Helical CT of the small bowel with an alternative oral contrast material in patients with Crohn disease

How the Radiologist Must Reason for a Correct Diagnosis in Patients With Small Bowel Mural Thickening Studied by CT or MRI: A Pictorial Review

Conditions that lead to small bowel mural thickening fall into a broad spectrum of diseases, including inflammatory, infectious, vascular or neoplastic. Computed tomography (CT) and Magnetic Resonance Imaging (MRI), especially CT-enterography and MR-enterography, permit evaluation of both entire small bowel and extraluminal structures. In CT/MR-enterography, the main prerequisite for the correct evaluation of small bowel is to obtain optimal intestinal distension. In fact, most errors are related to poor intestinal distension of the bowel which can lead to interpret as pathological a small bowel segment that is not very distended (false positive), or not to recognize presence of pathology in a collapsed segment (false negative). Once the examination has been performed, the images are analyzed in order to identify the presence of small bowel pathology. Pathology of the small bowel can manifest as endoluminal alteration and/or intestinal wall thickening. Once bowel wall thickening has been identified, the radiologist's first objective is trying to define benign or malignant nature of the alteration, using also patient's history and clinical features. Once the suspicion of benign or malignant pathology has been raised, the radiologist must try to formulate a diagnosis of nature. In this pictorial review we describe how the radiologist must reason for a correct diagnosis by answering a pattern of sequential questions in a patient with suspected small bowel disease studied by CT or MRI.

CT and MRI Evaluations in Crohn's Complications: A Guide for the Radiologist

Inflammatory bowel diseases (IBD) are a group of chronic inflammatory intestinal conditions with unknown etiology. Crohn's disease (CD) and ulcerative colitis (UC) are the two main types of IBD and they have some interchangeable and some different clinical and pathological characteristics. When diagnosis is performed for the first time, the majority of CD patients have a predominant inflammatory condition. As the disease progresses most patients experience the development of complications, such as abscesses, fistulas, perforation, strictures, and others. Both computed tomography (CT) and Magnetic Resonance Imaging (MRI) allow great view of the whole length of the intestinal tract together with the eventual extra-and intra-intestinal complications. MR enterography (MRE) and CT enterography (CTE), performed after oral administrations of contrast medium, have similar diagnostic accuracy for the diagnosis of CD and its complications. Even though CT is still the most familiar diagnostic technique used for studying CD worldwide, MRE have several important benefits that are leading to rapid increase in its employment in the last years. In particular, MRE allows a superior soft tissue contrast resolution compared to CT, offering a better visualization of bowel wall and its inflammatory and fibrotic characteristics. Moreover, Pelvic Magnetic Resonance is the principal technique in patients with perianal disease due to its ability of providing precise and fine detail images of the sphincter complex, which are crucial for evaluating pelvic disease. In this paper we describe common and uncommon complications in patients with CD, and explain how to identify their findings in CT and MR exams.

ACR Appropriateness Criteria® Crohn Disease

Three common clinical scenarios involving use of imaging in Crohn disease are covered. These include the initial evaluation of Crohn disease when the diagnosis has not been previously established, the evaluation for anticipated exacerbation of known disease, and the evaluation of disease activity during therapy monitoring. The appropriateness of a given imaging modality for each scenario is rated as one of three categories (usually appropriate, may be appropriate, usually not appropriate) to help guide evaluation. Pediatric presentation of Crohn disease and the appropriateness of imaging are not covered in this document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria Crohn Disease

Crohn disease is a chronic inflammatory disorder involving the gastrointestinal tract, characterized by episodic flares and times of remission. Underlying structural damage occurs progressively, with recurrent bouts of inflammation. The diagnosis and management of this disease process is dependent on several clinical, laboratory, imaging, endoscopic, and histologic factors. In recent years, with the maturation of CT enterography, and MR enterography, imaging has played an increasingly important role in relation to Crohn Disease. In addition to these specialized examination modalities, ultrasound and routine CT have potential uses. Fluoroscopy, radiography, and nuclear medicine may be less beneficial depending on the clinical scenario. The imaging modality best suited to evaluating this disease may change, depending on the target population, severity of presentation, and specific clinical situation. This document presents seven clinical scenarios (variants) in both the adult and pediatric populations and rates the appropriateness of the available imaging options. They are summarized in a consolidated table, and the underlying rationale and supporting literature are presented in the accompanying narrative. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Small intestinal contrast ultrasonography for the detection of small bowel complications in Crohn's disease: correlation with intraoperative findings and magnetic resonance enterography

BACKGROUND AND AIMS

In evaluating small bowel Crohn's disease (CD), small intestine contrast-enhanced ultrasonography (SICUS) is emerging as an alternative to magnetic resonance enterography (MRE). This retrospective study compared the diagnostic accuracy of SICUS and MRE with surgical findings, and their level of agreement.

METHODS

We identified a cohort of CD patients investigated by either SICUS and/or MRE that subsequently required resective bowel surgery within 6 months. The accuracy and agreement of SICUS and MRE to detect small bowel complications were compared with intraoperative findings using kappa coefficient (κ). Agreement between SICUS and MRE in those undergoing both modalities was also assessed.

RESULTS

A total of 67 patients were evaluated; 25 underwent SICUS and 17 underwent MRE prior to surgery. Another 25 patients underwent both SICUS and MRE. When compared with intraoperative findings, the sensitivity of SICUS and MRE was 87.5% and 100%, respectively, in detecting strictures, 87.7% and 66.7% for fistulae, 100% for both in identifying abscesses, 100% and 66.7% for bowel dilatation, and 94.7% and 81.8% in defining bowel wall thickening. When correlating SICUS and MRE with surgery, there was a high level of agreement in localizing strictures (κ = 0.75, 0.88, respectively), fistulae (κ = 0.82, 0.79) and abscesses (κ = 0.87, 0.77). Concordance between SICUS and MRE was substantial or almost complete in identifying stricturing disease (κ = 0.84), their number and location (κ = 0.85), fistulae (κ = 0.65), and mucosal thickening (κ = 0.61).

CONCLUSION

SICUS accurately identified small bowel complications and correlated well with MRE and intraoperative findings. SICUS offers an alternative in the preoperative assessment of CD.

Comparison of 3% sorbitol vs psyllium fibre as oral contrast agents in MR enterography

OBJECTIVE

To compare the degree of small bowel distension achieved by 3% sorbitol, a high osmolarity solution, and a psyllium-based bulk fibre as oral contrast agents (OCAs) in MR enterography (MRE).

METHODS

This retrospective study was approved by our institutional review board. A total of 45 consecutive normal MRE examinations (sorbitol, n = 20; psyllium, n = 25) were reviewed. The patients received either 1.5 l of 3% sorbitol or 2 l of 1.6 g kg(-1) psyllium prior to imaging. Quantitative small bowel distension measurements were taken in five segments: proximal jejunum, distal jejunum, proximal ileum, distal ileum and terminal ileum by two independent radiologists. Distension in these five segments was also qualitatively graded from 0 (very poor) to 4 (excellent) by two additional independent radiologists. Statistical analysis comparing the groups and assessing agreement included intraclass coefficients, Student's t-test and Mann-Whitney U-test.

RESULTS

Small bowel distension was not significantly different in any of the five small bowel segments between the use of sorbitol and psyllium as OCAs in both the qualitative (p = 0.338-0.908) and quantitative assessments (p = 0.083-0.856). The mean bowel distension achieved was 20.1 ± 2.2 mm for sorbitol and 19.8 ± 2.5 mm for psyllium (p = 0.722). Visualization of the ileum was good or excellent in 65% of the examinations in both groups.

CONCLUSION

Sorbitol and psyllium are not significantly different at distending the small bowel and both may be used as OCAs for MRE studies.

ADVANCES IN KNOWLEDGE

This is the first study to directly compare the degree of distension in MRE between these two common, readily available and inexpensive OCAs.

Small bowel obstruction following computed tomography and magnetic resonance enterography using psyllium seed husk as an oral contrast agent

The authors report a case series describing four patients who developed small bowel obstruction following the use of psyllium seed husk as an oral contrast agent for computed tomography or magnetic resonance enterography. Radiologists who oversee computed tomography and magnetic resonance enterography should be aware of this potential complication when using psyllium seed husk and other bulking agents, particularly when imaging patients with known or suspected small bowel strictures or active inflammation.

Comparison of the results of computerized tomographic and diffusion-weighted magnetic resonance imaging techniques in inflammatory bowel diseases

AIM

To compare the findings obtained by computerised tomography (CT) enterography, which uses oral neutral contrast material and non-contrasted diffusion-weighted magnetic resonance imaging (DW-MRI) technique and reveal the diagnostic value of DW-MRI in patients with inflammatory bowel diseases.

METHODS

Patients with established or clinically suspect diagnosis of inflammatory bowel disease were included in the study. CT enterography and DW-MRI obtained from the patients were evaluated by a radiologist blinded to the endoscopic and/or histopathological results. Duodenum, jejunum, ileal loops, ascending, transverse, descending colon, sigmoid colon and rectum were evaluated in that order as for general imaging quality, luminal distension and adequate visualization of the intestinal wall. Image qualities of neutral contrast CT-enterography and DW-MRI were compared.

RESULTS

The study included 31 patients. Based on statistical analyses, the best correlation between the results of CT-enterography and diffusion-weighted imaging (DWI) were observed in the evaluation of transverse colon, ileum and duodenum in order of decreasing frequency and with an almost perfect compatibility. Radiological findings of sigmoid colon, jejunum and descending colon were completely compatible. However, a moderate degree of compatibility was estimated between radiological findings of rectum and cecum.

CONCLUSIONS

Though conventional enteroclysis is the gold standard method among radiological imaging techniques used for the evaluation of inflammatory small intestinal abnormalities, CT enterography and DW-MRI are alternative methods that can be used effectively to obtain useful information.

Small intestine contrast ultrasonography vs computed tomography enteroclysis for assessing ileal Crohn's disease

AIM: To compare computed tomography enteroclysis (CTE) vs small intestine contrast ultrasonography (SICUS) for assessing small bowel lesions in Crohn's disease (CD), when using surgical pathology as gold standard.

METHODS: From January 2007 to July 2008, 15 eligible patients undergoing elective resection of the distal ileum and coecum (or right colon) were prospectively enrolled. All patients were under follow-up. The study population included 6 males and 9 females, with a median age of 44 years (range: 18-80 years). Inclusion criteria: (1) certain diagnosis of small bowel requiring elective ileo-colonic resection; (2) age between 18-80 years; (3) elective surgery in our Surgical Unit; and (4) written informed consent. SICUS and CTE were performed ≤ 3 mo before surgery, followed by surgical pathology. The following small bowel lesions were blindly reported by one sonologist, radiologist, surgeon and histolopathologist: disease site, extent, strictures, abscesses, fistulae, small bowel dilation. Comparison between findings at SICUS, CTE, surgical specimens and histological examination was made by assessing the specificity, sensitivity and accuracy of each technique, when using surgical findings as gold standard.

RESULTS: Among the 15 patients enrolled, CTE was not feasible in 2 patients, due to urgent surgery in one patients and to low compliance in the second patient, refusing to perform CTE due to the discomfort related to the naso-jejunal tube. The analysis for comparing CTE vs SICUS findings was therefore performed in 13 out of the 15 CD patients enrolled. Differently from CTE, SICUS was feasible in all the 15 patients enrolled. No complications were observed when using SICUS or CTE. Surgical pathology findings in the tested population included: small bowel stricture in 13 patients, small bowel dilation above ileal stricture in 10 patients, abdominal abscesses in 2 patients, enteric fistulae in 5 patients, lymphnodes enlargement (> 1 cm) in 7 patients and mesenteric enlargement in 9 patients. In order to compare findings by using SICUS, CTE, histology and surgery, characteristics of the small bowel lesions observed in CD each patient were blindly reported in the same form by one gastroenterologist-sonologist, radiologist, surgeon and anatomopathologist. At surgery, lesions related to CD were detected in the distal ileum in all 13 patients, also visualized by both SICUS and CTE in all 13 patients. Ileal lesions > 10 cm length were detected at surgery in all the 13 CD patients, confirmed by SICUS and CTE in the same 12 out of the 13 patients. When using surgical findings as a gold standard, SICUS and CTE showed the exactly same sensitivity, specificity and accuracy for detecting the presence of small bowel fistulae (accuracy 77% for both) and abscesses (accuracy 85% for both). In the tested CD population, SICUS and CTE were also quite comparable in terms of accuracy for detecting the presence of small bowel strictures (92% vs 100%), small bowel fistulae (77% for both) and small bowel dilation (85% vs 82%).

CONCLUSION: In our study population, CTE and the non-invasive and radiation-free SICUS showed a comparable high accuracy for assessing small bowel lesions in CD.

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.

Role of computed tomography enterography/magnetic resonance enterography: is it in prime time?

Today, cross-sectional imaging modalities, such as computed tomography enterography (CTE) and magnetic resonance enterography (MRE), are particularly suited to evaluate small bowel diseases, especially Crohn's disease (CD). It is well known that CTE/MRE can provide excellent assessment of disease activity as well as the macroscopic features, extramural abnormalities, and complications of the small intestine in patients with CD. In general, CTE is considered as the first-line modality for the evaluation of suspected inflammatory bowel disease and for long-term assessment or follow-up of these patients. Because of the advantage of lack of radiation, MRE is being used more frequently, especially in children or young patients with CD.

Magnetic resonance enterography for Crohn's disease: what the surgeon can take home

BACKGROUND

Crohn's disease (CD) is a life-long, chronic, relapsing condition requiring often morphological assessment. MR enterography (MRE) offers advantages of not using ionizing radiation and yielding intraluminal and intra-abdominal informations. The aim of our study was to identify how MRE can be useful in planning surgical procedures.

PATIENTS AND METHODS

In this retrospective study, 35 patients who underwent MRE and then surgery for CD were enrolled from 2006 to 2010. MRE findings were compared to intraoperative findings. Histology of operative specimens, systemic inflammatory parameters, and fecal lactoferrin were also evaluated. Cohen's κ agreement test, sensitivity and sensibility, uni-/multivariate logistic regression, and non-parametric statistics were performed.

RESULTS

MRE identified bowel stenosis with a sensitivity of 0.95 (95% CI 0.76-0.99) and a specificity of 0.72 (95% CI 0.39-0.92). The concordance of MRE findings with intraoperative findings was high [Cohen's κ = 0.72 (0.16)]. Abscesses were detected at MRE with a sensitivity of 0.92 (95% CI 0.62-0.99) and a specificity of 0.90 (95% CI 0.69-0.98) with a Cohen's κ = 0.82 (0.16). The grade of proximal bowel dilatation resulted to be a significant predictor of the possibility of using strictureplasty instead of/associated to bowel resection either at univariate or at multivariate analysis.

CONCLUSION

Our study confirmed that MRE findings correlate significantly with disease activity. Detailed information about abscess could suggest percutaneous drainage that could ease the following surgery or avoid emergency laparotomy. Proximal bowel dilatation can suggest the possibility to perform bowel sparing surgery such as strictureplasty.

CT enterography with polyethylene glycol solution vs CT enteroclysis in small bowel disease

OBJECTIVE

The aim of the study is to compare CT enterography with polyethylene glycol solution (PEG-CT) with CT enteroclysis (CT-E) in patients with suspected small bowel disease.

METHODS

145 patients underwent abdominal contrast-enhanced 16-row multidetector CT after administration of 2000 ml of PEG by mouth (n = 75) or after administration of 2000 ml of methylcellulose by nasojejunal tube (n = 70). Small bowel distension, luminal and extraluminal findings were evaluated and compared with small bowel follow-through examination in 60 patients, double contrast enema in 50, surgery in 25 and endoscopy in 35. Statistical evaluation was carried out by χ² testing. For both techniques we have also calculated the effective dose and the equivalent dose in a standard patient.

RESULTS

Crohn's disease was diagnosed in 64 patients, neoplasms in 16, adhesions in 6. Distension of the jejunum was better with CT-E than PEG-CT (p<0.05: statistically significant difference). No significant difference was present for others sites (p>0.05). Evaluation of pathological ileal loops was good with both techniques. The values of sensitivity, specificity and diagnostic accuracy were respectively 94%, 100% and 96% with CT-E, and 93%, 94% and 93% with PEG-CT. The effective dose for PEG-CT was less than the dose for the CT-E (34.7 mSv vs 39.91 mSv).

CONCLUSION

PEG-CT shows findings of Crohn's disease as well as CT-E does, although CT-E gives better bowel distension, especially in the jejunum, and has higher specificity than PEG-CT.

MRI for diagnosis and evaluation of inflammatory bowel disease

As a non-invasive and ionizing radiation-free cross-sectional imaging technique, magnetic resonance imaging (MRI) has shown a bright future in following up patients with inflammatory bowel disease (IBD), especially child and young adult patients. The application of new techniques in MRI makes it possible to obtain MRI images that are richer in information and to evaluate the activity of IBD more objectively and quantitatively. This improvement is of great significance for clinical decision-making and evaluation of drug efficacy in IBD patients.

ACR Appropriateness Criteria on Crohn's disease

In the past decade, new therapeutic agents have been developed that permit gastroenterologists to treat virtually all forms of Crohn's disease. The success of these treatments depends on an accurate diagnosis of the nature and extent of disease. Fortunately, radiologists now possess a powerful arsenal of imaging techniques to guide the choice of therapy. This article discusses the usefulness of both traditional and newer imaging techniques in the management of Crohn's disease and its various clinical presentations.

Do radiologists agree on the quality of computed tomography enterography?

This study aimed to assess variation between radiologists evaluating the quality of multi-detector computed tomography enterography. For 40 consecutive examinations, three experienced radiologists independently rated the following quality variables: % length of adequately filled bowel, bowel lumen diameters, bowel wall delineation, superior mesenteric vein, and bowel wall enhancement, artefacts, and total quality. We calculated the mean difference between observers with standard deviation (SD) for continuous variables and % total agreement, exact Fleiss kappa, and P-values (McNemar's test) for categorical variables. Depending on bowel segment (duodenum distal to bulb, jejunum, ileum, terminal ileum), mean difference between observers ranged from two to 33 (SD from 11 to 32) for % length of adequately filled bowel judged subjectively, 0-2 (SD 0-3) mm for smallest bowel lumen diameter and 0-4 (SD 3-7) mm for largest bowel lumen diameter. Agreement on bowel wall delineation was 80%/kappa 0.50 in duodenum, 90%/kappa 0.57 in jejunum, 75%/kappa 0.14 in ileum and 88%/kappa 0.17 in terminal ileum, where ratings differed between observers (P < 0.04). Agreement was 65%/kappa 0.18 for bowel wall enhancement judged subjectively. For contrast enhancement measured in Hounsfield Units, mean difference between observers ranged from two to 11 (SD 12-15) in normal jejunum wall and zero to one (SD 4-5) in the superior mesenteric vein depending on observer pair. Agreement was 78%/kappa 0.12 for image artefacts. Rating of total examination quality (good/optimal versus poor/very poor) differed between observers (P < 0.01); agreement was 60%/kappa 0.41. Many subjective evaluations varied between observers. We believe that measurements of bowel lumen diameters and contrast enhancement may be preferable.

Correlation of MRI-determined small bowel Crohn’s disease categories with medical response and surgical pathology

AIM: To determine whether magnetic resonance imaging (MRI) can be used to categorize small bowel Crohn’s disease (SB CD) into groups that correlate with response to medical therapy and surgical pathology.

METHODS: Data was collected from all patients with MRI evidence of SB CD without significant colonic disease over a 32-mo period. Two radiologists, blinded to clinical findings, evaluated each MRI and grouped them based on bowel wall thickness and wall enhancement. These categories were: (1) “fibrosis”, (2) “mild segmental hyper-enhancement and mild wall thickening”, (3) “mild segmental hyper-enhancement and marked wall thickening”, (4) “marked segmental transmural hyper-enhancement”. Patient response to additional medical therapy post-MRI was prospectively determined at 8-wk. Non-responders underwent endoscopy and were offered therapeutic endoscopy or surgery. Surgical pathology was assessed against the MRI category.

RESULTS: Fifty-five patients were included. Females and category “2” patients were more likely, and patients with luminal narrowing and hold-up less likely, to respond to medical therapy (P < 0.05). Seventeen patients underwent surgery. The surgical pathological findings of fibrosis and the severity of inflammation correlated with the MRI category in all cases.

CONCLUSION: Our findings suggest that SB CD can be grouped by the MRI findings and that these groups are associated with patients more likely to respond to continued medical therapy. The MRI categories also correlated with the presence and level of intestinal inflammation and fibrosis on surgical pathology, and may be of prognostic use in the management of CD patients.

Small-bowel imaging in Crohn's disease: a prospective, blinded, 4-way comparison trial

BACKGROUND

With the introduction of new techniques to image the small bowel, there remains uncertainty about their role for diagnosing Crohn's disease.

OBJECTIVE

To assess the sensitivity and specificity of capsule endoscopy (CE), CT enterography (CTE), ileocolonoscopy, and small-bowel follow-through (SBFT) in the diagnosis of small bowel Crohn's disease.

METHODS

Prospective, blinded trial.

SETTING

Inflammatory bowel disease clinic at an academic medical center.

PATIENTS

Known or suspected Crohn's disease. Exclusion criteria included known abdominal abscess and non-steroidal anti-inflammatory drug (NSAID) use. Partial small-bowel obstruction (PSBO) at CTE excluded patients from subsequent CE.

INTERVENTIONS

Patients underwent all 4 tests over a 4-day period.

MAIN OUTCOME MEASUREMENTS

Sensitivity, specificity, and accuracy of each test to detect active small-bowel Crohn's disease. The criterion standard was a consensus diagnosis based upon clinical presentation and all 4 studies.

RESULTS

Forty-one CTE examinations were performed. Seven patients (17%) had an asymptomatic PSBO. Forty patients underwent colonoscopy, 38 had SBFT studies, and 28 had CE examinations. Small-bowel Crohn's disease was active in 51%, absent in 42%, inactive in 5%, and suspicious in 2% of patients. The sensitivity of CE for detecting active small-bowel Crohn's disease was 83%, not significantly higher than CTE (83%), ileocolonoscopy (74%), or SBFT (65%). However, the specificity of CE (53%) was significantly lower than the other tests (P < .05). One patient developed a transient PSBO due to CE, but no patients had retained capsules.

LIMITATION

Use of a consensus clinical diagnosis as the criterion standard-but this is how Crohn's disease is diagnosed in practice.

CONCLUSIONS

The sensitivity of CE for active small-bowel Crohn's disease was not significantly different from CTE, ileocolonoscopy, or SBFT. However, lower specificity and the need for preceding small-bowel radiography (due to the high frequency of asymptomatic PSBO) may limit the utility of CE as a first-line test for Crohn's disease.

Computed tomography enterography and magnetic resonance enterography: the future of small bowel imaging

In the last 5 years, computed tomography enterography (CTE) and to a lesser extent magnetic resonance enterography (MRE) have supplanted the routine small bowel series and enteroclysis in the evaluation of many small bowel diseases, especially Crohn's disease. Both CTE and MRE use similar methods of bowel lumen opacification and distension and both have distinct advantages and disadvantages. Both have been most extensively studied in patients with Crohn's disease. What is certain is that these cross-sectional examinations have largely replaced the historic fluoroscopic examinations in the evaluation of the small bowel.

Head-to-head comparison of oral contrast agents for cross-sectional enterography: small bowel distention, timing, and side effects

OBJECTIVE

To determine small bowel distention, scanning time, and side effects of commercially available oral contrast agents used in cross-sectional enterography.

METHODS

Ten healthy volunteers ingested 2000 mL of water, methylcellulose, polyethylene glycol (PEG), or 1350 mL of low-concentration barium (LCB) followed by 500 mL water on different days. Magnetic resonance imaging occurred every 10 minutes from 30 to 90 minutes after ingestion. Small bowel distention was compared between time points and agents. Volunteers ranked side effects, drinking difficulty, and preference.

RESULTS

By quantitative assessment, PEG and LCB distended small bowel loops better than water and methylcellulose (P < 0.0001). Time to optimal distention of the terminal ileum was from 51 to 72 minutes. Water and methylcellulose had the fewest side effects. Water was the most preferred contrast and PEG the least.

CONCLUSIONS

Polyethylene glycol and LCB distend small bowel better than water and methylcellulose. Polyethylene glycol was the most difficult to drink and least preferred agent.

Optimization of contrast agents for small intestine computed tomography enteroclysis

AIM: To evaluate which contrast agents can fully distend the intestinal canal and demonstrate the enteric cavity and intestinal wall in computed tomography (CT) enteroclysis.

METHODS: After 8 healthy grown-up Beagles were anesthetized, a catheter was inserted to the Treitz ligament of duodenum, 654-2 was injected through the veins, and different contrast agents including pure water and milk and 10 mL/L angiografin were infused through the catheter. After MSCT plain scanning, enhancement scanning was performed. Width of the enteric cavity and thickness of the intestinal wall measured through the transverse section and multi-planar reconstruction were statistically analyzed. Plain scanning of intestinal wall was performed. CT values, contrast coefficient of enteric cavity and intestinal wall density, and difference in enteric cavity and intestinal wall density were measured 20 s, 30 s, 40 s, and 50 s after enhancement scanning.

RESULTS: All the beagles finished small-intestine CT enteroclysis. The enteric cavity widths were compared between pure milk, pure water and angiografin groups (F = 28.115, P < 0.01). There was no statistical significance in enteric cavity width between the pure water and angiografin groups, as well as in the thickness of intestinal wall between the three groups. The difference in CT value was 69.25 ± 6.28 HU when the contrast coefficient for the enteric cavity and intestinal wall was the best in pure milk and pure water groups.

CONCLUSION: Pure milk is an ideal contrast agent for small-intestine CT enteroclysis, which can fully distend the intestinal canal and demonstrate the enteric cavity and intestinal wall.

Crohn disease of small bowel: multidetector row CT with CT enteroclysis, dynamic contrast enhancement, CT angiography, and 3D imaging

BACKGROUND

CT could be used to evaluate abnormalities in the bowel wall, mesentery, adjacent structures, vasculature, and even the activity of Crohn disease (CD). To our knowledge, few direct comparisons of CD characterization using multidetector row CT with dynamic contrast enhancement, 3D imaging, CT angiography (CTA), and CT-enteroclysis (CT-E) on the same cohort of patients. The purpose of this study was to evaluate the diagnostic value of CD using multidetector helical CT with CT-E, dynamic contrast enhancement, 3D imaging, and CTA.

METHODS

Twenty-eight patients known or suspected CD underwent CT-E, dynamic contract enhancement, CTA, and 3D imaging. The multidetector CT series images were performed on eight-slice CT scanner. All the examinations were performed when water was used as an oral contrast starting 25 s after 140 mL of intravenous contrast agent was administered, followed by portal venous phase (60 s), and a 60-70 s delay, then sending 1.25-mm slices to the 3D workstation, CT angiograms and 3D images were reconstructed. All the images were reviewed to detect abnormalities of CD. The abnormalities of the bowel wall, mucosal and submucosal ulceration, prominent perienteric vasculature, sinus tracts or fistulae, abscess were evaluated.

RESULTS

Crohn disease was diagnosed in 28 patients by CT images, and 54 inflammatory segments were revealed. In active inflammatory cases, the diseased bowel wall thickened and the enhancement of diseased bowel wall increased significantly in 34 inflammatory segments of 22 cases, the enhancement of diseased bowel wall increased significantly but without the wall thickened in three patients. Prominent vasculature was found in CTA and 3D images in 21 patients with active diseases. In 16 patients, the sharp interface between bowel and mesentery was lost and the attenuation of fat increased. Sinus tracts or fistulae were observed in eight patients, four of 28 patients demonstrated abscesses, all were active inflammatory patients. In three chronic inflammatory patients, normal bowel, bowel lumen stricture, and the normal enhancement of the wall were displayed.

CONCLUSION

The abnormalities of CD and its complications can be identified by multidetector CT with CT-E, dynamic enhancement, CTA, and 3D imaging, and they are important methods in diagnosing CD. Complications of CD can be shown better when CT-E is performed.

Diagnostic value of CTE in patients with Crohn's disease

OBJECTIVE

The goal of our study was to compare the accuracy of computed tomography enteroclysis (CTE) to that of biopsy in detecting bowel wall alterations of the terminal ileum in Crohn's disease (CD).

SUBJECTS AND METHODS

A total of 43 patients with either diagnosed or suspected CD (16 females, 28 males) underwent CTE and ileoscopy. Ileoscopy diagnosed 35 patients with CD of the ileum, while 8 patients served as the control group.

RESULTS

Computed tomography enteroclysis detected CD in 31 patients (88%) and in none of the control group. According to the criteria used for evaluation of small bowel loop distension, 31 cases were (72%) with optimal distension, nine cases (%21) with good distension, and three cases (7%) with poor distension. Computed tomography enteroclysis showed that mean ileal wall thickness in patients with CD was 6.8 mm (range, 9.5-4.1 mm) and 1.79 mm in patients in the control group (range, 2.20-1.38 mm). Mean postcontrast wall density in patients with CD was 81.9 HU (range, 111.6-52.2 HU) and 41.1 HU (range, 49.8-22.4 HU) in the control group. Mean postcontrast wall density in 17 patients with active CD was 97 HU (range, 67-123 HU) and 62 HU (range, 46-87 HU) in 18 CD patients in remission. We calculated that the overall sensitivity and specificity of CTE in detecting the severity of CD were 89% and 100%, respectively. Positive predictive value was 100%; negative predictive value was 89%.

CONCLUSION

Our results indicate that CTE can reveal CD involvement of small bowel accurately and allow assessment of the degree of disease activity.

The patient with recurrent (sub) obstruction due to Crohn's disease

Stricturing Crohn's disease (CD) occurs in 12-54% of the CD patient population and is associated with significant morbidity and impaired quality of life. The detailed pathophysiology of stricture formation has not been fully elucidated, but is primarily associated with luminal narrowing secondary to inflammation and the fibrosis that ensues during mucosal healing. The diagnosis of stricturing disease is based on clinical signs and symptoms along with imaging modalities. The advantages and shortcomings of each imaging modality are discussed. Treatment options are based on the differentiation between inflammatory versus fibrous-predominant strictures; whereas the former can potentially be managed with conservative medical treatment, the latter necessitates a mechanical solution through endoscopy or surgery. Indications, contra-indications and success rates of the different therapeutic approaches are discussed.

Técnicas seccionales de imagen en la enfermedad de Crohn: ecografía, tomografía computarizada y resonancia magnética

Colonoscopy and Barium contrast studies continue to be the techniques of choice for the evaluation of mucosal lesions in Crohn's disease. However, these techniques have limited capacity for demonstrating the transmural and extramural extension of the disease. Although ultrasound, CT, and MRI cannot detect early lesions, these techniques satisfactorily show parietal and extraparietal changes caused by the disease, thus complementing the information provided in conventional studies. These three techniques enable the evaluation of the pathological segments, the presence of stenosis and dilatation, and extramural disease (fibrofatty proliferation, fistulae, phlegmons, and abscesses). This information is essential for classifying each patient into one of the three subtypes of Crohn's disease (inflammatory, stenotic, or fistulating). These techniques also enable the evaluation of signs that indicate inflammatory activity (hyperemia, wall enhancement, and increased mesenteric vascularization), and this information, together with the subtype, will determine the treatment. Ultrasound, CT, and MRI should be included in the complete evaluation of the patient with Crohn's disease, together with clinical examination, laboratory tests, and conventional imaging studies. We review the role of ultrasound, CT, and MRI in the diagnosis and evaluation of Crohn's disease, describing patient preparation and examination protocols, as well as the findings in these three techniques. We also discuss the advantages and limitations of each of these techniques and their current clinical roles in this context.

CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases

Computed tomographic (CT) enterography combines the improved spatial and temporal resolution of multi-detector row CT with large volumes of ingested neutral enteric contrast material to permit visualization of the small bowel wall and lumen. Adequate luminal distention can usually be achieved with oral hyperhydration, thereby obviating nasoenteric intubation and making CT enterography a useful, well-tolerated study for the evaluation of diseases affecting the mucosa and bowel wall. Unlike routine CT, which has been used to detect the extraenteric complications of Crohn disease such as fistula and abscess, CT enterography clearly depicts the small bowel inflammation associated with Crohn disease by displaying mural hyperenhancement, stratification, and thickening; engorged vasa recta; and perienteric inflammatory changes. As a result, CT enterography is becoming the first-line modality for the evaluation of suspected inflammatory bowel disease. CT enterography has also become an important alternative to traditional fluoroscopy in the assessment of other small bowel disorders such as celiac sprue and small bowel neoplasms.

Evaluation of bowel distention and bowel wall appearance by using neutral oral contrast agent for multi-detector row CT

PURPOSE

To prospectively evaluate the performance of an orally administered 0.1% barium suspension, Volumen, as a bowel-marking agent for multi-detector row computed tomography (CT).

MATERIALS AND METHODS

This HIPAA-compliant study was approved by the Institutional Review Board and conformed to the institutional standards for research funded by a commercial sponsor. A total of 60 patients (33 women, 27 men; average age, 58.2 years) who were referred for multi-detector row CT of the pancreas were randomized into two groups. Prior to examination, group 1 consumed 1200 mL of Volumen over a 30-minute period and group 2 consumed 1200 mL of a solution containing three parts water and one part methylcellulose over a 30-minute period. Results were independently reviewed by two radiologists who were unaware of the contrast agent used. The degree of distention and the visualization of mural detail were qualitatively scored on a five-point scale. Differences were evaluated by using the Mann-Whitney test at a confidence level of 95%.

RESULTS

There was significantly better distention in the stomach (P = .013), duodenum (P = .006), jejunum (P = .029), and ileum (P = .014) [corrected] in group 1 compared with group 2. Significant distention was also evident by comparing the products of the widest cross-sectional diameters in duodenum (P = .143), jejunum (P < .001), and ileum (P < .001). Group 1 also demonstrated significantly better visualization of mural features in the duodenum (P = .003), jejunum (P = .024), and ileum (P = .01) and a trend toward better visualization of mural features in the stomach (P = .092).

CONCLUSION

Oral administration of Volumen provided excellent distention and excellent visualization of mural features in the gastrointestinal tract.

Peroral CT Enterography with Lactulose Solution: Preliminary Observations

OBJECTIVE

The objective of our study was to evaluate lactulose solution as a new oral contrast agent with the use of peroral CT enterography to determine the adequacy of luminal distention and conspicuity of the bowel wall.

CONCLUSION

Peroral CT enterography performed with lactulose solution is a simple and noninvasive method of evaluating the small bowel by obtaining good distention. It can also be used at routine abdominal examinations as a negative contrast agent instead of iodinated oral contrast medium, especially for CT angiography.

Multi-detector CT enterography with iso-osmotic mannitol as oral contrast for detecting small bowel disease

AIM: To assess the feasibility and usefulness of multi-detector CT enterography with orally administered iso-osmotic mannitol as negative contrast in demonstrating small bowel disease.

METHODS: Thirteen volunteers and 38 patients with various kinds of small bowel disease were examined. We administered about 1500 mL iso-osmotic mannitol as negative contrast agent and then proceeded with helical CT scanning on a Siemens Sensation 16 scanner. All volunteers and patients were interviewed about their tolerance of the procedure. Two radiologists post-processed imaging data with MPR, thin MIP, VRT and INSPACE when necessary and then interpreted the scans, and adequacy of luminal distention was evaluated on a four-point scale. Demonstration of features of various kinds of small bowel disease was analyzed.

RESULTS: The taste of iso-osmotic mannitol is good (slightly sweet) and acceptable by all. Small bowel distention was excellent and moderate in most volunteers and patients. CT features of many kinds of diseases such as tumors, Crohn’s disease,and small bowel obstruction, etc. were clearly displayed.

CONCLUSION: Multi-detector CT enterography with iso-osmotic mannitol as negative contrast to distend the small bowel is a simple, rapid, noninvasive and effective method of evaluating small bowel disease.

Small bowel hydro-MR imaging for optimized ileocecal distension in Crohn's disease: Should an additional rectal enema filling be performed?

PURPOSE

To assess the impact of an additional rectal enema filling in small bowel hydro-MRI in patients with Crohn's disease.

MATERIALS AND METHODS

A total of 40 patients with known Crohn's disease were analyzed retrospectively: 20 patients only ingested an oral contrast agent (group A), the other 20 subjects obtained an additional rectal water enema (group B). For small bowel distension, a solution containing 0.2% locust bean gum (LBG) and 2.5% mannitol was used. In all patients, a breathhold contrast-enhanced T1w three-dimensional volumetric interpolated breathhold examination (VIBE) sequence was acquired. Comparative analysis was based on image quality and bowel distension as well as signal-to-noise ratio (SNR) measurements. MR findings were compared with those of conventional colonoscopy, as available (N = 25).

RESULTS

The terminal ileum and rectum showed a significantly higher distension following the rectal administration of water. Furthermore, fewer artifacts were seen within group B. This resulted in a higher reader confidence for the diagnosis of bowel disease, not only in the colon, but also in the ileocecal region. Diagnostic accuracy in diagnosing inflammation of the terminal ileum was 100% in group B; in the nonenema group there were three false-negative diagnoses of terminal ileitis.

CONCLUSION

Our data show that the additional administration of a rectal enema is useful in small bowel MRI for the visualization of the terminal ileum. The additional time needed for the enema administration was minimal, and small and large bowel pathologies could be diagnosed with high accuracy. Thus, we suggest that a rectal enema in small bowel MR imaging be considered.

Imaging of inflammatory bowel disease: CT and MR

Cross-sectional imaging has come to play a central role in the imaging of the abdomen. Concurrent to this, the role of CT and MRI in the imaging of inflammatory bowel disease has also increased in importance. These modalities offer numerous advantages over more traditional methods of radiologic diagnosis, and provide essential information not only for initial diagnosis, but for management, follow-up and detection of potential complications. On the horizon are several derivative techniques involving CT and MRI, potentially in combination with PET imaging; these may further improve the specificity and sensitivity of imaging modalities for diagnosis of inflammatory bowel disease.