are established techniques for small bowel evaluation. Dual-energy CT is a novel technique that has shown promise for the mesenteric ischemia and small bowel bleeding. Advanced US techniques and MRI sequences are being investigated to improve assessment of bowel inflammation, treatment response assessment, motility, and mural fibrosis. Novel radiotracers and scanner technologies have made molecular imaging the new reference standard for small bowel neuroendocrine tumors. Computational image analysis and artificial intelligence (AI) have the potential to augment physician expertise, reduce errors and variability in assessment of the small bowel on imaging.

SUMMARY

Advances in translational imaging research coupled with progress in imaging technology have led to a wider adoption of cross-sectional imaging for the evaluation and management of small bowel entities. Ongoing developments in image acquisition and postprocessing techniques, molecular imaging and AI have the strongest potential to transform the care and outcomes of patients with small bowel diseases.

Contrast-Enhanced Ultrasound (CEUS) in Non-Traumatic Abdominal Emergencies

Conventional ultrasound imaging (US) is the first-line investigation in acute non-traumatic abdominal emergencies, but sometimes it needs further examinations, such as computed tomography (CT), to reach a certain diagnosis. Contrast-enhanced ultrasound (CEUS), through injection of contrast medium, may provide the radiologist with additional information that could not be investigated with baseline US. It could help reach a diagnosis and rapidly determine the proper therapy in an emergency setting. The purpose of this review is to explain and illustrate the various possibilities and limitations of CEUS in acute non-traumatic abdominal diseases, in particular acute inflammation, parenchymal infarcts, and hemorrhages.

Contrast-enhanced ultrasonography in the evaluation of Crohn disease activity in children: comparison with histopathology

BACKGROUND

Contrast-enhanced ultrasound (US) of the bowel wall has been suggested as an alternative imaging modality for the follow-up of children with Crohn disease.

OBJECTIVE

To evaluate the diagnostic performance of contrast-enhanced US in the estimation of Crohn disease activity in children with histopathology as the reference standard.

MATERIALS AND METHODS

In 24 children with Crohn disease confirmed on histopathology, disease activity was evaluated on 40 bowel segments using US score and subjective and quantitative contrast-enhanced US evaluation. Contrast-enhanced US evaluation included enhancement pattern analysis with a graphic representation of log time-intensity curve and calculation of kinetic parameters with the definition of thresholds for disease activity, as determined by receiver operating characteristics curve analysis. The diagnostic accuracy of US with colour Doppler imaging and subjective and quantitative contrast-enhanced US were calculated.

RESULTS

Moderate or severe inflammation was identified in 18 segments and remission or mild inflammation was identified in 22 segments on histopathology. The quantitative contrast-enhanced US, namely the peak enhancement value, had 72.2% sensitivity (95% confidence interval [CI] 46.5-90.3), 100% specificity (95% CI 84.6-100.0) and 87.5% diagnostic accuracy (95% CI 73.2-95.8) in predicting moderate or severe grade inflammation at histopathology. The sensitivity, specificity and diagnostic accuracy of subjective contrast-enhanced US were 77.8% (95% CI 52.4-93.6), 77.3% (95% CI 54.6-92.2) and 77.5% (95% CI 61.6-89.2), respectively, and of US with colour Doppler imaging were 55.6% (95% CI 30.8-78.5), 86.4% (95% CI 65.1-79.1) and 72.5% (95% CI 56.1-85.4), respectively.

CONCLUSION

Quantitative contrast-enhanced US has the potential of becoming a complementary method in the evaluation of Crohn disease activity in children. Fibrosis may affect peak enhancement results and underestimate inflammatory activity.

Ultrasonography in infectious and neoplastic diseases of the bowel and peritoneum

Ultrasonography is not the most cited imaging technique for the evaluation of infectious and neoplastic diseases of the gastrointestinal tract and the peritoneum, but it is often the initial technique used in the initial workup for nonspecific clinical syndromes. Despite its limitations, ultrasonography's strengths enable it to provide meaningful diagnostic information. To discuss the most important ultrasonographic, clinical, and epidemiological findings for infectious disease, we follow a topographical approach: stomach (Anisakis), proximal small bowel (Giardia lamblia, Strongyloides stercoralis, Mycobacterium avium-intracellulare complex, and Cryptosporidium), distal small bowel (Yersinia, Salmonella, and Campylobacter), terminal ileum and cecum (tuberculosis), right colon (Entamoeba histolytica), left colon (Shigella), sigmoid colon and rectum, pancolitis (Clostridium difficile, Cytomegalovirus, and Escherichia coli), and peritoneum. To discuss the ultrasonographic and clinical findings of the most common neoplastic diseases, we follow a nosological approach: polyploid lesions as precursors of tumors, carcinomas, neuroendocrine tumors, hematological tumors, mesenchymal tumors, and metastases. We briefly discuss tumors of the peritoneum and the use of ultrasonography to guide percutaneous biopsy procedures.

The establishment of a regression model from four modes of ultrasound to predict the activity of Crohn's disease

To establish a multi-parametric regression model from four modes of ultrasound to predict the activity of Crohn's disease (CD) noninvasively. Score of 150 of the Crohn’s Disease Activity Index (CDAI) was taken as the cut-off value to divide the involved bowel segments of 51 patients into the active and inactive group. Eleven parameters from four modes of ultrasound (B-mode ultrasonography, color Doppler flow imaging, contrast-enhanced ultrasonography and shear wave elastography) were compared between the two groups to investigate the relationship between multimodal ultrasonic features and CD activity. P < 0.05 was considered statistically significant. Parameters with AUC larger than 0.5 was selected to establish the prediction model of CDAI. Totally seven ultrasound parameters (bowel wall thickness, mesenteric fat thickness, peristalsis, texture of enhancement, Limberg grade, bowel wall perforation and bowel wall stratification) were significantly different between active and inactive group. A regression model was established based on the seven parameters as followed: CDAI = 211.325 + 3.186BWT − 53.003BWS + 6.280BWP + 0.392MFT + 22.239PS + 79.012LG + 72.793TE. (R² = 0.72, P = 0.037). The multimodal ultrasound parametric regression model was designed to predict CDAI score invasively. The model has the potential to provide an alternative method for quantifying the CD activity.

Evaluation of Crohn's Disease Activity: Development of an Ultrasound Score in a Multicenter Study

OBJECTIVE

Our goal in this multicentric prospective study was 2-fold: first, to test the diagnostic accuracy of ultrasound, color Doppler imaging (CDI), and contrast-enhanced ultrasound (CEUS) in identifying disease activity in patients with Crohn's disease (CD) compared with endoscopy as the reference standard; and, second, to construct a sonographic score that allows disease activity to be detected.

MATERIALS AND METHODS

Seventy-two patients with CD from 3 hospitals underwent within a 30-day period both colonoscopy and ultrasound (US), including mural thickness, CDI, and CEUS, prospectively as part of clinical care. A multivariate analysis was carried out to assess the influence of each of the ultrasound variables in predicting endoscopic activity. We then developed a predictive ultrasound score for disease activity, and a receiver operating characteristic (ROC) curve was constructed to determine the area under the ROC curve (AUC) and the best cut-off score value to discriminate between active and inactive disease.

RESULTS

Sonographic findings that were independent predictors of the presence of active disease at endoscopy were wall thickness, color grade, and contrast parameters. A score based on those variables showed high accuracy in predicting active disease, with an area under the ROC curve of 0.972. A simpler index, without contrast parameters, also showed high accuracy in detecting disease activity (AUC, 0.923).

CONCLUSION

A score based on wall thickness, color Doppler grade, and contrast parameters showed high accuracy in predicting active disease. A score without including the use of contrast agent had practically similar results and is easier to use in monitoring response to treatment.

Contrast-enhanced ultrasound of the pediatric bowel

Contrast-enhanced ultrasound (CEUS) has emerged as a valuable modality for bowel imaging in adults and children. CEUS enables visualization of the perfusion of the bowel wall and of the associated mesentery in healthy and disease states. In addition, CEUS images can be used to make quantitative measurements of contrast kinetics, allowing for objective assessment of bowel wall enhancement. Bowel CEUS is commonly applied to evaluate inflammatory bowel disease and to monitor treatment response. It has also been applied to evaluate necrotizing enterocolitis, intussusception, appendicitis and epiploic appendagitis, although experience with these applications is more limited. In this review article, we present the current experience using CEUS to evaluate the pediatric bowel with emphasis on inflammatory bowel disease, extrapolating the established experience from adult studies. We also discuss emerging applications of CEUS as an adjunct or problem-solving tool for evaluating bowel perfusion.

Ultrasound findings of Crohn's disease: correlation with MR enterography

Crohn's disease is a chronic inflammatory bowel disease characterized by periods of relative inactivity alternating with acute flare-ups. Imaging techniques play a fundamental role in the diagnosis and follow-up of Crohn's disease, providing information on the extent of disease, disease activity, and the presence of extramural complications. Because of the frequent re-evaluation required by the relapsing nature of Crohn's disease and the relative young age at which most patients are diagnosed, techniques that use ionizing radiation are best avoided in monitoring this population. Thus, magnetic resonance enterography (MRE) and ultrasonography (US) are the preferable techniques. Various studies have demonstrated that US is accurate in assessing the gut. Despite some clear advantages over MRE, US has long been underused in the evaluation of intestinal disease. This review presents an overview of the main imaging findings in Crohn's disease, correlating representative US images with MRE and surgical pathology specimens. We conclude that US reliably depicts both bowel-related and mesenteric features of Crohn's disease and US findings correlate strongly with MRE findings.

Correlation of minimally invasive imaging techniques to assess intestinal mucosal perfusion with established markers of chronic inflammatory enteropathy in dogs

Background

Minimally invasive diagnostic imaging techniques to detect intestinal inflammation in dogs are lacking. Contrast‐enhanced ultrasound (CEUS) and endoscopic narrow band imaging‐like endoscopy (Storz Professional Image Enhancement System [SPIES]) might allow quantification of intestinal mucosal perfusion and microvessel density in chronic inflammatory enteropathy (CIE) of dogs.

Hypothesis/Objectives

Markers of mucosal perfusion as determined by CEUS and SPIES endoscopy are potentially useful diagnostic markers to help characterize CIE and correlate with histological inflammation type and severity.

Animals

Thirty client‐owned dogs diagnosed with CIE at a referral hospital were prospectively enrolled.

Materials and Methods

Data from CEUS, SPIES, and white light (WL) endoscopy were correlated with World Small Animal Veterinary Association (WSAVA) endoscopy and histology scores and vessel density as determined by immunohistochemistry for von Willebrand factor (vWF). Automated linear modeling was used to determine predictors of endoscopic and histologic severity.

Results

Duodenal histology correlated with SPIES data (area percentage value, rho = 0.424, P = .04). White light endoscopy parameters correlated with SPIES parameters in the duodenum. Colonic histology correlated positively with CEUS, whereas colonic CEUS parameters correlated inversely with vWF expression. Several duodenal parameters combined predicted duodenal histology scores to a level of 73.4%. For the colon, 2 parameters contributed more than others to 73.1%.

Conclusion and Clinical Importance

Minimally invasive CEUS and SPIES appear feasible to assess intestinal perfusion in CIE. Use of SPIES endoscopy may be promising for assessing small intestinal inflammation, whereas CEUS could be used to assess colonic perfusion and inflammation. Both techniques need to be investigated further for their clinical utility.

The use of contrast-enhanced ultrasound for chronic inflammatory bowel disease

Intestinal ultrasound is a non-invasive, inexpensive, accessible imaging technique that is appropriate for the study of patients with inflammatory bowel disease (IBD). It provides an assessment of inflammatory activity and complications with a diagnostic accuracy similar to that of magnetic resonance imaging (MRI) and computed tomography (CT). Furthermore, it has proven to be of great value for the follow-up and monitoring of these patients. The addition of contrast enhancement has improved the diagnostic ability of intestinal ultrasound in the assessment of both inflammatory activity and complications. The development of dynamic studies able to quantify contrast arrival and determine a number of parameters in time-intensity curves (TICs) has increased the capability of intestinal ultrasound to identify inflammation and predict response to biologic therapy.

Usefulness of intestinal ultrasound in inflammatory bowel disease

Imaging techniques play a fundamental role in the initial diagnosis and follow-up of inflammatory bowel disease. Intestinal ultrasound has high sensitivity and specificity in patients with suspected Crohn's disease and in the detection of inflammatory activity. This technique enables the early diagnosis of intra-abdominal complications such as stenosis, fistulas, and abscesses. It has also proven useful in monitoring the response to treatment and in detecting postsurgical recurrence. Technical improvements in ultrasound scanners, technological advances such as ultrasound contrast agents and elastography, and above all increased experience have increased the role of ultrasound in the evaluation of the gastrointestinal tract. The features that make ultrasound especially attractive include its wide availability, its noninvasiveness and lack of ionizing radiation, its low cost, and its good reproducibility, which is important because it is easy to repeat the study and the study is well tolerated during follow-up. This review summarizes the role of intestinal ultrasound in the detection and follow-up of inflammatory bowel disease.

Clinical value of contrast-enhanced ultrasound for the differential diagnosis of specific subtypes of uterine leiomyomas

OBJECTIVE

To improve the accuracy of clinical diagnosis by analyzing different contrast-enhanced ultrasound (CEUS) imagines of specific subtypes of uterine leiomyomas.

METHODS

A total of 147 female patients received preoperative CEUS examination. The scanning plane of the biggest tumors for CEUS was found by common B-mode ultrasonographic scanning on pelvic cavity, then 1.5 mL SonoVue were injected into the median cubital vein. According to the CEUS images, the lesion enhanced time, enhanced level and enhanced morphology were recorded. The time-intensity curve was acquired and analyzed, meanwhile, the relevant parameters were calculated, including rise time (RT), peak intensity (PI), time to peak (TTP) and mean transit time (MTT).

RESULTS

In cellular uterine leiomyoma group, the percentage of high enhancement, early enhancement was higher, equal enhancement and synchronic enhancement were lower than those in the common uterine leiomyomas group. In hysteromyoma with hyaline degeneration group, the percentage of high enhancement, early enhancement was lower, while low enhancement and delayed enhancement were higher than those in the common uterine leiomyomas group. The ratio of PI in cellular uterine leiomyoma group was the highest, but the ratios of RT, TTP and MTT were the lowest of the three benign groups. The ratio of PI in hysteromyoma with hyaline degeneration group was the lowest, while the ratios of RT and TTP was the highest among the three benign groups.

CONCLUSION

Different pathological types of uterine leiomyomas have their own signal performance on CEUS. CEUS can be used to infer their pathological types and help differential diagnosis.

Contrast-enhanced US in Pediatric Patients: Overview of Bowel Applications

Contrast material-enhanced US is a technique that is approved by the U.S. Food and Drug Administration for the characterization of liver lesions and intravesicular applications in children; however, contrast-enhanced US has several other pediatric applications in clinical practice. The most common application is for patients with inflammatory bowel disease (IBD). Contrast-enhanced US can be used to diagnose IBD, distinguish regions of active or chronic inflammation of the bowel wall, and evaluate associated complications such as abscesses, fistulas, and strictures. Dynamic contrast material evaluation provides qualitative and quantitative information about mural and mesenteric blood flow, which is essential in the determination of disease activity in these patients. It also has the potential to provide a means of monitoring the response to therapy beyond endoscopy or MR enterography. In addition to its use for IBD, contrast-enhanced US can be used to assess for bowel perfusion when problem solving in patients with necrotizing enterocolitis, neonatal bowel infarction, or intussusception. It is a useful imaging technique to fortify diagnoses that may otherwise be indeterminate, such as appendicitis, epiploic appendagitis, intraluminal bowel masses, and complex cysts. Finally, innovative applications such as shear-wave elastography have the potential to provide information about the stiffness of the bowel wall. Online supplemental material is available for this article. ©RSNA, 2020 See discussion on this article by Watson and Humphries.

Double contrast-enhanced ultrasonography of a small intestinal neuroendocrine tumor: a case report of a recommendable imaging modality

A 57-year-old male presenting with spontaneously relieved abdominal cramp and distension was admitted to the West China Hospital. The diagnosis remained unclear after colonoscopy and computed tomography. Double contrast-enhanced ultrasonography was then performed and a neoplasm in the small intestine was suspected, supported by a thin-section computed tomography and positron emission tomography/computed tomography. This was confirmed pathologically after surgery to be a small intestinal G1 neuroendocrine tumor. Surgery was performed to remove approximately 25 cm of small bowel and a 3-cm solid mass located in the mesentery. The patient had a complete recovery and was tumor-free at the final follow-up. Small intestinal tumors including neuroendocrine tumors have always posed a diagnostic challenge. This case indicated that double contrast-enhanced ultrasonography is feasible in detection of small intestinal neuroendocrine tumors, and it may be an advisable approach assisting diagnosis of small intestinal tumors.

Sonographic assessment of infectious diseases of the gastrointestinal tract: from scanning to diagnosis

BACKGROUND

Sonography of the gastrointestinal (GI) tract is a practical, safe, inexpensive, and reproducible diagnostic tool for the evaluation, diagnosis, and follow-up of infectious bowel disease. The modality is rapidly gaining prominence among clinicians on a global scale. In the United States, however, ultrasound of the bowel remains underutilized primarily due to insufficient experience among radiologists and sonographers in performing sonographic bowel assessment. This lack of experience and knowledge results in misinterpretations, missed diagnoses, and underutilization of this modality in patients with acute abdomen, with the majority of GI pathology on sonography discovered incidentally.

OBJECTIVES

This article aims to demonstrate the characteristic sonographic findings associated with GI infectious processes as well as provide dedicated ultrasound protocols for evaluation of the GI tract.

CONCLUSION

This article serves a twofold purpose, raising awareness of the utility of this imaging modality within the radiology community and also providing practical teaching points for sonographic evaluation of infectious disorders of the GI tract.

Imaging Inflammation and Infection in the Gastrointestinal Tract

A variety of seemingly non-specific symptoms manifest within the gastrointestinal (GI) tract, particularly in the colon, in response to inflammation, infection, or a combination thereof. Differentiation between symptom sources can often be achieved using various radiologic studies. Although it is not possible to provide a comprehensive survey of imaging gastrointestinal GI tract infections in a single article, the purpose of this review is to survey several topics on imaging of GI tract inflammation and infections. The review discusses such modalities as computed tomography, positron emission tomography, ultrasound, endoscopy, and magnetic resonance imaging while looking at up-an-coming technologies that could improve diagnoses and patient comfort. The discussion is accomplished through examining a combination of organ-based and organism-based approaches, with accompanying selected case examples. Specific focus is placed on the bacterial infections caused by Shigella spp., Escherichia coli, Clostridium difficile, Salmonella, and inflammatory conditions of diverticulitis and irritable bowel disease. These infectious and inflammatory diseases and their detection via molecular imaging will be compared including the appropriate differential diagnostic considerations.