CT enterography

Neoplastic Diseases of the Small Bowel

The incidence of small bowel tumors is increasing over time. Until recently, their diagnosis was delayed and it was often reached only at the time of surgery. New diagnostic tools, such as capsule endoscopy, device-assisted enteroscopy, and dedicated small bowel cross-sectional imaging techniques, have been introduced recently in clinical practice. The combination of these tools allows medical practitioners to detect small bowel tumors at an early stage and to reach a definite diagnosis before surgery, thus enabling minimally invasive treatments.

Multimodality imaging of diseases of the duodenum

The duodenum is a unique segment of intestine, occupying both intra and extra-peritoneal locations. There is a wide spectrum of abnormalities of the duodenum that range from congenital anomalies to traumatic, inflammatory, and neoplastic entities. The duodenum may be overlooked on cross-sectional imaging due to its location and small size. Duodenal pathologies may, therefore, be missed or wrongly diagnosed. Knowledge about duodenal pathologies and optimal imaging techniques can increase diagnostic yield and permit optimal patient management. Conventionally, the duodenum was evaluated with upper GI studies on fluoroscopy; however, endoluminal evaluation is better performed with endoscopy. Additionally, a broad array of cross-sectional imaging modalities permits comprehensive assessment of the duodenum and surrounding viscera. While endoscopic sonography is increasingly used to locally stage duodenal malignancies, MDCT remains the primary modality widely used in the detection and characterization of duodenal abnormalities. MRI is used as a "problem solving" modality in select conditions. We present a comprehensive review of duodenal abnormalities with an emphasis on accurate diagnosis and management.

Video Capsule Endoscopy in Patients with Chronic Abdominal Pain with or without Associated Symptoms: A Retrospective Study

BACKGROUND

Chronic abdominal pain (CAP) is a common indication for gastroenterology referrals. More insidious causes of CAP isolated to the small bowel, such as malignancies and Crohn's disease, are rising in incidence and causing more gastroenterologists to evaluate their patients with video capsule endoscopy (VCE). However, the role of VCE in patients with CAP is still unclear.

AIMS

We assessed the efficacy of VCE in patients with CAP and whether it led to findings that contributed to disease management and meaningful interventions.

METHODS

This retrospective study evaluated 607 capsule endoscopy studies at an open referral endoscopy unit. Ninety of the studies were for CAP. These studies were compared to those performed for other indications to compare diagnostic yield. In addition, we investigated whether VCE led to an intervention that improved clinical outcomes.

RESULTS

Overall, the number of abnormal findings in CAP patients was significantly lower than VCE performed for other indications (24.4% vs 39.0%, respectively p = 0.009). When patients with CAP presented with other pertinent clinical findings (e.g. nausea, weight loss, anemia, history of in inflammatory bowel disease, etc.), the likelihood of an abnormal finding increased to a level that was not different from those who received VCE for other indications (27.1%, p = 0.10). The findings from VCE lead to changed management and improved outcomes in 16.2% of CAP patients with associated symptoms. However, the subgroup that benefited the most were those who had a prior history of Crohn's disease. Patients with CAP who did not have any associated symptoms continued to have a significantly lower abnormal finding rate compared to those who received VCE for other indications (19.4%, p = 0.03) and VCE rarely led to a change in management that would improve outcomes (5.6%).

CONCLUSIONS

VCE for CAP has a lower rate of abnormal findings than other indications. However, VCE is a useful diagnostic tool that can help provide a possible etiology of CAP in patients with associated symptoms. However, a change in management from VCE is likely to be limited to those with a history of Crohn's disease.

CT and MR enterography in evaluating small bowel diseases: when to use which modality?

MR and CT techniques optimized for small bowel imaging are playing an increasing role in the evaluation of small bowel disorders. Several studies have shown the advantages of these techniques over traditional barium fluoroscopic examinations due to improvements in spatial and temporal resolution combined with improved bowel distending agents. The preference of MR vs. CT has been geographical and based on expertise and public policy. With the increasing awareness of radiation exposure, there has been a more global interest in implementing techniques that either reduce or eliminate radiation exposure. This is especially important in patients with chronic diseases such as inflammatory bowel disease who may require multiple studies over a lifetime or in studies that require sequential imaging time points such as in assessment of gastrointestinal motility. MRI has many properties that make it well suited to imaging of the small bowel: the lack of ionizing radiation, the improved tissue contrast that can be obtained by using a variety of pulse sequences, and the ability to perform real time functional imaging. Moreover, MR modalities allow visualization of the entire bowel, without overlapping bowel loops, as well as the detection of both intra- and extraluminal abnormalities.The intra- and extraluminal MR findings, combined with contrast enhancement and functional information, help to make an accurate diagnosis and consequently characterize small bowel diseases.

Application of MSCT enterography in the evaluation of Crohn's disease

The assessment of small bowel abnormalities has always been a challenging task for radiologists and gastroenterologists. Conventional radiologic and endoscopic evaluations are often limited by the length and caliber of small bowel loops. CT enterography, a robust new method with high spatial and isotropic spatial resolution, is a variant of conventional CT technique optimized for the evaluation of the small bowel. Crohn's disease is an inflammatory disease which can involve different areas of the gastrointestinal tract, and it was characterized by segmental and transmural inflammation, with the terminal ileum being the most common site of involvement. CT enterography is well tolerated by these patients and enables accurate, efficient assessment of lesions arising from the small bowel wall or surrounding organs. In this article, we discuss the principle of CT enterography and its use in the evaluation of Crohn's disease.

Quantitative measures of comb sign in Crohn's disease: correlation with disease activity and laboratory indications

To determine retrospectively if quantitative measures of the comb sign at CT enterography correlated with laboratory indications in Crohn's disease. We retrospectively included 72 known CD patients (47 male and 25 female patients) and 41 normal controls who had undergone CT enterography (CTE) from 2008 to 2010 and had high-sensitive C reaction protein (Hs-CRP) and erythrocyte sedimentation rate (ESR) results. We divided the 72 CD patients into two groups based on disease activity which was determined by Rutgeerts' score. 41 patients were characterized as active disease while 31 patients were as inactive disease. For each individual, one reformatted coronal CTE image in which the comb sign (vasa recta) was most obviously displayed was selected by two experienced radiologists in a double blind manner. For each image, 20 regions of interest (ROI) with area of 1 cm(2) were drawn and placed over the site where the comb sign exists; the comb sign amount was counted in each ROI and recorded. Total amount of the comb sign were assessed from 20 ROI data. Quantitative comb sign results were compared with Hs-CRP and ESR level. Quantitative comb sign score is significantly higher in the CD group than in the control group at both the arterial stage and venous stage (P < 0.001). Quantitative comb sign score is obviously higher in active CD patients than in inactive CD patients both at arterial stage and venous stage (3.63 vs. 2.86 at arterial stage; 3.53 vs. 2.90 at venous stage). ESR level was well correlated with quantitative comb sign score both at arterial and venous stage whereas Hs-CRP has no significant correlation at either stage. Quantitative comb sign results did well in predicting CD activity with the accuracy rate of 78.4% at arterial stage and 80% at venous stage when using 3.33 as the cutoff of quantitative comb sign score. Quantitative comb sign score is a promising CTE parameter in predicting CD activity and be well correlates with the ESR level.

Crohn's disease: CT enterography manifestations before and after treatment

PURPOSE

The purpose of this study was to determine whether CT enterography (CTE) changes of Crohn's disease (CD) after treatment correlated with clinical remission.

MATERIALS AND METHODS

We retrospectively studied 50 known CD patients (male: 35; female: 15) with clinical remission in a period of 3 years (2005-2008). CD was diagnosed by clinical, enteroscopic and pathologic manifestations. Clinical remission was identified by experienced gastroenterologists using the combing criteria of clinical, endoscopy and laboratory tests. First CTE and endoscopy exams were performed during their first hospitalization in our hospital meanwhile CD diagnosis was made during that time. Repeated CTE and endoscopy exams were done after treatment. CTE findings were determined by two experienced radiologists with double-blind approach. Each patient was analyzed for the CTE parameters including bowel wall attenuation, bowel wall thickening (>3mm), bowel wall thickening types (type A: multilayered mural stratification; type B: two layers with strong mucosal enhancement and prominent low-density submucosa; type C: two layers without strong mucosal enhancement; type D: homogeneous enhancement) comb sign, luminal stenosis (mild: luminal diameter 2-3 cm; moderate: luminal diameter 1-2 cm; severe: luminal diameter<1cm) and the presence of extraenteric complications (such as fistulas and abscess). All the quantitative parameters were measured three times by each review.

RESULTS

After treatment, bowel wall thickening was attenuated in 88% of CD patients. Thickness of bowel wall was decreased from 8.8 ± 2.8mm to 6.4 ± 1.9 mm (P<0.001). CT value of bowel wall in portal stage was also declined from 90.0 ± 15.4 (HU) to 73.4 ± 14.2 (HU (P<0.001). The percentage of patients with type A or B bowel wall thickening was decreased from 78.7% to 35.4%, while those with type C or D thickening was increased from 21.2% to 64.6% (P<0.001). The percentage of patients with comb sign was decreased from 88% to 60% (P=0.001). The percentage of patients with moderate or severe luminal stenosis was reduced from 74% to 32% (P<0.001). The ROC (receiver operating characteristic) analysis showed bowel wall attenuation (A(z)=0.89) and bowel wall thickness (A(z)=0.81) were the two best parameters to predict disease activity, and combining of these two values was better than using them solely (κ=0.71, P<0.001). The bowel wall attenuation (OR=9.56, P<0.001) and bowel wall thickness (OR=3.32, P=0.001) were significantly correlated with the disease activity in the following logistic regression analysis.

CONCLUSION

Therapeutic effect of CD and disease activity can be properly evaluated by CTE.