Ultrasonography as a primary diagnostic tool in patients with inflammatory disease and tumors of the small intestine and large bowel

Basic practices for gastrointestinal ultrasound

The standard diagnostic modalities for gastrointestinal (GI) diseases have long been endoscopy and barium enema. Recently, trans-sectional imaging modalities, such as computed tomography and magnetic resonance imaging, have become increasingly utilized in daily practice. In transabdominal ultrasonography (US), the bowel sometimes interferes with the observation of abdominal organs. Additionally, the thin intestinal walls and internal gas can make structures difficult to identify. However, under optimal US equipment settings, with identification of the sonoanatomy and knowledge of the US findings of GI diseases, US can be used effectively to diagnose GI disorders. Thus, the efficacy of GIUS has been gradually recognized, and GIUS guidelines have been published by the World Federation for Ultrasound in Medicine and Biology and the European Federation of Societies for Ultrasound in Medicine and Biology. Following a systematic scanning method according to the sonoanatomy and precisely estimating the layered wall structures by employing color Doppler make diagnosing disease and evaluating the degree of inflammation possible. This review describes current GIUS practices from an equipment perspective, a procedure for systematic scanning, typical findings of the normal GI tract, and 10 diagnostic items in an attempt to help medical practitioners effectively perform GIUS and promote the use of GIUS globally.

Insights into the role of gastrointestinal ultrasound in ulcerative colitis

Endoscopic evaluation with histological sampling is the gold standard for the diagnosis and follow-up of patients with inflammatory bowel disease (IBD), but in the past few years, gastrointestinal ultrasound (GIUS) has been gaining ground. Due to the transmural nature of inflammation in Crohn's disease, GIUS has been mainly applied in this context. However, GIUS is now being reported to be accurate also for ulcerative colitis (UC). This review summarizes current knowledge on the use of GIUS in UC, with a focus on clinical practice. The review covers topics such as GIUS parameters, especially bowel wall thickness; the use of GIUS in assessing disease extent and in monitoring disease activity; GIUS indexes and scores; and the combination of GIUS with transperineal ultrasound for a better assessment of the rectum. With the always growing body of evidence supporting the accuracy of GIUS in UC, this diagnostic imaging modality can be expected to play a bigger role in disease flare evaluation, early treatment monitoring, and acute severe disease management.

Systematic Review: Clinical Utility of Gastrointestinal Ultrasound in the Diagnosis, Assessment and Management of Patients With Ulcerative Colitis

BACKGROUND AND AIMS

Gastrointestinal ultrasound is useful in the assessment of patients with Crohn's disease, but its application in ulcerative colitis [UC] is less well established. Here we systematically review the role of gastrointestinal ultrasound in patients with UC.

METHODS

Searches of the PUBMED and EMBASE databases were performed with the following search strategy: [ultrasound OR sonography] AND [intestinal OR bowel] AND [ulcerative colitis OR inflammatory bowel disease]. The final search was performed in August 2019.

RESULTS

Of 6769 studies identified in the search with a further two studies found from other sources, 50 studies met the inclusion criteria. Increased bowel wall thickness and detection of increased blood flow by colour Doppler were the most often applied criteria for defining disease activity and distribution. When compared with other reference investigations, gastrointestinal ultrasound accurately determined disease extent, severity and response to medical therapy. While further information can be obtained from haemodynamic measurements of the abdominal vessels and contrast-enhanced ultrasound, their clinical value was uncertain. Likewise, hydrocolonic sonography has few advantages over standard gastrointestinal ultrasound examination. Of several scoring systems proposed, there is disparity between the measures and a general lack of validation. There has been limited application of gastrointestinal ultrasound in acute severe ulcerative colitis with toxic megacolon, and, while performing well in children, normal limits differ from those in adults.

CONCLUSION

Current evidence indicates that gastrointestinal ultrasound has utility in the non-invasive assessment of patients with UC. Continued advances in technology with better image resolution, validation of scoring systems and application at the point of care by gastroenterologists are likely to contribute to increased use of gastrointestinal ultrasound in routine clinical practice.

Impact of intestinal ultrasound on the management of patients with inflammatory bowel disease: how to apply scientific evidence to clinical practice

Technological improvements and growing sonographers' expertise boost the role of intestinal ultrasound (IUS) in assessing patients with inflammatory bowel diseases (IBD). Non-invasiveness, low cost and good reproducibility make IUS attractive. Leveraging on the Authors' long-term field experience, this review focuses on the IUS role in IBD patients' clinical management. For detecting IBD, particularly Crohn's disease, the IUS parameters - above all the evidence of a thickened bowel wall (BWT) - show very good diagnostic accuracy similar to that of MRI or CT scan. The standard IUS parameters are not accurate enough to detect inflammatory activity, but intravenous contrast-enhanced US (CEUS) is highly accurate in ruling active inflammation out. However, its routinely use remains limited in clinical practice and its parameters need standardization. IUS is accurate in detecting IBD main complications: in particular, fistulae and abscesses. As to stenosis the recent introduction of IUS-based elastographic techniques allows to differentiate prevalently inflammatory from highly fibrotic strictures. IUS proves valid also for monitoring IBD patients. In particular, the evidence of transmural healing, defined as BWT normalization, has got an important prognostic meaning, as associated with better long-term clinical outcomes. Post-surgery CD recurrence can be suggested by early IUS assessment.

Gastrointestinal ultrasound in inflammatory bowel disease: an underused resource with potential paradigm-changing application

Evolution of treatment targets in IBD has increased the need for objective monitoring of disease activity to guide therapeutic strategy. Although mucosal healing is the current target of therapy in IBD, endoscopy is invasive, expensive and unappealing to patients. GI ultrasound (GIUS) represents a non-invasive modality to assess disease activity in IBD. It is accurate, cost-effective and reproducible. GIUS can be performed at the point of care without specific patient preparation so as to facilitate clinical decision-making. As compared with ileocolonoscopy and other imaging modalities (CT and MRI), GIUS is accurate in diagnosing IBD, detecting complications of disease including fistulae, strictures and abscesses, monitoring disease activity and detecting postoperative disease recurrence. International groups increasingly recognise GIUS as a valuable tool with paradigm-changing application in the management of IBD; however, uptake outside parts of continental Europe has been slow and GIUS is underused in many countries. The aim of this review is to present a pragmatic guide to the positioning of GIUS in IBD clinical practice, providing evidence for use, algorithms for integration into practice, training pathways and a strategic implementation framework.

Role of Bowel Ultrasound in the Diagnosis and Follow-up of Patients with Crohn's Disease

Crohn's disease (CD) is an inflammatory chronic bowel disorder; it can involve the whole gastrointestinal tract, but its localization in the ileum or colon is most common. The reference standard for the diagnosis of CD is ileocolonoscopy with histologic assessment. The reference standard for the detection of any complications is surgery. However, imaging techniques have an important role both in the detection/localization of CD and in the follow-up of CD patients. In the last few years, the technical development of ultrasound equipment, the advent of new technologies such as elastography and mostly the increased expertise of sonographers have boosted the role of bowel ultrasound in assessment of the gastrointestinal tract. In fact, bowel ultrasound is particularly attractive thanks to its widespread availability, non-invasiveness, low cost and good reproducibility, as it can be easily repeated during follow-up. The aim of this article is to provide an extensive overview of the actual role of bowel ultrasound in the detection and follow-up of patients with CD.

Failure of gastroenterologists to apply intestinal ultrasound in inflammatory bowel disease in the Asia-Pacific: a need for action

Intestinal ultrasound (IUS) is a cheap, noninvasive, risk-free procedure that is significantly underutilized in the diagnosis and management of patients with inflammatory bowel disease (IBD) in the Asia-Pacific region. More cost-effective methods of monitoring disease activity are required in light of the increasing global burden of IBD (especially in Asia), the advent of personalized medicine, and the rising cost of healthcare. IUS is a prime example of a technique that meets these needs. Its common clinical applications include assessing the activity and complications of IBD. In continental Europe, countries such as Germany and Italy use this imaging tool as the standard of care and have integrated it into management protocols. There are formal training programs in these countries to train gastroenterologists in IUS, and it is used in an outpatient setting during patient consultations. Barriers to its use in the Asia-Pacific region include lack of experience and research data, and there are few established centers with active training programs. These concerns can be addressed by investing more in IUS service provision and by increasing allocation of resources toward local research and training. Increased uptake of IUS will ultimately benefit patients with IBD.

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.

Mucosal healing in Crohn's disease: a systematic review

The traditional goals of Crohn's disease therapy, to induce and maintain clinical remission, have not clearly changed its natural history. In contrast, emerging evidence suggests that achieving and maintaining mucosal healing may alter the natural history of Crohn's disease, as it has been associated with more sustained clinical remission and reduced rates of hospitalization and surgical resection. Induction and maintenance of mucosal healing should therefore be a goal toward which therapy is now directed. Unresolved issues pertain to the benefit of achieving mucosal healing at different stages of the disease, the relationship between mucosal healing and transmural inflammation, the intensity of treatment needed to achieve mucosal healing when it has not been obtained using standard therapy, and the means by which mucosal healing is defined using current endoscopic disease activity indices. The main clinical challenge relates to defining the means of achieving high rates of mucosal healing in clinical practice.

Small intestinal tumors: diagnostic accuracy of enhanced multi-detector CT virtual endoscopy

OBJECTIVE

To study the diagnostic accuracy of enhanced multi-detector CT virtual endoscopy (MDCT-VE) for small intestinal tumors.

MATERIALS AND METHODS

125 patients were examined by multi-detector CT (MDCT: 54 on 4-slice; 71 on 64-slice) following standard gastrointestinal tract cleansing, oral double contrast aerogenesis agent, and rectal gas administration. Unenhanced CT was performed, followed by enhanced CT in supine (30 and 80s delay after 100 mL standard intravenous contrast medium) and prone positions (180s delay). Supplementary CT in the lateral position was performed if small bowel was not well-filled. Images were reviewed on post-processing workstations with Virtual Endoscopy software.

RESULTS

33/125 patients had proven small intestinal tumors: ten stromal tumors, nine lymphoma, eight adenocarcinomas, three hemangiomas, one each lipoma, Brunner gland adenoma, and hamartoma. 92 were nontumors. MDCT-VE correctly identified 30/33 cases with one false-positive diagnosis: sensitivity 90.9%, specificity 98.9% and accuracy 96.8%.

CONCLUSION

Small intestinal MDCT-VE technique has high diagnostic accuracy for the detection of intestinal tumors. Contrast enhancement and adequate intestinal tract gas-filling can improve the detection rate for small intestinal tumors.

Imaging for luminal disease and complications: CT enterography, MR enterography, small-bowel follow-through, and ultrasound

The advent of cross-sectional enterography has revolutionized small-bowel imaging, providing comprehensive, reproducible evaluation of CD and its complications. Continued collaboration between radiologists and gastroenterologists is critical to ensure further progress toward the common goals of classifying disease activity, predicting response to treatment, and appropriate triage to medical versus surgical therapy.

Ultrasound of the small bowel in Crohn's disease

Several radiological and endoscopic techniques are now available for the study of inflammatory bowel diseases. In everyday practice, the choice of the technique to be used depends upon its availability and a careful evaluation of diagnostic accuracy, clinical usefulness, safety, and cost. The recent development of innovative and noninvasive imaging techniques has led to a new and exciting area in the exploration of the gastrointestinal tract, especially in Crohn's disease patients by using ultrasound with oral or intravenous contrast.

Noninvasive imaging of the small bowel in Crohn's disease: the final frontier

The substantial morbidity and mortality associated with Crohn's disease underlines the importance of accurate assessment at presentation, during follow-up, when investigating complications, and when evaluating the response to therapeutic interventions. Accurate methods are required to quantify the severity and extent of disease.

Systematic review: the use of ultrasonography, computed tomography and magnetic resonance imaging for the diagnosis, assessment of activity and abdominal complications of Crohn's disease

BACKGROUND

Cross-sectional imaging techniques, including ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI), are increasingly used for evaluation of Crohn's disease (CD). Aim  To perform an assessment of the diagnostic accuracy of cross-sectional imaging techniques for diagnosis of CD, evaluation of disease extension and activity and diagnosis of complications, and to provide recommendations for their optimal use.

METHODS

Relevant publications were identified by literature search and selected based on predefined quality parameters, including a prospective design, sample size and reference standard. A total of 68 publications were chosen.

RESULTS

Ultrasonography is an accurate technique for diagnosis of suspected CD and for evaluation of disease activity (sensitivity 0.84, specificity 0.92), is widely available and non-invasive, but its accuracy is lower for disease proximal to the terminal ileum. MRI has a high diagnostic accuracy for the diagnosis of suspected CD and for evaluation of disease extension and activity (sensitivity 0.93, specificity 0.90), and is less dependent on the examiner and disease location compared with US. CT has a similar accuracy to MRI for assessment of disease extension and activity. The three techniques have a high accuracy for identification of fistulas, abscesses and stenosis (sensitivities and specificities >0.80), although US has false positive results for abscesses. As a result of the lack of radiation, US or MRI should be preferred over CT, particularly in young patients.

CONCLUSIONS

Cross-sectional imaging techniques have a high accuracy for evaluation of suspected and established CD, reliably measure disease severity and complications; they may offer the possibility to monitor disease progression.

New concepts in intestinal imaging for inflammatory bowel diseases

In the last decade, multiple imaging technologies have been developed that improve visualization of the mucosal, mural, and perienteric inflammation associated with inflammatory bowel diseases. Whereas these technologies have traditionally been used to detect and stage suspected enteric inflammation, we review new, emerging roles in detecting clinically occult inflammation (in asymptomatic patients) and inflammatory complications, predicting response prior to therapy, assessing response after therapy, and enteric healing. We compare the relative performance of these technologies in detecting inflammation, focusing on their advantages and disadvantages and how they might complement each other. We also discuss their potential benefits for patients and clinical trials, reviewing technologic developments and areas of research that could provide important insights into the pathophysiology of inflammatory bowel diseases-related enteric inflammation.

Inflammatory bowel disease: a systematic review on the value of diagnostic testing in primary care

AIM

The clinical presentation of inflammatory bowel disease in primary care represents a diagnostic challenge as its symptoms are heterogeneous and common. To assist the primary care physician, we have summarized the available evidence on diagnostic tests in patients with abdominal symptoms.

METHOD

We searched PubMed and Embase and screened references. Studies were selected if the design was a primary diagnostic study. Patients were adults attending with nonacute abdominal symptoms. Tests included clinical assessment, blood or faecal tests or abdominal ultrasonography. Quality assessment using a modified version of the QUADAS tool and data extraction was performed by two reviewers independently. Diagnostic two-by-two tables and pooled estimates of sensitivity and specificity are given. We refrained from pooling when there was considerable clinical or statistical heterogeneity.

RESULTS

A total of 24 studies were included. While the diagnostic performance of the individual symptoms was highly variable (range sensitivity 0.0-0.96, specificity 0.09-1.0), the performance of symptom-based classification systems was both more consistent and better (sensitivity 0.65-1.0, specificity 0.17-0.82). Among faecal and blood tests, calprotectin was studied most frequently and showed the best results (sensitivity 0.61-1.0, specificity 0.71-1.0). Statistical pooling for ultrasonography resulted in a sensitivity of 0.73 (0.65-0.80) and a specificity of 0.95 (0.91-0.97).

CONCLUSION

Although calprotectin and ultrasonography showed consistent and promising findings, none of the studies was performed in primary care. To assist primary care physicians in diagnostic decision making, we urgently need high quality studies performed in primary care.

Use of small bowel imaging for the diagnosis and staging of Crohn's disease--a survey of current UK practice

OBJECTIVES

This study used a postal survey to assess the current use of small bowel imaging investigations for Crohn's disease within National Health Service (NHS) radiological practice and to gauge gastroenterological referral patterns.

METHODS

Similar questionnaires were posted to departments of radiology (n = 240) and gastroenterology (n = 254) identified, by the databases of the Royal College of Radiologists and British Society of Gastroenterologists. Questionnaires enquired about the use of small bowel imaging in the assessment of Crohn's disease. In particular, questionnaires described clinical scenarios including first diagnosis, disease staging and assessment of suspected extraluminal complications, obstruction and disease flare. The data were stratified according to patient age.

RESULTS

63 (27%) departments of radiology (20 in teaching hospitals and 43 in district general hospitals (DGHs)) and 73 (29%) departments of gastroenterology replied. These departments were in 119 institutions. Of the 63 departments of radiology, 55 (90%) routinely performed barium follow-though (BaFT), 50 (80%) CT, 29 (46%) small bowel ultrasound (SbUS) and 24 (38%) small bowel MRI. BaFT was the most commonly used investigation across all age groups and indications. SbUS was used mostly for patients younger than 40 years of age with low index of clinical suspicion for Crohn's disease (in 44% of radiology departments (28/63)). MRI was most frequently used in patients under 20 years of age for staging new disease (in 27% of radiology departments (17/63)) or in whom obstruction was suspected (in 29% of radiology departments (18/63)). CT was preferred for suspected extraluminal complications or obstruction (in 73% (46/63) and 46% (29/63) of radiology departments, respectively). Gastroenterological referrals largely concurred with the imaging modalities chosen by radiologists, although gastroenterologists were less likely to request SbUS and MRI.

CONCLUSION

BaFT remains the mainstay investigation for luminal small bowel Crohn's disease, with CT dominating for suspected extraluminal complications. There has been only moderate dissemination of the use of MRI and SbUS.

Value of mucosal assessment and biomarkers in inflammatory bowel disease

Clinical remission at a single point in time provides surprisingly little predictive value for future inflammatory bowel disease (IBD) activity owing to the waxing and waning nature of the disease course. Furthermore, patients often present with complications of IBD despite apparent clinical remission, suggesting that undetected subclinical inflammation is driving these complications. This has led to research on a variety of surrogate markers of biologically significant asymptomatic inflammatory disease activity, including endoscopic healing, histologic normalization and biomarkers of inflammation in the blood and stool. If these have strong predictive value, they could be used to risk-stratify patients and justify the early use of immunomodulators and anti-TNF agents. Mucosal healing has been associated with positive outcomes in IBD, but the supporting data are largely retrospective and subject to channeling bias, and it is not clear whether complete mucosal healing produces better outcomes than partial healing. Stool and blood biomarkers correlate well with mucosal inflammation, but are imperfect surrogates for mucosal healing. Before using surrogate markers of intestinal inflammation to justify long-term, potentially toxic and costly therapy, prospective longitudinal studies are needed to identify surrogate end points with cut points that justify changes in therapy, and which therapies provide cost-effective benefits for mild, moderate or severe inflammation.

Ultrasound and inflammatory bowel disease

Transabdominal bowel sonography is a fast, efficient, and cheap way of examining the intestines. It is also virtually hazard-free and well accepted by patients. During the last 20 years, it has been established as a procedure for detecting bowel disease early in the diagnostic workup. Although rather unspecific, the method is sensitive for detection of bowel disease and can be applied to find the extent and location of inflammatory bowel disease. In patients with known ulcerative colitis and Crohn disease, it can also be used for follow-up because it is easily repeatable and radiation-free. Because it can be applied to find both intraluminal and peri-intestinal pathological features, it is a particularly valuable tool for the detection of complications of Crohn disease as stenosis, fistulas, and abscesses. Neither B-mode nor Doppler techniques have been proven obviously useful in categorizing disease activity, but new techniques using intravenous contrast might come closer to solving this question. Finally, recent longitudinal studies using transabdominal bowel sonography show that it can also give important prognostic information and be used for monitoring the effect of therapy.

Sonography of the small intestine

In the last two decades, there has been substantial development in the diagnostic possibilities for examining the small intestine. Compared with computerized tomography, magnetic resonance imaging, capsule endoscopy and double-balloon endoscopy, ultrasonography has the advantage of being cheap, portable, flexible and user- and patient-friendly, while at the same time providing the clinician with image data of high temporal and spatial resolution. The method has limitations with penetration in obesity and with intestinal air impairing image quality. The flexibility ultrasonography offers the examiner also implies that a systematic approach during scanning is needed. This paper reviews the basic scanning techniques and new modalities such as contrast-enhanced ultrasound, elastography, strain rate imaging, hydrosonography, allergosonography, endoscopic sonography and nutritional imaging, and the literature on disease-specific findings in the small intestine. Some of these methods have shown clinical benefit, while others are under research and development to establish their role in the diagnostic repertoire. However, along with improved overall image quality of new ultrasound scanners, these methods have enabled more anatomical and physiological changes in the small intestine to be observed. Accordingly, ultrasound of the small intestine is an attractive clinical tool to study patients with a range of diseases.

Reproducibility of bowel ultrasonography in the evaluation of Crohn's disease

BACKGROUND

Bowel ultrasonography is increasingly used in the detection and follow-up of patients with Crohn's disease, but a limitation to its further diffusion is the lack of standardisation of ultrasonography parameters.

AIMS

This study aimed to standardise the most common bowel ultrasonography parameters in order to develop an unequivocal imaging interpretation and to assess bowel ultrasonography reproducibility.

PATIENTS

Twenty patients with Crohn's disease were examined.

METHODS

Six ultrasonographers (mean bowel ultrasonography experience=16 years) performed the study. They chose and discussed a common assessment methodology concerning eight ultrasonography parameters: bowel wall thickness, bowel wall pattern, bowel wall blood flow, enlarged mesenteric lymph nodes, mesenteric hypertrophy, abdominal free fluid, and stenosis or fistulae at four preliminary meetings. The day of the study operators were randomised to two rooms where they independently and in turn performed ultrasonography scans. Interobserver agreement was scored by kappa statistics.

RESULTS

Excellent k values were observed for bowel wall thickness (0.72-1). k Values were poor for bowel wall pattern (-0.22-0.85) and good for bowel wall blood flow (0.53-0.89). The presence of lymph nodes was reproducible (0.56-0.90) except in one case (0.25). Concordance on free fluid was excellent (0.85-1), whereas that on mesenteric hypertrophy was generally poor (0.14-0.69). Agreement was excellent for stenosis (0.81-1) whereas that for fistula was fair in room abscesses (0.31-0.48) and very good in room B (0.87-1).

CONCLUSION

Bowel ultrasonography signs used in Crohn's disease can be standardised as most of them showed a fair to good reproducibility. In particular, bowel wall thickness, the most relevant parameter for Crohn's disease detection, showed an excellent reproducibility.

Technology Insight: new techniques for imaging the gut in patients with IBD

Advances in techniques for imaging the gut continue to drive the rapid development of modalities for diagnosing and assessing the activity of IBD. Abdominal ultrasound and magnetic resonance enterography have shown great potential for the diagnosis of IBD and assessment of its distribution, with the benefit of avoiding radiation exposure and serving as a safe option for pregnant patients. CT enterography or CT enteroclysis, with neutral or negative contrast, seems to be a sensitive and specific modality for detecting disease in the small bowel. The role of CT or magnetic resonance colonography in patients with IBD remains uncertain and these modalities are now best reserved for patients who decline or cannot undergo standard endoscopic evaluations. Capsule endoscopy might be the most sensitive modality for the detection of mucosal small bowel disease, but its specificity remains in question. Double-balloon endoscopy is an exciting new tool that has the distinct advantage of enabling biopsy or treatment of lesions detected during the procedure. All these techniques are at the forefront of the rapidly evolving field of imaging the gut in patients with IBD.

Imaging of gastrointestinal and hepatic diseases during pregnancy

Imaging of the abdomen for suspected gastrointestinal and hepatic disease during pregnancy is assuming greater importance. Like clinical evaluation, imaging of the abdomen and pelvis is challenging but is vitally important to prevent delayed diagnosis or unnecessary interventions. Also choice of imaging modality is influenced by factors which could impact on fetal safety such as the use of ionising radiation and magnetic resonance imaging. This article discusses important issues in imaging of gastrointestinal and hepatic disease in pregnancy and the puerperium.

Imaging of the small bowel in Crohn's disease: A review of old and new techniques

The investigation of small bowel morphology is often mandatory in many patients with Crohn’s disease. Traditional radiological techniques (small bowel enteroclysis and small bowel follow-through) have long been the only suitable methods for this purpose. In recent years, several alternative imaging techniques have been proposed. To review the most recent advances in imaging studies of the small bowel, with particular reference to their possible application in Crohn’s disease, we conducted a complete review of the most important studies in which traditional and newer imaging methods were performed and compared in patients with Crohn’s disease. Several radiological and endoscopic techniques are now available for the study of the small bowel; each of them is characterized by a distinct profile of favourable and unfavourable features. In some cases, they may also be used as complementary rather than alternative techniques. In everyday practice, the choice of the technique to be used stands upon its availability and a careful evaluation of diagnostic accuracy, clinical usefulness, safety and cost. The recent development of innovative imaging techniques has opened a new and exciting area in the exploration of the small bowel in Crohn’s disease patients.

Bowel ultrasound in Crohn's disease

Most published studies have found bowel ultrasound to be a useful tool in the management of Crohn's disease. Indeed, it has been successfully used as the imaging technique of choice in screening patients with clinically suspected Crohn's disease. In these patients, bowel ultrasound, which is well accepted by patients, non-invasive and of low cost, may be the first diagnostic tool employed for young patients and can be used in the preliminary diagnostic work-up prior to further invasive tests. The most important application of bowel ultrasound is, however, in the follow-up of patients already diagnosed with Crohn's disease, in whom it may be useful to assess the site and extent of the lesions and to ensure the early detection of intra-abdominal complications, particularly abscesses and strictures. In this regard, improving the ultrasound assessment of intramural blood flow by means of colour power-Doppler ultrasonography and intravenous contrast agents may help to differentiate fibrotic and inflammatory strictures, and to discriminate inflammatory masses from intra-abdominal abscesses. Despite several attempts to correlate ultrasound findings with clinical and biochemical activity, there are as yet no convincing data on the usefulness of ultrasound in assessing the activity of Crohn's disease. In contrast, preliminary results are in agreement regarding the usefulness of ultrasound in the assessment of postoperative recurrence and in monitoring the outcome of the disease following surgery. In fact, the persistence of a thickened bowel wall or increased high bowel wall thickening at ultrasound following surgery has been identified as an index of early surgical recurrence. How these data may be usefully employed in the management of individuals with Crohn's disease needs to be investigated in further studies.

Role of US in detection of Crohn disease: meta-analysis

PURPOSE

To evaluate the accuracy of ultrasonography (US) in the detection of Crohn disease in adults by systematically reviewing both cohort studies (those including patients whose clinical characteristics were consistent with those caused by an inflammatory bowel disease) and case-control studies (those in which patients with Crohn disease were compared with patients with other bowel diseases or healthy control subjects).

MATERIALS AND METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were used to retrieve all the cross-sectional studies that assessed the diagnostic accuracy of US against that of one of several predefined reference standards (ie, radiologic, endoscopic, or histologic findings). The studies that fulfilled the inclusion criteria were identified, and their methodological quality was evaluated. Of the 2860 primary studies identified, two case-control and five cohort series fulfilled the inclusion criteria. Statistical analysis was performed by using the summary receiver operating characteristic (SROC) model.

RESULTS

The ranges of US sensitivity and specificity for the diagnosis of Crohn disease reported for the included series were 75%-94% and 67%-100%, respectively; the heterogeneity of these values prevented the calculation of a cumulative value. The SROC curve revealed a clear cutoff effect that depended on the chosen bowel wall thickness threshold. Sensitivity and specificity of 88% and 93%, respectively, were achieved when a bowel wall thickness threshold greater than 3 mm was used, and sensitivity and specificity of 75% and 97%, respectively, were achieved when a threshold greater than 4 mm was used.

CONCLUSION

US examination seems appropriate for confirming or excluding Crohn disease as a diagnosis in a clinical context characterized by a pretest probability of Crohn disease that ranges from 12% to about 60%. In particular, for Crohn disease limited to the ileum, US may represent a valid alternative to the small-bowel series, while for colonic involvement US may be useful in ruling out the diagnosis.

Focal bowel wall changes detected with colour Doppler ultrasound: diagnostic value in acute non-diverticular diseases of the colon

We performed a study to determine if colour Doppler findings may help to identify the cause of wall thickening in acute non-diverticular diseases of the colon. The study group included 66 patients admitted to the emergency department with a final diagnosis of infectious colitis (n=23), inflammatory colitis (n=10), ischaemic colitis (n=23) and malignant tumours (n=10). The following ultrasound features were assessed: maximal wall thickness, wall stratification, arterial flow in the colonic wall and arteriolar resistive index. Higher values of wall thickness were observed in malignant tumour (18.2+/-6.2 mm, p<0.001). Moderately thickened wall (6.6+/-1.3 mm, p< or =0.06), preserved stratification (90% versus 46% in the remainder of the study population) and lower resistive index (0.51+/-0.10, p< or =0.05) were significantly related to inflammatory colitis. Absence of arterial flow was more frequently observed in ischaemia (43% versus 12% in the remainder of the study population). In conclusion, despite some overlap, both ultrasound and colour Doppler features are helpful in the differential diagnosis of colonic thickening related to non-diverticular colonic lesions.

Intestinal imaging of children with acute rotavirus gastroenteritis

OBJECTIVE

To examine the morphology and motility of the distal small bowel of infants with rotavirus gastroenteritis using non-invasive/non-ionizing imaging technology.

METHODS

Prospective, non-randomized observational study of five infants with symptomatic rotavirus infection. Infants were imaged by real-time magnetic resonance imaging (MRI) and ultrasound within 5 days of onset of gastroenteritis symptoms. Imaging studies were repeated in the convalescent period 5 to 9 weeks later.

RESULTS

Three of five infants had a significant increase in the ileal wall thickness visualized by ultrasound during acute rotavirus infection compared with convalescence. The number and size of mesenteric lymph nodes visualized by ultrasound appeared similar in the acute and convalescent phases, as did peristaltic activity assessed by MRI.

CONCLUSION

Abdominal ultrasound can detect changes in ileal wall thickness in infants with rotavirus infection. These changes may reflect ileal inflammation elicited by viral infection. Such studies may prove useful in evaluating morphologic response to attenuated rotavirus vaccines.

Modern imaging of Crohn's disease using bowel ultrasound

Technological advancement of ultrasound (US) equipments and understanding of bowel appearances with high resolution US during the last decade has led to consideration of this imaging procedure as an important tool for inflammatory bowel diseases assessment. In particular, Crohn's disease (CD) for its pathologic characteristics (that is, inflammatory infiltration of the entire bowel wall with possible extension to the surrounding mesentery) is the disease entity which has mainly taken advantage from this non-invasive, radiation-free technique. Beside correctly defining anatomic location and extension of CD lesions within the bowel in the majority of cases, US also shows perigut abnormalities and may demonstrate complications such as fistulas and abscesses. With the help of Power Doppler function, some additional information may be obtained about the local activity of the disease which is particularly useful in the presence of strictures. New US technologies (such as those using intravenous bolus contrast agents or oral nonabsorbable anechoic solutions) may further improve diagnostic capability of US in this context, thus probably revolutioning the diagnostic approach to this disease in the near future, particularly during follow-up in CD of the small bowel.

Activity of Crohn disease: value of Color-Power-Doppler and contrast-enhanced ultrasonography

Diagnosis and follow-up of Crohn disease (CD) often require invasive instrumental examinations, with a high risk of iatrogenic damage. Ultrasound (US) examination of bowel walls could be the first choice in managing patients with CD. We evaluated the role of tissue color power Doppler (CPD) and B-mode US with intravenous injection of contrast medium in the detection of disease activity. In our series, 52 patients with CD underwent US examination. Each study was completed with tissue CPD and US with intravenous injection of contrast medium (Sono Vue) to evaluate intestinal wall vascularization as an index of disease activity. We then compared our results with those from clinical and laboratory tests and follow-up. Data from US examination with intravenous injection of Sono Vue partly agreed with clinical and laboratory tests and CPD in disease activity evaluation but were most useful in the follow-up. Bowel US examination associated with CPD and in particular US contrast medium injection can be used to detect CD activity and modulate therapy and follow-up.

Role of early ultrasound in detecting inflammatory intestinal disorders and identifying their anatomical location within the bowel

BACKGROUND

Although bowel ultrasound is a widely accepted diagnostic tool in bowel diseases, its value as the primary imaging procedure in patients with symptoms/signs suggestive of inflammatory bowel disorders is still unclear.

AIM

To investigate the accuracy of bowel ultrasound compared with barium X-ray studies, computed tomography, endoscopy and bowel surgery in the initial assessment of inflammatory bowel disorders.

METHODS

Four hundred and eighty-seven patients hospitalized consecutively for symptoms or signs suggestive of a bowel disorder between December 1999 and March 2002 were initially enrolled in the study. All patients underwent bowel ultrasound as the first imaging procedure within 36 h of admission; radiographic evaluations, endoscopy and/or surgery were then performed as appropriate and the results of these investigations were used as the gold standard.

RESULTS

Three hundred and thirty-six patients had pathological findings of the bowel detectable at ultrasound as the final diagnosis. The main organic disorders found were Crohn's disease (56%), ulcerative/indeterminate colitis (30%), bowel tumours (5%), appendicitis/diverticulitis (2%) and other inflammatory conditions (8%). The overall sensitivity and specificity of bowel ultrasound were 85% and 95%, respectively, whereas the positive and negative predictive values were 98% and 75%, respectively. Comparisons of ultrasound with X-ray or endoscopic results by disease localization showed that the diagnostic performance of ultrasound was higher for inflammatory conditions of the ileum and sigmoid/descending colon (sensitivity of 92% and 87%, respectively), whereas abnormalities localized in the rectum, duodenum and proximal jejunum were often missed by ultrasound.

CONCLUSIONS

In expert hands, bowel ultrasound is highly predictive of inflammatory disease localized in the ileum or colon, and may well be used as the primary imaging method when Crohn's disease or ulcerative colitis is suspected on a clinical basis.

Ultrasonographic and clinicopathologic findings in 21 dogs with intestinal adenocarcinoma

In a retrospective study of 21 dogs with intestinal adenocarcinoma, the signalment, clinical presentation, laboratory findings, ultrasonographic features, treatment, and outcome were reviewed. Anorexia (n = 16), vomiting (n = 15), diarrhea (n = 10), and weight loss (n = 9) were the most common clinical signs reported. Ultrasonographic features that were evaluated included location, length, wall thickness, echogenicity, regional motility, layering, regional lymphadenopathy, and fluid accumulation proximal to the lesion site. All lesions were transmural and associated with complete loss of wall layering. Maximum wall thickening at the lesion site ranged from 7 to 17 mm (median 12 mm, mean 11.9 mm). Most of the dogs had a lesion measuring from 23 to 63 mm in length, (median 40 mm, mean 42 mm). Most intestinal lesions were poorly echogenic and had an irregular lumen. Fluid accumulation proximal to the lesion site was identified in 17 of 21 dogs, and in 13 of 17 dogs the fluid accumulation was considered moderate to severe. Regional lymphadenopathy and/or nodular mesentery/omentum were noted in 12 of 21 dogs. The tumor was located in small intestine for 15 dogs and in the colon for the remaining 6 dogs. Fifteen dogs were treated by surgical resection of the intestinal mass. Their median survival time was 233 days. Only gender appeared to influence survival. Female dogs lived a median of 28 days, whereas male dogs lived a median of 272 days.

Abdominal pain and bowel dysfunction: diagnostic role of intestinal ultrasound

BACKGROUND

Abdominal pain and irregular bowel habits are common among young people. Irritable bowel syndrome is frequent in the general population and has important economic and social costs. Inflammatory bowel diseases are chronic processes with an acute or indolent onset in young people. Differential clinical diagnosis between irritable bowel syndrome and inflammatory bowel disease can be difficult since symptoms and signs are often non-specific.

OBJECTIVE

To evaluate the role of intestinal ultrasound, a non-invasive, simple and cheap diagnostic tool, in the differentiation between organic and functional bowel diseases.

METHODS

Abdominal and intestinal ultrasound examinations were performed on 313 consecutive outpatients presenting with abdominal pain and irregular bowel habits lasting more than 3 months. These patients had no symptoms or signs indicative of organic disorders and no previous diagnosis of organic disease. An intestinal wall thickness of more than 7 mm was considered diagnostic for inflammatory bowel disease. Subsequently, we compared the ultrasound results with diagnoses obtained following the traditional criteria (radiological and endoscopic examinations).

RESULTS

Intestinal ultrasound for the diagnosis of inflammatory bowel disease showed 74% sensitivity, 98% specificity, a positive predictive value of 92% and a negative predictive value of 92%.

CONCLUSIONS

In our experience, intestinal ultrasound seems important as a first diagnostic tool in young patients without clear symptoms or signs of organic diseases, and can be used as an indication that subsequent invasive tests are required.

Transabdominal ultrasonography of the small bowel after oral administration of a non-absorbable anechoic solution: comparison with barium enteroclysis

AIM

The aim of this study was to determine if oral administration of a non-absorbable anechoic solution conveys any benefit during abdominal ultrasound (US), with special reference to its accuracy.

MATERIALS AND METHODS

Fifty-three adult out-patients scheduled for small bowel barium enema (SBE) were included. The day before SBE all patients underwent abdominal US before and after oral administration of an isotonic non-absorbable electrolyte solution containing polyethylene glycol (PEG-ELS). Sensitivity and specificity were evaluated using SBE as a gold standard.

RESULTS

After ingestion of PEG-ELS satisfactory distension of the intestinal lumen was obtained (11-25 mm) with sequential visualization of jejunoileal loops in 30.9 +/- 17.3 min. In 15 out of 53 cases both US and SBE showed bowel changes characteristic of Crohn's disease. In three out of 53 cases both US and SBE showed neoplasms. In one out of 53 cases US was negative, SBE positive for local nodularity and ulcerations typical of Crohn's disease. In one out of 53 cases US was negative, SBE positive for macronodularity consistent with coeliac disease. In five out of 53 cases US was negative, while SBE was positive for mininodularity expressive of lymphoid hyperplasia. In 28 out of 53 cases both examinations were negative.

CONCLUSION

PEG-ELS administration allows a thorough US investigation of the small bowel, with fair sensitivity (72%) and excellent specificity (100%). False negative findings are mainly due to lymphoid hyperplasia, a feature of uncertain significance in adults.

Prognosis of ischemic colitis: comparison of color doppler sonography with early clinical and laboratory findings

OBJECTIVE

The objective of this study was to compare the value of color Doppler sonography with early clinical and laboratory findings in determining the prognosis of patients with ischemic colitis.

SUBJECTS AND METHODS

We reviewed the early clinical, laboratory, and color Doppler sonographic data of 24 patients with ischemic colitis. The patients were divided into two groups on the basis of their outcome. The first group comprised the patients with transient ischemia who recovered uneventfully, and the second group included the patients who needed surgery because of symptomatic transmural colic gangrene or colic stricture. Clinical data and laboratory values were compared with color Doppler sonographic findings including colic wall thickness, presence of stratification, and arterial flow in the bowel wall.

RESULTS

At univariate analysis, increased age (p = 0.007), leukocyte count (p = 0.030), lactate dehydrogenase level (p = 0.030), blood lactate level (p = 0.041), and absence of vascular flow in the colic wall (p<0.001) were significantly related to complicated ischemic colitis. At multivariate analysis, absence of arterial flow was the only significant predictor of complicated ischemic colitis (p = 0.002), with a sensitivity of 82%, a specificity of 92%, a positive predictive value of 90%, and a negative predictive value of 86%.

CONCLUSION

Absence of arterial flow in the wall of the ischemic colon on initial color Doppler sonography is suggestive of an unfavorable outcome and is more closely associated with outcome than early clinical and laboratory findings.

Transient appendiceal enlargement in a patient with colonic amebiasis: sonographic detection and follow-up

A case of colonic amebiasis with no clinical signs of acute appendicitis but with sonographic visualization of an enlarged appendix is reported. As antiamebic therapy resolved the clinical signs and symptoms of the amebiasis, the sonographic appearance of the appendix returned to normal. Thus, an enlarged appendix does not necessarily indicate clinical appendicitis in patients with colonic amebiasis.

Sonographic findings in methamphetamine-induced ischemic colitis

Ischemic colitis is a clinicopathologic condition that commonly occurs in elderly patients with atherosclerotic disease or diabetes mellitus. Uncommon etiologies include vasculitis and use of drugs such as oral contraceptives, phenobarbital, nasal decongestants, dextroamphetamine, and cocaine. Recent studies have shown sonography and CT to be helpful in the evaluation of the colitides. We report the sonographic and CT findings in an unusual case of methamphetamine-induced ischemic colitis. Sonography and CT revealed diffuse thickening of the large bowel wall. Methamphetamine abuse should be considered in the differential diagnosis of the colitides, particularly in the setting of a young patient with a history of drug use and no other predisposing conditions.

Role of ultrasonography in the diagnosis of postsurgical recurrence of Crohn's disease

OBJECTIVE

Ultrasonography is a valid tool in the diagnosis of Crohn's disease, but its sensitivity, specificity, and overall accuracy in the diagnosis of postoperative recurrence are still not well established. The aim of this study was to evaluate the accuracy of ultrasonography compared with endoscopy in the diagnosis of postoperative recurrence of Crohn's disease.

METHODS

Forty-seven patients resected for Crohn's ileitis were studied by ultrasonography and colonoscopy to detect possible recurrence of the disease; 10 patients operated on for cancer of the right colon were used as controls. Six patients with Crohn's disease were excluded from the study because of failure to endoscopically reach the anastomosis; the remaining 41 patients had both ultrasonography and colonoscopy over a period of 14 days. Sonographic recurrence was defined as the presence of >5 mm thickness of the ileal wall.

RESULTS

Sensitivity, specificity, and overall accuracy of ultrasonography in diagnosis of postoperative recurrence were 81%, 86%, and 83% respectively. Positive predictive value was 96% and negative predictive value was 57%.

CONCLUSION

This study is the first to assess the role of ultrasonography in comparison with endoscopy in detecting Crohn's disease recurrence after surgery. Our data suggest that ultrasonography should be used first in the case of clinical suspicion of Crohn's disease recurrence, reserving ileocolonoscopy for negative or uncertain cases.